Reptile Medicine and Surgery in Clinical PracticeReptile Medicine and Surgery in Clinical Practice
Edited by

Bob Doneley

University of Queensland
Queensland, Australia

Deborah Monks

Brisbane Bird and Exotic Veterinary Service
Queensland, Australia

Robert Johnson

South Penrith Veterinary Clinic
New South Wales, Australia

Brendan Carmel

Warranwood Veterinary Centre
Victoria, Australia

This edition first published 2018
© 2018 John Wiley & Sons Ltd.
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Library of Congress Cataloging‐in‐Publication Data
Names: Doneley, Bob, editor. | Johnson, Robert, Dr., editor. | Monks,
Deborah, 1972– editor. | Carmel, Brendan, editor.
Title: Reptile medicine and surgery in clinical practice / edited by Bob
Doneley, Deborah Monks, Robert Johnson, Brendan Carmel.
Description: Hoboken, NJ : Wiley, 2017. | Includes bibliographical references
and index. |Identifiers: LCCN 2017033936 (print) | LCCN 2017035572 (ebook) |ISBN 9781118977682 (pdf ) | ISBN 9781118977699 (epub) | ISBN 9781118977675 (hardback)Subjects: LCSH: Reptiles–Diseases | Reptiles–Surgery. | MESH: Reptiles |Animal Diseases | Surgery, Veterinary
Classification: LCC SF997.5.R4 (ebook) | LCC SF997.5.R4 R466 2017 (print) |NLM SF 997.5.R4 | DDC 639.39–dc23
LC record available at https://lccn.loc.gov/2017033936
Cover Design: Wiley
Cover Image: Courtesy of Bob Doneley
Set in 10/12pt Warnock by SPi Global, Pondicherry, India
10

9

8 7

6 5

4

3

2

1

As always when producing a book like this, there are many people who have helped usalong the way, often unnoticed. We would like to dedicate this book to those people:
the authors who contributed their time and expertise; our veterinary colleagues andclients who, while not directly contributing to this book, taught us much about reptiles
and their care, medicine and surgery; and our work colleagues who endured our
distraction while we put this book together. Lastly, but by no means the least, we
dedicate this book to our families who have patiently supported us in not just thisbook, but in all aspects of our lives and careers.
Thank you!

vii

Contents
List of Contributors xi
Preface xv
1

Taxonomy and Introduction to Common Species 1
Bob Doneley2

Anatomy and Physiology of Reptiles 15
Bairbre O’Malley

3

Behaviour in the Wild and in Captivity 33
Robert Johnson

4

Husbandry and Nutrition 45
Michelle Kischinovsky, Aidan Raftery and Shivananden Sawmy

5

Enclosure Design 61
Michael McFadden, Deborah Monks, Bob Doneley and Robert Johnson

6Lighting 75
Frances M. Baines

7

Reproduction 91
Timothy J. Portas

8

Reptile Paediatrics 105
Deborah Monks and Bob Doneley9

Setting Up and Equipping a Reptile Practice 115
Bob Doneley, Shane Simpson, Angela M. Lennox and John Chitty

10

The Reptile Consultation 125
Bob Doneley and Brendan Carmel

11

Diagnostic Testing 135
Rachel E. Marschang, Frank Pasmans, Tim Hyndman, Mark Mitchell and An Martel

viii

Contents

12

Diagnostic Imaging 145Zdeněk Knotek, Shane Simpson and Paolo Martelli

13

Clinical Techniques and Supportive Care 159
Kimberly Vinette Herrin

14

Reptile Pharmacology 175
Tim Hyndman

15

Nutritional and Metabolic Diseases 185
Brendan Carmel and Robert Johnson

16

Infectious Diseases and Immunology 197
Tim Hyndman and Rachel E. Marschang

17

Differential Diagnoses: A Problem‐Based Approach 217
Helen McCracken, Brendan Carmel, John Chitty, Bob Doneley,
Robert Johnson, Angela M. Lennox, Deborah Monks and Annabelle Olsson

18

Disorders of the Integument 255
Linda Vogelnest

19

Diseases of the Gastrointestinal System 273
Robert Johnson and Bob Doneley20

Diseases of the Cardiovascular System 287
Tegan Stephens and Alex Rosenwax

21

Diseases of the Respiratory System 299
Melinda L. Cowan

22

Disorders of the Reproductive System 307
Timothy J. Portas

23

Diseases of the Urinary Tract 323
Peter Holz24

Diseases of the Nervous System 331
Hamish Baron and David N. Phalen

25

Disorders of the Musculoskeletal System 345
Adolf K. Maas

26

Diseases of the Organs of Special Senses 357
Alex Rosenwax and Tegan Stephens

27

Analgesia and Anaesthesia 369
Annabelle Olsson and Mark Simpson

Contents

28

Surgery 383
Zdeněk Knotek and Stacey Leonatti Wilkinson

29

Turtle Shell Repair 397
Jane Roffey and Sasha Miles

30

Necropsy 409
Catherine M. Shilton

31

Reptile Parasitology in Health and Disease 425
Jan Šlapeta, David Modrý, Robert Johnson

32

Nursing the Reptile Patient 441
Gary Fitzgerald and Emma Whitlock

33

Euthanasia 449
Tim Hyndman
Appendix 1: Formulary 453
Appendix 2: Reference Intervals for Commonly Kept Reptile Species 473
Index 481

ix

xi

List of Contributors
Frances M. Baines MA, VetMB, MRCVS

Gary Fitzgerald BApSci (Veterinary Technology)

UV Guide UK
GovilonAbergavenny
United Kingdom

University of Queensland Veterinary Medical
CentreUniversity of Queensland
GattonQueensland
Australia

Hamish Baron BVSc (Hons), MANZCVS(Avian Health)Avian Reptile and Exotic Pet
Hospital
Faculty of Veterinary Science
The University of Sydney
Camden
New South Wales
Australia
Brendan Carmel BVSc, MVS, GDipComp,
MANZCVS (Unusual Pets)

Warranwood Veterinary Centre
Warranwood
Victoria
Australia
John Chitty, BVetMed, CetZooMed, MRCVS

Anton Vets
Andover
Hampshire
United Kingdom
Bob Doneley BVSc, FANZCVS(Avian Medicine)

Associate Professor, Avian and Exotic Pet
Service
University of Queensland
GattonQueensland
Australia

Kimberly Vinette Herrin DVM, BA Biology, MS(Biological Oceanography), MANZCVS(Zoo Medicine)

Taronga Wildlife Hospital
Taronga Conservation Society Australia
Mosman
New South Wales
Australia
Peter Holz BVSc, DVSc, MACVSc, Dipl ACZM

Faculty of Veterinary and Agricultural
Sciences
University of Melbourne
Melbourne
Victoria
Australia
Tim Hyndman BSc, BVMS, PhD, MANZCVS(Veterinary Pharmacology)

Murdoch University
Perth
Western Australia
Australia
Robert Johnson BVSc, MANZCVS (Feline),
CertZooMed, BA

South Penrith Veterinary Clinic
PenrithNew South Wales
Australia

xii

List of Contributors

Michelle Kischinovsky DVM, MRCVSAn Martel DVM, PhD, Dip ECZM (WPH)

Avian and Exotic Animal Clinic
Manchester
United Kingdom

Department of Pathology, Bacteriology,
and Avian Diseases
Ghent University
Merelbeke
BelgiumZdeněk Knotek DVM, PhD, Dip ECZM
(Herpetology)

Faculty of Veterinary Medicine
University of Veterinary and Pharmaceutical
Sciences
Brno
Czech Republic

Paolo Martelli

Melinda L. Cowan BVSc (Hons), MANZCVS(Medicine Surgery of Unusual Pets), FANZCVS(Avian Medicine)

Senior Veterinarian
Melbourne Zoo
Victoria
Australia

Small Animal Specialist HospitalNorth Ryde
SydneyNew South Wales
Australia
Angela M. Lennox DVM, DABVP‐Avian; ECZM‐(Small Mammal)

Avian and Exotic Animal Clinic
Indianapolis
Indiana
USA
Stacey Leonatti Wilkinson DVM, DABVP(Reptile and Amphibian)

Avian and Exotic Animal Hospital ofGeorgia
PoolerGeorgia
USA
Adolf K. Maas III DVM, DABVP (Reptile andAmphibian Practice), CertAqV

ZooVet Consulting PLLC
Bothell
Washingon
USA
Rachel E. Marschang PD Dr.med.vet., Dip ECZM
(Herpetology), FTÄ Mikrobiologie, ZB Reptilien

Laboklin GmbH & Co. KG
Bad Kissingen
Germany

Cert Zoo Med
Director of Veterinary Services
Hong Kong
Helen McCracken BSc(Vet), BVSc, MVS

Michael McFadden BSc (Hons)

Curator, Native Fauna
Taronga Conservation Society Australia
Mosman
New South Wales
Australia
Sasha Miles BVSc (Hons), MANZCVS(Avian Health - Caged and Aviary Birds)

Veterinarian
Brisbane Bird and Exotics Veterinary
Service
Queensland
Australia
Mark Mitchell DVM, MS, PhD, Dip ECZM
(Herpetology)

Director, Veterinary Teaching Hospital
Professor, Zoological Medicine
Louisiana State University
School of Veterinary Medicine
Department of Veterinary Clinical
Sciences
Los Angeles
California
USA
David Modrý MVDr, PhD

Department of Pathology andParasitology
Faculty of Veterinary Medicine

List of Contributors

University of Veterinary andPharmaceutical Sciences Brno
Brno
Czech Republic
Deborah Monks BVSc, CertZooMed,
FANZCVS (Avian Medicine), DECZM (Avian)

Brisbane Bird and Exotics Veterinary Service
Greeenslopes
Brisbane
Queensland
Australia
Bairbre O’Malley MVB, CertVR, MRCVS

Bairbre O’Malley Veterinary Hospital
Bray
Co. Wicklow
IrelandAnnabelle Olsson BVSc, MSc, PhD, MANZCVS

Boongarry Veterinary Surgery
Aeroglen
Quennsland
AustraliaFrank Pasmans DVM, PhD, Dip ECZM
(Herpetology)

Department of Pathology, Bacteriology,
and Avian Diseases
Ghent University
Belgium
David N. Phalen DVM, PhD, Dip ABVP (Avian)Jane Roffey BVSc, BA, GCM(VP)

South Penrith Veterinary Clinic
SydneyNew South Wales
Australia
Alex Rosenwax BVSc(hons), MANZCVS(Avian Health)

Bird and Exotics Veterinary Clinic
Waterloo
SydneyNew South Wales
Australia
Shivananden Sawmy BSc (Hons),
BVM&S, MRCVS

Avian and Exotic Animal Clinic
Manchester
United Kingdom
Catherine M. Shilton BSc, DVM, DVSc

Senior Veterinary Pathologist
Berrimah Veterinary Laboratories
Berrimah, Northern Territory
Australia
Mark Simpson BVSc, MANZCVSSugarloaf Animal HospitalWest Wallsend
New South Wales
Australia

Associate Professor
School of Veterinary Medicine
University of Sydney
Camden
New South Wales
Australia

Shane Simpson BVSc (Hons), GCM(VP)

Timothy J. Portas BVSc, MVSc, MANZCVS, DACZM

Sydney School of Veterinary Science
Faculty of Science
University of Sydney
New South Wales
Australia

Zoo and Wildlife Veterinary Consultancy
Queensland
Australia
Aidan Raftery MVB, CertZooMed, CBiol,
MRSB, MRCVS

Avian and Exotic Animal Clinic
Manchester
United Kingdom

Karingal Veterinary HospitalFrankston
Victoria
Australia
Jan Šlapeta MVDr, PhD

Tegan Stephens BVSc(Merit), MANZCVS(Unusual Pets)

Bird and Exotics Veterinary Clinic
Waterloo

xiii

xiv

List of Contributors

SydneyNew South Wales
Australia
Linda Vogelnest BVSc, MANZCVS, FANZCVSSpecialist Veterinary Dermatologist
Associate Lecturer University of Sydney
Small Animal Specialist Hospital
New South Wales
Australia

Emma Whitlock RVN BSc (Hons),
VNSc, PgDip, MCAM

Hospital Manager
Veterinary Department
Currumbin Wildlife Sanctuary
Currumbin
Queensland
Australia

xv

Preface
The word ‘herpetology’ is from Greek herpeton,‘creeping animal’ and ‐logia ‘knowledge’. It is
the term used to describe the study of reptiles and amphibians. Some sources describe
those who keep reptiles as ‘herpetoculturists’and the hobby as ‘herpetoculture’. It is ahobby that has been in existence for over
300 years, with an increasing focus andenthusiasm in the last 50 years. ‘Herps’, asthese enthusiasts are known, keep an often
bewildering array of snakes, lizards, turtles,
tortoises, and crocodiles in conditions ranging from sophisticated to almost primitive.
From a few enthusiasts breeding reptiles for ahobby, we now see reptiles commonly kept as
children’s pets.
In the last 40 years, the veterinary care ofthese fascinating animals has grown at an
amazing rate. From a few pioneers seeing ahandful of clients, we now see reptiles presented for veterinary care presented at many
companion animal practices, as well as a
growing number of specialist reptile hospitals and clinics. Reptile medicine and surgery, once unheard of in the veterinary
curriculum, is now a growing subject area inmost university veterinary courses.
We still have a long way to go, but our
body of knowledge is growing exponentially.

Reptile medicine is one area where, on an
almost daily basis, clinicians will see something that has either never been described,
or only a handful of cases seen somewhere
else. Given this, no textbook can hope tohold all knowledge, even for a brief periodof time.
This book does not attempt to be anencyclopaedic reference encompassing all­
veterinary knowledge on reptile medicine.
That task is beyond the scope (and word
count) of this book. Rather, it is a handbook
designed to assist busy clinicians in their
day to day approach to the increasing
flow of reptile patients, and as a study guidefor veterinarians and veterinary students.
To that extent we have gathered a team ofveterinary experts from around the worldand sought their input in their areas ofexpertise.
We hope that the reader finds this book auseful tool to assist them in their approachto reptile medicine and surgery. If it helps
you to provide better care, or to help you
solve a problem, we will consider this book a
success.
Bob Doneley, Deborah Monks, RobertJohnson, Brendan Carmel

11
Taxonomy and Introduction to Common Species
Bob Doneley­Taxonomy
Class Reptilia is one of the largest groupsof vertebrates, with over 10,000 species. It
is also the oldest, evolving some 310–320
million years ago during the Carboniferous
period. They share several common characteristics: all are covered with scales or scutes
and are ectothermic. Most lay amniotic eggs
(oviparity), although some are live bearers(viviparity, including ovovivaparity). They may
be carnivorous, omnivorous or herbivorous.
Class Reptilia is made up of four orders:
Squamata, Testudines, Crocodilia andRhynchocephalia (Table 1.1). Each order isfurther divided into sub‐orders, families,
genera and species.
Squamata
Squamates are characterized by their scaled
skin, which is shed periodically (ecdysis),and a moveable quadrate bone that allows
the maxilla to open wide relative to the restof the skull. The order is divided into threesub‐orders: Lacertilia (the lizards), Serpentes(the snakes) and Amphisbaenia (the worm
lizards), although some classifications place
Amphisbaenia within Lacertilia.
Lacertilia has five infraorders based mainly
on morphological similarities between familygroups. These are the Diploglossa (including
the glass lizards and the American leglesslizards), Gekkota (the geckos, the blind ­lizards
and the legless lizards), Iguania (including theagamids, chameleons, iguanas, anoles, collared
lizards and the neotropical ground lizards),
Platynota (varanids and Gila monsters) andScincomorpha (including skinks, tegus, plated
lizards and spiny‐tail lizards). Most are omnivorous or carnivorous. They are primarily oviparous, although some are ovoviviparous.
Serpentes
has
two
infraorders:
Alethinophidia (including the boas, pythons,vipers, elapids, colubrids, file snakes andrattle snakes) and Scolecophidia (the­blind snakes). All snakes are carnivorous.
Most are oviparous, although some are
ovoviviparous.
Amphisbaenia has five families found in
the northern hemisphere, Africa and SouthAmerica. They are largely legless squamateswith rudimentary eyes capable of only detecting light (two species have rudimentary forelimbs). Their skin is loosely attached to thebody, and appears to be their means of locomotion; the skin moves and ‘drags’ the body behind
it. They are carnivorous, with strong jaws
and interlocking teeth. Most species lay eggs,
although some are known to be ovoviviparous.
Testudines
Testudines, sometimes known as Chelonia,
are the turtles, tortoises and terrapins. They
are characterized by a bony or cartilaginous

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

2

Reptile Medicine and Surgery in Clinical PracticeTable 1.1 Reptile orders.
Order and sub‐order

Common nameSpecies (n)Squamata

Squamates

9,671

Lacertilia

Lizards

5,987

Serpentes

Snakes3,496

Amphisbaenia

Worm lizards

188

Testudines

Turtles, tortoises and terrapins

341

Crocodylia

Crocodiles, gharials, caimans and alligators

25

Rhynchocephalia

Tuataras

1

shell developed from their ribs. There issome confusion in the terminology. In North
America, ‘turtle’ is used to describe the wholeorder, while in Europe and Australia it refers
to freshwater and sea‐dwelling chelonians,
with ‘tortoise’ used to describe terrestrial,
non‐swimming species. ‘Terrapin’ is a term
used to describe several small species of turtle living in fresh or brackish water. Terrapins
do not form a taxonomic unit and are notclosely related. There are two suborders of
Testudines: the Pleurodirans (three families),
also called the side‐necked or long‐necked
turtles, have long necks that are folded sideways to align them with the shell; theCryptodirans (eleven families), or short‐neckturtles and tortoises, pull their neck straightback to conceal their head within the shell.
Sea turtles are Cryptodirans, although they
have lost the ability to retract their heads.
Crocodylia
Crocodylia, an order of large, predatory,semi‐aquatic reptiles, is divided into threefamilies: Crocodylidae (the true crocodiles),Alligatoridae (the alligators and caimans)and Gavialidae (the gharial and false
gharial).
Rhynchocephalia
Rhynchocephalia is a primitive order of lizard‐
like reptiles that includes only one living species, the Tuatara (Sphenodon punctatus) of

New Zealand. There is debate as to whether
S. guntheri is a separate species. They areslow‐growing, reaching sexual maturity at
10–20 years, and breed until they are at least
60 years old. It takes the female between one
to three years to develop eggs and up to sevenmonths to form the shell. It then takes between
12 and 15 months from copulation to hatching. Thus, reproduction occurs at two‐ to five‐
yearly intervals, the longest of any reptile.
Tuatara lack external ears and possess aparietal eye (a light‐sensitive spot located on
the top of the animal’s head, thought to play arole in setting circadian rhythms). They arecapable of autotomy and have only rudimentary hemipenes. Tuatara have unique dentition, namely two rows of acrodont teeth in
the maxilla and one row in the mandible.

­Commonly Kept Species
Key
The following abbreviations are used in thissection:d, daysG, gestation
I, incubationm, months
O, oviparous
OV, ovoviviparous
PBT, preferred body temperaturey, years

Taxonomy and Introduction to Common Species

TablesTable 1.2 Lizards
Table 1.3 Geckos●● Table 1.5 Chameleons

Table 1.6 Snakes
Table 1.7 Turtles●● Table 1.8 Tortoises

●●

●●

●●

●●

Figure 1.1 Bearded dragons (courtesyof Bob Doneley).

Figure 1.2 Blue‐tongued skinks(courtesy of Bob Doneley).

3

Table 1.2 Lizards.

ReptileabcOriginSpecies

HabitatDiet

Sexualmaturity

Australia Most common:
Beardedinland or central (Pogona
dragonvitticeps)(Figure 1.1)
eastern (P. barbata)blacksoil (P. henrylawsoni)
dwarf (P. minor)
Others include:
western (P. minima)
northwest (P. mitchelli)
Nullarbor (P. nullarbor)
Kimberley (P. microlepitoda)

9–24 maTerrestrial Omnivorous,
although thejuveniles are
initially
insectivorous but
will eat vegetables
and flowers as
they growAustralia eastern (Tiliqua scincoides
Blue‐
scincoides)
tonguedpygmy (T. adelaidensis)
skink
centralian (T. multifasciata)(Figure 1.2)
blotched (T. nigrolutea)
western (T. occipitalis)

Terrestrial Omnivorous

Shingleback Australia Also known as bobtail lizard(T. rugosa)
FrilledlizardAustralia Chlamydosaurus kingii

ThermalRelative
Mode of Incubation or gradienthumidity Longevity
reprod. Gestation(°C)
PBT (°C) (%)(years)(I) 61–74 d
at 30–31 °C(P. vitticeps)

28–40

18–36 mb OV(G) 3–5 m

Terrestrial Omnivorous

18–36 mc OVPrimarilyarboreal

12–18 m(male)
to 2–3 y(female)Primarily
insectivorous but
will accept somevegetables

Depending on species (small species mature younger than larger species).
Male matures earlier than female.
This species forms close pair bonding and should be paired before sexual maturity.

O

O

35

25–40

10–15

25–35
28–32
(higherforinlandspecies)

25–40

10–15

(I) 4–5 m

36–40

25–45

25–40

10–15

(I) 60–90 d

32–37

28–38

50–70

10–15

Table 1.3 Geckos.

aReptileOriginSpecies

HabitatDiet

Sexualmaturity

Mode ofreprod.

Incubation or
Gestation

Thermalgradient (°C)

PBT (°C)

Relative
humidity (%)

Longevity(years)Leopardgecko

Pakistan,northern India
and Asian desert
regions

Eublepharismacularius

Terrestrial

Insectivorous

1yO(I) 45–60 d

21–32

26

20–40

6–10 (large
males canlive up to 20)

Tokay
gecko

North‐east
India, Nepal,
Indonesia andthe Philippines

Two species: Gekko
gecko gecko andG. g. azhari

Arboreal

Insectivorous

1–2 y

O

(I) 60–100 d

27–28

25–31

55–80

10–20

Knob‐
tailedgecko

Australia

9 species; mostcommonly kept:
three‐lined(Nephrurus levis)
central rough(N. amyae )Terrestrial

Insectivorous

7–12 mO(I) 57–70 d(N. levis)
77–94 d(N. amyae)

20–30

26

Keep oneend of theenclosure
moist

7–8
(N. levis);
9–11(N. amyae)

Crestedgecko

New Caledonia

Correlophus ciliatus, Arboreal
also known as the
New Caledonian
crested gecko,
Guichenot’s giant
gecko or eyelash
gecko

Insectivorous

6–9 m (male) O
12 m (female)(I) 60–90 da

21–29

Heat
50–70
intolerant

At room temperature; up to 120 days at cooler temperatures.

15–20

Table 1.4 Chameleons.

aMode ofreprod.

Incubation or
Gestation

Thermalgradient (°C)

1yInsectivorous
but will takesome vegetables
and fruitO

120–270 d

Arboreal

Insectivorous

7m

O

Iguana iguana

Arboreal

Herbivorous

18 m

China andIndochina

Physignathus
cocincinus, also
known as Thaiwater dragon, green
water dragon, andAsian water dragon

Arboreal

Insectivorous,
although they
will eat somevegetables

Australia,
Africa, Asia
and Indonesia

Currently 78 species Most terrestrial
recognizeda
but somesemi‐arboreal
and somesemi‐aquatic

Carnivorous

ReptileOriginSpecies

Habitat

Diet

Veiledchameleon(Figure 1.3)

Saudi Arabia
and Yemen(Chamaeleo
calyptratus), also
known as the
Yemen chameleon

Arboreal

Pantherchameleon

Madagascar

Furcifer pardalisGreeniguana(Figure 1.4)

Mexico,CentralAmerica andthe Caribbean

Chinesewater
dragonVaranids

SexualmaturityPBT (°C)

Relative
humidity (%)

Longevity(years)24–35
by day

–

50–60

4–8

240 d

24–35

–

50–70

5–7

O

70–105 d

26–35

35

65–75

15–20

1–2 y

O

55–65 d

29–33

–

40–80

15–25

3–5 y

O

170–265 d

30–40

35–36

60–80

10–20

Some of the more common species include: Lace monitor (Varanus varius), Australia; Gould’s monitor (V. gouldii, also known as the sand monitor), Australia; Merton’s water monitor(V. mertensi), Australia; Savannah monitor (V. exanthematicus, also known as Bosc’s monitor), Africa; Nile monitor (V. niloticus), Africa; Black‐throated monitor (V. albigularis ionidesi), Africa.

Table 1.5 Snakes.

Mode of Incubation or
reprod. Gestation

Thermalgradient(°C)

Relative
Longevity
PBT (°C) humidity (%) (years)

O

55–65 dwhen
incubated
at 31 °C

20–32

29–30

40–80c15–30

Carnivorous After 2.4 y O(male);
After 3.6 y(female)50 d whenincubated
at 31 °C

20–32

30–32

40–70d15–20

Sexualmaturity

ReptileOriginSpecies

HabitatDiet

Carpetpythons

Australia

3 species, with 4 subspeciesa,bSemi‐
arboreal

Carnivorous 18–24 m(male);
24–36 m(female)Green python Australia and(Figure 1.6)
Papua New
GuineaAlso known as chondropython Arboreal
or green tree python(M. viridis)

Antaresia
spp.

Spotted python (Antaresia
maculosa); Children’s python(A. childreni), pygmy python(A perthensis); Stimson
python (A. stimsoni) – 2
subspecies: western(A. s. stimsoni) and eastern(A. s. orientalis)

Terrestrial Carnivorous 2–3 yO

55–60 dat 31 °C

26–32

29–32

50–70

15–30

Black‐headed python(Aspidites melanocephalus)
and the Woma python(A. ramsayi)

Terrestrial Carnivorous 18–24 m

O

50–60 dat 31 °C

28–36

28–32

40–50

15–25

Semi‐
arboreal

OV

100–120 d

27–33

–

50–70

20–30

Australia

Aspidites spp. Australia

Boa
constrictor

Boa constrictor constrictor ,Mexico,also known as theSouth
America and red‐tailed boa
the Caribbean

Carnivorous 3–4 y(Continued )Table 1.5 (Continued)aHabitatDiet

Sexualmaturity

Mode of Incubation or
reprod. Gestation

Thermalgradient(°C)

Relative
Longevity
PBT (°C) humidity (%) (years)

ReptileOriginSpecies

Rainbow boa

SouthAmerica

Epicrates cenchria, also known Terrestrial Carnivorous 2.5–4 yas the slender boa

OV

150 d

21–30

–

70–90

15–20

Ball python

AfricaPython regius, also known as
the royal python

Terrestrial Carnivorous 11–18 m(male),
20–36 m(female)O

50–60 d

27–32

50–60

–

20–35

Corn snake

North
America

Pantherophis guttatus

Terrestrial Carnivorous 2 yor semi‐arboreal

O

70 d

24–30

–

50–60

20–25

Centralian carpet python (Morelia bredli); South western carpet python (M. ariegate); Diamond python (M. spilota spilota); Jungle carpet python (M. s. cheynei; Figure 1.5); Coastal carpet
python (M. s. mcdowelli); Murray/Darling carpet python (M. s. metcalfei); Darwin carpet python (M. s. ariegate).
In addition to these, there are four other Morelia species: the scrub python (M. amesthistina), the rough‐scaled python (M. carinata), the green python (M. viridis, see below) and the
Oenpelli python (M. oenpelliensis).
cVaries with species but in this range.
d
Avoid constant high humidity.
b

Sexualmaturityy(male),
20–36 m(female)ous 2 y
O

O

OV

70 d

50–60 d150 dMode of Incubation or
reprod. Gestation

24–30

27–32

21–30

Thermalgradient
(°C)

–

50–60

–

50–60

–

70–90

20–25

20–35

15–20

Relative
Longevity
PBT (°C) humidity (%) (years)

M. spilota spilota); Jungle carpet python (M. s. cheynei; Figure 1.5); Coastal carpet
M. s. ariegate).
), the rough‐scaled python (M. carinata), the green python (M. viridis, see below) and theMode ofreprod.

Incubation or
Gestation

Table 1.6 Turtles.

PBT (°C)

Relative
humidity
(%)

Water
24–26
Air 22–26

–

–

30–40
(possibly
longer)In response to lowtemperatures,
embryos enter adiapause, whichenables them tosurvive over winterin nests, resulting ina year‐longincubation period

Water
22–26

–

–

30–40 (orlonger)O

45–60 d

25–28

–

–

15–20

O

60 d at 30 °C

Water
24–28

–

–

Over 40

47–64 d at 28–29 °C

Water
24–28

–

–

75–100

Sexualmaturity

Carnivorous

7–8 y(male);
10–12 y(female)O

90–150 d

Semi‐aquatic

Carnivorous

9–11 y(male),
14–15 y(female)O

The genus
Emydura is stilltaxonomicallycontroversiala,bSemi‐aquatic

Initially
carnivorous but
becomeomnivorous as
they get older

5–6 y(male),
10–12 y(female)c

Australia

Myuchelys
latisternum

Semi‐aquatic

Predominantly
carnivorous but
will take somevegetables

10 y(male),
20 y(female)Australia

Elusor macrurusSemi‐aquatic

OmnivorousO
25 y(male), 30
y (female)

ReptileOriginSpecies

HabitatDiet

Easternlong‐necked
turtleAustralia

Chelodinalongicollis, also
known as thesnake‐necked
turtleSemi‐aquatic

Broad shelledturtleAustralia

C. expansa

Short‐necked Australia
turtles(Emydura
spp;
Figure 1.8)
Saw‐shelledturtleMary riverturtleThermalgradient(°C)

Longevity(years)(Continued )Table 1.6 (Continued)

Mode ofreprod.

Incubation or
Gestation

16 y(male),
18 y(female)O

86–102 d

Thermalgradient(°C)

PBT (°C)

Relative
humidity(%)

Longevity(years)

Water
26–30
Air 26–28

–

–

35–40

ReptileOriginSpecies

HabitatPig‐nosed
turtleNorthern
Australia
andsouthern
New Guinea

Carettochelys
insculpta, also
known as thepitted‐shelledturtle or Fly riverturtleSemi‐aquatic, Omnivorous
verging on
completely
aquatic

Red‐eared
sliderSouthern
UnitedStates andnorthern
Mexicod

Trachemys scripta Semi‐aquatic, Carnivorous as
freshwater
juveniles,
elegans or
becoming
red‐eared terrapin
omnivorous as
they get older

3–5 y

O

59–112 d, depending Wateron temperature
24–30
Air 24–32

–

–

30–50

Musk turtle

South‐east
Canada andeastern
UnitedStatesSternotherus
odoratus

Predominantly
carnivorous but
adults will eat
some vegetablematerial

4y(male),
10 y(female)O

65–86 d

Water
20–23
Air 23–30

–

–

50

Omnivorous

2–4 y(male);
6–10 y(female)O

72–80 d

Water
24–27
Air 27–32

17–23

–

25–30

Painted turtle Southern
Canada, theUnitedStates andnorthern
MexicoSemi‐aquatic

Chrysemys picta) Semi‐aquaticwith 4 subspecies:
eastern (C. p.
picta), western(C. p. bellii),
southern (C. p.
dorsalis), Midland(C. p. marginata)

Diet

SexualmaturityaAccepted species are currently: Macquarie turtle (E. macquarii); Murray river turtle (E. m. macquarii); Krefft’s turtle (E. m. krefftii); – Fraser island short‐neck turtle (E. m. nigra); Cooper
creek turtle (E. m. emmotti); Red‐bellied short‐necked turtle or Jardine river turtle (E. subglobosa); Red‐bellied short‐necked turtle (E. s. subglobosa); Worrell’s short‐necked turtle (E. s.
worrelli); Northern yellow‐faced turtle (E. tanybaraga); Victoria river red‐faced turtle (E. victoriae).
b
As well as the genus Emydura, other short‐neck turtles include the Mary River turtle (Elusor macrurus) and the saw shell turtle (Myuchelys latisternum); see individual entries.
cSome species may have delayed onset of sexual maturity.
dThis is an invasive species and has become established in the wild elsewhere in the world.

Table 1.7 Tortoises.

a

ReptileOriginSpecies

HabitatDiet

SexualMode of Incubation or
maturity reprod. Gestation

ThermalPBT Relative
Longevity
gradient (°C) (°C) humidity (%) (years)

Mediterranean
tortoises

North Africa,
western Asia
and Europe

Currently 5 species accepted.
Likely that some will bereclassified based on DNA
differencesa

Terrestrial

Herbivorous

9–12 yO

55–100 d,
dependingon species

21–32

–

30–50

30–100

Sulcata

Centrochelys sulcata, also
Northern
known as the African spurred
Africa andsouthern edge tortoiseof the Sahara
desert

Herbivorous
Terrestrial;burrows into
the groundto escape the
heat

5–8 y

O

90–120 d

29–40

–

Low

50–150

Leopardtortoise

Eastern andSouthern
Africa, from
Sudan to thesouthern
Cape

Stigmochelys pardalis

Terrestrial

6–15 yO

24–38
150–400 d
at 28–32 °C,
often following
a cooling
period of 30 d
at 18–24 °C–

Low

80–100Box turtle

United Statesand Mexico

Genus Terrapene are terrestrial Terrestrial
members of the American
pond turtle family (Emydidae).
Currently, 4 species areclassified within the genus and12 taxa are distinguishedb

Omnivorous 7–10 yO

56–75 dat 29 °C

24–32

–

60–80

50–100Star tortoise(Figure 1.10)

India andSri Lanka

Geochelone elegans, also
known as the Indian star
tortoise

Terrestrial

HerbivorousO
6–8 y(male),
10–12 y(female)90–170 d

24–32

–

<40

30–80

Red‐footed
tortoise

NorthernSouth
America

Chelonoidis carbonaria, alsoclassified as Geochelone
carbonaria)

Terrestrial

O
Omnivorous 6–8 y(male),
8–12 y(female)105–202 d

21–30

–

50–70

20–30

Herbivorous

Russian tortoise (Testudo horsfieldii), also known as Horsfield’s tortoise; Hermann’s tortoise (T. hermanni); Spur‐thighed or Greek tortoise (T. graeca; Figure 1.9); Kleinmann’s tortoise(T. kleinmanni), also known as the Egyptian tortoise; Marginated tortoise (T. marginata).
Common box turtle (T. carolina); Florida box turtle (T. c. bauri); Eastern box turtle (T. c. carolina); Gulf coast box turtle (T. c. major); Mexican box turtle (T. c. mexicana); Three‐toed box turtle(T. c. triunguis); Yucatán box turtle (T. c. yucatana); Coahuilan box turtle (T. coahuila); Spotted box turtle (T. nelsoni); Northern spotted box turtle (T. n. klauberi); Southern spotted box turtle(T. n. nelsoni); Ornate box turtle (T. ornata), also known as the Western box turtle; Desert box turtle (T. o. luteola).

bFigure 1.3 Veiled chameleon (courtesyof Brendan Carmel).

Figure 1.4 Green iguana (courtesy of
Bob Doneley).

Figure 1.5 Jungle carpet python(Morelia spilota cheynei; courtesy of
Bob Doneley).

Taxonomy and Introduction to Common Species

Figure 1.6 Green python (courtesy of
Bob Doneley).

Figure 1.7 Corn snake (courtesy ofRobert Johnson).

Figure 1.8 Short‐necked turtle(Emydura spp; courtesy of Bob
Doneley).

13

14

Reptile Medicine and Surgery in Clinical Practice

Figure 1.9 Spur‐thighed or Greek
tortoise (Testudo graeca; courtesy ofJohn Chitty).

Figure 1.10 Star tortoise (courtesy of
Bob Doneley).

15

2
Anatomy and Physiology of Reptiles
Bairbre O’Malley­Introduction
As a veterinary surgeon it is impossible totreat reptiles without a thorough understanding of their anatomy and physiology.
For example, to anaesthetize a turtle we need
to be aware of the challenges of a species witha large lung volume, no diaphragm or intercostal muscles and known to able to breath
hold for many hours. When presented with
an iguana for tail amputation, the veterinary
surgeon needs to understand the importanceof not always stitching the wound site as inmany cases a new stump may regenerate.
Likewise, therapeutic and enteral treatments
will fail unless the vet understands ectothermy and the need to provide adequate
temperature levels to allow drugs and food tobe metabolized and digested. This chapter
aims to help vets to gain a basic understanding of structure and function of chelonians,
lizards and snakes and highlights their relevance to clinical practice.

­Metabolic Rate
Reptile metabolism is slow, being one‐fifth toone‐seventh that of a mammal of equivalentsize. Metabolic rate varies with temperature,
diet, size and species. For example, the primitive New Zealand tuatara has one of the lowest metabolic rates while the varanid monitors

have the highest metabolism of most lizards.
In general, passive ‘sit and wait’ predators suchas pythons and boas also have lower metabolism while active ‘seek and hunter’ insectivorous lizards have higher metabolic rates.
Thermoregulation
Reptiles are ectothermic: they are unable togenerate their own body temperature. Unlike
mammals that draw their heat from food,reptiles derive their heat from the environment. Ectothermy has some advantages inthat reptiles do not need major food sources
to meet energy demands. For example, a reptile of equivalent size as a mouse will havejust one‐tenth the energy requirement. This
lower energy requirement and efficient foodconversion has enabled reptiles to endure
long hibernation and night cooling and tosurvive in arid deserts. Reptiles can use
basking, changes in skin colouration andcardiovascular shunting to increase bodytemperature, and use shade seeking, soaking
in water and gular fluttering to reduce bodytemperature.
The main disadvantage of ectothermy isthat all activity is limited by ambient temperature, such that many reptiles become inactive and vulnerable at night and have tohibernate when temperatures drop. They
have a much lower aerobic capacity thanendotherms and need to switch rapidly to

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

16

Reptile Medicine and Surgery in Clinical Practiceanaerobic metabolism for any vigorous activity such as diving, chasing prey or escaping
predation. Although anaerobic metabolism
is independent of temperature, it drainsenergy reserves tenfold. As reptiles also
­rapidly build up lactic acid, they easily getfatigued so cannot sustain intense activity
levels for more than two to three minutes.
Preferred Optimum
Temperature Zone
The preferred optimum temperature zone is
the temperature range of the reptile’s natural
habitat. It usually lies between 20°C and 38°C
but can vary by 4–10°C, depending on thespecies. Within this range, each species has apreferred body temperature for each metabolic function such as predation, digestion
and reproduction (Table 2.1).
Mechanism of Thermoregulation
Reptiles derive their heat via heliothermy orthigmothermy or a combination of the two.
Heliothermy means obtaining radiant heatby basking in the sun and is used by chelonian and diurnal lizards. Thigmothermy isacquiring thermal heat via conduction with
hot surfaces and is common in nocturnal orforest species. Reptiles also use physiologicaland behavioural means of thermoregulation.
They raise their body temperature by increasing their heart rate to pump warm bloodfrom the core to the periphery. Their three‐chambered heart can also shunt blood fromright to left, to the peripheral blood vessels
bypassing the evaporative cooling of thelungs. Lizards also heat up by increasing melanin pigment in their skin or by selecting adark background. Snakes coil up to conserve
heat and uncoil to lose heat, while lizards
angle their body axis perpendicular to thesun to heat up and face the sun to cool down.
Many lizards cool down by panting or gular
fluttering, which is when they hold theirmouth open to vibrate their throat. They alsocool down by shade seeking and plunging
into water.

Table 2.1 Preferred body temperature (PBT)
of commonly kept species.
SpeciesPBT (°C)

Turtles:
Eastern long‐necked turtle (Chelodina
longicollis)

26

Box turtles (Terrapine sp.)

26–32

Snakes:Children’s python (Antaresia childreni)

30–33Ball python (Python regius)c. 29

Carpet python (Morelia spilota)

29–33

Diamond python (Morelia spilota
spilota)29

Burmese python (Python molurus)c. 29

Water python (Liasis fuscus)

34

Boa constrictor (Boa constrictor
constrictor)

c. 29

Corn snake (Elaphe guttata)

25–29

Lizards:
Eastern blue‐tongued lizard (Tiliqua
scincoides scincoides)

28–32

Shingleback lizard (Tiliqua rugosa)

33

Eastern bearded dragon (Pogonabarbata)

35–39

Lace Monitor (Varanus varius)

35

Green iguana (Iguana iguana)

28–32

Tortoises:
Most species

28–31

Sources: Carmel and Johnson 2014; Rossi 2006.

­External Anatomy
Chelonia
The dome of the shell is called the carapace
and the flat under part the plastron. The joint
between is called the bridge. The shell isformed from dermal bone and consists ofabout 60 bones formed from the modified
pectoral and pelvic limb girdles, trunk vertebrae, sacrum and ribs. These are covered bykeratinized epidermal scales called scutesthat are innervated and bleed if damaged.

Anatomy and Physiology of Reptiles

Growth occurs by the addition of new keratin
layers to the base of each scute. The limb
girdles lie inside the fused shell and are­
attached by powerful fan shaped pectoraland pelvic muscles.
Anatomical modification depends onwhether the species is terrestrial, marine or
freshwater. Terrestrial species have a high‐dome carapace with short stubby legs.
Freshwater species have webbed feet anda smooth shell. Marine species are very
streamlined with a flat soft shell and their
metacarpus/tarsus and phalanges are elongated for swimming, similar to flippers.
Aquatic species can hold their breath forlong periods and use anaerobic and non‐pulmonary respiration through skin, pharynx and cloaca.
Lizards
Although lizards are modified for swimming,
flying and climbing, they are generally elongated and circular in cross‐section. Bearded
dragons, however, are horizontally compressed while arboreal lizards such as thechameleon are vertically compressed. Some
species, like iguanas and chameleons, havedramatic sexual dimorphic characteristics:
crests, spines, heavy jowls and pronounced
femoral pores. The tail is usually long andcan be prehensile, as in chameleons, or as asite of fat storage, as in the leopard gecko.
Autotomy means self‐amputation and is amechanism present in some species such as
iguanas, bearded dragons, skinks and geckos,
to escape predators. The tail drops off owing
to vertical fracture planes and in many casesa new tail tip may regrow. Many geckos haveadhesive lamella on their digits to allow thenwalk vertically on smooth surfaces while thechameleon has pincer‐like zygodactyl feetadapted for climbing.
Snakes
The snake has evolved its body for crawling
so has few external features (Figure 2.1).
Elongation has also resulted in organa­ symmetry with the right‐side organs lying
cranial to and being larger than the left. The
cranial third contains the heart, trachea,
oesophagus, thyroid and proximal lung.
The middle third has the stomach. liver,lung, spleen and pancreas. The caudal third
has the small and large intestines, kidneys
and gonads. The belly is slightly flattened
to aid locomotion with single scales called
gastropeges.

­Integument
Contrary to popular belief, reptiles do nothave a ‘slimy skin’ but in fact very dry skin,because they have few skin glands. Water
loss is prevented by a heavily keratinized epithelium with a lipid layer. There are scent‐type glands under the thigh in some lizards
and musk glands near the cloaca in somesnakes and turtles. These tubular skin invaginations are better developed in males andproducing a waxy secretion that has a pheromonal function.
The epidermis is both thick and thin toform scales. These scales provide protection
but also play a role in permeability. Within
the epidermis there are three layers. The
inner layer is called the stratum germinatum
and consists of cuboidal cells that produce
the protein keratin and the dividing cells of
the intermediate layer. The intermediate
layer contains lipids that help to provide awater permeable barrier in the skin. The
outer stratum corneum is heavily keratinized
into the scales. This thick keratinized skinmeans that reptile have far less sensory
innervation in their skin, which is why they
are at risk of thermal burns.
The dermis consists of connective tissue,
blood, lymphatic vessels and nerves.
Pigment cells or chromatophores provide
elaborate colouration, most notably seenin the chameleon. In some species of lizards, such as skinks, the dermis has bonyplates, called osteoderms, and in chelonia
this has fused with the vertebrae to form
the shell.

17

18

Reptile Medicine and Surgery in Clinical Practice(a)Trachea

Proximal
lung

Heart
Precardial fat padand thyroid gland

Oesophagus

(b)
Lung

Oesophagus

Liver

AirsacLung

StomachSpleen, pancreas
and gall bladder

Small
intestine(c)Terminal
airsacSmallintestine

Colon

Coelomic fat pads

CloacaVent

Figure 2.1 Internal anatomy of a snake: a) Cranial third: trachea, thyroid, heart, proximal lung and oesphagus;b) Middle third: liver, lung, stomach, spleen and pancreas; c) Caudal third: colon and coelomic fat pads.

EcdysisEcdysis is the shedding of skin; it is controlled
by the thyroid gland. Lizards and chelonians
shed piecemeal. Snakes tend to shed thewhole skin in one piece from snout to vent. It
is colourless because the pigment cells are in
the dermal layer. In a healthy snake the wholeprocess can take up to abut 2 weeks. During
ecdysis, the cells in the intermediate layer
replicate to form a new three‐layer epidermis. Once this is complete, lymph diffuses
into the area between the two layers andenzymes are released to form the cleavage
zone. The old skin is shed and the new epithelium hardens to form the new skin.

Dysecdysis or failure to shed occurs when
there is low environmental humidity or
when the reptile is ill. Malnutrition anddebilitation leads to dehydration and hypoproteinaemia, rendering them unable toproduce the enzymes needed to form thecleavage zone.

­Skeletal System
Skull
Reptiles are divided into two subclasses
based on the presence or absence of openings in the temporal region of the skull. TheseAnatomy and Physiology of Reptiles

Figure 2.2 Modified anapsid skull ofchelonian, lateral and dorsoventral
views.

(a)

Frontal boneParietal bone

Post orbital
SquamosalboneMaxillarybone

Quadratojugal
bone

Quadrate
Lateral view(b)

Quadratojugal
boneParietal bone

Post orbital

Frontal bone

MaxillaDorsoventral view

‘fenestrae’ lie behind the eyes and provide
better attachment for the jaw musculature(Figure 2.2).
Anapsid

Chelonia are anapsid (without arches) as
they lack true temporal openings. The headis small so it can be retracted inside the shell
but large adductor muscles, sturdy skull andshort jaw still enables them to have a powerful bite.
Diapsid

The tuatara (Rhynchocephalia) and crocodile have two temporal openings on theirskull so are truly diapsid while snakes andlizards are modified diapsid (Figure 2.3).

Lizards have only one dorsal opening whilesnakes have an even more modified diapsid
skull, having lost the temporal arch between
the two openings. This has enabled the quadrate bone to move backward and forwards
with no firm connection in a condition
known as streptostyly. This has given snakes
and lizards a kinetic skull, which is thought
to enable the upper and lower jaw to close
over prey. Lizards have very strong adductor
muscles which extend from the temporal
region to the lower jaw enabling the jaw tosnap close like a trapdoor over prey (andunwary fingers).
The snake has the most kinetic skull of all
and the skull is designed to allow a reptile
with a small mouth to eat large enough prey

19

20

Reptile Medicine and Surgery in Clinical PracticeDepressor
mandibulae(Jaw opening)

External adductor(jaw closing)

Figure 2.3 Lizard skull showing thepowerful adductor (jaw closing)muscles.

Pterygoideus(Jaw closing)Prefrontal bone

Pterygoidbone

MaxillaSquamosalbone

Quadratebone
ColumellaBraincasePremaxilla

Mandible

Figure 2.4 Skull of a simple snake.

to sustain its body size and length (Figure 2.4).
It has no temporal arch, interorbital septumor middle ear cavity. The brain case is heavily
ossified to protect it from struggling prey andall tooth bearing bones are able to moveindependently. Snakes lack a mandibularsymphysis so the jaw bones can move apartand literally ‘walk’ its jaw along the prey. The
quadrate bone, which articulates with thelower jaw and palatomaxillary arch, also hasa very loose articulation. Snakes often yawn
after a meal to allow their jawbones reposition themselves.

Vertebrae
Reptiles rest their belly along the ground so
the backbone is not rigid but highly flexible.
The spine is divided into presacral, sacral andcaudal region. Chelonia have 18 presacralvertebrae – 8 free cervical and 10 trunk vertebrae fused into the dermal bone of theshell. The neck and tail are highly flexible
with well developed epaxial and hypaxial
muscles. Chelonia are classed into two suborders according to their mode of retracting
their head into their shell. The pleurodira orside necks are more primitive, being unableAnatomy and Physiology of Reptiles

to retract their head into their shell instead
placing it sideways. The cryptodira have aneck that forms a vertical ‘S’ bend. This has
enabled them to be more successful, as they
are able to retract their head completely into
their shell.
Lizards have a highly mobile and flexible
backbone, well developed legs and a long tailfor counterbalance. All the vertebrae except
the cervical vertebrae bear ribs, leaving little

flank area. Primitive lizards and tortoises
have short limbs directed sideways. Advanced
lizards have their limbs rotated more towards
their body so that the elbow faces caudally
and the knee cranially, creating better shock
absorption.
Snakes have up to 400 vertebrae pre‐cloacally,each with its own pair of ribs and large axial
skeletal muscles (Figure 2.5). Each vertebra
has five separate articulations, creating an
Left lung

Color codeHeart

Orange = gastrointestinal tract
Light Blue = respiratory tract

Thyroid gland

Right lung
Liver

Oesophagus

Trachea

StomachGall bladder

Large intestine
Vas deferens

Pancreas
Right kidney

Ureters

Right testis

SpleenSmall intestine

Right adrenal
gland

RectumRight airsac

Left testis

CloacaLeft kidney

Left adrenal
gland

Anal scale(divided)

Figure 2.5 Internal anatomy of a snake (male) with coelomic fat pads removed to show caudal viscera.

21

22

Reptile Medicine and Surgery in Clinical Practice

extremely flexible backbone. The intercostal
and hypaxial muscles not only help in locomotion but also in respiration and the passage ofprey. In the process of elongation the snake has
lost its pectoral and pelvic girdles. However, insome of the more primitive snakes such as
boas and pythons, pelvic vestigial spurs can beseen on either side of the vent.

­Cardiovascular System
In chelonians, the heart lies in the midline
just caudal to the pectoral girdle (Figures 2.6
and 2.7). In most lizards (Figures 2.8 and 2.9),
it lies at the level of the pectoral girdle but
has descended caudally to the more mammalian location of mid‐thoracoabdominal cavity in the more advanced monitor lizards. In
snakes, the heart lies just cranioventral to thetracheal bifurcation, about one‐quarter ofthe way down the body (Figure 2.1).

Gall bladder

Liver

Colon

Chelonia, snakes and lizards have a three‐chambered heart (two atria and one ventricle), whereas crocodiles have four chambers.
The right atrium receives deoxygenatedblood from the circulation via a large chamber the sinus venosus. There are two aortas:
the left gives rise to the coeliac, cranial mesenteric and left gastric arteries before uniting
with the right aorta caudal to the heart. A
large ventral abdominal vein lies along theinner surface of the midline and must be
avoided when ­making a coeliotomy incision.
A renal portal system is also present (see urinary section).
The ventricle is divided into three subchambers, the cavae venosum, arteriosum
and pulmonale. Although there is no permanent division, oxygenated and deoxygenatedblood never actually mixes, due to atrioventricular valves, a muscular ridge, pressure
differential and the timing of ventricular
contractions.

TestesKidneyCoprodeum

StomachUreterLungs
Trachea
Oesophagus

Urinary
bladder
Vent

Heart
Thyroid

PelvisSpleenSmallintestine

Urodeum
Proctodeum
Tail

Figure 2.6 Ventral view of a chelonian after plastron and trunk muscles have been removed.

Anatomy and Physiology of Reptiles
Trachea
Oesophagus
Primary
bronchus

Parathyroid

Lungs

Thyroid

Liver
Right atrium
Stomach
Ventricle
SpleenLarge colon

Small
intestine
Urinary bladder

Ascending colon

Vent

Figure 2.7 Midsagittal view of a chelonian.

Intracardiac Blood Shunting
The undivided ventricle also plays an­important role in thermoregulation and theability to breath hold because blood can be
shunted towards or away from the lungs
depending on pulmonary resistance. During
peak ­
respiration, pulmonary resistance is
low so deoxygenated blood flows throughthe lungs. During periods of oxygen starvation (for example when snakes swallow
prey or turtles dive) the pulmonary arteries vasoconstrict. This increases pulmonary

resistance and shunts blood away from thelungs to the systemic circulation.
Clinical Significance of Blood Shunting

The ability of reptiles to shunt blood awayfrom their lungs systemically and switch toanaerobic metabolism presents challenges
for anaesthesia, especially with aquatic chelonians that can hold their breath for hours.
It also explains why many reptiles withchronic pneumonia are slow to recover, as
the increased lung resistance of the infection

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Reptile Medicine and Surgery in Clinical Practice
TracheaParathyroids

ThymusRightatriumVentricle
Liver

Thyroid

Lungs
Oesophagus

Gall bladder

StomachPancreas

SpleenSmallintestine

Left ovary

Right ovary
Colon
Urinary
bladder
CloacaFigure 2.8 Ventral view of a female lizard.

Left oviduct
KidneyUreterRectumAnatomy and Physiology of Reptiles
StomachLung

SpleenDorsal aorta

TestesEpididymis

Oesophagus

KidneyColon
UreterHemipenis

Left atrium
Right atrium
Ventricle

Liver
Gall
bladder

Duodenum
CloacaPancreas

Urinary
bladder

Figure 2.9 Lateral, mid‐sagittal view of a male chameleon.

diverts the blood supply away from where it
is most needed.
Blood Volume
Normal blood volume is approximately 5–8%
body weight; 10% of this can be safely takenfrom a healthy reptile during blood sampling.
Blood Cells
Reptile erythrocytes are nucleated and have alonger lifespan than in mammals and birds.
The haematocrit varies with temperatureand season rather than high altitudes andhypoxia as in mammals. The white blood
cells include heterophils, eosinophils,
basophils, lymphocytes, monocytes and­azurophils. Azurophils are unique to reptiles.
They are like monocytes but are smaller
in size and have a red‐purple cytoplasm.

networks and large reservoirs, called cisternae,
at the site of mammalian lymph nodes. As thelymphatic system is so developed, dilution ofblood samples with lymph during venepuncture is common.
Chelonia have a highly developed lymphatic system and this is why oedema is acommon presenting symptom for many illnesses. Their skin has a network of lymphatic
vessels that are widely meshed. These vessels
become superficial as they near the attachment of the skin to the shell. The orbits have
two lymphatic vessels that extend into both
eyelids and some species, such as the red‐
eared terrapin, have a lymphatic ring aroundthe base of the neck. In snakes, dilation of thelymph vessels (lymph hearts) is found oneither side of the tail base where the vessels
are protected by modified forked caudal
vertebrae.

­Immune System­Respiratory System

Reptiles have a better developed lymphatic
system than a venous system. They lack lymph
nodes but have vast plexiform lymphatic

Reptiles have large‐volume lungs that function not only for gas exchange but are usedfor vocalization, display and buoyancy.

25

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Reptile Medicine and Surgery in Clinical PracticeUpper Tract

Clinical Note

Air enters through the external nares, thenasal sinus and internal nares. The glottis
lies quite rostrally, usually just behind the
tongue. It remains closed at rest, opening
only for respiration via the glottis dilator
muscles.

The lack of diaphragm and ability to coughand primitive bronchociliary transport­system means that reptiles easily get respiratory disease. Reptiles suffering from pneumonia will tend to seek the cooler end of
their vivarium to reduce the demand foroxygen.

Lower Respiratory Tract

Ventilation

The trachea has incomplete tracheal rings,
with the dorsal fourth being membranous.
In contrast to mammals, the lung volume islarge but only has 1% of the surface area ofa mammal of equivalent size. The lungparenchyma is simple and sac like, with ahoneycomb network of faveoli – the reptile
unit of gaseous exchange. The mucociliary
lining of the tract is primitive, making thempoor at clearing exudates. There is no­diaphragm and the combined pleuroperitoneal space is called the coelom. In moreadvanced species, such as monitor lizards,
a membrane called the postpulmonary­septum divides the pleural cavity from theperitoneal cavity.
There are three types of lung anatomy
based on the degree of partition of the­lungs. Snakes and some lizards have single‐
chambered, primitive unicameral lungs.
Chameleons and iguanas have paucicameral(few‐chambered) lungs with no intrapulmonary bronchus. Chelonians, monitor lizards
and crocodiles have advanced multicameral(multichambered) lungs with an intrapulmonary bronchus.

Despite their lack of diaphragm, reptiles
breathe via negative pressure breathing.
Respiration is triphasic, with expiration,
inspiration and relaxation (breath‐holding).
Air is inhaled and expired by the action of theintercostal and/or trunk muscles.

Control of Respiration
Respiration in reptiles is controlled by risingtemperature and not acid base balance andpartial pressure of carbon dioxide as in mammals. A rise in temperature increases metabolic rate and hence oxygen demand,
stimulating respiration and increasing tidal
volume. Low oxygen levels also stimulates
respiration – hence the need to be careful not
to overventilate reptiles with oxygen during
cardiopulmonary arrest.

Chelonia
Chelonia have an easily visible glottis at theback of a short fleshy tongue. In cryptodira,
the trachea is very short and bifurcates rapidly to allow for head retraction. The lungs
are advanced, being multicameral, andoccupy a large volume in the dorsal half of the
body cavity. They are separated from the ventral cavity and the viscera by a thin nonmuscular postpulmonary septum. There is no
expandable chest, as the ribs, sternum andbackbone are modified into a hard shell, andthere is no diaphragm (Figures 2.6 and 2.7).
Instead, chelonians breathe by using theirpowerful trunk muscles to expand and­contract the lungs by attachment to the postpulmonary septum.
Chelonians can hold their breath for very
long periods (up to 33 hours in aquatic species) as they are very tolerant of hypoxia andare able to convert to anaerobic metabolism.
They have the highest bicarbonate concentration of all vertebrates, which helps them tobuffer lactic acid accumulation.
Lizards
Lizards breathe by expansion and contractionof the ribs. More primitive lizards have theheart at the level of the pectoral girdle andunicameral lungs. Intermediate species haveAnatomy and Physiology of Reptiles

paucicameral lungs, with some having air
sacs (Figure 2.9). The more advanced species
like the monitor lizards have multicamerallungs with a single intrapulmonary bronchus.
As the lungs now extend cranioventrally, theheart lies more caudally in the mid‐sternum.
SnakesIn snakes, the glottis is very mobile and canbe extended laterally while feeding to allow
breathing while ingesting prey. In the p­ rocessof body elongation, more advanced species
have evolved only one lung (Figures 2.1 and
2.5). The more primitive Boidae have twolungs, although the right lung is slightly
longer. The lungs are simple and unicameral.
Like some lizards, the caudal third is nonrespiratory and functions like an air sac.
Respiration is via the dorsal and ventrolateralintercostal muscles and some species use theair sac like a bellows.

­Digestive System
The digestive tract is shorter than that of
mammals and can vary from the simple tractof carnivores to the larger colons and caecumof herbivores. All snakes are carnivorous.
Most lizards are omnivorous or insectivorous, with only 3% being herbivorous. About
25% of the Chelonia are herbivorous.

Dentition
Reptile teeth are composed of enamel, dentine
and cement but they lack a periodontal membrane. They are polyphyodontic, meaning thatthey are resorbed and replaced at a rapid rateduring life. This enables simple teeth to bealways sharp. There are three types of teeth,
depending on the reptile’s feeding habits.
Acrodonts have teeth attached to the crest of
the bone, as seen in chameleons and water
dragons. Pleurodont teeth have an eroded
labial side and are attached to a higher‐sided
labial wall (snakes and iguanas). Thecodonts
have teeth embedded in a bony socket but withno periodontal membrane, as in crocodiles.
Chelonians have no teeth, so they are unable to chew but instead they have a shorthorny beak with sharp edges. Most snakes
seen in veterinary practice have six rows ofteeth – four upper and two lower. Their teeth
are long, thin and backwards‐pointing toprevent the escape of prey. Copious amountsof saliva are produced by the salivary glands
during swallowing to moisten and lubricate
the prey. In venomous species some maxillary teeth are modified into fangs.
Rear‐Fanged Snakes

In about one‐third of colubrids, the caudal
labial salivary gland becomes modified into
the Duvernoy’s gland, which lies behind theeye (Figure 2.10). Venom passes from thisSquamosal
Quadrate

MaxillaPalatoquadrate
Venom glandwith long duct

Figure 2.10 Skull of an advanced snake showing the location of the venom gland. The duct opens into thegrooved front fangs.

27

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Reptile Medicine and Surgery in Clinical Practicegland into modified teeth at the caudal maxilla. These create rear fangs which incapacitate the prey so that it cannot damage thesnake’s mouth while it is being eaten.
Front‐Fanged Snakes

In front‐fanged snakes, the venom gland islarge and separated from the labial gland andbehind the eye with a large duct running­rostrally into fangs at the rostral maxilla. In
Elapidae, the fangs remain erect and cannot
fold. Viperidae have highly modified fangs,
which are so long that they have to be folded
backwards in a sheath along the roof of themouth when not raised for striking.

­Gastrointestinal Tract
The stomach is small and gastroliths canoften be seen on radiographs in Chelonia. In
snakes, the stomach is fusiform with no well‐developed cardiac sphincter, causing easy
regurgitation of food. The liver is large in all
reptiles and very elongated in snakes. A gall
bladder is usually present and the main bile
pigment is biliverdin. The pancreas is
attached to the mesenteric border of theduodenal loop and in some snakes it is fused
to create a splenopancreas. A caecum is
prominent in herbivorous reptiles such as
iguanas and tortoises. Reptiles do not havesubcutaneous fat but instead store fat as ‘fatbodies’ in the caudal coelom or in the tail.
The rectum ends in a pouch called the cloaca (Latin for sewer.) The anterior chamberor coprodeum collects the faeces; a middle
chamber called the urodeum is where theureter and reproduction system enters and aposterior chamber called the proctodeum
where all wastes collect prior to excretion.
Cloacal scent glands are present in somesnakes and serve as a warning mechanism,producing foul‐smelling secretions.
Digestion
In snakes, digestion begins as soon as evenpart of the prey reaches the stomach and is a
rapid process. Absorption, however, is very

slow, as the whole prey is used, including theskeleton, it may take up to five days for large
snake to digest a rat. The keratinous structures, such as fur, are finally excreted as an
undigested pad called the felt. Herbivorous
lizards are hind‐gut fermenters (Figures 2.6–
2.8). They have a short small intestine but thelarge intestine (caecum and colon) takes up
50% of the length. Gut transit time is muchslower in herbivores, often taking several
days to digest the cellulose food.
Clinical Note

Digestion is dependent on the ambient temperature, food composition and the physicalhealth of the animal. The practice of force
feeding solid food items to a sick or debilitated reptile leads to putrefaction, not digestion, so is not recommended.
Feeding Frequency
Reptiles, being ectoderms, can survive on afraction of the food input of birds and mammals as they expend no energy on thermogenesis (Bennett and Nagy 1977). Their low
metabolic rate and efficient food conversion
allows them to eat less frequently. Large carnivorous snakes such as pythons can lastmonths between each feed. To conserve
energy, their gut and digestive enzymes
become dormant during fasting and thenexperience a rapid increase in metabolic rateand enzymatic activity when they eat to help
them digest their prey. They have also
adapted their gastrointestinal tract so thatwhen food enters, the quiescent gut rapidly
hypertrophies, together with the heart, pancreas, liver and kidneys. Once digestion iscompleted, the reverse happens and allaffected organs atrophy back to normal size.

­Urinary System
The kidneys are lobed and are located in thedorsocaudal coelom. In chelonians and lizards they are symmetrical but the right kidney lies cranial to the left in snakes(Figures 2.1, 2.5–2.9). Chelonians and mostAnatomy and Physiology of Reptiles

lizards have a urinary bladder connected tothe cloaca by a short urethra. In terrestrial
chelonians that hibernate it is large and bi‐
lobed and serves as an organ for water storage. Snakes and lizards that lack a bladderreflux urine into the distal colon for water
absorption. Reptile kidneys lack a loop of
Henle, renal pelvis and pyramids. In malesnakes and lizards, the terminal segment of
the kidney has become a sexual segment,
which is under androgen control.
Clinical Note
The dorsocaudal location of the kidneys
means that nephromegaly commonly resultsin constipation – this is commonly seen inaged iguanas.
Osmoregulation
Tortoises and snakes drink by sucking up fluid
while lizards can lap with their tongues.
There is also some minor absorption throughthe skin and condensation of the nasal passages. As reptiles lack a loop of Henle, they
are unable to concentrate urine beyond theosmotic values of blood plasma.
Aquatic and semi‐aquatic reptiles have noneed to conserve water so they excreteammonia and urea. To help to conserve
water, terrestrial species excrete uric acid,
which precipitates out as pasty white urates,
while aquatic species excrete urea. Although
this helps to minimize water loss, one major
disadvantage is that because uric acid issecreted via the kidney tubules it is still
excreted even when the reptile is dehydrated.
Consequently, dehydrated reptiles or thosewith renal problems can easily develop gout,a build‐up of uric acid in the bloodstream
which then precipitates into urate crystals
deposited in joints (articular gout) and visceral organs (visceral gout).
Renal Portal System
The reptile kidney has a dual afferent blood
supply consisting of the renal arteries and therenal portal vein. This vein bypasses the renal

glomerulus and enters at the level of the kidney tubules, where it helps to secrete urates.
It also plays a role in water conservation
because when the glomerular filtration rate
slows down during dehydration, the renal
portal system will keep the renal tubules perfused to prevent necrosis. Control of therenal portal system in is unknown but it isthought that, like in birds, there is a valve system so that when the body is under stressthese valves close and send blood directly tothe heart.
Clinical Notes

As venous return from the hind limb goesstraight to the kidney tubule, injecting drugs
into the caudal half of the body could theoretically lower serum concentration and leadto renal toxicity from nephrotoxic drugs.
However, this applies mainly to drugs
excreted by tubular secretion so aminoglycosides such as gentamycin and amikacin,
which are excreted via glomerular filtration,
would not be affected. Although renal portal
flow increases to the kidney when the animal
is dehydrated, when the glomerulus is closed
epithelial transport ceases. Thus, althoughmore drug enters the kidney it will not necessarily be excreted.

­Reproductive System
The Male
The right testis lie adjacent to the vena cavaand is connected to it by tiny vessels. The
left testis has its own blood supply but lies
intimately with the left adrenal gland.
Lizards and snakes have two extra cloacal
hemipenes which lie just caudal to the cloaca. In many lizards they can be visualized
externally as bulges in the proximal ventral
tail base. They are blind‐ended organs that
become engorged by lymph and blood andevert ­during mating. Only one hemipene isused during copulation. The organ is erectedby vascular engorgement and muscularaction and is everted to protrude throughthe cloaca. Chelonia and crocodiles have

29

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Reptile Medicine and Surgery in Clinical Practicedeveloped the ventral proctodeum in a single
intracloacal phallus which cannot be
inverted. The hemipene and chelonian phallus is solely an organ of reproduction so canbe amputated if damaged or necrotic.
The Female
The female has paired ovaries and oviducts
which lie at the same level cranial to the kidneys in chelonians and lizards and lies
asymmetrically in snakes. The ovaries function in the production of oestrogens andgametogenesis. They are saccular in shapeand covered with follicles. The right ovarylies close to the vena cava while the leftovary lies close to the left adrenal gland. The
oviducts not only provide egg transport but
also albumin, protein and calcium for egg
formation. In viviparous reptiles the uterine
section is thickened and muscular to holdthe developing embryo.

­Endocrine System
Thyroid Glands
In chelonians and snakes, this gland is
unpaired and spherical and lies just ventral to
the trachea cranial the heart. It can be paired,bi‐lobed (most common) or unpaired in lizards. It functions for metabolism (subject totemperature) and plays an important role inshedding and growth.
Parathyroid Gland
Unlike in mammals, the parathyroid glands
are not found within the thyroid gland but
are located near the thymus or ultimobranchial bodies. Chelonians and snakes
have two pairs while lizards have one or two,
depending on the species. The parathyroids
control calcium and phosphorous levels.
Lizards and chelonians on low calcium diets
develop hypocalcaemia, which stimulates
increase production of parathyroid hormone.
This then acts to mobilize calcium from thebones to increase serum calcium. Nutritional
secondary hyperparathyroidism and osteopenia eventually results.
Adrenal Glands
These are yellow or red in colour and lie retroperitoneally in chelonians and closely
adherent to the gonads in lizards and snakes.
Pancreas
This forms a C‐shaped loop in chelonians. In
lizards it has three parts and in snakes it isoften pyramidal in shape and is often intimately linked to the spleen. As in mammals, it
has both exocrine and endocrine functions.

­Nervous System
Reptiles have 12 cranial nerves. The brain
comprises 1% of the body mass and reptiles
have well‐developed optic lobes, reflecting
their excellent vision. Unlike in mammals,
the spinal cord extends to the tail tip andthere is no cauda equina. The spinal cord has
locomotor centres, giving it some local
autonomy from the brain. This means thatspinal cord injuries could have a better prognosis than in mammals.
SensesHearing

Only crocodiles have an external ear. In otherreptile species the tympanic membrane is theouter limit of the middle ear and is coveredby modified skin. The middle ear has only
one bone, called the columella, which is
attached to the tympanic membrane and thequadrate bone of the lower jaw. Vibrations
pass from the air or ground to the tympanic
membrane to the columella, which thenmoves the peri‐lymphatic fluid to give rise tonerve impulses. A short broad auditory tube
leads from the middle ear to the pharynx
and, as in birds, is not closed. The inner ears

Anatomy and Physiology of Reptiles

contain the organs of balance, the three semicircular canals, the utricle and saccule andthe organ of hearing, the cochlea.
Hearing in reptiles is poor. Lizards have thebest hearing but they are sensitive only to anarrow range of low‐frequency sounds.
Snakes and burrowing lizards lack an external or middle ear and transmit sound insteadby bone conduction.
Taste and Touch

Reptiles have taste buds on their tongue andoral epithelium. The tongue is an organ oftaste, touch and smell.
Olfaction

All reptiles have an accessory olfactory organ
called the Jacobson organ. These are paired
domed cavities and lie over the vomer boneson the rostral roof of the oral cavity, innervated by a branch of the olfactory nerve.
Olfaction is well developed in chelonians but
most highly developed in snakes, which
receive data by flickering their tongue in andout from a sheath beneath the glottis.
Sight

The principle receptors are the eyes, with theparietal gland and possibly the skin forming
secondary receptors. In some lizards, such as
the iguana, the parietal gland is well developed. It is located in the dorsal midline of thehead and connects to the pineal gland. It consists of a lens and retina and although it does
not form images it may function in thermoregulation, basking and reproduction.
Lizards and chelonians have scleral ossicles.
As in birds, the iris is controlled by skeletal
muscle so is nonresponsive to mydriatics likeatropine. In chelonians, the lacrimal gland is
modified into the salt gland. Chelonians haveno nasolacrimal ducts so lose tears by evaporation – hence giving the impression they are
weeping. Chelonians and most lizards haveeyelids, with the upper eyelids being larger
and less mobile than the lower. Snakes havefused their eyelids into a single protective
scale over the cornea, called the spectacleor brille. Sight and colour vision is well developed in chelonians and insectivorous lizards,
which need keen eyesight to catch prey. Most
lizards have only a narrow binocular field,
which is why they cock their head to get thebest monocular vision. Chameleons have thebest vision of all. Sight is poor in snakes.
Heat Sensing – The Sixth Sense

Some snakes possess specialized infrared
reception or pits, which enable them to sense
warm‐blooded prey and strike to catch them,even in total darkness. These pits are richly
innervated by the trigeminal nerve and are so
sensitive that they can detect a temperature
variation even 0.003 °C.

ReferenceBennett, A.F. and Nagy, K.A. (1977) Energy
expenditure in free ranging lizards. Ecology
58 (3), 698–700.
Carmel, B. and Johnson, R. (2014) Husbandry,in A Guide to Health and Disease in
Reptiles and Amphibians. Reptile

Publications, Burleigh BC, Australia, pp.
39–91.
Rossi, J. V. (2006) General husbandry andmanagement, in Reptile Medicine andSurgery 2nd ed. (D. Mader, ed.), Saunders
Elsevier, St Louis, MO. pp. 25–41.

Further Reading
Bennett, A.F and Dawson, W.R. (1976)
Metabolism, in Biology of the Reptilia,

Volume 5, Physiology A (C. Gans and W.R.
Dawson, eds). Academic Press, London,

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Reptile Medicine and Surgery in Clinical Practicepp. 127–211.Bentley, P.J. (1976)
Osmoregulation, in Biology of the Reptilia,
Volume 5, Physiology A (C. Gans and W.R.
Dawson, eds). Academic Press, London,
pp. 356–408.
Dantzler, W.H. (1976) Renal Function, in
Biology of the Reptilia, Volume 5, Physiology
A (C. Gans and W.R. Dawson, eds).
Academic Press, London, pp. 447–496.
Evans, H.E. (1986) Reptiles: introduction andanatomy, in Zoo and Wildlife Medicine, 2ndedn (M.E. Fowler, ed.). W.B. Saunders,Philadelphia, PA, pp. 108–132.
Fox, H. (1977) The urogenital system of
reptiles, in Biology of the Reptilia, Volume 6,
Morphology E (C. Gans and T.S. Parsons,eds). Academic Press, London, pp. 1–122.
Holz, P.H. (1999) The reptilian renal–portal
system: influence on therapy, in Zoo andWild Animal Medicine, Current Therapy,
4th edn (M.E. Fowler and R.E. Miller, eds).
W.B Saunders, Philadelphia, PA,
pp. 249–252.
Holz, P.H. Barker I.K., Burger J.P. et al (1997)
The effect of the renal portal system on
pharmokinetic parameters in the red eared
slider (trachemys scripta elegans). Journalof Zoo and Wildlife Medicine, 28 (4),386–393.
King, G.M. and Custance, D.R. (1982) The
Lizard, in Colour Atlas of Vertebrate

Anatomy. Blackwell Scientific, Oxford,
pp. 4.1–4.10.
Minnich, J.E. (1982) The use of water, in
Biology of the Reptilia, Volume 12,
Physiology C. Physiological Ecology (C. Gans
and F.H. Pough, eds). Academic Press,
London, pp. 325–386.
Ottaviani, G. and Tazzi, A. (1977) The
lymphatic system, in Biology of the Reptilia,
Volume 6, Morphology E (C. Gans and T.S.
Parsons, eds). Academic Press, London,
pp. 315–458.
O’Malley, B. (2005) Clinical Anatomy andPhysiology of Exotic Species: Structure andFunction of Mammals, Birds, Reptiles andAmphibians. Elsevier Saunders,Philadelphia, PA.
Pincheira‐Donoso, D., Bauer A.M., Meiri S.
and Uetz P. (2013) Global taxonomic
diversity of living reptile. PLOS One, 8 (3),e59741.
Pough, F.H., Andrew, R.M., Cadle, J.E. et al.
(1998) Herpetology. Prentice Hall,Englewood cliffs, NJ.
Perry, S.F. and Duncker, H.R. (1978) Lungarchitecture, volume and static mechanics infive species of lizards. Respiratory
Physiology, 34, 61–81.
Pough, F.H., Janis, C.M. and Heiser J.B. (2002)
Vertebrate Life, 6th ed. Prentice Hall,Englewood Cliffs, NJ. pp. 270–341.

33

3
Behaviour in the Wild and in Captivity
Robert Johnson­Introduction
Little has been written on the behaviour ofcaptive reptiles that is useful for the practising veterinarian. It is important that the clinician is able to distinguish between normallyoccurring behaviours and what is pathological. Owners and keepers may report behaviours as unusual when they are not. Animal
behaviour, together with structure and function, are the three phenotypic manifestations
shaped through natural selection and adaptation. It can be difficult to distinguishbetween pathophysiological responses andnormal ethological components of reptilian
behaviour. Often, disease will manifest as adirect result of behavioural factors. Observed
behaviours in reptiles are often directly
related to thermoregulatory and other physiological requirements. This chapter highlights some unique features of reptilian
structure, function and behaviour pertinent
to the exotic animal consultation.

­Normal Needs
and Behaviour of Captive
ReptilesThe physical, social and behavioural requirements of captive reptiles have been described(Greenberg 1992):

Box 3.1 A hierarchy of reptilian needs.
Homeostasis:
SafetySociality

Social dominance:
Reproductive
success:

Thermoregulation,
nutrition, water balance.
Predator evasion,
hibernacula.
Daily or seasonal social
behaviour (predatory
behaviour, social andreproductive behaviour,
migration for food or
reproductive sites, torpor).
Does the animal manifest
priority of access to valued
resources (Figure 3.1)?
Fitness, fecundity.

(Greenberg 1992)

Inextricably linked with this hierarchy ofneeds is the issue of animal welfare. Generalcriteria for the welfare of captive animals havebeen previously described in the literature as
the ‘five freedoms of animal welfare’ (freedom
from hunger and thirst, discomfort, pain,
injury and disease, fear and distress, and freedom to express normal behaviour). Trends in
captive animal management are now moving
beyond the five freedoms towards a life worth
living. The absence of suffering is not necessarily good welfare. Animal care needs to be
directed at more than mere survival, minimum standards or ability to reproduce.
Keeping standards should include validated

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

34

Reptile Medicine and Surgery in Clinical Practice

Figure 3.1 Male eastern water dragonassuming a dominant posture.

Figure 3.2 An outdoor enclosure provides a natural environment for a red‐bellied black snake.

enrichments, replacing negative experienceswith positive ones (Figure 3.2).

­Physiological Responses
Health problems in captive reptiles can be
related to an aspect of reptilian physiology or
behaviour rather than to a primary disease
process. Physiology and structure–function

relationships have been shown to be important principles of normal species‐specificbehaviour. Physiological parameters to beconsidered when assessing normal behaviourin captive reptiles are thermoregulation, postprandial metabolism, olfaction, vision, chemosensation, water exchange, feeding response,
digestion, respiration and circulatory factors(see Chapter 2 for more detailed information).
Consequently, disease in captive reptiles isBehaviour in the Wild and in Captivity

more often than not a manifestation ofincorrect or inappropriate husbandry practices affecting these processes.
Body Temperature and Ectothermy
Reptiles are termed ‘ectothermic’ because
they are dependent upon external heatsources rather than internal heat production.
Unlike in endothermic animals such as mammals and birds, metabolic heat production in
reptiles is usually insufficient to raise thebody temperature significantly above that of
the ambient surroundings. Two importantconsequences of ectothermy are highly relevant to husbandry.
First, energy use derived from food or
fat stores is lower because metabolic heat is
not required to maintain body temperature.
The food requirement is further loweredby behaviours that entail relatively long periods of inactivity. The extent to which foodrequirements are connected with both bodytemperature and activity varies with species
and the circumstances of captivity. Weightloss due to excessive energy expenditure
related to ‘escape’ or exploratory activity canoccur while in new or inadequate enclosures,with conspecific aggression or related stressand disease or parasitism. Collectively, thesesigns are termed maladaption.
Second, reptiles are not poikilothermic(cold‐blooded) and most are capable ofvery precise thermoregulation by behaviour.
Maintaining a prolonged constant body temperature is not required physiologically inmost cases and can be harmful. Variabilityof body temperature has importance withrespect to species variation, seasonal acclimatization, feeding and nutrition, activity
reproduction and disease.
Thermoregulation can occur by:
movement between a heat source (e.g.
­sunlight, warm substrate) and a heat sink(e.g. shade, water, burrow)●● postural adjustments (e.g. changes inbody volume, shape orientation, posture;
Figure 3.3)●● physiological responses (e.g. heat production in muscle tissues in some species,●●

Figure 3.3 A juvenile perentie thermoregulating in a spread‐eagled posture.

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Reptile Medicine and Surgery in Clinical Practicecolour changes, circulatory changes andventilatory adjustments to increase water
evaporation from mucous membranes).
At high temperatures reptiles may pant or
gape. Captive animals should not be kept inconditions where they are exposed to hightemperatures without the opportunity of‘behavioural avoidance’. Conversely, at temperatures below the regulated range reptiles
become torpid and sluggish and digestionceases.
Preferred Body Temperature
Care of reptiles requires knowledge of theunique thermal requirements of a species.
Preferred body temperature is species, andsometimes subspecies, dependent. In captivity, diurnal and/or arboreal species requirea radiant heat source, whereas nocturnallyactive and/or predominately terrestrial species may avoid a photothermal (light and heat)source and may prefer a thermally variable
substrate or subfloor heating. In most cases,
however, a daily thermal cycle or behaviouralaccess to thermal variation is desirable(Figure 3.4). Decreased environmental temperature plus a reduced photoperiod will
stimulate oogenesis and spermatogenesis.
Snakes and lizards become more aggressivewith higher temperatures, especially above
the preferred body temperature.
Body Temperature and Disease
Inappropriate thermal exposure can suppress the immune systems of reptiles andcan operate in conjunction with other formsof stress imposed by captivity. The inability
to cool below activity temperatures forprolonged periods can affect appetite­
and reproduction. Bacterial infections can
induce reptiles to select a body temperatureseveral degrees above ‘normal’ levels.
Elevated body temperature enhances thesurvival of animals infected with a potentially lethal pathogen. It is therefore bad­husbandry to cool sick reptiles.

Figure 3.4 A shingleback skink is freely able tomove to or away from a heat source.

Light and Photoreception
Both the quality and quantity of light haveimportant consequences for the physiology
and health of captive reptiles (see Chapter 6
for more detailed information). The eyes are
the main receptors for light; however, thepineal gland (the third eye) and possibly theskin also have some role to play. Annual
cycles of day length may affect appetite,metabolism and reproduction. However,environmental temperature rather than lightappears to be the more influential factor
affecting reproduction.
Unlike their mammalian counterparts,
nocturnal snakes have small eyes comparedwith diurnal snakes. Geckos and most nocturnal mammals have large eyes, owing totheir sole reliance on vision. Nocturnal hunters (snakes) rely upon a combination of scent,heat and vision (Figure 3.5). Most snakes andlizards have well‐developed vision as well as achemosensory system. Recent studies revealthat reptiles may perceive ‘light‐flicker’, such

Behaviour in the Wild and in Captivity

Figure 3.5 Common tree snakes arenocturnal hunters (courtesy of M.
Wilson).

as that produced by ultraviolet lights connected to alternating current sources (Wooet al. 2009).
Chemoreception and Acoustic
Sensation
Chemoreception in reptiles uses a combination of the olfactory system, taste buds (notin all squamates) and the vomeronasal system. Most squamates use visual and chemical signals for communication (geckos also
use acoustic signs). Crocodiles also respondto acoustic stimuli. Chemoreception occurs
in reptiles by tongue‐flicking over the vomeronasal organ – paired sensory organs in the
rostral aspect of the upper mouth (Figure 3.6).
Tongue‐flick rate is an accurate and proportional measure of a snake’s level of interest in
its environment, particularly while searching
Figure 3.6 A yellow‐faced whip snake
tongue flicking.

for food. Tongue‐flicking of captive elapids
often indicates that they are about to defaecate. Flicking usually ceases once eliminationis complete. Tongue‐flicking may also be asign of distress. Some keepers recommend
not cleaning a hide box too scrupulously,
leaving an odour for the snake to sense.
Other keepers recommend the keeping of asmall amount of faeces in a pot within thevivarium to satisfy the olfactory needs of thecaptive reptile.
Water Exchange and Humidity
Reptiles lose water by evaporation across theskin and respiratory membranes and by
excretion (urine and faeces). Evaporation may
account for more than half of the total water
loss. As a result, exposure of captive reptiles
to inappropriate levels of ambient humidity

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Reptile Medicine and Surgery in Clinical Practice(if terrestrial) or salinity (if aquatic or amphibious) can alter hormone levels, cause weightloss and suppress reproduction.
Digestion and Nutrition
The rate of feeding varies with a multiplicity
of factors, including species, animal size, age,temperature, activity, reproductive status,
season, disease, parasite burden and stress. Ifa ‘healthy’ reptile habituated to captivity
refuses food, the item should be removed
until the next scheduled feeding.
Gastrointestinal transit times vary from
species to species. While some reptiles, especially skinks, produce faeces within hours of
feeding, others may retain faeces for months.
Passage of faeces is facilitated by warmth andactivity. Retention of gut contents can aid inwater absorption. Recently fed reptiles needwarmth and seclusion. Digestion ceases at
low temperatures and food can putrefy in thegut of a cool animal.
Respiration and Circulation
Temperature change, excitement, activity
and ecdysis can produce marked changes in
respiration.
Pain and Stress
Pain perception and stress in reptiles and theresultant physiological responses are not wellunderstood. For example, handling is a common stressor in captive reptiles. Improper
handling, in addition to crowding and poor
hygiene, can produce physiological deterioration leading to reduced growth, suppressed
reproductive capacity and increased mortality from disease. Often, sick animals presented for veterinary examination have ahistory of over handling. Similar to birds andmammals, reptiles in pain will often exhibit
aggressive behaviour. Snakes suffering frommite infestation will seek water for soaking toease their discomfort.

­Behaviour Patternsof Captive Reptiles
Behaviour patterns may be divided into
maintenance and distance‐reducing behaviours. Captive environments can easily create
behavioural and spatial restrictions, leading
to maladaptive reactions such as hyper‐ andhypoactivity, co‐occupant aggression, variable environmental temperature preferences,interaction with transparent boundaries,
aggression and adaptability.
Maintenance Behaviours
Maintenance behaviours include feeding andthermoregulatory responses.
FeedingPrehension, chewing

The scleroglossa (geckos,
snakes and monitor lizards) have prehensile
jaws and actively seek out foods via sensory
capabilities. Iguania (iguanas, chameleons)lack these characteristics and wait for the foodto come to them. They capture food with theirsticky tongues.

Heat sensing pits Most pythons, except thereptile eaters (Aspidites spp., womas andblack‐headed pythons) possess heatsensing (labial) pits, small indentations in
the upper and lower jaws. These infrared
sensory organs work in conjunction withthe visual system in seeking prey. It is also
thought that infrared imaging systems
may also be used for finding basking sites
and shelter.

Pythons, usually ambush
hunters, strike violently when prehending
their prey. The food item is thenconstricted and swallowed. Womas andblack‐headed pythons, being reptile‐eating
ground dwellers, will often push prey
items up against a firm surface instead of
constricting them, an adaptive behaviour
useful in a burrow, where there is insufficientspace for constriction.

Constriction

Behaviour in the Wild and in Captivity

Envenomation Elapids (most of the Australian
venomous snakes) will strike and then release,following the prey for a few minutes after theattack to consume it. Some venomous snakes,
such as brown snakes, constrict as well. It has
been proposed that this is due to the shortfangs in this species. Colubrid snakes will
swallow prey items live in the wild.
Captive Feeding Routines

In order to train pythons to strike only at prey
items, thereby reducing potential distress or
injury to keepers, it is preferable to feed snakes
in a container separate from their enclosure.
The pythons should be accustomed to handling by gentle lifting with a probe or jigger
every one to two days. The snake becomesused to being handled and lifted from its
enclosure and will usually not strike. Despite
being social reptiles, bearded dragons, especially juveniles, may need to be fed separately.
Males tend to ‘bully’ females, dominating thefood supply. Turtles often bite each other when
feeding, particularly on the hind limbs and tail.
Hyperactivity and Hypoactivity

Reptiles will become hyperactive at ambient
temperatures above their preferred bodytemperature. Signs of heat stress will become
evident if the temperature increases above atolerable level. These signs include panting
and mouth gaping in lizards, hyperactivity,
escape behaviour and seeking the point furthest from the heat source. Hypoactivity
will occur when reptiles are kept below theirpreferred body temperature or preferred
optimal temperature zone.
Distance‐Reducing Behaviour
Distance‐reducing behaviours include aggregation, courtship and mating, post‐ovipositional, territorial, combat and anti‐predator
behaviour.
Social or Solitary?

It is important to know which species arenaturally gregarious and which prefer to besolitary. Sometimes reptiles within one genus

39

will display wide variations in social behaviour. Bearded dragons can be successfully
kept in a harem situation with one male andseveral females; however, two males willoften fight when placed in the same enclosure. Cannibalism is common in Antaresia
species (children’s pythons etc.), Aspidites
species (womas and black‐headed pythons)and most of the Elapidae.
Head Bobbing, Hand Waving, Digging,
Tail Whipping

Bearded dragons of both sexes ‘head bob’ andwave their forelimbs. Males do it more vigorously. Females are more submissive and tend to
mimic the behaviour of their male cage mate.
Courtship and Mating

After a period of cooling to stimulate spermatogenesis, males of most species of reptile will
eat and enter a period of hyperactivity andmate‐seeking behaviour. Males will also engage
in mock combat. Snakes, monitors and skinks
particularly show this behaviour. The beards ofmale bearded dragons turn black when they
are sexually mature and active.
The Gravid State

A gravid python will typically expose its
ventrum and shiver periodically. Pre‐­­
ovipositional anorexia is common. Dragons,­chameleons, monitors and turtles will exhibit
digging behaviour just prior to oviposition.
Egg laying usually occurs within 24 hours.
Often, pythons will become restless after­oviposition and egg removal. Artificial eggs
or egg shells from earlier clutches can be
introduced to settle the snake.
Maternal Incubation

Morelia spp. are particularly good at maternal incubation of eggs. The snake will wrap
around its eggs and shiver sporadically. The
eggs may be left alone for extended periods
as the female basks opportunistically andthen returns to the eggs, maintaining them at
a temperature of 29–30 °C and a humidity of
approximately 65%. The female may not eat

40

Reptile Medicine and Surgery in Clinical Practiceduring the incubation period and will become
protective and more aggressive.

behaviours may be more prevalent during
handling or attempts at handling, such as:

Mock Combat●●

Male reptiles of many species engage in ­ritualor mock combat. This is particularly prevalent
in lizards, monitors (Varanidae) and elapid
snakes (Elapidae) and normally occurs in themating season (Figure 3.7). Male pythons‘pace’ the enclosure when they are ready tomate, appearing as if they are hungry. Defensive

catalepsy, tonic immobility
tail flicking, tail autotomy●● eversion of hemipenis or phallus●● excretion of faeces, urine, urates, scentgland excretion (turtles)●● bluff and threat displays (Figure 3.8)●● colour change●● shedding skin●●

Figure 3.7 Two adult male lace monitors engaged in mock combat.

Figure 3.8 Shingleback skink in a bluff
defensive posture.

Behaviour in the Wild and in Captivity

Figure 3.9 Excessive constriction
when handling is an indicator of stress.

constricting, balling (Figure 3.9)
withdrawal of head, limbs and tail(chelonians)●● striking or attacking.
●●●●­Fitness and Environmental
Enhancement
Lack of fitness appears to have a negative
effect on normal physiological responses
in captive reptiles. Attention should be paid
to the captive environment to maximize
the opportunity for snakes to move aroundthe exhibit and maintain muscle tone andstrength.
Figure 3.10 Captive green pythons
spend much of their time perching.

Pythons
While most species of pythons spend a substantial part of the time on the ground, several species are also climbers, such as Morelia
spilota (carpet and diamond pythons). In
captivity, the opportunity to climb is notoften provided. Captive pythons are predisposed to dystocia. Decreased muscle tone,
reduced strength and lack of fitness may be
mitigating factors in this process.
Green Pythons
In captivity, green pythons spend most of thetime coiled on a perch (Figure 3.10). Thesesnakes are much more active in the wild,

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Reptile Medicine and Surgery in Clinical PracticeTable 3.1 Signs of comfort and discomfort in captive reptiles (adapted from Warwick 1995).
ComfortDiscomfort

Alertness

Hyper‐alertness

Relaxed state

Escape attempts, repeated inflation/deflation cycles

Calmly smelling or tasting objects

Mock or actual attacks

Subtle changes in body posture‘Clutching’ object or handler

Gradual body movements and locomotion

Feigning deathModerate to relaxed grasp on handler

Hiding head

Normal to relaxed breathing

Inflation of the bodySleeping

Rapid gular pulsation

Absence of signs of discomfort

Open‐mouth defence posture
Open‐mouth breathing
Defecation with handling
Projection of penis or hemipenis
Regurgitation
Vocalization (crocodile, gecko)
Pigmentation change

preferring to move or climb vertically as theyhunt or seek a mate. Suggestions for improving captive conditions include the provisionof more opportunities to climb. Enclosurestend to be very sterile and not enriching.
Keepers of this species tend to be more
focused on providing the perfect temperature and humidity and little else. Offering athermal mosaic could stimulate snakes tomove around the cage more.

­Signs of Comfort
and Discomfort
The comfort or discomfort of a captive
reptile may be determined by assessing forthe presence or absence of certain behavioural and physiological responses(Table 3.1).

References
Greenberg, N. (1992) The saurian psyche
revisited: lizards in research, in The Careand Use of Amphibians, Reptiles and Fish in
Research (D.O. Schaeffer, K.M. Kleinow and
L. Krulisch, eds), Scientists Center for
Animal Welfare, Bethesda, MD, pp. 75–91.
Warwick, C. (1995) Psychological andbehavioural principles and problems, in

Health and Welfare of Captive Reptiles(C. Warwick, F. Frye and J.B. Murphy, eds),
Chapman and Hall, London, pp. 205–238.
Woo, K.L., Hunt, M., Harper, D. et al.
(2009). Discrimination of flicker
frequency rates in the reptile tuatara(Sphenodon). Naturwissenschaften, 96 (3),415–419.

Behaviour in the Wild and in Captivity

Further Reading
Bradley, T. (2002) Reptile behaviour basics forthe veterinary clinician, in Proceedings,
Association of Reptilian and Amphibian
Veterinarians Annual Conference, Reno,
Nevada. Association of Reptilian andAmphibian Veterinarians, Reno, NV,
pp. 165–170.
Gillingham, J.C. (1995) Normal behaviour, in
Health and Welfare of Captive Reptiles,(C. Warwick, F. Frye and J.B. Murphy, eds),
Chapman and Hall, London, pp. 131–164.
Green, T.C. and Mellor, D.J. (2011) Extending
ideas about animal welfare assessment toinclude ‘quality of life’ and related concepts.
New Zealand Veterinary Journal, 59 (6),263–271.
Greer, A. (1997) Pythonidae – Pythons, in The
Biology and Evolution of Australian Snakes,
Surrey, Beatty and Sons, Chipping Norton,
NSW, pp. 24–83.
Hernandez‐Divers, S.J. (2000) Reptile
behaviour, in Proceedings, Association of
Reptilian and Amphibian Veterinarians
Annual Conference, Reno, Nevada,
Association of Reptilian and Amphibian
Veterinarians, Reno, NV, p. 183.
Lillywhite, H.B. and Gatten, R.E. (1995)
Physiology and functional anatomy, in
Health and Welfare of Captive Reptiles(C.Warwick, F. Frye and J.B. Murphy, eds),
Chapman and Hall, London, pp. 5–31.
Lock, B.A. Behavioural and morphologic
adaptations, in Reptile Medicine andSurgery, 2nd ed. (D.R. Mader ed.). Elsevier,
St Louis, MO, 2006, pp. 163–179.
Luz, S, Keil, R., Meyer, W. and Martelli,P. (2002) Diagnosis of some common
diseases in snakes, with respect to theunderstanding of disease‐induced behaviouralchanges. Proceedings, European Associationof Zoo and Wildlife Veterinarians (EAZVW)
4th Scientific Meeting, joint with the annual
meeting of the European Wildlife Disease
Association (EWDA) May 8–12, 2002,
Heidelberg, Germany.
Pough, F.H. (2003) Communication, in
Herpetology, 4th ed. (F.H. Pough, R.M.
Andrews, J.E. Cadle, et al.). Prentice Hall,
UpperSaddle River, NJ.
Warwick, C. (1990) Reptilian ethology incaptivity: observations of some problems
and an evaluation of their aetiology. Applied
Animal Behaviour Science, 26, 1–13.
Warwick, C., Frye, F.L. and Murphy, J.B. (1995)
Introduction: Health and welfare of captive
reptiles, in Health and Welfare of Captive
Reptiles (C. Warwick, F. Frye and J.B. Murphy,eds), Chapman and Hall, London, pp. 1–4.

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4
Husbandry and Nutrition
Michelle Kischinovsky, Aidan Raftery and Shivananden Sawmy­Introduction

Behaviour and Environmental
Enrichment

A large percentage of disease in reptiles canbe referred back to inadequate husbandry
and/or nutrition. A fundamental understanding of the requirements, habits andbehaviours of the presented species isessential to provide optimal veterinary careand to improve chances of recovery.

Historically, captive reptile environments
were only enriched to provide more interesting viewing but, increasingly, the welfare
value of enrichment is being recognized (seeChapter 3 for more details). Reptiles provided with environmental enrichment are
more active and develop increased physicalskills. The enrichment needs to be appropriate to the species to increase choices available to stimulate normal behaviour, at thesame time allowing the reptile some control
over their environment.

Ectothermy
Ectothermy is the ability of an animal to regulate its body temperature by moving
between the different temperature zones in
its environment. This is in contrast to endotherms, which rely mainly on the heat frominternal metabolic processes to control bodytemperature. All reptiles are classed as ectotherms but some are able to generate enoughmetabolic heat to raise their body temperature above that of the surrounding environment; for example, the incubation behaviourof some python species. Female pythons coilaround the clutch of eggs and if the ambient
temperature drops they shiver, producing
heat and maintaining the eggs at an eventemperature.

­Basic Concepts
Housing
The captive environment should mimic thenatural habitat. The shape and interior designof the enclosure will depend on whether the
animal is arboreal, terrestrial, semi‐aquatic
or aquatic, so knowledge of the natural history of the species is essential. As a generalrule, arboreal species should have a morevertical enclosure with furniture and foliage

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

46

Reptile Medicine and Surgery in Clinical Practicefacilitating climbing and shelter, whereas­terrestrial species require more horizontal
space, with objects and substrate allowing forhiding and digging or burrowing. The size ofthe enclosure will be dependent on:
the species; for example, some very active
snakes such as racers (Coluber spp.), gartersnakes (Thamnophis spp.)and corn snakes(Pantherophis guttatus), may need a larger
space than less active snakes, such as boas
and pythons, of similar body length●● the size of the animal (at time of acquiring
and as it grows)●● the number of animals housed together●● whether it is a breeding pair (potential offspring and breeding facilities)●● whether the same sex conspecifics are present (a larger enclosure will be required for
territories; see conspecifics section).
●●

Enclosure heat and humidity should be controlled to mimic the natural preferences ofthe species. The enclosure should also belarge enough to accommodate a temperature
gradient (horizontally or vertically), basking
lights or spots, furniture and feeding bowls, a
retreat box and appropriate environmental
enrichment objects (see Chapter 3 for behaviour and Chapter 5 for enclosure design). For
aquatic and semi‐aquatic species, the enclosure should be large enough to house a land
and a water area, as well as a water filteringsystem. Some aquatic species may require asubmersible water heater.
The opening of the enclosure should besituated to allow easy and stress free retrievalof the reptile from the vivarium, as well aseasy access for feeding and cleaning without
risk of the animal escaping. Non‐climbing
species, such as turtles and tortoises, areoften housed in enclosures without tops. An
effective and secure closing mechanism isimportant as some reptiles, especially snakes,
have a remarkable tendency to squeeze
through seemingly impossibly small gaps.
Venomous and dangerous species should be
kept in a locked enclosure.
The positioning of the enclosure should beconsidered. Some reptiles thrive in habitats

exposed to sunlight and high humidity, whileothers prefer shadier environments and good
ventilation, such as many chameleon species.
Species such as the African spurred tortoise(Centrochelys sulcata) and many lizards,
aquatic and semi‐aquatic turtles can, where
the climate is appropriate, be kept in outdoor
enclosures or ponds.
Environmental Enrichment
A stimulating habitat will, in most cases,
enable the reptile to be more active and­encourage natural species‐specific behaviours such as foraging, hunting, hiding andburrowing (see also Chapter 3). This encourages exploration of the environment. Any
objects potentially harmful if ingested should
be securely placed or fastened. Knowledge ofthe species natural habitat and routines areinvaluable. The environment should be safe;
there should be no harmful materials or toxic
plants and any large objects such as rocks
should be fixed.
Mentally stimulating activities for all reptiles include foraging and the stalking of prey.
Natural scent trails can be made by burrowing or dragging a prey item through theenclosures of snakes and carnivorous lizards.
Insectivores can be fed a variety of different
live insects, some winged, jumping and burrowing, for stimulation. Live fish and worms
can be released for aquatic species and otherpartially aquatic reptiles such as garter snakes(Thamnophis spp.) and Chinese water dragons (Physignathus cocincinus). Omnivores andherbivores can be offered whole leaves andgreens, still on their stalks or suspended high
up to allow mimicking tearing food frombushes or trees.
The habitat should aim to stimulate thesenses by varying temperatures, light andhumidity to mimic natural conditions
throughout a day. Social reptiles benefit frombeing housed with conspecifics, althoughknowledge of their social structure is imperative to avoid aggression or stress. Some may
benefit from enclosures co‐inhabited withother compatible species, such as arboreal

Husbandry and Nutrition

lizards with terrestrial tortoises, choosing
species that have similar climate requirements
and no risk of transmissible pathogens.
HygieneGood hygiene is good husbandry. Faecal
material, urates and any uneaten food should
be removed on a daily basis. The importanceis greater when dealing with decaying plantor animal feed. Removing leftover or uneaten
live insects from the enclosure also allows forthe monitoring of appetite and the task functions as part of a daily survey of the animals
overall wellbeing. Additionally, some insect
species will bite the reptile if not removed
from the enclosure.
Some enclosure materials are easier tomaintain and disinfect than others. Artificial
plants are ideal in a hospital setting but maylack visual appeal and enrichment. Some­natural materials commonly used, such as
plywood, are difficult to disinfect if not correctly sealed with a waterproofing agent. An
easily cleaned and inexpensive substrate suchas newspaper or paper towelling should be
used for sick animals.
If the humidity, temperature gradient orventilation are incorrect, growth ofunwanted pathogens (bacteria or fungus)
may occur – even if the substrate or foliage
is not harmful to the animal.
Good hand hygiene is indispensable, both
before and after animal handling, not only tolimit the risk of zoonotic infections but also
to prevent cross‐infection of other animals.
Healthy animals should be handled or treatedfirst and the sick or immunocompromised
last. Excessive cleaning may remove naturally
occurring healthy environmental organisms,
may disturb the animals unnecessarily, causing a stress response which may lead to
immunosuppression.
While adequate caging and environmental
enrichment are imperative for the maintenance of a healthy and thriving animal in a
private, zoo or school collection, the facilities
provided in a hospital setting have different
goals. Short‐term patients will tolerate astark environment, although humidity andheat should be provided and carefully controlled, especially given that sick reptiles
often do not thermoregulate properly. The
entire enclosure, furniture and its substrateshould be easily cleaned out and disinfected.
Water Quality
Water must be available to all species at all
times. Snakes will often drink out of a bowl,
in which they often also submerge themselves (to aid shedding). Lizards and tortoises often rehydrate themselves whensoaked in water baths but will readily learn
to drink out of a shallow bowl in their enclosure. Some lizards, such as the crested
geckos (Correlophus ciliatus) and anoles(Anolis spp.) tend to lick condensing water
droplets off the sides of the enclosure after
misting, whereas water drippers with catch
systems are ideal for chameleons.
Good water quality is fundamental for theheath of aquatic species. Semi‐aquatic andaquatic reptiles must be able to submerge
themselves fully. Many reptiles defecate in
the water. Turtles and some lizards andsnakes will forage in or use water to facilitate
swallowing and, in doing so, will leave fooddebris, which can act as a nidus for pathogens. Constant insults to the water can cause
rapid changes in the salinity and pH levels
and can increase nitrogen levels, which canpromote unfavourable algae and bacterial
blooms. Contaminated water or poor water
quality may lead to disease.
As aquatic reptiles tend to produce morewaste than fish, a high‐quality water filteringsystem is advised. This can be chemical, biological or mechanical, and often a combination of the latter two is used. The water must
be dechlorinated where there is biologicalfiltration.
The frequency of cleaning of water dishes
and pools will largely depend on the stocking
density, temperatures, quality of the filtration
system and the frequency and type of feed. A
subjective visual assessment of the water canbe made but even though it may look clean,

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Reptile Medicine and Surgery in Clinical Practiceit can still house excessive amounts of nitrogenous and bacterial waste. Readily available
commercial water testing kits are recommended. Feeding the reptile in a separate
container outside the enclosure can limit thefrequency of water changes required.
Conspecifics
The majority of reptiles are solitary by natureand interact only with conspecifics during
the breeding season. They will often form
hierarchies, with the high‐ranking animals
sometimes competing for the best basking
spots, feed or retreat sites, which may cause achronic state of stress in lower‐ranking animals or may even causing physical injuries.
Males are usually more territorial, and more
so in the presence of another male; thisis especially true during breeding season.
Sexually mature male green iguanas (Iguana
iguana) have been known to exhibit very
offensive aggression during breeding season(December to March in the northern hemisphere) and have even been known to attack
human owners during this period. Extra careshould be taken when handling large lizard
or snake species. It is not uncommon for lizards to tolerate living together for a numberof years and then to exhibit aggressive behaviour when reaching sexually maturity.
For the species tolerating social housing,one male should generally be kept with several
females to avoid sexual dominance aggression(for more information, see Chapter 3).

­Transport
Transport requirements will depend on thejourney distance, species, size and number ofindividuals and, importantly, the ambient
temperature. Reptiles must be provided withadequate ventilation during transport andkept warm (24–30 °C) while avoiding overheating. A thermometer should be used tomonitor temperature. Improvised containers

such as a jar or cardboard box with air holes
punched in the lid or commercial rodent carriers can be used. Insulated containers are
best, such as a commercial purpose‐ orhomemade polystyrene or cooler box, to help
to prevent the temperature from rising above
30 °C. All reptiles should be placed in an
escape‐proof container; for example a cloth
bag tied with a knot placed within a securebox for snakes. A hot‐water bottle wrappedin a towel (to ensure that there is no directcontact between the animal and the heatsource) should be placed inside the container.
Each animal should have some form of identification, such as a tag or microchip and,
when transporting multiple reptiles, several
boxes can be placed inside one larger insulated container. The containers should besecure in the transport vehicle to reduce therisk of trauma and movement. Note thatvenomous species should be transported
in clearly labelled, locked, containers,
together with the necessary documentation,anti‐venom and envenomation emergency
protocol (also see Chapter 10).

­Handling and Restraint
for Feeding and Husbandry
PurposesPlease refer to the reptile consultation(Chapter 10) and clinical techniques(Chapter 13) chapters for a detailed description of handling and restraint techniques forveterinary examination purposes. Please
note that only the chelonians and squamates
are covered in this textbook.

­Sex Identification
Sex identification of reptiles can be challenging, especially with juveniles. Some species
exhibit varying degrees of sexual dimorphism. Please refer to Chapter 7 for further
information.

Husbandry and Nutrition­Preventative Health Care
Key considerations for maintaining captive
reptiles in good health include the following:
Research the desired species prior toacquisition.
●● Source new animals from a reputable andethical source. Avoid purchasing wild‐caught animals (illegal in some countries)
as they are more likely to carry parasites
and will be less capable of adapting into
captivity.
●● Maintain good husbandry and nutritional
practices that mimic those in the wild
where possible.
●● Keep good records.
●● Maintain effective biosecurity and quarantine protocols.
●● Have an experienced reptilian veterinarian
examine the animals on a regular basis.
●●

Quarantine
A quarantine protocol should be in place forany reptile collection. All new acquisitions
should be quarantined for a minimum of six
months. Quarantine periods need to be constantly reviewed according to the most recent
information available. See Chapter 16(Infectious Diseases and Immunology) for
further details.
New arrivals should be kept in a separate
room with dedicated equipment and cage
furniture. Owners or keepers should adhere
to strict biosecurity measures such as footbaths, wearing disposable gloves and effective hand sanitization. Shower and change
clothes between units and manage the
newly acquired animals last during thedaily routine.
Quarantined reptiles should be kept under
optimum husbandry conditions and regularly monitored for their appetite, behaviourand defecation. Prior to acquisition, eachindividual reptile should ideally have had an
examination and ancillary diagnostic tests, as
determined by a veterinarian experienced

with reptiles. This may not be performed inpractice, so each specimen should undergoa full clinical examination, husbandry review
and diagnostic tests while in quarantine.
Faecal screening for pathogenic protozoa
and helminths should be performed (seeChapter 31). Haematology, biochemistry
and infectious disease screening should
be considered where applicable for, forexample, herpesvirus, inclusion body disease, ­sunshine virus, ferlavirus, adenovirus(see Chapter 16).
Record Keeping
Good record keeping allows the owner,
keeper or veterinarian to recognize signsof ill health at an early stage, to address
suboptimal husbandry and environmental­
parameters and may allow retrospective
identification of a problem. It is essential tokeep a detailed record of environmental
parameters such as temperature, humidity
and ultraviolet light emission (and the frequency that the light bulb needs changing).
Animals should be weighed regularly using
accurate digital scales. Weight checks priorto, during and post‐hibernation in tortoises
are essential, for example.
Behavioural changes, clinical signs, appetite and frequency of defecation (including
anomalies in consistency and colour) should
be noted. Frequency of cleaning and disinfection or alterations to cage furniture should
be logged. Measurements such as total lengthand snout‐to‐vent length in squamates andcarapace length in chelonians can be usefulfor monitoring growth and body condition.

­Nutrition
Reptiles have evolved to fill many ecologicalniches, resulting in large variations in dietaryrequirements. As a general rule, reptiles canbe divided into herbivores, omnivores andcarnivores.

49

50

Reptile Medicine and Surgery in Clinical Practice

Herbivory
There are no herbivorous snakes. The green
iguana is the most common herbivorous lizard species seen in many parts of the world.
A large pitfall of herbivorous diets in captive reptiles is the inability of many keepers
to provide the correct calcium to phosphorus
ratio, which should be greater than two toone, and the appropriate level of calcium inthe diet. Table 4.1 lists the greens that arecommonly fed. Romaine and red lettuce varieties are often recommended but these plants
have inadequate calcium to phosphorus
ratios and a relatively low calcium content.
The herbs listed in the table have a very highcalcium to phosphorus ratio and a very highcalcium content.
Oxalates are often stated as having aneffect on the availability of the calcium in thediet. There are no studies looking at the
impact of the oxalate content in the diet ofherbivorous reptiles. Oxalates are broken
down by bacteria in the gut of herbivorous
mammals, releasing the calcium for absorption. Levels of oxalates found in the commonly fed plants listed here should not cause
any problems.
Brassicas (plants in the cabbage family)
contain varying amounts of thiocyanate
which can interfere with iodine uptake.
Hypothyroidism is, however, very rarely
diagnosed in reptiles.
The reptile diet should be a mixture of different plant types. Care should be taken to
ensure that a variety is actually eaten and thatthe animal does not selectively feed. Dietaryimbalances will show up quickly in rapidly
growing juveniles and reproductively active
females. Other adult individuals may takemonths or years for some deficiencies tocause obvious clinical signs.

the omnivores commonly presented for treatment are eating a mixture of plant material
and invertebrates. From Table 4.2 it can beseen that the calcium content of the commonly fed invertebrates is very low and there
is a negative calcium to phosphorus ratio.
The one exception in the chart are phoenix
worms, the larvae of the black soldier fly,although there are concerns about the digestibility of their calcium content.
Good care of the invertebrates before feeding will help convert them into a more balanced food item. The feeder invertebrates are
best fed a formulated diet that is fortified
with calcium and vitamin A. Much of the calcium in the insect diet is not absorbed fromthe gastrointestinal tract so, with a short gut
transit time, they need to be eaten within anhour of feeding.
Most plants contain high levels of vitamin
A so hypovitaminosis A is only seen in reptiles that are predominantly insectivorous.
Carnivory
Some chelonians, some lizards and all snakes
are carnivores. Carnivorous reptiles can bedivided up into those feeding predominantly
on vertebrates and those feeding on invertebrates. The limitations of a largely invertebrate diet are covered in the section onomnivory. Nutritional imbalances involving
calcium and phosphorus are unlikely tooccur when the diet is largely vertebrate species. Thiamine deficiency and obesity are themost commonly seen nutritional disorders
with a diet of vertebrates (see Chapter 15).
Hypovitaminosis A is relatively common in
insectivorous reptiles. Obesity is also a common problem in carnivorous reptiles, largelya result of overfeeding, although reduced
activity will also play a part.

Omnivory
Many lizard and chelonian species are omnivorous. There are no omnivorous snakes. The
main challenges of an omnivorous diet are
the calcium content, the calcium to phosphorus ratio and the vitamin A content. Most of­Snake Nutrition
Nutritional disorders are rarely reported
in snakes as they are generally fed a whole
prey item, which is usually a nutritionallyTable 4.1 Commonly fed greens.

Vegetable/herb

Calcium(mg/100 g)

Phosphorus(mg/100 g)

Ca : P ratio

Vitamin A(iu/100 g)

Fibre(g/100 g)

Carbohydrate(g/100 g)

Protein(g/100 g)

Water(g/100 g)

Parsley138

58

2.4 : 1

8424

3.3

6.33

2.97

87.71

Cos/Romaine

33

30

1:1

8710

2.1

3.29

1.23

94.61

Red

33

28

1:1

7492

0.9

2.26

1.33

95.64

Iceberg

18

20

1:1

502

1.2

2.97

0.9

95.64

Cabbage

40

26

2:1

98

2.5

5.8

1.28

92.18

Kale

150

92

1.5 : 1

9990

8.8

4.3

Cress

81

76

1:1

6917

1.1

5.5

2.6

89.4

Dandelion

187

66

3:1

10161

3.5

9.2

2.7

85.6

Pak choi

105

74

1 : 0.7

4468

1

2.1

1.5

95.32

Broccoli

47

66

1 : 1.5

623

2.6

6.64

2.82

89.3

Spinach

99

49

2:1

9377

2.2

3.63

2.86

91.4

Turnip greens

190

42

4.5 : 1

11587

3.2

7.13

1.5

89.67

Marjoram (dry)

1990

306

6:1

8068

40.3

60.56

12.66

7.64

Thyme

405

106

4:1

4651

14

24.45

5.56

65.11

Tarragon (dry)

1139

313

3.5 : 1

4200

7.4

50.22

22.77

7.74

Spearmint

199

60

3:1

4054

6.8

8.41

3.29

85.55

Lettuce:

Source: US Department of Agriculture Food Composition Database.
Ca, calcium; P, phosphorus.

Table 4.2 Commonly fed invertebrates.

Species (cricket house)

Calcium(mg/100 g)

Phosphorus(mg/100 g)

Ca : P ratio

Vitamin A(iu/100 g)

Acheta domesticus

40.7

295

1 : 7.25< 100

Mealworm larvae

16.9

285

1 : 16.86< 100

Superworm larvae (Zophobas
morio)

17.7

237

1 : 13.39

Waxworm (Galleria mellonella)

24.3

195

1 : 8.02

Phoenix worm (Hermetia illucens)

934

356

2.62 : 1

Source: modified from Latney and Clayton 2014.

Crude fat(g/100 g)

Crude protein(g/100 g)

Water(g/100 g)

6.8

20.5

69.2

5.4

23.7

61.9

< 100

17.7

19.7

57.9

< 100

24.9

4.13

31.4

14

17.5

61.2

Husbandry and Nutrition

complete package. Mammalian prey items(usually thawed rabbits, rats and mice) arefed, even though some of the more commonly kept reptile species feed on reptiles in
the wild. They will usually readily accept
mammals, especially if this is the only foodprovided from hatching. Some species ofsnakes eat mainly invertebrates in the wild
but these species are very rarely maintainedin captivity. Only humanely killed preyshould be fed.
Overfeeding leading to obesity is a common problem in snakes. The prey item fed
should be approximately equal to or slightly
greater than the diameter of the snake at thelevel of its stomach. Feeding frequency will
depend on the species of snake, its age andreproductive status. Some species are more
active and feed more frequently; for example,
the colubrids, whereas, in general, boas andpythons feed less frequently as they are lessactive. Juvenile animals need to feed more
frequently because of their increased growthrequirements. Larger snakes will eat muchlarger prey and, depending on size, may only
feed every one to three months. Gartersnakes mainly eat amphibians and fish in thewild. In captivity, they are commonly fed fish
and thiamine deficiency may result (seeChapter 15).
Anorexia is a common presenting sign insnakes. Investigation of an anorexic snake
should start with a thorough clinical examination together with an evaluation of thehusbandry.
Clean water should always be available.
The water bowl should be large enough toallow the snake to soak. This is especially
important for some species, such as theshort‐tailed pythons.

­Lizard Nutrition
Whether terrestrial or arboreal, lizards can
be classed as herbivorous, omnivorous or
carnivorous, with the vast majority being
insectivorous (Table 4.3). Research is stilllacking on the natural diets of some captive
species. Some reptiles with a preferential
food source in the wild may thrive well in
captivity on an alternate or commerciallymanufactured diet. There may be seasonalvariation of dietary choices, which should
aim to be replicated in captivity. Knowledgeof the lizard’s natural diet is essential.
Herbivores
The commonly kept green iguana (Iguana
iguana), chuckwallas (Sauromalus spp.),spiny‐tailed lizards (Uromastyx spp.) andless so the prehensile‐tailed skinks (Corucia
zebrata) are considered primary herbivores.
They thrive on a plant‐based diet throughout life and rely on hind‐gut fermentation
to digest these high‐fibre diets. Some otherlizards generally considered herbivorous
have undergone an ontogenetic shift froma carnivorous diet as juveniles towards herbivory as adults. There may also be variation in the type of foliage consumed as ajuvenile compared with the adult stage.
A variety of fresh chopped greens darkgreen and leafy vegetables can be fed andsome may benefit from high‐protein foods
such as beans, peas or lentils (Table 4.2).
Many species tolerate fruit in their diets, aswell and flowers and nectar, is preferential
for some. Although still considered truly herbivorous, some have been known in the wild
to occasionally supplement their diet witheggs or insects and in captivity these areoften provided.
Some commercially available diets are sufficient for certain commonly kept species.
Additional supplements (calcium, minerals
and vitamins) can be added to the diet whereindicated. Some herbivorous species have avery specialized diet, eating only one kind ofplant or fruit; for example, many anoles only
eat nectar. Some plants, flowers or vegetables
may be toxic to lizards. Avocado, rhubarb,
eggplant, tulips, daffodils and azaleas have all
been suggested as toxic but little is known ofthese effects; so if uncertain, then it is best toomit from the diet.

53

54

Reptile Medicine and Surgery in Clinical PracticeTable 4.3 Commonly presented lizard species based on preferred food categories (food list not extensive).
Diet typeSpecies

Suggested diet

Herbivorousa

Green iguana (Iguana iguana)

Leafy greens, mixed vegetables and fruits,squash, peas, beans and alfalfa hay

Prehensile‐tailed skink (Corucia
zebrata)

Generally as above

Chuckwalla (Sauromalus spp.):Mixed vegetables and fruits, squash, peas,
flowers; occasional insects or egg

Common chuckwalla (S. ater)
Spiny‐tailed lizard (Uromastyx spp.)
Mali uromastyx (Uromastyx (dispar)
maliensis)
Omnivorous

Bearded dragon (Pogona spp.):
Inland bearded dragon (Pogona
vitticeps)

Mixed leafy greens, flowers, seeds, carrots, sweet
potato and squash; occasional insect
Approx. 60% invertebrates, 40% vegetable
matter; juveniles more carnivorous than adults

Rankin’s bearded dragon (Pogona
henrylawsoni)
Argentine tegu (Salvator merianae)

Approx. 50% fruits and 50% whole vertebrates,
invertebrates, egg; juveniles require more protein

Veiled chameleon (Chamaeleo
calyptratus)

40–70% invertebrates and 30–60% vegetable
matter (more so adults)

Water dragon:

80–95% invertebrates and 10–15% vegetable
matter; occasional small fish, snails and rodents

Chinese water dragon (Physignathus
cocincinus)
Eastern water dragon (Intellagama
lesueurii lesueurii)
Crested gecko (Correlophus ciliatus)

Mainly invertebrate insects; soft and pureed fruit
baby food or custom blends

Giant day gecko (Phelsuma grandis)

Generally as above

Blue‐tongued skink (Tiliqua spp.)

Approx. 50% vegetables, 25% fruits and 25%
invertebrates (mainly snails)

Carnivorous:
Vertebratesb

Bosc’s (or savannah) monitor (Varanus Rodents (mice, rats), large insects, snails, fish
exanthematicus)

Invertebratesc Green anole (Anolis carolinensis)

Primarily invertebrates; rarely will eat small
amount of fruit and vegetables

Leopard gecko (Eublepharismacularius)

Mixed invertebrates

Fat‐tailed gecko, African fat‐tailed
gecko (Hemitheconyx caudicinctus)

Mixed invertebrates

Jackson’s chameleon (Trioceros
jacksonii)

Mixed invertebrates

Panther chameleon (Furcifer pardalis) Mixed invertebratesa

For example, vegetables, leafy greens, fruits, flowers, beans, lentils, seeds, nectar.
For example, mice, rats, gerbils, day‐old chicks.
c
For example, beetles, hoppers, roaches, worms, flies, snails, crustaceans.
bHusbandry and Nutrition

Omnivores
Most lizards are omnivorous, with some having a more herbivorous diet and others amore carnivorous. The majority of the carnivorous portion of the diet comprises invertebrates (insects), although some of the larger
lizards will occasionally eat small rodents,
chicks or other prepared meat. Often, owners will feed a few select insect species, so
advice should be given to promote feeding ofa highly varied diet. Feeding a uniform or
unsuitable diet may lead to nutritional disorders (see Chapter 15 for more details).
Most lizards that feed on invertebrates willreadily eat a wide variety of insect species. A
general invertebrate diet typically includes a
selection of cockroaches, crickets, grasshoppers, locusts, larvae, flies and worms (mealworms, silkworms, phoenix worms, giant
mealworms, waxworms; Table 4.3). Somewill eat earthworms, snails, spiders, beetles,
moths and other wild caught insects. Most
lizards respond to movement, so feeding live
and well‐nourished invertebrates (as discussed in the omnivory section) is goodpractice. Generally, the size of the prey item
should be no larger than the distance between
the lizard’s eyes. Insects not consumed in one
sitting should be removed as some are known
to inflict bites.
Juvenile bearded dragons and tegu species
rely on a more carnivorous diet and will shift
towards a less protein‐rich diet as theymature. Some skinks and geckos, such as theday gecko (Phelsuma spp.) and the crested
gecko (Correlophus ciliatus), have uniquenutritional requirements and commonly
include fruit and nectar in their diet. In captivity, this is commonly substituted withsweet fruit puree and fruit‐flavoured baby
food, although proprietary fruit and nectar
foods are available.
Carnivores
Lizards that feed purely on other vertebrates(mammals, birds or other reptiles) are notcommonly kept as pets. The Bosc’s monitor(Varanus exanthematicus), also known as

the savannah monitor, is a lizard commonly
encountered as a pet, which almost exclusively feeds on vertebrate prey. The Tokay
gecko (Gekko gecko), with its opportunistic
feeding habits, will readily eat small rodents
and lizards as well as invertebrates. Most
monitors, chameleons, collared lizards,
anoles, basilisks, skinks and geckos have a
predominantly invertebrate diet, describedin more detail in the ‘omnivore’ section.
All vertebrate feed should be dead andserved fresh or rapidly thawed. All feed,
including uneaten invertebrates, should be
removed if not consumed within a sitting, as
they will decay or may bite and inflict injury
on the lizard.

­Chelonian Nutrition
Chelonians can be herbivorous, carnivorousor omnivorous (Table 4.4). Terrestrial chelonians are typically entirely herbivorous oromnivorous, while aquatic species tend be
mostly omnivorous or carnivorous. Certain
herbivorous species may also have opportunistic omnivorous habits. Herbivorous chelonians are hind‐gut fermenters, with microbial
fermentation of ingesta occurring in the large
intestines. The gut flora also produces digestible energy from fibre, additional microbial‐
derived protein and volatile fatty acids bymodifying plant material.
The ideal diet for captive chelonians should
mimic that of the species in the wild. The key
to nutritional management of captive chelonians is to avoid dependence on one or two
food items. Nutritional disorders arise frompoorly balanced or unsuitable diets, as well
as from poor husbandry. In theory, a balanced diet and appropriate husbandry should
preclude the use of dietary supplements.
However, it is often recommended that all
captive chelonians should be supplemented
with calcium and appropriate vitamins tocounteract the (likely) limitations of theirdiet and husbandry. All chelonians should
also be offered regular access to fresh water
for drinking and bathing.

55

56

Reptile Medicine and Surgery in Clinical PracticeTable 4.4 A classification of commonly presented chelonians based on diet and habitat.
Habitat

Herbivores

Omnivores

Carnivores

Terrestrial

Horsfield’s tortoise (Testudo
horsfieldi)

Red‐footed tortoise(Chelonoidis carbonaria)

None

Hermann’s tortoise(T. hermanni)

Yellow‐footed tortoise(C. denticulata)

Spur‐thighed tortoises(e.g. T. graeca)

African hingeback tortoises(Kinixys spp.)

Marginated tortoise(T. marginata)Elongated tortoises(Indotestudo spp.)

African spurred tortoise(Geochelone [Centrochelys]
sulcata)
Leopard tortoise (G. pardalis)
Indian star tortoise (G. elegans)
Aldabra Giant tortoise(Aldabrachelys gigantea)
Radiated tortoise (G. or
Astrochelys radiata)
North American gopher
tortoises (Gopherus spp.)
Green sea turtle (Chelonia
mydas)
Semi‐aquatic and None
Aquatic (marine)
species

Red‐eared slider (Trachemys
scripta elegans)

Long‐necked turtles(Chelodina longicollis)

Map turtles (Graptemys spp.) Snapping turtles(Chelydra spp.)
Asian leaf turtle (Cyclemys
dentata)Matamata (Chelus
fimbriatus)

American side‐necked turtles Soft‐shelled turtles(Platemys spp.)(Trionyx spp.)
Short‐necked turtles(Emydura spp.)

Terrestrial Chelonians
Herbivores

To avoid selective feeding and to meet theirnutritional requirements, herbivorous tortoises should be fed a wide variety of plantsrich in fibre, minerals such as calcium, andvitamins (e.g. A and D3). The calcium tophosphorus ratio of the diet should be 1.5–2
to 1. Additionally, the diet should be low inprotein (Table 4.5).
Herbivorous tortoises should ideally be
fed daily with a variety of mixed vegetation

supplemented with a multivitamin and mineral supplement. All food items should bethoroughly washed prior to feeding to
remove any potential toxic residues. The useof commercial pelleted diets is currently notrecommended as a complete diet because of
their high protein content, which can cause
an abnormally rapid growth and selective
feeding in some species of tortoises.
Omnivores

Captive omnivorous chelonians (terrestrial
and aquatic species) do well when fed plantHusbandry and Nutrition

Table 4.5 A rough guide to feeding common terrestrial herbivorous chelonians.
Category

ExamplesComments

GreensGrass

Grass can be used as a food source only by some species
Rhubarb should never be offered due to its toxic oxalate
content

Kale
RocketWatercress
Dandelion leaves
and flowers
Spring greens
Cabbage
SpinachForage andwild plants

CloverEnsure that no poisonous plants are present

Nasturtium
Rose
BramblePlantain
NettlesLilac

and animal matter in proportions ranging
from 50 : 50 to 90 : 10, depending on species,
age and habitat variations. Just like herbivorous tortoises, terrestrial omnivorous chelonians should be fed a wide variety of food items
and it is essential to avoid items too high inanimal protein (and hence phosphorus) as
they can cause abnormal carapacial and bone
growth. Supplementation with a high calcium
and vitamin powder is recommended tomaintain a good calcium to phosphorus ratio,
since some food items, such as insect pupae
and larvae, are high in phosphorus but low in
calcium. They may also be dusted with calcium immediately prior to feeding but dustingon its own is not sufficient.
Semi‐Aquatic Chelonians
The majority of semi‐aquatic chelonians areomnivorous and exploit a wide variety offood sources in their natural habitats.
Feeding recommendations for terrestrial
and semi‐aquatic chelonians are provided inBox 4.1. Most juveniles tend to be carnivorous but consume a higher proportion ofplant material as they mature; for example,
adult red‐eared sliders (Trachemys scripta
elegans) become increasingly more herbivorous. Nutritional imbalance and disease canresult if semi‐aquatic chelonians are fed
meat, fish pieces or prawn‐only diets andthus multivitamin and calcium supplementation must be provided if they are offeredthese food items. Adult semi‐and aquaticchelonians should only be fed two to fourtimes a week, depending on species and life
stage, as obesity is common. Many semi‐aquatic species will not eat unless they are
fed in water. It is recommended to use a separate feeding tank to avoid soiling the maintank with uneaten food. Some species prefer
to consume partly decomposed vegetation
instead of fresh food items.
Aquatic Chelonians
Aquatic chelonians are initially carnivorousas hatchlings but become omnivores once
they reach adult life (Box 4.2). Obligate carnivores include certain marine species, suchas loggerhead turtles (Caretta caretta) and57

Box 4.1 A general guide to feeding terrestrial and semi‐aquatic omnivorous chelonians.
Vegetation (greens; 50–90% of diet)
Collard greens
Mustard greens●● Dandelion●● Chard●● Kale●● Parsley●● Squash●● Carrots●● Broccoli●● Spinach●●●●

Animal protein (10–50% of diet)●●

Invertebrates (e.g. earthworms, crickets,
waxworms, woodlice, slugs, silkworms andsnails)Raw whole fish (e.g. sardines)
Whole mice●● Pinkies●● Trout pellets (soaked)●●●●

Comments
Whole fish are nutritionally more complete
compared with gutted fish and should beoffered periodically to provide vitamin A.
●● Adult mice are nutritionally superior to pinkies.
●● Cat and dog foods can have particularly highfat and vitamin D3 contents and should be
avoided or only fed occasionally, as they cancause soft tissue mineralization.
●● Commercial turtle flakes (rich in dried
shrimp) may lack vitamins and minerals.
●●

Box 4.2 Selected food preferences for carnivorous aquatic chelonians kept in captive
environments.
Freshwater species:
Long‐necked turtles (Chelodina longicollis)●● Snapping turtles (Chelydra spp.)●● Matamata (Chelus fimbriatus)●● Softshell turtles (Apalone spp.)●●

Preferred foods:
Mice●● Earthworms●● Shrimp (with shells)●● Trout●● Slugs●● Snails●● Wild‐caught invertebrates●● Day‐old chicks●● Trout chow●● Turtle flakes●● Tubifex worms●● Waxworms●● Mealworms●● Grasshoppers●●

Comments:
Ideally feed whole vertebrate prey items.
●● Insects should only be a minor part of the diet.
●● Occasionally, a variety of greens and aquaticplants can also be offered.
●● Commercial turtle and fish diets are poor
nutritional substitutes, so should only be fed
in minimal amounts.
●●

Marine species:
Green sea turtle (Chelonia mydas; the only
herbivorous sea turtle)●● Hawksbill turtle (Eretmochelys imbricata)●● Loggerhead turtle (Caretta caretta)●●

Preferred foods:
Crustaceans●● Molluscs●● Sea grasses●● Algae●● Trout pellets●●

Comments:
Captive sea turtles will eat fish, crustaceans,
and molluscs and may be acclimated to­balanced diets in pellet or gelatin form.
●● A fish‐based multivitamin containing thiamine (25 mg/kg of fish) and vitamin E(100 iu/kg of fish) should be provided daily.
●● In the wild:○○ Green sea turtles feed on sea grasses andalgae.
○○ Loggerhead, Kemp’s ridley and Olive r­ idley
turtles prey on molluscs and crustaceans.
○○ Hawksbills prefer sponges.
○○ Leatherback turtles specialize on jellyfish.
●●Husbandry and Nutrition

freshwater chelonians, such as soft‐shell­turtles (Apalone spp.), with the latter species
also consuming a small amount of vegeta-tion. Obesity is common in captive adultaquatic chelonians, so they should only be
fed three to four times a week.

Reference
Latney, L. and Clayton, L. (2014) Updates onamphibian nutrition and nutritive value ofcommon feeder insects. Veterinary Clinics

of North America: Exotic Animal Practice,
17 (3), 347–367.

Further Reading
Almli, L.M. and Burghardt, G.M. (2006)
Environmental enrichment alters the
behavioral profile of ratsnakes (Elaphe).
Journal of Applied Animal Welfare Science,
9 (2): 85–109.
Barten, S.L. (2006) Lizards, in Reptile Medicine
and Surgery, 2nd ed. (D.R. Mader, ed.).
Elsevier, St Louis, MO, pp. 59–77.
Berger, S., Martin II, L.B., Wikelski, M. et al.
(2005) Corticosterone suppresses immune
activity in territorial Galápagos marine
iguanas during reproduction. Hormones andBehavior, 47 (4), 419–429.
Boyer, T.H. and Boyer, D.M. (2006) Turtles,
tortoises, and terrapins, in Reptile Medicine
and Surgery, 2nd ed., (D.R. Mader, ed.).
Elsevier, St Louis, MO, pp. 78–99.
Burghardt, G.M. (2013) Environmental
enrichment and cognitive complexity inreptiles and amphibians: concepts, review,
and implications for captive populations.
Applied Animal Behaviour Science, 147(3–4), 286–298.
Calvert, I. (2004) Nutrition, in BSAVA Manualof Reptiles, 2nd ed. (S.J. Girling and P. Raiti,eds). British Small Animal Veterinary
Association, Gloucester, pp. 18–39.
Calvert, I. (2004) Nutritional problems, in
BSAVA Manual of Reptiles, 2nd ed. (S.J.
Girling and P. Raiti, eds). British Small
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pp. 289–308.
Chapple, D.G. (2003) Ecology, life‐history, andbehavior in the Australian Scincid genus

Egernia, with comments on the evolution ofcomplex sociality in lizards. Herpetological
Monographs 17: 145–180.
Cooper, J.E. (2010) Terrestrial reptiles: lizards,
snakes and tortoises, in The UFAW
Handbook on the Care and Management ofLaboratory and other Research Animals, 8thed. (R. Hubrecht and J. Kirkwood, eds).
Wiley‐Blackwell, Oxford, pp. 707–730.
Dierenfeld, E. and King, J (2008) Digestibility
and mineral availability of Phoenix worms,
Hermetia illucens, ingested by mountainchicken frogs, Leptodactylus fallax. Journalof Herpetological Medicine and Surgery, 18:
100–105.
Donoghue S. (2006) Nutrition, in Reptile
Medicine and Surgery, 2nd ed. (D.R.
Mader, ed.). Elsevier, St Louis, MO,
pp. 251–298.
Eatwell, K. (2010) Lizards, in BSAVA Manualof Exotic Pets: A Foundation Manual, 5th ed.
(A. Meredith and C. Johnson‐Delaney, eds).
British Small Animal Veterinary
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Ernst, C. and Barbour, R. (1989) Turtles of theWorld. Smithsonian Institution Press,
Washington, D.C.
Flanagan, J.P. (2015) Chelonians (Turtles,
Tortoises), in Fowler’s Zoo and Wild Animal
Medicine, Volume 8. (R.E. Miller and M.E.
Fowler, eds). Elsevier Saunders, St Louis,
MO, pp. 27–37.
Ganesh, C.B. and Yajurved, H.N. (2002) Stressinhibits seasonal and FSH‐induced ovarian

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292 (7), 640–648.
Gardner, M.G., Pearson, S.K., Johnston, G.R.
and Schwarz, M.P. (2016) Group living insquamate reptiles: a review of evidence forstable aggregations. Biological reviews of theCambridge Philosophical Society, 91(4),925–936.
Gramanzini, M., Di Girolamo, N., Gargiulo S.
et al. (2013) Assessment of dual‐energy
x‐ray absorptiometry for use in evaluating
the effects of dietary and environmental
management on Hermann’s tortoises(Testudo hermanni). American Journal of
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Greenberg, N., and Crews, D. (1990) Endocrineand behavioral responses to aggression andsocial dominance in the green anole lizard,
Anolis carolinesis. General and Comparative
Endocrinology, 77, 246–255.
Jessop, M. and Bennett, T.D. (2010) Tortoises
and Turtles, in BSAVA Manual of Exotic
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Meredith and C. Johnson‐Delaney, eds).
British Small Animal Veterinary
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Johnson, J.H. (2004) Husbandry and medicineof aquatic reptiles. Seminars in Avian andExotic Pet Medicine, 13 (4), 223–228.
Klaphake, E. (2010) A fresh look at metabolicbone diseases in reptiles and amphibians.
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McArthur, S., Wilkinson, R., Meyer, J., et al.
(2004) Medicine and Surgery of Tortoises
and Turtles. Blackwell Publishing, Oxford.
Mans, C. and Braun, J. (2014) Update oncommon nutritional disorders of captive
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Reptilia, order Squamata, (lizards): iguanas,tegus, in Biology, Medicine, and Surgery ofSouth American Wild Animals (M.E. Fowler
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Norton, T.M. and Walsh, M.T. (2012) Sea
turtle rehabilitation in Fowler’s Zoo andWild Animal Medicine: Current Therapy,
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O’Malley, B. (2005) Clinical Anatomy andPhysiology of Exotic Species. Saunders‐Elsevier, St. Louis, MO.
Polis, G.A. and Myers, C.A. (1985) A Survey of
intraspecific predation among reptiles andamphibians. Journal of Herpetology, 19 (1),99–107.
Raftery, A. (2004) Clinical examination, in
BSAVA Manual of Reptiles, 2nd ed. (S.J.
Girling and P. Raiti, eds), British Small
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(A. Meredith and C. Johnson‐Delaney, eds),
British Small Animal Veterinary
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Rossi, J.V. (2006) General husbandry andmanagement, in Reptile Medicine andSurgery (D. R. Mader, ed.), St Louis, MO,
Saunders, pp. 25–41.
Silvestre, A.M. (2014) How to assess stress in
reptiles. Journal of Exotic Pet Medicine, 23(3), 240–243.
Varga, M. (2004) Captive maintenance andwelfare, in BSAVA Manual of Reptiles, 2nded. (S.J. Girling and P. Raiti, eds), British
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Gloucester, pp. 6–17.
Wilkinson, S.L. (2015) Reptile wellness
management. Veterinary Clinics of North
America Exotic Animal Practice, 18,
281–304.

61

5
Enclosure Design
Michael McFadden, Deborah Monks, Bob Doneley and Robert Johnson­Introduction
Before acquiring any reptile species, carefulconsideration must be given to exactly how
the species will be housed. This must take
into account the species behaviour, size
and thermoregulatory requirements. Reptile
housing not only provides safety and secu­
rity, it also allows specific physiological needs
to be met. Being ectothermic, the provisionof heat and ultraviolet light, with appropriate
gradients for each, is crucial for reptilian
health. With these facts in mind, possibly the
first decision to make is whether the species
will be housed indoors or outdoors.

I­ ndoor or Outdoor
Enclosures
There are many advantages to housing reptiles
in indoor enclosures. They allow the keeper
better control of the reptile’s environment, as
there is no exposure to natural elements suchas rainfall or extreme fluctuations in tempera­
ture. Electrical devices such as heaters andlights can be safely employed without contact
with water, and the temperature within thefacility can be carefully controlled to suit the
species. Housing reptiles inside also minimizes
the risk of contact with wild reptiles or poten­
tial predators and reduces the risk posed byparasites (if managed appropriately). There are
disadvantages, however. There is a need toreplicate natural environmental cues, with theassociated cost of purchasing and maintaining
heating and lighting devices and the limita­
tions of available space.
Conversely, there is a range of benefits tohousing a species in an outside enclosure.
Heating and lighting are free and readily
available, assuming that the outdoor enclo­
sure has been positioned in a location where
the reptiles have access to sunlight for at least
eight hours a day and the species being kept isfrom a climatically similar natural environ­ment. By accessing natural sunlight, it pro­vides the reptiles with a much better source ofultraviolet B than that provided by artificial
light sources. Outdoor enclosures permit the
species to be exposed to numerous cues (e.g.
natural photoperiod and seasonal variationsin temperature) that can stimulate normal
behaviours, including feeding and reproduc­tion. They are less restricted on space thanindoor enclosures. Possibly the primary dis­advantage is that outdoor enclosure use is

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

62

Reptile Medicine and Surgery in Clinical Practicelargely limited to those species found in asimilar climatic zone, otherwise artificial
heating may need to be provided.
Almost any species of reptile can be main­tained in an indoor enclosure assuming thatall vital needs, such as spatial requirements,
adequate basking sites and the provision ofultraviolet B light, are met. Smaller species
can be much easier to maintain indoors,
owing to their smaller spatial needs and therelative ease of providing temperature gradi­
ents. Larger species, such as large monitorsand crocodilians, require much larger enclo­
sures. However, this can be achieved success­fully, as demonstrated by many zoos.
Species most suitable for outdoor enclo­
sures are those that have evolved in a climate
similar to that where the enclosure is located.
Care must be taken to consider humidity,rather than just temperature, as housing arid
species in humid coastal environments may
result in respiratory infection during thecooler months. Other species may be kept
outdoors as long as careful attention has been
paid to ensure their requirements are met.
For example, a tropical or sub‐tropical species
may be kept outdoors in a temperate environ­ment assuming that additional basking sites
and night heating have been provided.

­General Housing
Considerations
When designing enclosures, both indoors
and out, there are some basic points to con­sider: location, design, construction materi­als, access, furniture, heating and lighting.

provide basking areas within each enclosure.
Enclosures should generally be raised off thefloor, to prevent the cold being absorbed
from below, especially if facility flooring is
concrete.
Direct sunlight directed on a glass enclo­
sure can quickly raise the temperature topotentially lethal levels. This mistake issometimes made by those erroneously
believing that sunlight through a window will
provide for the ultraviolet needs of the rep­tile, unaware that the ultraviolet light is fil­tered out by glass or plastic.
Outdoor

Outdoor enclosures are best positioned
where they will receive direct sunlight for atleast eight hours per day, allowing ther­
moregulation and providing access to natural
ultraviolet light. Both basking areas andshade must be provided to allow the animal
to thermoregulate. In those species in whichbreeding is anticipated, appropriate nestingsites (with appropriate substrate) should be
provided (Figure 5.1).
Turtles, crocodilians, some agamids andsome snakes are aquatic or require regularaccess to water. Stagnant water will cause
numerous hygiene issues, so most outdoor
enclosures have a pond and a filtration sys­
tem both to remove particulate waste and toaerate the water. Regular water testing is stillrequired, as is pond cleaning. Water loss due
to evaporation needs to be carefully moni­
tored, as this will concentrate soluble waste
products within the water.
DesignIndoorLocation
Indoor

It is best to locate enclosures within a well‐insulated room that does not fluctuate greatly
in temperature. To make heating more costeffective, some larger hobbyists will heat aroom to a minimum optimum body temper­
ature for the species being housed and thenThe ultimate design of any reptile enclosure
will be largely dependent on the natural his­
tory and behaviour of the species being kept.
Before designing an enclosure, it is impor­tant to research the key life history attributesof the species. This includes whether it is ter­
restrial or arboreal, to help to determine
whether a horizontal or vertical enclosure isrequired. Determine whether it is nocturnal

Enclosure Design

Figure 5.1 This outdoor enclosure offers great basking opportunities (courtesy of Robert Johnson).

or diurnal, which greatly affects how to opti­
mize the heating of the enclosure. Other
attributes, such as whether the species is par­tially aquatic or fossorial, is assessed as thiswill influence whether a focus should bemade on providing a sizable water body or asuitable deep substrate.
The size of a reptile enclosure can be quite
variable, depending on the species. There are
no distinct rules that determine the size of an
enclosure and the it can vary greatly, even
within a genus or between species of thesame size. However, there do exist minimum
enclosure requirements in some jurisdic­
tions. An ideal enclosure is large enough toallow the reptiles within it to exhibit natural
behaviours, including basking, hiding, move­
ment (whether terrestrial or arboreal) andthe ability to use a temperature gradient.
Care should be taken not to provide an
enclosure that is too large. Unfortunately,

many well‐meaning new keepers often pro­vide their juvenile pythons with a large, open
enclosure with a basking light for heat. Thesejuvenile snakes inevitably occupy a shelter at
a suboptimal temperature and refuse to feed.
A smaller enclosure, particularly with several
hides, will usually make a younger snake feel
more secure, thus allowing it to feel safe
while feeding and thermoregulating.
OutdoorHousing a reptile outdoors usually allows fora larger, better ventilated enclosure. These
enclosures need to be predator and pest
proof, secure against both reptile escapeand unauthorized human entry, provide
adequate access to heat and light and suffi­
cient protection from extremes of tempera­ture, especially heat. The presence of aerial
predators such as crows or hawks may
necessitate roofing.

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Reptile Medicine and Surgery in Clinical Practice

If the enclosure is well positioned, electric­
ity costs can be reduced by permitting thereptiles to bask in natural sunlight, rather
than supplying artificial ultraviolet light andheating. It should be noted that animals
housed outdoors may still require someheated areas.
Construction Materials
Indoor

The selection of materials for indoor enclo­
sures depends on the species, the desired
enclosure design and the climatic conditions
within the room in which it will be located.
Factors that can often guide a decision on
choice of materials include the weight of thematerials, cost, insulation properties andhow easy it is to clean and disinfect. Three ofthe most commonly chosen materials to con­struct enclosures are glass, plastic and tim­ber. Although commonly used, caution
should be applied when employing materials
that may swell when exposed to moisture,including melamine, chipboard and medium‐
density fibreboard (MDF).

Glass is one of the most commonlyused construction materials for reptile
enclosures. It can be aesthetically pleasing
and is commercially available in a wide rangeof sizes, largely due to the aquarium trade.
Traditionally, glass reptile terraria werepurchased as fish tanks. If using a fish tank fora lizard or snake, great care must be taken to
ensure that the lid will adequately contain thereptile, as most fish tanks are not sold withtight‐fitting, well‐ventilated lids. Currently,
there is a range of glass terraria available
specifically designed for reptiles. These
include a number of attractive, front‐opening
enclosures with ventilation panels on thesides and/or roof. Aquatic turtles are usually
maintained indoors in fish tanks with dry
docking platforms. It is important that theseare stable, as unstable platforms may not be
used by the animal (Figures 5.2 and 5.3).
Disadvantages of glass include its cost,weight and insulation properties. Glass
enclosures can be quite expensive, although
the greater range of commercially available
enclosures now may ensure prices remaincompetitive. Glass is a poor insulator, so heat

Glass

Figure 5.2 This converted aquarium tank houses Nephrurus asper geckos. The easily accessible lid prevents
access of other animals into the enclosure. In this case, heating is by way of heat cord under the substrate(courtesy of Deborah Monks).

Enclosure Design

Figure 5.3 This glass reptile enclosure has inbuilt vents but can require insulation during colder seasons as
glass does not tend to retain heat (courtesy of Bob Doneley).

can be rapidly lost from an enclosure if there
is a significant difference between the tem­
perature within and outside of the enclosure.
Additionally, for nervous specimens, it ispossible that they may feel less secure in an
enclosure that is transparent on all sides.
Certain animals may not perceive glass as abarrier and may cause severe rostral rub inju­
ries through repeated abrasion while pacing.
Plastic There are a range of plastic
enclosures widely used for housing reptiles.
These include smaller plastic‐lidded
containers, plastic tubs positioned in a racksystem and commercially available moulded
plastic enclosures. They are generally light inweight, easy to disinfectant and arewaterproof. However, plastic also has anumber of disadvantages, including having
poor insulation properties, becoming easily
scratched and turning brittle or warpingwhen exposed to heat or ultraviolet light.
The smaller plastic enclosures have beensuccessfully used for juveniles or small spe­cies, such as geckos or young pythons.

However, they are generally only available insmaller sizes, restricting their use to only
small specimens. For larger specimens, there
is now a range of larger, aesthetically pleasing
moulded plastic enclosures available from anumber of suppliers. However, apart fromcost, these enclosures also have some disad­vantages. They may warp over time, affecting
the ability of the glass doors to close tightly.
In some brands, the raised front below thesliding doors can quite easily conceal a snake,making it difficult to see a specimen before
opening the enclosure. Additionally, although
the enclosures are designed to conveniently
stack on top of each other to use the space
efficiently, replacing a light globe may require
removal of all of the enclosures (Figure 5.4).
Timber is the most commonly usedmaterial for building reptile enclosures. It is
sturdy, affordable and has good insulation
properties. Timber enclosures can be built toany desired size or specification and thematerials are readily available. However, caremust be taken to ensure the timber and theTimber65

66

Reptile Medicine and Surgery in Clinical Practice

Figure 5.4 These plastic moulded enclosures are easy to disinfect (courtesy of Bob Doneley).

joins have been properly sealed to prevent
moisture directly contacting the exposed
timber, leading to the timber rotting. Marine
grade timber is often used as it is more resis­
tant to moisture and humidity as well as being
very sturdy. Exposed hardware can sometimes
cause lacerations or abrasions (Figure 5.5).
Outdoor

Although outdoor enclosures may be madeof similar materials to indoor enclosures,simply using ‘indoor’ enclosures outside
diminishes many of the benefits of housing
reptiles outdoors.
Pits: some species are amenable to being
kept in dug‐out, secured pits (Figures 5.1
and 5.6). The sides should offer limited
purchase for escape, although top covers
are often recommended to protect the ani­mals from predators.
●● Wire and wood/metal: some species, suchas arboreal snakes, do well in aviary style
enclosures made from wire mesh on
wooden or metal frame. If using wood, it isimportant that it is sealed to prevent con­tamination. It should be non‐toxic.
●●

Figure 5.5 Timber enclosure suitable for a python.
There is a range of thermal options for this snake, as
well as different substrates to increase
environmental stimulation (courtesy of Deborah
Monks).

Enclosure Design

Figure 5.6 A secure outdoor enclosure, suitable for red‐bellied black snakes (courtesy of Michael
McFadden).

Glass/Perspex: institutions displaying ani­mals to the public often use half‐length
Perspex or glass to prevent contact but
allow sight of the animals. Terrestrial ani­mals can be housed this way, althougharboreal animals may escape. It is impor­tant that there are no protuberances near
the enclosure perimeter which could be
used to assist escape.
●● Ponds: aquatic animals such as turtles andcrocodilians will require an outdoor water
source as well as land. Filtration and water
quality are discussed later in this chapter.
It is important that the water source isaccessible, with a non‐slip substrate tofacilitate entry and exit. Additionally,cleaning must be easy to accomplish andusually there needs to be some sort offiltration.
●●

Whatever construction materials are used, it
is important that there are no sharp points or
areas in which the animals may be injured ortrapped.
Access for Feeding, Cleaning when
Dealing with Venomous Reptiles

Venomous reptiles should be housed in lock­able enclosures within a locked room. Hideboxes fitted with sliding and secure doors
can serve as transport containers or as tem­porary housing during cage cleaning(Figure 5.7). The appearance of the enclosure
should strike a happy medium between pro­viding a ‘natural’ enclosure and one that is
easily maintained, and that access to thesnake is not hindered by a proliferation ofcage furniture. Front‐opening enclosures are
preferable; however, a barrier at ground level

67

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Reptile Medicine and Surgery in Clinical Practice

Figure 5.7 Venomous reptiles kept in locked enclosure (courtesy of Bob Doneley).

may need to be in place to prevent the escapeof smaller and more active species. In someregions, venomous snakes can be kept out­
doors in pits or in well‐fenced enclosures(Figures 5.1 and 5.6). Access to these areas
should be strictly controlled.
Furniture
Food and Water Dishes

Almost all species require a water dish,pond or other source of fresh water. The
exceptions are species that will only accept
water from rain or dew, including arboreal
exotic species such as chameleons, which
may need a daily spray or mist to rehydrate.
Even so, water sources will add to enclosure
humidity which is important for some tropi­
cal species.
Food dishes are used for species being fed
non‐live food items. After feeding is com­plete, they should be removed and cleaned.
Additionally, food dishes may be used for live
invertebrate feeding in situations where
impaction from substrate may be a problem
or where the species cannot be tong fed andthere is a potential for the crickets to either
escape or elude the reptile.
Privacy Shelters

Most reptiles require shelters that permit
them to hide. Exceptions to this include large
or arboreal reptiles that would sleep on abranch or in the open under natural condi­
tions. A shelter will provide a sense of secu­
rity in the reptile, reducing stress levels andpermit the reptile to thrive. Some reptiles,
such as hatchling pythons, may not com­mence feeding if a shelter site is not provided.
Shelters can take many forms, including rockcaves, disposable cardboard boxes or com­
mercially sold plastic reptile hides. Shelters
must not be excessively large or animals will
not feel secure within. Entry points should be
sufficiently wide to permit twice the animal’s
width. Outdoor enclosures can also use hol­
low logs, grass and shrubbery as a more natu­
ralistic hide area.
Branches

Natural branches and vines or commerciallyavailable artificial alternatives can assist theEnclosure Design

aesthetics of an enclosure and support natural
behaviours in an arboreal reptile. Care must
be taken to secure these furnishings when
installing them, so that they do not fall, poten­
tially causing injury. Similarly for rock‐dwelling
reptiles, natural or artificial rocks can beplaced in an enclosure to facilitate basking
platforms and rock crevices in which to shel­ter. However, these must be situated carefully
so as not to collapse upon the reptile.
Plants are often difficult to maintain insidewithout appropriate plant lighting, plants do
improve the aesthetics of a cage. Often placedin aquaria, plants also fulfil a nutritional
function for some species of turtles. Plants
will often grow better in outdoor enclosures.
Other Furniture

Other pieces of cage furniture may be visu­
ally pleasing for the owner but not fulfil any
useful function for the animal. Furnituremust be sufficiently secured to avoid injury
or entrapment.
Heat Source
See Chapters 4 and 6 for a detailed discussion
on various heating options. It is worth notingthat reptiles appear to be relatively insensitive
to thermal pain, so direct contact with heating
elements must be avoided. Heating elements
should be enclosed to prevent reptiles coming
into contact with them (Figure 5.8) and heatpads and heat rocks should have a secondary
thermostat system to prevent overheating.
Insufficient heating leads to immunosuppres­sion, among other physiological issues. It isequally important to avoid overheating, as
reptiles can perish in high temperatures. Even
if the animals within an outdoor enclosure areacclimatized to the local conditions, there
should be a back‐up plan for heat provision in
the case of poor or cold weather persisting for
more than 24 hours.
Aquatic animals may need the water sources
heated, which is done most commonly using afish tank heater. As with any heating element,a secondary thermometer should be used
to check the accuracy of the heat provision

Figure 5.8 Cage to prevent direct animal access toheat lamp. This is an essential part of adequate
husbandry (courtesy of Deborah Monks).

(Figure 5.9). With some large or aggressive
animals, the heater should be caged to avoid
damage and possible electrocution.
Lighting
Ultraviolet lighting is extremely importantfor calcium metabolism in many species (seeChapter 6 for more detail). Please note thatlights can also cause burns from heat pro­duction, so should be caged if there is achance that an animal may come into directcontact with them.

69

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Reptile Medicine and Surgery in Clinical Practice

Figure 5.9 Thermometer andhygrometer (courtesy of Bob Doneley).

Table 5.1 Advantages and disadvantages of various substrate options.

Substrate

Cost

Ease of replacement
and cleaning

Visualisationof droppings

Naturalistic

Risk ofingestion

Newspaper

£

☺☺☺

Easy

No

No

Recycled newspaper
pellets (e.g. cat
litter)

£

☺☺

Easy

No

Yes

Pine chips££☺☺

Moderate

No

Yes

Coconut fibre

£££

☺☺

Difficult

Yes

Yes

Synthetic turf£££ but
multiple
use

☺☺☺

Easy

No

No

Sand

££

☺

Easy

Yes

Yes

Substrate
There are many different substrate options
for reptiles and the appropriate substrate
may vary according to time of year and clini­
cal need (Table 5.1). Animals kept without
substrate not uncommonly have difficultywith mobility, due to lack of traction. The
glare from overhead lighting reflected fromthe flooring can cause stress, especially inglass‐bottomed enclosures.
Pest Control
It is important that all outdoor enclosures are
securely pest‐proofed to ensure the safety of
the reptiles and to prevent potential escape.
Rats and mice are capable climbers and canalso dig under a wall. For this reason, allenclosures should either have a solid or meshbase or the walls must be dug at least 50 cm
into the ground. Enclosures for smaller spe­
cies should be fully enclosed to prevent
access from other predators, such as birds orcats. Depending on the local invertebrate
population and the species kept, measures
may need to be taken to protect insectivo­rous animals from ingesting poisonous orexcessively hard bodied insects.

­Breeding Racks
Breeding racks are a popular style of housing
employed by larger breeders or keepers withlarge reptile collections. They are typicallydesigned as a portable rack on wheels with

Enclosure Design

many shelves containing plastic tubs
(Figure 5.10). There are a number of instanceswhere breeding racks can be useful. They
allow for the efficient holding of a large num­
ber of reptiles in a relatively small space.
Examples of where this may be beneficial
include research programmes or for the rear­ing of large numbers of juvenile snakes.
Other advantages of using a rack include thelow electricity cost (as the enclosures are

typically heated via energy efficient heat tapeor cords) and ease of disinfection (as the tubs
are typically plastic and easy to wash).
There are, however, disadvantages associ­ated with breeding racks. It is usually notpossible to provide effective lighting to theenclosures within a rack as, in most rack
designs, lighting cannot be suspended above
the tubs, leaving room lighting as the solesource of light. For this reason, these

Figure 5.10 A small rack system, often used for housing breeding animals (courtesy of Emma McMillan).

71

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Reptile Medicine and Surgery in Clinical Practiceenclosures have only limited use in diurnal
basking species and should not be used forspecies requiring ultraviolet B. There are
extremely limited opportunities to provide
environmental enrichment to animals in
breeding racks, which may cause welfare
concerns. In the advent of a contagious dis­ease, quarantine and infection control arevery difficult to establish in a rack system.
Species most suitable for breeding racks
are typically nocturnal species. These species
are better suited to lower daytime light levels,
have lower requirements of ultraviolet B lightand naturally regulate their body tempera­ture through the ambient temperature andby resting on warm surfaces, similar to thataccessible on the heated base of a tub in abreeding rack. Such groups of reptiles can
include geckos, pythons and many elapid
snakes.
Breeding racks are especially useful forjuvenile snakes. Juvenile snakes typicallyrequire a relatively small enclosure, with suit­able hides, a water bowl and a heat gradient,with a warm spot provided by under‐floor
heating. They are also best housed individu­
ally to minimize stress and reduce the risk ofcannibalism. These needs are easily met
within a typical breeding rack, which canhouse hatchlings in an efficient manner.
The size of breeding racks is extremely var­iable. Commercial racks are available in arange of sizes from those suitable for geckos
and hatchling snakes to those that aredesigned for large pythons. Rack systems canalso be easily custom designed and con­structed around a particular size of tub thatbest suits the reptile to be kept.
Breeding racks are typically heated using
under‐floor techniques, such as heat tape orheat cord. These heating products are quite
efficient, as they have low wattage and canprovide a suitable temperature gradient
within a tub. They are usually easily installed
but in all instances where wiring is required,
always use a qualified electrician. Heat cords
may need to be recessed within the base of
the shelf of the rack to ensure that the tubs
can be easily slid into and out of the rack

without catching. It may also be necessary tohave more than one row of heat cord per
shelf, especially for medium to larger tubs, toensure that there is a suitably large heatedarea with an even heat distribution. To avoid
malfunction, a thermometer should be used
to confirm adequate heat provision, thus pre­venting both under‐ and over‐heating.
It is important to ensure that the tubs
within a rack system receive adequate venti­
lation. A lack of ventilation within an
enclosed tub can easily create conditions thatare excessively moist and humid, especiallyafter a snake urinates or if a water bowl ispartially spilled. Typically, ventilation is pro­vided by either mesh panels or drilled holes
along the sides and rear of the tub. If drilling
holes, it is imperative to ensure that the holes
are small enough that there is no risk that the
animal will fit its head through them.

­Aquatic Enclosureand Water Quality
Whether indoors or outdoors, aquatic andsemi‐aquatic species need to have access tohealthy, hygienic water, preferably with anactive nitrogen cycle. Faeces and urinary
waste products, leftover food and decom­
posing plant material release toxic ammonia.
The conversion of this ammonia to progres­sively less toxic chemicals is called the nitro­
gen cycle. Denitrifying bacteria convert
ammonia into nitrite and then nitrate, whichis removed via regular water changes orabsorbed by aquatic plants. After first add­
ing water, it takes about six weeks for a nitro­
gen cycle to completely establish. Plants andsmall amounts of organic material should be
regularly but gradually added during thistime. Filtration should be installed andactive. Water quality should be tested regu­
larly to track the establishment of the nitro­
gen cycle.
With indoor tanks, once the nitrogen cycle
is established, between 10% and 20% of thewater should be removed and replaced oncea week. This is in addition to replacing anyEnclosure Design

water loss from evaporation. Gravel orsiphon vacuums are useful, as they clean thesubstrate at the same time as removing water.
It is important to only clean between 10%
and 20% of the substrate at any one time,
avoiding disturbing large pockets of anaero­
bic bacteria and overloading the denitrifying
bacteria or reducing total levels of denitrify­
ing bacteria. Leftover food and floating fae­
ces should be removed from the tank daily.
Filtration is very important, both to remove
waste and to oxygenate the water. For indoor
aquaria, at least one large, external canister
filter is required, which will circulate three tofour water volumes per hour. Tank volume
can be calculated using the formula:length multiplied by width by height of thewater column (all in metres) volume (litres)
For outdoor ponds, a similar water flowrate is recommended. Measure the height of
the water level, not the height of the entire
tank. External filters often have three types offiltration: chemical (activated charcoal),
physical (sponge) and biological (ceramic orplastic ‘biospheres’ coated in denitrifying
bacteria). The return of filtered water to thetank is usually via a spray bar that breaks thesurface tension of the water and oxygenates it.
The internal components of the filter
should be cleaned in a bucket of tank or pond
water, never with tap water. This is to pre­serve all the good bacteria in the filter thatassist with the nitrogen cycle. Water quality
should be tested regularly, even after thenitrogen cycle is well established, as there
may be differences throughout the year.

­Summary
Ultimately, the choice of enclosure and thedesign is the owner’s choice. Species require­ments, individual behavioural needs, owner
preference for naturalistic versus utilitarian,cost and ease of maintenance all factor into the
choice. From a veterinary perspective, better‐designed enclosures will tend to lead to health­ier animals, as they supply a better microclimate
and secure options for the animals.

­Further Reading
More information on reptile enclosures canbe found in herpetocutural literature, includ­ing the Australian Birdkeeper Publications

series A Guide to … books covering different
reptile species (lizards, pythons, elapid
snakes, varanids, etc.).

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6
Lighting
Frances M. Baines­Introduction
Lighting is surely one of the most neglected
and misunderstood aspects of reptile husbandry. The provision of species appropriate
levels of full spectrum lighting is vital.
Evolutionary processes determine that optimal levels of heat, light and ultraviolet (UV)
are likely to be the ‘natural’ levels thatthe reptile experiences in its microhabitatwith favourable environmental conditions.
Reptiles self‐regulate their exposure to solar
radiation. Deviations from the optimal range
are likely to act as stressors, with negative
repercussions on health. Much attention has
been paid in the past to thermoregulationand the need for thermal gradients in thevivarium; the importance of similar, superimposed visible light and UV gradients isnow becoming more widely recognized.

­The Solar Spectrum
The part of the electromagnetic spectrum
that is found in sunlight (Figure 6.1) includes
short‐wavelength infrared (IR‐A: 750–
1500 nm), so‐called visible light (visible tohumans; 400–780 nm) and ultraviolet (UV).
Ultraviolet light is subdivided into UVA(320–400 nm) and UVB, only part of which(290–295 nm, depending upon solar altitude,

to 320 nm) is present in sunlight, since earth’s
atmosphere blocks hazardous shorter wavelengths (UVB below 290 nm and all UVC)
from reaching the surface.
Infrared
Short‐wavelength infrared (IR‐A) is responsible for the warming effect of sunlight.
During its passage through the atmosphere,
water vapour absorbs certain wavelengths
strongly, so that when it reaches earth’s surface it is ‘water filtered’. This naturally filtered
IR‐A penetrates deeply through the skinwithout excessive heating of water moleculesin the tissues. Basking reptiles absorb water‐
filtered IR‐A extremely effectively; solar radiation may pass right through the dorsal skinto the internal organs of small‐bodied specimens. IR‐A also warms the surface of theearth, which re‐radiates in far longer wavelengths (IR‐B and IR‐C; 1400–1,000,000 nm).
Long‐wavelength infrared does not penetrate
the epidermis. Its heat energy is absorbed
entirely by the upper layers of the skin, fromwhich it must be conducted or carried byconvection in bodily fluids to deeper tissues.
This type of radiation is absorbed from warm
surroundings by the ventral skin of the reptile; where the skin is in contact with substrate, heat transfer by conduction also takes
place. Infrared is invisible to humans andReptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

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Reptile Medicine and Surgery in Clinical Practice

Figure 6.1 The solar spectrum is part of the electromagnetic spectrum which extends from around 290–
295 nm (depending upon solar altitude) in the UVB range, to 1500 nm in the short‐wavelength infrared.

most reptiles, although some snakes can perceive the longer wavelengths (above 3000 nm)
through their facial pit organs.
Visible Light and Ultraviolet A
Retinal cone cells are responsible for colour
vision. Humans have three types of cone cell,
responding only to what we call ‘visible light’.
Most reptiles have a fourth cone type, which
responds to UVA, enabling vision in theultraviolet (Figure 6.2). This extra dimension
to colour perception is vital to many reptile
species for intraspecific recognition anddetection of food items, since UVA‐reflective
markings are found on many animals andplants. Some nocturnal geckos lack the red‐sensitive cone but their green‐sensitive
cone also responds to red light. Some havefull colour vision in dim moonlight thathumans can barely see.
Sunlight has powerful effects unrelated toconscious vision. Non‐visual photoreceptors
are found in the retina, the pineal body andthe parietal eye (where present). Reptiles
possess deep brain photoreceptors that
respond to sunlight’s glow through the skull.
These transmit information as to the lengthof day and night, the sun’s position in the sky
and the intensity and proportion of short‐wavelength light to the suprachiasmatic
nuclei within the hypothalamus, which setscircadian and circannual rhythms. Pineal
melatonin secretion, governed by the photoperiod and body temperature, is also partof this neuroendocrine network, which controls much daily and seasonal behaviour
including activity levels, thermoregulationand the reproductive cycle. Non‐visual perception can be very sensitive to small changes

Figure 6.2 The spectral sensitivities of light‐sensitive
retinal cone cells in human (modified from Vorobyev
2004), geckos (modified from Roth and Kelber 2004)
and turtle (modified from Loew and Govardovskii
2001). Humans have cone cells most responsive to
blue, green and orange‐red wavelengths, and the lens
blocks wavelengths below 400 nm from reaching theretina. The reptile lens permits wavelengths fromaround 350 nm to reach the retina and cone cells
maximally responsive to UVA expand their range ofvision. Note also the differences in peak sensitivities
and wavelength ranges between species. The turtle‘red’ cone, for example, enables it to perceive longer
wavelengths than either man or gecko.

Lightingin light levels; for example, nocturnal
species monitor aspects of daylight from­their hiding places.

opportunity for exposure. Some diurnal
species have skin with a much higher resistance than mammals to UV damage fromsunlight.

Ultraviolet B
UVB in sunlight is an effective disinfectant. It
has direct effects upon the immune system inthe skin, upregulates melanin synthesis,
stimulates production of beta endorphins(giving sunlight its feel‐good factor),
improves skin barrier functions and induces
nitric oxide production, which has localized
protective effects. UVB is best known for its
role in enabling the skin synthesis of vitamin
D3, the primary source of this essential pro‐hormone in most vertebrates. For synthesis
to occur, sunlight must contain UVB in wavelengths between 290 and 315 nanometres.
Since short‐wavelength UV is strongly scattered by the atmosphere, the amount of
UV‐B in sunlight depends upon the solar
altitude. When the sun is low in the sky, near
dawn and dusk or at higher latitudes in winter, there is very little UVB in the spectrum.
As the sun rises, the rays have a shorter paththrough the atmosphere, so less scattering
occurs and UV levels rise.
By midday in the tropics, the UV in direct
sunlight may be extreme. The damaging
effects of excessive exposure to ultraviolet
radiation include DNA damage and oxidative stress. However, reptiles have evolved
both behavioural traits and skin physiology
to optimize their vitamin D3 production
while maintaining adequate protection fromthe UV levels they encounter in their naturalenvironment. Thermoregulatory behaviour
is a major determinant of UV exposure.
Many diurnal species, for example, bask primarily in the morning before UV levels arehigh. Some species also behaviourally regulate their UV exposure according to theirvitamin D3 status. Nocturnal lizards haveskin which permits much greater UV transmission than diurnal desert lizards exposed
to strong sunlight. They may also synthesize
vitamin D at a much faster rate, presumably
enabling adequate synthesis despite reduced­Vitamin D3
Vitamin D3 synthesis in reptiles requires
ultraviolet light and warmth. UVB converts
7‐dehydro‐cholesterol, bound to theplasma membrane of cells in the epidermis,
to previtamin‐D3. A temperature‐sensitiveisomerization then transforms this into
vitamin D3; when a reptile is within its
preferred optimum temperature range,­­conversion will be much faster than at low
temperatures. Overproduction does notoccur; if exposure to sunlight is prolonged,
excess previtamin‐D3 and vitamin D3 in theepidermis are converted into apparently
inert photoproducts.
Vitamin D3 is then transported in the
bloodstream to the liver, where it is enzymatically converted into 25‐hydroxy‐vitamin D3(25(OH)D3). This is the main storage form of
the vitamin, measured to estimate vitamin D
status. Circulating 25(OH)D3 is the substrate
for the hormone, 1,25 di‐hydroxy‐vitamin
D3 (1,25(OH)2D3), or calcitriol, synthesizedwithin renal cells. Vitamin D receptors in­kidney, intestine and bone cells respond to
calcitriol to maintain calcium and phosphorus homeostasis. Serum calcitriol levels
are normally extremely low, increasing in
response to raised parathyroid hormone­levels and low serum calcium or phosphorus.
Vitamin D receptors are also found inalmost every organ in the vertebrate body.
The cells of many organs, including the brain,
vascular smooth muscle and macrophages,
also possess enzymatic ability to produce
intracellular calcitriol with a purely autocrine
and paracrine function, in mammals, regulating genes controlling responses to seasonalchanges, cell division and both innate andadaptive immune systems. Whether thisoccurs in reptiles is not yet known but its
cutaneous synthesis in reptiles is well

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Reptile Medicine and Surgery in Clinical Practice

Figure 6.3 The effects of visible light (including UVA) upon the neuro‐endocrine network, and UVB plus
infrared upon the vitamin D3 pathway. Sunlight has significant effects upon the whole body, via these twosystems.

established. Figure 6.3 is a graphical representation of some of the effects of sunlight upon
the reptile body.

­Natural Sunlight
No artificial lighting system can provide thefull spectrum and intensity of natural sunlight, its subtle changes in colour as a day
progresses, or approximate the sun’s movement across the sky. Many reptiles benefit
from outdoor enclosures whenever ambient
temperatures are suitable. Direct sunlightrequirement depends upon the species but
all require access to full shade and shelter.
Outdoor shelters within these enclosures can

now be covered with special horticultural,
UV‐transmitting plastic sheeting, which enables vitamin D3 synthesis ‘under cover’ andwhich may even prolong the season that canbe spent outdoors.
Ordinary glass and most plastics block all
UVB and some UVA. However, windows andskylights can be glazed with special UV‐transmitting acrylics or low‐iron glass. UV‐transmitting acrylics allow up to 80%
transmission of UVB; low iron glass may
allow 50% through. Supplementary UVB may
be required if natural sunlight levels outside
are low. Heat build‐up caused by direct sunlight through glass and plastics must neverbe ignored. Vivaria should never be positioned in front of sunlit windows.

Lighting­Artificial Sunlight
Many reptiles in captivity must rely upon
artificial lighting but it is virtually impossible
to simulate sunlight using just one type of
lamp. Varying degrees of success can beachieved by combining so‐called ‘basking
lamps’ with specialist reptile lamps emitting
UVA and UVB. Providing a species‐appropriate
basking zone with a gradient into shade willallow the reptile to decide how much heat,visible light and UV radiation it experienceseach day. Both the spectrum and the intensityof the infrared, light and UV must be considered when constructing the necessary gradients across the vivarium (Figure 6.4).
Basking Lamps
Incandescent (tungsten or halogen) lamps
provide infrared and visible light for creatingbasking zones but this is deficient in blue and
UVA, contains no UVB and is of low

intensity. To simulate sunlight, additional
high‐intensity
lighting
isrequired.
Incandescent lamps connected to timers can
produce a simple ‘sunrise and sunset’ effect.
Timers can switch them on just before, and
off just after, other lamps in the vivarium.
Thermal burns are a hazard when using
incandescent lamps. These emit primarily
IR‐A but this includes the wavelengths
removed from natural sunlight by atmosphericmoisture. They also emit longer‐wavelength
IR‐B and some IR‐C. Prolonged exposure may
dangerously overheat the skin surface andwater molecules in the epidermis before
deeper structures reach optimum temperatures. If the beam is narrow and only warms asmall portion of the body, the reptile may
remain under the lamp long enough for serious burns to occur. It is therefore essentialthat any basking zone covers an area at least as
large as the whole body of the animal and thatthe radiation is evenly distributed with nofocal ‘hot spots’. Thermal imaging (Figure 6.5)

Figure 6.4 A simplified representation of a photo‐microhabitat: ultraviolet, visible light and heat gradients aresuperimposed and all fall from a maximum in direct sunlight to a minimum in deep shade. When creating
photo‐microhabitats in captivity, this principle must apply, with species‐appropriate maximum and minimum
levels for each component of the ‘artificial sunlight’.

79

(a)
32.0
31.0
30.0
29.0
28.0
27.0
26.0
25.0
24.0
23.0
22.0
21.0
20.0
19.0
18.0
17.0
16.0
15.0
14.0
13.0
°C

(b)
26.0
25.5
25.0
24.5
24.0
23.5
23.0
22.5
22.0
21.5
21.0
20.5
20.0
19.5
19.0
18.5
18.0
17.5
17.0
16.5
16.0
15.5
15.0
14.5
14.0
13.5
13.0

°C

Figure 6.5 Thermal images. A: Wild specimen of an adult Testudo graeca, located basking in natural sunlight in
its microhabitat, Murcia, Spain. B: Adult T. graeca in captivity, basking under a 100‐watt mercury vapour ‘spot’
lamp. Note the contrast between the almost uniform body temperature of the sun‐warmed animal and theextremely localized heating provided by the basking lamp. The head and limbs of animal B remain at ambient(air) temperature. The areas of greatest heating are along the sutures between the bones of the carapace,suggesting that there may be excessive heat transfer to water molecules in the tissues and blood vessels
concentrated in these areas (images courtesy of A.C. Highfield).

LightingFigure 6.6 A graphical representation of the infrared distribution from ‘spot’ and ‘flood’ type bulbs used atvarying distances above a basking zone. The goal must be to achieve uniform basking zone temperatures
across an area as wide as the entire body of the animal. Smaller ‘spots’ increase the risk of thermal burns as
they cannot warm the whole animal evenly (courtesy of M. Versweyveld).

reveals the contrast between the uniformbody temperature of a reptile basking in natural sunlight and one under a ‘basking lamp’
with a narrow beam. The abnormal heating ofjust the top of a tortoise carapace from ‘spot’lamps may contribute to localized dehydration and development of pyramiding deformities often seen in captive tortoises.
Figure 6.6 is a graphic representation of theinfrared distribution from ‘spot’ and ‘flood’
type bulbs used at varying distances above abasking zone. To create a large enough zone
to accommodate the entire body of a reptile
flood bulbs (with beam angles of 30 degrees
or more) are essential. These must be positioned well above the animal and more than
one bulb may be necessary.
Incandescent lamps should be controlledusing dimming thermostats. Surface temperatures underneath basking lamps must
be measured directly as they are very different from ambient (air) temperatures. Non‐contact infrared thermometers (popularly
known as ‘temperature guns’) are best forthis purpose.
Ceramic heaters and heat mats are excellent background or night‐time heaters but
they emit no UV, visible light or IR‐A, only
IR‐B and IR‐C. These wavelengths are notfound in sunlight so these products are notideal for creating basking zones.

Coloured Lamps
Coloured lamps should be avoided. Reptiles
need full‐spectrum white light during theday. Most so‐called ‘infra‐red’ heat lamps are
simply incandescent bulbs made with red
glass. Their red light distorts colour visionand only weakly stimulates the non‐visual
pathways governing circadian rhythms.
The use of red or blue ‘moonlight’ lamps atnight is not recommended. Reptiles can see
both colours. Moonlight is not blue, beingreflected sunlight – white light too dim forhuman colour vision. Reptiles should not be
illuminated at night, as their circadianrhythms require regular periods of darkness
and daylight, easily achieved by keeping thelamps on timers.
Visible Light
Metal halides are the only readily available
products that can reproduce the full brilliance of sunlight. These are discharge lamps
requiring external ballasts, which cannot be
used with a thermostat. High‐quality bulbs
used for household and industrial floodlighting, in appropriate fixtures, produce goodvisible light including UVA but no UVB.
‘Daylight’ versions (colour temperature
5500–6500 K) are suitable choices for a large
vivarium, when combined with a UVB lamp.

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Reptile Medicine and Surgery in Clinical Practice

Positioning of the lamp is crucial. At close
range, the visible light is extremely intenseand could damage the eyes if placed in an
animal’s direct line of sight instead of directly
above the vivarium. These lamps also emit
significant infrared so similar cautions tothose described above apply regarding thepossibility of thermal injury.
‘Daylight’ fluorescent tubes and compact
lamps are sometimes called ‘full‐spectrum’
lights but most brands emit no UVB and very
little UVA. They can be useful for improving
general light levels in cooler areas of a vivarium. New ‘high‐output’ slim fluorescenttubes (T5‐HO; diameter 16 mm) produce
much more intense illumination than traditional, wider tubes (T8; diameter 25 mm).
Light‐emitting diode (LED) lighting is a
recent innovation. There are two types of LED:
1) ‘White’ LEDs, which use a blue LED and aphosphor to simulate white light. The
spectrum of these contains no UVA or
UVB at all and is deficient in cyan (turquoise) and red.
2) LEDs that emit just one colour, in a very
narrow band of wavelengths. ‘White’ iscreated using a combination of red, blueand green LEDs in a single bulb. This lightwill not appear white to any animal withretinal cones having different sensitivities
to that of a human. In theory, multiple
LEDs covering a wide range of wavelengths could be blended to create a more
sun‐like spectrum but, at present, suitable
UVA and UVB LEDs are not available.
Neither type of LED should be the primarylight source in a vivarium. They may besuitable for supplementary lighting or forenhancing plant growth.
Ultraviolet Lamps
Numerous manufacturers now make UVB‐
emitting bulbs for reptiles. There are fourmain types of UVB lamp (Figure 6.7). Althoughbrands vary, certain characteristics such as
beam shape, heat and light output are common to most lamps within each category.
Both the UV and infrared output must be

considered when positioning lamps over abasking zone. Narrow beams creating ‘hot
spots’ of either type of radiation must be
avoided. Some mercury vapour lamps andmetal halides produce sufficient heat to contribute to basking zones and previously discussed cautions regarding infrared radiation
apply.
High‐quality products from well‐known
brands should be chosen. Cheap, inferior products may not have suitable spectra, output or
longevity. Independent test results for a rangeof products are available (e.g. www.uvguide.
co.uk) but these provide rough guides only. UV
irradiance at reptile level will be affected by thesize and wattage of the lamp, how long it has
been in use, the fixture used and the presenceof mesh or reflectors, as well as shade frombranches, rocks and so on. Even the ambient
temperature and fluctuations in the line voltage
can affect irradiance. Solarization of the glasscauses a slow loss of UVB transparency, andhence UVB output, over time. Ideally, lamps
should be tested with a UV meter in place at
the closest lamp‐to‐reptile distance, with tests
repeated monthly to monitor decay.
The most suitable meter currently available
is the Solarmeter® 6.5 model UV Index Meter(Solartech Inc; ZooMed Digital UV Index
Radiometer, ZooMed Laboratories Inc). The
UV Index is a measure of the solar UV intensity at the Earth’s surface relevant to its effecton human skin but this meter’s sensitivity
response also follows the action spectrum forvitamin D3 synthesis fairly closely, making thismeter suitable for measuring UV from bothsunlight and lamps. It is a scientific instrument. Cheap ‘sun‐smart’ UV Index meters are
not an alternative. Many have sensors that do
not register short wavelength UVB and so cannot give accurate readings with reptile lamps.
Concerns are sometimes expressed regarding the 100–120 Hz ‘flicker’ characteristic ofself‐ballasted mercury vapour lamps andfluorescent tubes run on magnetic ballasts.
The flicker is too rapid for the human eye,which has a flicker fusion frequency of up to
60 Hz. Reptile flicker fusion frequency issimilar to that of humans so lamp flicker
should not be a problem for reptiles. IfLightingFigure 6.7 The main types of UVB lamp used in reptile husbandry. In the middle column are graphicalrepresentations of the UV gradients which form beneath each lamp type when in use. The shapes of these
gradients vary between brands, and are modified by reflectors, mesh, etc.

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Reptile Medicine and Surgery in Clinical Practiceelectronic ballasts are used, no species willsee flicker, since these operate at 40,000–
120,000 flicker fusion frequency Hz.

­Estimating the Ultraviolet
Requirement: The Ferguson
Zone Concept
There are few scientific data to back the recommendation of any particular level of UVB
for any species. Very few field studies havebeen made of the UV exposure of wild reptiles. Measurements must be taken in theirmicrohabitat, where exposure varies widely,
from diurnal species basking in full sun tonocturnal animals receiving low level UV
while sleeping (Figure 6.8). Suitable UV levels
for any species may be estimated using a concept described by Ferguson et al. (2010). The
daytime UV exposure of 15 species of reptiles
in the field was recorded. Species wereassigned into four sun exposure ranges or‘zones’ according to their basking and/or daylight exposure habits, which have since been
designated ‘UVB zones’ or ‘Ferguson zones’(Table 6.1). The average of all the readings(a)taken for each species might be seen as a suitable ‘mid‐background’ level of UV for the species. The ‘Maximum UV Index recorded’refers to the highest UV Index in which a reptile from this species was found. This provides
a rough guide as to the upper acceptable limit
for the UV gradient to be provided in captivity. In theory, any species may be assigned to azone based on its behaviour in its microhabitat. Box 6.1 lists Ferguson zone designations
for some popular reptile species.
A suitable UV gradient in the vivarium,chosen to match the correct Ferguson zone,
will enable the animal to self‐regulate its
exposure. A full range of UV levels is vital,from zero (full shade) to a maximum at theclosest point possible between the reptile
and the UVB lamp.

­Providing the Ultraviolet
Gradient
UVB can be provided for indoor enclosures in
two ways. The ‘shade method’ provides low‐level ‘background’ UV over a large proportionof the animal’s enclosure, with a gradient to(b)

Figure 6.8 Measurement of the daytime UV Index exposure of two tropical lizards occupying very different
microhabitats. (a) Basking marine iguana, Amblyrhynchus cristatus venustissimus, Galapagos, in direct sunlight;
UV Index 8.3 (photo by the author). (b) Nocturnal animals may receive significant UV exposure during daylight
hours. Sleeping leaf‐tailed gecko, Uroplatus sp., Madagascar, on tree trunk in light shade; Madagascar UV Index
1.2. The arrow indicates the position of the eyes of this cryptic lizard, lying head down against the bark of thetree (courtesy of L. Warren).

Lighting

Table 6.1 The Ferguson zones. The mean Ultraviolet Index (UVI) exposure levels of lizards and snakes spot‐
checked in the field during their activity period in the spring–early summer breeding season have determined
their grouping into one of four photo‐microhabitat ‘zones’, with increasing average exposure levels from zone
1 to zone 4. Fifteen species were studied. The average number of sightings per species was 14 (range 3–30);
summarized from Ferguson et al. (2010).

Zone

Characteristics

1

Crepuscular or
shade dweller,
thermalconformer

2

3

4

Zone
range UVISpeciesCommon name

0–0.7

Agkistrodon piscivorus

Cottonmouth watermoccasin

0.6

Elaphe obsoleta

Texas rat snake

0.8

Anolis lineotopus

Jamaican brown anole

1.4

Nerodia fasciata

Broad‐banded water snake

1.1

Thamnophis proximus

Western ribbon snake

1.1

Anolis grahami

Jamaican blue‐pants anole

1.1

Anolis carolinensis

Green anole

3.0

Nerodia erythrogasterYellow‐bellied water snake

2.7

Uta stansburiana
stejnegeri

Desert Side‐blotched
Lizard2.9

Sceloporus undulatus
hyacinthinus

Eastern Fence Lizard

4.9

Anolis sagrei

Cuban brown Anole

4.1

Sceloporus olivaceous

Texas Spiny Lizard

7.4

Holbrookia maculata

Lesser Earless Lizard

4.5

Sceloporus graciosus

Sagebrush Lizard

9.5

Partial sun/occasional
basker,thermoregulator

0.7–1.0

Open or partial
sun basker,
thermoregulator

1.0–2.6

Mid‐day sunbasker,thermoregulator

2.6–3.5

Maximum
UVI recorded

Box 6.1 Ferguson zone designations for 55 reptile species commonly kept in captivity.
As assigned by the British and Irish Association of Zoos and Aquariums’ Reptile & Amphibian
Working Group (Baines et al. 2016).
Lizards (zone)
Crested gecko (1)Crocodile skink (1)Leopard gecko (1)Tokay gecko (1)Australian water dragon (2)Emerald tree monitor (2)Fire skink (2)Green anole (2)Monkey‐tailed skink (2)Pygmy chameleon (2)Scheltopusik (2)Wonder gecko (2)Blue‐tongued skink (2–3)
Chinese water dragon (2–3)
Electric blue day gecko (2–3)

Panther chameleon (2–3)
Black‐and‐white tegu (3)Frilled lizard (3)Standing’s day gecko (3)Sudan plated lizard (3)Yemen chameleon (3)Bearded dragon (3–4)
Bosc or savannah monitor (3–4)
Collared lizard (3–4)
Green iguana (3–4)
Chuckwalla (4)Uromastyx (4)Tortoises and turtles (zone)
Ornate box turtle (2)Red Foot tortoise (2)

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Reptile Medicine and Surgery in Clinical Practice

Yellow‐footed tortoise (2)Common musk turtle (2–3)
European pond turtle (3)Indian star tortoise (3)Leopard tortoise (3)Spotted turtle (3)Cooter (3–4)
Painted turtle (3–4)
Red‐eared slider (3–4)
Sulcata or African spurred tortoise (3–4)
Yellow‐bellied slider (3–4)
Snakes (zone)
Burmese python (1)Burmese python (1)zero in shade. This would be suitable forshade‐dwelling reptiles and occasional baskers (i.e. those in Ferguson zones 1 and 2, suchas the leopard gecko and many snakes;
Table 6.2). A UV Index up to approximately
1.0 at the closest access point would seemappropriate. Fluorescent T8 (1‐inch diameter)
UVB tubes may be used if the animals will beclose to the lamps; T5‐HO UVB tubes would
be suitable if positioned at much greater
distances.
The ‘sunbeam method’ provides a higher
level of UV for species known to bask indirect sunlight. The aim is to provide UV
similar to that experienced during a typicalearly to mid‐morning basking period, which
is when most reptiles bask extensively. Thishigher level needs to be restricted to thebasking zone (like a sunbeam) with a gradient to zero in shade. It can be provided forthe full photoperiod. This method would
seem appropriate for reptiles in Ferguson
zones 3 and 4; for example, the bearded
dragon (Table 6.2). T5‐HO UVB tubes are
suitable if used with an aluminium reflector;
UVB metal halide and mercury vapour
lamps may also be successful. Althoughsome zone 4 reptiles will bask above UVI 7.0,
even these bask mainly in the early morningand late afternoon, when levels are aroundUVI 3.0–5.0. For safety, a UV Index of

Emerald tree boa (1)Green tree python (1)Milksnake (1)Reticulated python (1)Amethystine python (1–2)
Corn snake (1–2)
Rough green snake (1–2)
Boa constrictor (2)Red‐tailed rat snake (2)Rough green snake (1–2)
San Francisco garter snake (2)Western hognose snake (2)Diamond python (3)7.0–8.0 should be considered the absolute
maximum UV Index at reptile level for bothzone 3 and zone 4 reptiles, since the UV
spectrum from artificial lighting is not thesame as from natural sunlight. Figure 6.9 is agraphical representation of a basking zone
created for a zone 3 reptile, showing superimposed heat, light and UV gradients produced by multiple lamps.
Zone 2 (occasional baskers) in larger enclosures providing plentiful shelter would probably use this type of UV gradient as well, withthe lamps supplying a maximum UV Index ofaround 3.0.
UVI meter readings from a selection of
new UVB lamps, on sale at the time of writing, are shown in Table 6.2. Readings weretaken from directly beneath the lamps, withno mesh between lamp and reptile. Vivarium
mesh screens typically block 30–40% of thelight and UVB.

­Excessive Ultraviolet
Exposure/Non‐Terrestrial
UVB and UVC
All guidelines to date are still experimental. It
is vital to watch the animals’ responses and toadjust the UV levels immediately if problems

Lighting

Table 6.2 UV Index readings from individual samples of 21 UVB emitting lamps sold for use with reptiles,
available in the UK at the time of writing. The lamps were all ‘seasoned’ for approximately 100 hours before
testing and measurements taken after 30 minutes warm‐up time. Readings were taken with a Solarmeter®
6.5 UV Index Meter from directly beneath each lamp at the stated distances. Except where stated, tests wereconducted on lamps in simple, open fixtures with no reflectors or shades. No mesh, glass or plastic was placed
between the lamp and the meter. (Numbers in brackets: UV Index too high – lamp is unsuitable at thisdistance).
Distance from lamp (cm)Brand name and type

Wattage

20

ExoTerra Repti‐Glo 2.0

20 W

0

Arcadia Natural Sunlight 2% UVB T8

18 W

0.3

Arcadia D3 Reptile 6% UVB T8

18 W

0.7

ExoTerra Repti‐Glo 5.0

20 W

ZooMed Reptisun 10.0 T8

18 W

Arcadia D3+ 12% Reptile UVB T8
Arcadia D3+ Reptile 12% UVB T8 with reflector

30

40

50

0.2

0.1

0.1

0.4

0.2

0.2

1.5

0.9

0.6

0.4

1.5

0.9

0.6

0.4

18 W

1.5

0.9

0.6

0.4

18 W

3.2

2.0

1.3

0.9

ZooMed Reptisun T5‐HO 5.0

24 W

0.7

0.5

0.3

0.2

Arcadia D3 Reptile 6% UVB T5

24 W

2.0

1.2

0.7

0.5

ZooMed Reptisun T5‐HO10.0

24 W

1.2

0.8

0.5

0.4

Arcadia D3+ Reptile 12% UVB T5

24 W

2.9

1.8

1.2

0.8

Arcadia D3+ Reptile 12% UVB T5 with reflector

24 W

6.3

3.6

2.3

1.6

ExoTerra Reptile UVB 100

25 W

1.6

0.8

0.4

0.3

ExoTerra Reptile UVB 200

25 W

1.8

0.9

0.5

0.3

Arcadia Natural Sunlight Compact Lamp

20 W

0.5

0.2

0.1

0.1

Arcadia D3+ 10%UVB Compact Reptile Lamp

23 W

2.7

1.3

0.8

0.5

ZooMed ReptiSun 5.0 Compact Lamp

26 W

0.5

0.3

0.1

0.1

ZooMed ReptiSun 10.0 Compact Lamp

26 W

1.8

0.9

0.4

0.3

Lucky Reptile Bright Sun UV Desert 35 W PAR30

35 W(27.9)(15.1)(9.6)

6.5

Lucky Reptile Bright Sun UV Desert 70 W PAR30

70 W

3.9

1.7

0.8

0.5

150 W

(14.1)

6.3

3.5

2.1

ExoTerra SunRay 35 W PAR30

35 W(26.2)(10.3)

5.4

3.3

ExoTerra SunRay 50 W PAR30

50 W(11.0)

5.0

2.8

1.7

ExoTerra SunRay 70 W PAR30

70 W(17.3)

7.4

4.0

2.4

ExoTerra Solar Glo 160 W

160 W

1.7

1.0

0.5

0.4

Arcadia D3 Basking Lamp 100 W

100 W

4.3

2.3

1.3

0.9

Arcadia D3 Basking Lamp 160 W

160 W

5.1

2.7

1.6

1.1

T8 fluorescent tubes (all 610 mm length):

T5 High Output fluorescent tubes (550 mm length):

Compact fluorescent lamps:

Metal halides: Lucky Reptile Bright Sun Flood Jungle 150 W
PAR38

Mercury vapour lamps:

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Reptile Medicine and Surgery in Clinical Practice

Figure 6.9 A graphical representation of a basking zone created for a reptile in Ferguson zone 3 or 4, using a
combination of incandescent basking lamps for infrared and visible light, a metal halide lamp (non‐UVB‐
emitting) for visible light and UVA, and a T5‐HO UVB fluorescent tube. The UV Index gradient from an Arcadia
T5 D3+ 12% UVB fluorescent tube fitted with a reflector is shown approximately to scale (courtesy of
M. Versweyveld).

are seen. Albino and hypomelanistic animals,
which lack protective melanin, may be atincreased risk of UV‐induced skin damage
and cancer. They are likely to need much
lower UV levels than normally pigmented
conspecifics.
A few brands of lamp sold for use with reptiles were previously found to emit hazardous, very‐short‐wavelength UVB and UVCnever found in natural sunlight. These havecaused photo‐kerato‐conjunctivitis in many
reptiles, with severe photo‐dermatitis, burns
and death in a significant number of cases(Figure 6.10). Once the problem was identified, the manufacturers withdrew theselamps from sale but there is the possibility
that similar products may be available.
Excessive exposure to UV must also be
avoided as high doses of ‘solar’ UVB andUVA can result in eye and skin damage and,in mammals, can lead to the formation ofskin cancers. Squamous cell carcinomas havebeen reported in captive reptiles but the relevance of their association with use of artificial UV lighting is as yet undetermined.

­General Recommendations
for Reptile Keepers
Captive reptiles need a sufficiently large,
species‐appropriate microhabitat withsuitable heat, light and UV gradients, shelters and basking areas, so they can selecttheir preferences at all times as they wouldin the wild. Provision of adequate shade isvital for all species.
●● The sources of UV, visible light and infrared radiation must be positioned close
together, simulating sunlight and creatinga basking zone at least as large as the wholebody of the animal. Multiple lamps may berequired in some cases. The effects are
additive for all wavelengths so overlapping
beams must be used with caution.
●● Suitable levels of UV for any species may
be estimated from knowledge of theirbasking habits and micro‐habitat in thewild. The Ferguson zones offer a range ofsuitable irradiances, using the UV Index,
for four different categories of basking
behaviour (Ferguson et al. 2010). The●●

Lighting

(a)

(b)

(c)

Figure 6.10 Three lizards exposed to hazardous, abnormally short‐wavelength UVB from ‘problem’ compact
fluorescent lamps marketed in 2006–07 (see text). A: Juvenile blue‐tongue skink (Tiliqua scincoides) withphoto‐kerato‐conjunctivitis, after 24 hours’ exposure (courtesy of A. Murphree). B: Yellow‐footed tortoise(Geochelone denticulata) with photo‐kerato‐conjunctivitis, after 3 days’ exposure (courtesy of M. Buono).
C: Albino leopard gecko hatchling (Eublepharis macularius) with extensive, very severe UV ‘burns’ after 2 daysof exposure; the animal died two days later (courtesy of M. Buono).

Solarmeter model 6.5 UV Index Meter is asuitable tool to measure lamp irradiance inthe vivarium.
●● Basking temperatures and ambient temperatures must be suitable to ensure basking behaviours – and therefore UV
exposure times – are natural, neither
abnormally short nor prolonged. It is vitalto check the temperatures reached under alamp. Take into account the height of theanimal.
●● Lamps should always be positioned above
the animals so the shape of the head andupper eyelids, and eyebrow ridges whenpresent, shade the eyes from the direct
light. Lights shining sideways may causestress, and intense visible light, as well as
UV, can cause eye damage.

All lamps present an electrical risk. Many
can also cause thermal and/or UV burns at
close range. All bulbs should be inaccessible to the animals; wire guards may be necessary. Wide wire mesh should be chosen
where possible, to maximize light and UVtransmission.
●● Ordinary glass or plastics must not be
placed anywhere between the lamp and theanimal as these typically block transmission of all UVB.
●● Reptiles rely upon a distinct day and night
to set their circadian rhythms. Timers
should be used to provide the correct photoperiod for the species. If backgroundheat is required at night, ceramic heaters
or heat mats mounted on a rear wall areappropriate, as they emit no ­visible light.
●●

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Reptile Medicine and Surgery in Clinical Practice

References
Ferguson, G.W., Brinker, A. M., Gehrmann, W. H.
et al. (2010) Voluntary exposure of somewestern‐hemisphere snake and lizard
species to ultraviolet‐B radiation in the field:
how much ultraviolet‐B should a lizard or
snake receive in captivity? Zoo Biology, 29(3), 317–334.
Loew, E.R. and Govardovskii, V.I. (2001)
Photoreceptors and visual pigments in the

red‐eared turtle, Trachemys scripta elegans.
Visual Neuroscience, 18 (5), 753–757.
Roth, L.S.V. and Kelber, A. (2004) Nocturnal
colour vision in geckos. Proceedings of theRoyal Society of London Biological Sciences,
271 (Suppl 6), S485–S487.
Vorobyev, M. (2004) Ecology and evolution ofprimate colour vision. Clinical andExperimental Optometry, 87 (4/5), 230–238.

Further Reading
Baines, F.M. (2010) Photo‐kerato‐conjunctivitis
in reptiles, in Proceedings ARAV 1stInternational Conference on Reptile andAmphibian Medicine, Munich, 4–7 March
2010. (S. Öfner and F. Weinzierl, eds), Verlag
Dr. Hut, München, Germany, pp. 141–145.
Baines, F.M., Chattell, J., Dale, J. et al. (2016)
How much UV‐B does my reptile need? The
UV‐Tool, a guide to the selection of UV
lighting for reptiles and amphibians in

captivity. Journal of Zoo and Aquarium
Research, 4 (1), 42–63.
Highfield, A.C. (2015) The Effect of Basking
Lamps on the Health of Captive Tortoises
and other Reptiles. Tortoise Trust, http://
www.tortoisetrust.org/articles/
baskinghealth.html (accessed 2 June 2017).
Hossein‐nezhad, A. and Holick, M.F. (2013)
Vitamin D for health: a global perspective.
Mayo Clinic Proceedings, 88 (7), 720–755.

91

7
Reproduction
Timothy J. Portas­Reproductive Strategies
in Reptiles
Considerable variation exists in the reproductive strategies both between and within
the various reptilian taxa, including reproductive activity, frequency of reproduction inseasonal breeders, clutch size, degree ofparental care and age at sexual maturity.
Reptiles are either oviparous (egg laying) or
viviparous (live bearing), with most species
being oviparous. Viviparity does not occur incrocodilians or chelonians but occurs inapproximately 20% of squamate species,
including blue‐tongued skinks and shingleback lizards (Tiliqua spp.), various chameleon species, most vipers and rattle snakes(Crotalus spp.), most boas and some colubrids. Reproduction in temperate species
tends to be seasonal, reflecting the thermal
requirements for embryogenesis, while intropical species reproduction may be­continuous or influenced by other environmental factors such as rainfall or seasonalvariations in resource availability. Seasonallybreeding reptiles may produce a single ormultiple clutches in a given season.

­Anatomy and Physiology
The reader is referred to Chapter 2 for abrief discussion of reproductive anatomy.
Pertinent aspects of reproductive physiology
and egg anatomy are discussed in this chapter.
Reptile Reproductive Physiology
The reproductive physiology of many reptile
species is poorly understood, although two
broad patterns of reproductive behaviour are
evident in reptiles – associated and dissociated. In the associated pattern, sexual behaviour is correlated with gonadal steroid
concentrations and, in the case of females, isassociated with ovulation. In the dissociatedpattern, sexual behaviour is not mediated bygonadal steroid concentration and is related
to environmental factors such as temperature. For males that exhibit a dissociated pattern, mating occurs at a time when gonadal
activity is low and hence stored gametes produced in the previous breeding season areused. For females that exhibit a dissociatedpattern, mating occurs early in the breeding
season and sperm are stored for fertilization

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

92

Reptile Medicine and Surgery in Clinical Practiceof ova that subsequently develop. Spermstorage has been demonstrated in a numberof reptile species and in some species sperm
may be stored for up to several years. In somespecies, females frequently mate with multiple males and multiple paternity is possible
in the resulting clutches.

anatomical form between and even withintaxonomic groups, accurate gender assessment can be challenging. Additionally, somespecies of reptile, particularly snakes, aremonomorphic and sex cannot be accurately
determined on the basis of external
morphology.

Egg Anatomy

Chelonians

Reptile egg shell morphology varies both
between and within the various taxonomic
groups largely as a result of the degree of egg
shell calcification. The eggs of crocodilians,
some chelonians and some gekkonids haverigid shells, while other chelonians, mostsquamates and the tuatara (Sphenodon punctatus) produce eggs with a parchment‐like,
soft and pliable shell. Reptile eggs lack a­chalaza, the fibrous ligament that suspends
the yolk centrally within the albumen.
Consequently, the yolk, which has a higher
specific gravity than albumen, settles to thebottom of the egg while the embryo floats
and subsequently attaches to the top of theegg. As a result, rotation of the egg during
incubation may result in embryonic mortality. Except in the immediate post‐oviposition
period, care should be taken to ensure thateggs are not rotated during incubation.

Adult chelonians generally exhibit sexual
dimorphism. Males tend to have longer tails
and a greater distance between the caudal
margin of the carapace and the cloacal opening than females (Figure 7.1). Additionally,
males frequently have a concave plastron tofacilitate mounting the female during copulation. Other secondary sexual characteristics that provide clues to the gender ofchelonians include elongated toenails on theforelimbs of male terrapins, eye colourationin terrapins, carapace shape and a generally
larger body size in females compared withmales. While sexually mature chelonians
exhibit dimorphism, sexual maturity may not
be reached until 10 years of age or later insome species. Sub‐adult and juvenile (including hatchlings) chelonians may be sexed bycoelioscopic examination of the gonads.

Parthenogenesis
Parthenogenesis refers to asexual reproduction in which an egg develops without fertilization by spermatozoa. Parthenogenesis is
uncommon in reptiles but has been reported
most frequently in lizards (various speciesof Gekkonidae, Agamidae, Chamaelonidae,
Xantusiidae, Lacertidae and Teiidae) andrarely in snakes.

Crocodilians
Gender assessment in crocodilians is typically achieved by digital examination of the
cranioventral cloaca; males have a larger
penis while females have a smaller clitoris.
The penis may be exteriorized for visual
examination if there is doubt on palpation(Figure 7.2). Adult male crocodilians typically grow to a larger size than females.
Lizards­Gender Assessment
in Reptiles
Accurate determination of the sex of individual captive reptiles is imperative for successful
breeding. Given the immense variation in

A number of techniques may be employed
for gender assessment in lizards. Males possess paired hemipenes, which are inverted in
the ventral tail base. In some species, a prominent hemipenal bulge is apparent, which canbe used for gender assessment. A hemipenal

Reproduction

(a)

(b)

Figure 7.1 Comparison of the tails of male (a) and female (b) broad‐shelled turtles (Chelodina expansa).

Figure 7.2 Phallus extruded through the cloacal
opening of an American alligator (Alligator
mississipiensis).

bulge is present in some iguanids and varanids and in most gekkonids. Some male gekkonids have prominent paracloacal spurs(Figure 7.3). The hemipenes of some varanids contain mineralized, radiodense hemibacula and radiography of the tail base can beused to determine the sex of those species
where these occur (Figure 7.4). Hemipenaltransillumination, using a suitably bright

light applied to the tail base, can be used to
identify the presence of absence of hemipenes in small species of agamids, gekkonids,
varanids and scincids. Repeatable sex identification was demonstrated in free living eastern blue‐tongued lizards (Tiliqua scincoides)
using ratios of head width to snout ventlength and head width to trunk length. The
technique showed significant predictability
with respect to sex identification in both
adult and sub‐adult lizards.
‘Probing’ or the introduction of a sterile,
lubricated, blunt‐tipped, sexing probe into
the invaginated or inverted hemipenal
pocket, can be used for gender assessment. A
probe inserted into the hemipenal pocket
will penetrate further in a male than in a conspecific female. Manual eversion of the hemipenes, as described below for snakes, mayalso be used. Ultrasonographic visualizationof the hemipenes and gonads has been
described in bearded dragons (Pogona vitticeps). Contrast radiography and contrast
computed tomography have been effectively
used to identify the hemipenes of a range oflizard species. Some gekkonids, iguanids andagamids have femoral pores on the ventral
aspects of the thigh which are noticeably
larger in adult males than adult females but

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Reptile Medicine and Surgery in Clinical Practice

Figure 7.3 Hemipenal bulge andparacloacal spurs evident in a malehelmeted gecko (Diplodactylus
galeatus).

Figure 7.4 Mineralized hemibacula within thehemipenes are clearly evident in this radiograph ofan adult male perentie (Varanus giganteus).

are of a similar size in juvenile lizards (Funk2002). Ultrasonography and radiography
may be used to identify ovaries, follicles or
eggs in females (Figure 7.5). Coelioscopy may
also be used to visualize the gonads for gender assessment. Molecular sex assessment
has also been described for some lizard species (Phillips et al. 2016).

Figure 7.5 Vitellogenic follicles are clearly evident inthis radiograph of an eastern bearded dragon(Pogona barbarta). The homogenous nature ofcoelomic cavity contents can make radiographic
visualization of follicles challenging but, in this case,contrast provided by the lizard inflating itself with
air in a threat display, enables the follicles to beclearly visualized.

Reproduction

(a)

(b)

Figure 7.6 Comparison of cloacal spurs in the green tree python (Morelia viridis). The male is on the left (a) andthe female on the right (b).

Snakes‘Probing’, as described for lizards, is the mostcommon method for assessing the sex ofsnakes. In female snakes, the sexing probe
can be inserted to a depth of between 0–5
subcaudal scales, depending on the species.
In male snakes, the sexing probe can beinserted to a depth of between 7–19 subcaudal scales depending on the species. For­neonatal and juvenile snakes, in which probing carries a higher risk of trauma, manual
eversion of the hemipenes is used. The hemipenes are most commonly everted using­digital pressure. Saline, injected caudal to thehemipenes, may also be used to evert thehemipenes but carries a risk of infection,­prolapse and hemipenal trauma, and is notrecommended. Ultrasonography and contrast radiography for identification of thehemipenes have both been employed for gender assessment in snakes with ultrasonography more consistently accurate. Various
secondary sexual characteristics may be used
for assessing the gender of snakes, including abroader more slowly tapering tail in males
compared with females and the presence ofspurs lateral to the cloaca in pythons and boasthat are generally larger in males than females(Figure 7.6). Owing to variation between andwithin species, secondary sexual characteristics should not be relied on alone for genderassessment in snakes.

­Breeding Management
Prior to breeding, female reptiles must be inappropriate body condition to support the
metabolic demands of egg or fetus production and free from underlying disease to
maximize the chances of successful reproduction. To ensure that adequate resources
are available to support reproduction, captive reptiles should be in excellent body condition prior to cooling and the subsequent
breeding season.
Appropriate environmental cues are necessary for the induction of reproductive
behaviour in reptiles. Cooling or brumation
is frequently used in temperate species to initiate breeding behaviour. Feeding of temperate species should cease before cooling or
brumation commences: at least two weeks
for snakes and several days for chelonians
and lizards. Ensuring that animals are ingood health and free from disease prior to

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Reptile Medicine and Surgery in Clinical Practicecooling or brumation is important as thesetemperature changes may be associated with
reduced immune function. In tropical species, photoperiod adjustment and dietary
manipulation may be sufficient with excessive or inappropriate cooling being potentially detrimental to the reptile’s health. If
cooling is used in tropical species, temperature drops should be smaller and of shorter
duration; typically, a reduction in the overnight temperature while still providing a limited period of heating during the day.

­Mating
Males and females may be left together year
round or separated outside of the breeding
season and introduced for breeding purposes. The presence of a male prior to thebreeding season has been shown to be necessary for folliculogenesis, vitellogenesis,
ovulation and oviposition in some snakeand chelonian species. The sequential introduction of multiple males may be necessary
to stimulate breeding behaviour in somesquamate and chelonian species and ensure
fertilization. The decision to permanently
house together or introduce only for breeding purposes will depend upon the species
in question, the propensity for aggression
both during and after the breeding season
and the experience and preference of theherpetoculturalist. Mating in many species
is preceded by a period of courtshipbehaviour.

­Determination of Gravidity
The ability to determine whether a female
reptile is gravid or pregnant is clinicallyimportant to allow for optimal management
and monitoring through to oviposition orbirth and for the diagnosis of dystocia. In
many squamate species, the mid or caudal
body becomes distended due to the presenceof eggs or fetuses. The presence of large

intracoelomic fat pads in some females willcomplicate diagnosis when relying on thistechnique. In many gekkonids, eggs are often
visible through the translucent ventral skinand can be differentiated from abdominal fat
pads by the slightly asymmetrical positioningof the eggs. Transillumination of the coelomic cavity may aid in diagnosis of species
with less translucent skin. In many agamids,
the outline of eggs are readily visible against
the body wall. Behavioural changes in gravid
females, including increased basking behaviour, inappetance and positional changes,
may also provide some indication of reproductive status. Palpation is most applicablein snakes but can also be used in lizards. The
bony shell of chelonians makes palpation difficult in this group but, with practice, eggs
may be detected via palpation and ballotment through the inguinal fossa. During
vitellogenesis, females reptiles can be
expected to have elevations in total calcium,
phosphorus, total protein, albumin, globulin,cholesterol (often marked) and triglycerides.
For definitive diagnosis of gravidity, radiography and/or ultrasonography are often
employed. Radiography is particularly useful in chelonians as the calcified shells of
their eggs are readily apparent. While eggs
can be detected ultrasonographically via theinguinal fossa, the number of eggs cannot
be determined by this method. In contrast,
the poorly mineralized shells of many squamate species, particularly in the immediate
post‐ovulatory period, can be difficult todifferentiate radiographically from preovulatory follicles (Figure 7.7). Ultrasoundexamination is therefore useful for determining gravidity in many squamate species
in the immediate post‐ovulatory period(Figure 7.8). The relatively homogenousradiographic appearance of coelomic cavity
structures in many species limits the usefulness of radiography for assessing reproductive status in the preovulatory period. For
viviparous species, ultrasonography is also
appropriate, although in the later stages ofgestation fetuses are also readily apparent
with radiography.

Reproduction

(a)

(b)

Figure 7.7 (a) In the immediate post‐ovulatory period, the poorly mineralized shells and large number of
eggs produced by some squamate species such as this green iguana (Iguana iguana) may be difficult todifferentiate from preovulatory follicles radiographically. (b) In this lace monitor (Varanus varius), the large
egg size and more mineralized shells immediately prior to oviposition are readily distinguishable
radiographically.

Figure 7.8 Ultrasonographic
appearance of an egg in a reticulated
python (Python reticulatus). Note thehyperechoic shell and relatively
homogenous echogenicity of the egg
contents.

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Reptile Medicine and Surgery in Clinical Practice­Determination of Lengthof Gestation
Determining the length of gestation in reptiles can be challenging, as it is influenced
not only by species specific factors but also
various environmental and physiological factors. Environmental factors can influence thelength of gestation, with higher temperatures
reducing gestation length. In some species,
copulation and ovulation may be separated
by significant periods of time and sperm
storage has been documented in numerous
species. Impending oviposition or parturition can be preceded by various species‐
specific behavioural changes such as the
excavation of nest chambers in chelonians,
some oviparous lizards and some crocodilians, the construction of nesting mounds insome crocodilians, and ecdysis at a variableinterval before oviposition (termed a pre‐layshed) in many snakes and gekkonids.

­Managing Gravid Females
Reproduction requires increased metabolic
expenditure on the part of breeding females.
Females producing multiple clutches over thecourse of a breeding season have a high metabolic cost of reproduction. Careful management of nutrition is required and, given thatmany species cease to eat and lose weight prior
to oviposition, optimal nutrition in the immediate postpartum period is required. These
animals also have a high demand for various
vitamin and minerals, in particular calcium.
Inappropriate nutritional management ofbreeding females poses a risk not only to thehealth of the female but also to the viability of
any offspring produced. The reader is referred
to Chapter 15 for a more complete discussionof metabolic and nutritional diseases.

­Egg Laying
Wild gravid females are able to choose
appropriate oviposition sites within theirenvironment. In captivity, oviposition sites

are limited to those provided by the herpetoculturalist. A sound knowledge of species‐
specific requirements is necessary to ensure
an appropriate oviposition site is provided.
Failure to provide an appropriate oviposition site may result in dystocia (common inchelonians and some iguanids) or the rapid
desiccation of deposited eggs. Most chelonians and many lizards will excavate a nesthole for oviposition. A substrate that meetsthe species specific requirements for excavation, moisture content and temperature
should be provided. Potentially suitablenesting substrates include sand, peat moss,
coir peat, sphagnum moss or a combinationof these, depending upon the species. In lizards, this nesting material is generally moistened and provided in a secure nesting box.
The nesting substrate should be of sufficientdepth for excavation of an adequate chamber; at least twice the snout‐vent length oflizards and deeper than the length of thehind limbs in chelonians. In some lizard species, no next box is required and eggs are laid
under bark (or cage furniture) or, in the caseof some gekkonids, glued to cage furniture.
For snakes, a secure nesting hide with moistened substrate is provided, although nonest chamber is excavated. Mound nesting
crocodilians will need to be provided with
sufficient vegetation to build a mound of
decomposing material in which the eggs
can be laid.
Egg brooding, in which the female coils
tightly around the egg mass, occurs in most
python species. In addition to providing protection for the egg mass from predators,some python species are facultatively endothermic, providing a stable thermal environment for the eggs. Egg brooding behaviour
has also been shown to ensure stable environmental humidity for the egg mass.
Clutch size varies enormously between
taxonomic groups. Some examples are: terrestrial chelonians and anoles (Anolis spp.),which lay a single egg per clutch; scincids andgekkonids, which lay two eggs; through tosome marine turtles, which lay up to 200 eggs
in a single clutch. Similar variation occurs inviviparous species. Knowing the number ofReproduction

eggs likely to be produced is important in
helping to establish cases of dystocia. The
number of clutches produced each season
varies, with some species producing multiple
clutches, through to the tuatara, which only
produces eggs once every four years. Those
species producing a smaller number of eggs
per clutch tend to lay multiple clutches per
seasons. In the captive setting, environmental manipulation can be employed to obtain
multiple clutches from animals that would
typically only produce one clutch per season
in the wild. Viviparous species typically produce a maximum of one clutch per year.
Cessation of feeding in the later stages ofpregnancy is common in viviparous species
and females tend to be in poor body condition postpartum.
Excavation of multiple nesting chambers
without oviposition, straining, inappetance,
dehydration and coelomic cavity distension,and lethargy are all potential clinical signs ofdystocia. The reader is referred to Chapter 22
for a detailed discussion of the diagnosis andmanagement of dystocia. Potential causes of
egg mortality include inappropriate humidity, hyper‐ and hypothermia and microbial
infections.

­Multiple Clutches
Snakes tend to produce larger clutches of
eggs than do lizards of a similar body mass
but they typically only produce one clutch
per season. In captivity, many herpetoculturalists seek to maximize the reproductive
output of their animals. Some snakes, in particular some colubrids and pythons, can be‘pushed’ to reproduce at a much earlier age
than in the wild by feeding more regularly
than required for maintenance (Stahl 2001).
Reproductive maturity is associated withbody size rather than age in many reptiles.
This ‘hypernutritional’ approach can also be
used to obtain two to three clutches from afemale in a season. A reduced reproductive
life span and health problems are more likely
with this approach. In some species of lizard
in which multiple clutches of eggs areproduced in one season, overbreeding canresult in marked loss of body condition in thefemale and metabolic imbalances, such as
hypocalcaemia, as the female’s body reserves
are depleted through excessive egg production. Strategies for halting reproduction inthese animals include removal of the male,although additional clutches may still be produced due to sperm storage, cessation of
feeding and lowering environmental temperature. Manipulating food intake and environmental temperatures may be detrimental infemales in poor body condition and should
be undertaken with caution.

­Egg Incubation
In the captive setting, most eggs are removed
from the oviposition site and artificially incubated. Suitable substrates in which to incubate reptile eggs include vermiculite, perlite,
sphagnum moss, peat moss, coir peat mossand sand (Figure 7.9). Species‐specificrequirements will dictate the suitability ofthese various incubation media and also theamount of water required to ensure appropriate hydration during incubation. Key
physiological factors influencing artificially
incubated eggs include temperature, humidity and gas exchange.
Temperature variably influences incubation duration, gender determination (inspecies with temperature‐dependent sex­
determination), pigmentation, hatchling size,
post‐embryonic growth, locomotor performance and behaviour, and the incidence ofdevelopmental anomalies. Most reptile eggs
are incubated at between 28 °C and 32 °C,
although considerable species specific variation in optimum incubation temperatureexists (Table 7.1). Lower incubation temperatures generally result in larger hatchlings
with smaller yolk reserves. Higher incubation temperatures typically result in a shorter
duration of incubation as embryonic metabolic processes are temperature dependent.
However, this relationship is not linear and isalso determined by genetic factors. Higher
incubation temperatures generally result in

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Figure 7.9 Two clutches of eggs from
Cooktown ring‐tailed geckos(Cytrodactylus tuberculatus) being
incubated in moistened vermiculate.
The adherence of substrate to the shellis common in gekkonids.

Table 7.1 Average clutch size, recommended egg incubation temperatures and incubation length for selected
reptile species.
Incubation
Species

Averageclutch (n)Temperature (°C)

Length (days)

Green iguana (Iguana iguana)

10–35

28–32

64–113

Bearded dragon (Pogona vitticeps)

4–35

27–31

55–86

Veiled chameleon (Chamaeleo calyptratus)

30–80

27–31

120–209

Leopard gecko (Eublepharis macularius)

2

26–31

45–65

Savannah monitor (Varanus exanthematicus)

12–20

27–30

138–194

Reticulated python (Python reticulatus)

40–45

29–31

70–105

Ball python (Python regius)

2–15

29–32

53–60

Burmese python (Python bivittatus)

30–40

30–32

55–70

Green tree python (Morelia viridis)

10–20

30–31.5

52–53

Carpet python (Morelia spilota)

9–54

31–32

57–78

Corn snake (Pantherophis guttatus)

20–25

25–29

60–65

Black rat snake (Pantherophis obsoletus)

6–16

25–29

50–76

Spectacled cobra (Naja naja)

10–45

26–28

54–80

Red–eared slider (Trachemys scripta elegans)

1–22

28–30

60–90

Eastern long–necked turtle (Chelodina longicollis)

4–24

27–31

60–85

Eastern box turtle (Terrapene carolina carolina)

2–7

28–30

50–75

Leopard tortoise (Stigmochelys pardalis)

3–19

28–30

120–200

Hermann’s tortoise (Testudo hermanni)

4–5

28–31

60–66

African spurred tortoise (Centrochelys sulcata)

1–17

27–31

81–170American alligator (Alligator mississippiensis)

2–28

28–33

55–76

Fresh water crocodile (Crocodylus johnstoni)

4–20

29–34

75–85

Tuatara (Sphenodon punctatus)

6–18

18–22

330–450

Reproduction

faster growth after hatching. Excessively highincubation temperatures may result inembryonic mortality and an increased incidence of embryonic abnormalities.
Temperature‐dependent sex determination occurs in all crocodilians, some chelonians and lizards and the tuatara but has notbeen documented in snakes. Higher or lower
temperature in reptiles exhibiting temperature‐dependent sex determination variably
produces more or less individuals of a given
sex, depending upon the species. There istypically a transitional temperature range of
2–3 °C in which equal numbers of males andfemales are produced. Four broad classes oftemperature‐dependent sex determination
are recognized:
type 1 – in which higher incubation­temperatures produce more females andlower temperatures more males (manychelonians)●● type 2 – in which higher incubation temperatures produce more males and lower
temperatures more females (some crocodilians and lizards)●● type 3 – in which both higher and lower
incubation temperatures produce more
females while more males are produced at
midrange temperatures (some crocodilians, lizards and chelonians)●● type 4 – in which lower incubation temperatures produce more males, intermediate temperatures produce more females
and higher incubation temperatures produce equal numbers of both sexes (onegekkonid species).

influenced by temperature and contact withthe substrate. The water potential of thesubstrate (the amount of water available tothe egg from the ­substrate) and resulting
gas exchange can have profound influenceson hatchling size and yolk metabolism.
Monitoring and active management of bothtemperature and humidity is therefore
vitally important during incubation. This
information is critical to the veterinarianinvestigating egg mortality during incubation and morbidity and mortality in theimmediate post‐hatching period.

­Determination of Egg
Viability●●

Incubation humidity is influenced by environmental humidity, the moisture content
of the substrate and the water potential of
the substrate. Water is absorbed by the egg
principally in its gaseous phase, althoughabsorption of liquid water is also possible.
Water absorption and loss is greatest insoft‐shelled eggs and the egg volume andweight change in response to water absorption or loss. Water exchange in eggs is

Determining whether or not eggs are fertileand monitoring of fertile eggs is usuallyachieved by transillumination of the egg usinga bright light source in a darkened room. This
technique, known as candling, allows for visualization of the internal structures of theegg, including the air cell and developing
blood vessels. Nonviable eggs may also exhibit
abnormal colouration, excessive adherence of
substrate, obvious microbial contamination
and, for soft‐shelled eggs, changes to the normal turgidity of the egg.

­Hatching
Impending hatching may be evidenced byvarious changes to the egg up to several days
before hatching, including the loss of calcareous shards from hard‐shelled eggs, and fluid
formation or dimpling of the surface of soft‐shelled eggs. At hatching, a tooth or tooth‐like structure on the tip of the upper jaw or
beak, which is shed post‐hatching, is used torupture the embryonic membranes and egg
shell, allowing the neonatal reptile to escapethe confines of the egg. In crocodilians, chelonians and the tuatara, the egg tooth or

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Figure 7.10 A neonatal carpet python(Morelia spilota) emerging from therecently pipped egg. Note thepresence of depressions in the shells of
the other eggs. This is a normal change
seen immediately before hatching inmany species with soft‐shelled eggs.

caruncle is a horny outgrowth of the upper
jaw. In squamates, the egg tooth is a true dentinal tooth attached to the premaxilla.
Following opening of the egg shell or ‘pipping’, the neonatal reptile may remain in theegg from several hours to several days
(Figure 7.10). The duration of time the neonate remains in the egg varies considerably
among taxonomic groups and during thistransitional phase, various physiological andanatomical changes may occur, including
resorption of the remnant yolk sack, the transition to pulmonary respiration and unfolding of the carapace and plastron in chelonians.
Knowledge of species‐specific times spent in
the egg shell following pipping is importantwhen deciding whether to assist in the hatching process, as early removal from the shell
may be deleterious to the hatchling.

­Embryonic Mortality
Late embryonic death is a relatively common
problem that may affect entire or partial
clutches of oviparous species from all reptiletaxa. Affected embryos are typically full termor near term at the time of death and are­discovered when fertile eggs fail to hatch at
the expected time. Potential causes may berelated to maternal nutrition and body condition; incubation parameters such as temperature, humidity and gaseous exchange;
infection; inbreeding; and egg rotation during
incubation. Determining the cause of embryonic mortality requires a thorough review ofthe husbandry regime under which the adult
reptiles are managed, a review of incubation
parameters and necropsy and microbiological examination of dead embryos.

References
Funk, R.S. (2002) Lizard reproductive medicine
and surgery. Veterinary Clinics of North
America Exotic Animal Practice, 5, 579–613.
Phillips, C.A. Roffey, J.B. Hall, E. and Johnson R.
(2016) Sex identification in the easternblue‐tongued lizard (Tiliqua scincoides

White, ex Shaw, 1790) usingmorphometrics. Australian Veterinary
Journal, 94 (7), 256–259.
Stahl, S.J. (2001) Reptile production medicine.
Seminars in Avian and Exotic Pet Medicine,
10, 140–150.

Reproduction

Further Reading
Brown, D. (2014) A Guide to Australian
Lizards in Captivity. Reptile Publications,Burleigh.
Bucy, D.S., Guzman, D.S. and Zwingenburger,
A.L. (2015) Ultrasonographic anatomy ofbearded dragons (Pogona vitticeps). Journalof the American Veterinary Medical
Association, 246, 868–876.
DeNardo, D. (2006) Reproductive biology, in
Reptile Medicine and Surgery 2nd ed.
(D.R. Mader, ed.), Elsevier, St. Louis, MO,
pp. 376–390.
Di Ianni, F., Volta, A., Pelizzone, I. et al. (2015)
Diagnostic sensitivity of ultrasound,radiography and computed tomography forgender determination in four species oflizard. Veterinary Radiology and Ultrasound,56, 40–45.
Divers, S.J. (2014) Diagnostic endoscopy, in
Current Therapy in Reptile and Medicine
and Surgery, (D.R. Mader and S.J. Divers,
eds). Elsevier, St. Louis, MO, pp. 154–178.
Gnudi, G., Volta, A., Di Ianni, F. et al. (2009)
Use of ultrasonography and contrast
radiography for snake gender determination.
Veterinary Radiology and Ultrasound,
50, 309–311.
Hochleithner, C. and Holland, M. (2014)
Ultrasonography, in Current Therapy in
Reptile and Medicine and Surgery(D.R. Mader and S J. Divers, eds), Elsevier,St. Louis, MO, pp. 107–127.
Köhler, G. (2005) Incubation of Reptile Eggs.
Krieger Publishing Company, Melbourne,
Australia.
Lourdais, O., Hoffman, T.C.M. and DeNardo,
D.F. (2007) Maternal brooding in theChildren’s python (Antaresia childreni)
promotes egg water balance. Journal ofComparative Physiology B, 177, 569–577.
McArthur, S. (2004) Reproductive system, in
Medicine and Surgery of Tortoises andTurtles (S. McArthur, R. Wilkinson and
J. Meyer, eds), Blackwell Publishing, Oxford,
pp. 57–63.
Rivera, S. (2008) Health assessment of thereptile reproductive tract. Journal of Exotic
Pet Medicine, 17, 259–256.
Shine, R. (2003) Reproductive strategies insnakes. Proceedings of the Royal Society of
London B, 270, 995–1004.
Sykes, J.M. (2010) Updates and practical
approaches to reproductive disorders in
reptiles. Veterinary Clinics of North America
Exotic Animal Practice, 13, 349–373.
Wright, K.M. (2004) Breeding and neonatalcare, in BSAVA Manual of Reptiles, 2nd ed.
(S.J. Girling and P. Raiti, eds). British Small
Animal Veterinary Association, Gloucester,
pp. 40–50.

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8
Reptile Paediatrics
Deborah Monks and Bob Doneley­Introduction
Paediatrics is the medicine and surgery of
neonatal, juvenile and sub‐adult animals. As
with other groups, reptile paediatrics has
considerable overlap with other disciplines of
medicine and surgery. Reptiles have a varietyof reproductive strategies (see Chapter 7),
which means that development of foetuses
can occur either externally (oviparous) orinternally (as either viviparous or ovoviviparous young).

­Hatching/BirthOviparous neonates
Assuming that the egg is successfully fertilized and that oviposition has occurred without incident, foetal development of oviparous
species is entirely dependent on external
conditions. Hygiene is, of course, critical, as
is the provision of species appropriate temperature and humidity (see Chapter 7).
Veterinary intervention during the incubation process is usually limited to egg necropsies. An egg necropsy is performed whenneonates fail to hatch or are diagnosed asdead in shell after development has started.
Although there are documented species‐
specific incubation times, temperature andhumidity may alter those times (within asmall window), which can obscure theexpected date of hatch. In general terms,
assisted hatching is performed when:
the remainder of the clutch has hatched anda small number of eggs have exhibited minimal activity suggestive of imminent hatch●● the hatching process is initiated by a neonate but stalls●● candling reveals a live hatchling past thelongest expected duration of incubation●● the egg was damaged at some point andrequired repair; the hatchling may have difficulty exiting the egg unassisted because of
the means or amount of repair required.
●●

The process of hatching heralds a massive
physiological change for the neonate, especially of the respiratory system (Figures 8.1
and 8.2). Given these complexities, it isironic that hatch interventions are usuallylimited to simple incisions of the shell (toallow the change to air from egg respiration
while the foetus rests) and assisted fluids
and hydration to foetuses that have become
weakened during the hatching process. It is
important to avoid forceful removal of the
foetus from the egg, as the yolk sac must be
internalized before hatching commences. If
this does not occur, the yolk sac is prone totrauma and infection, both of which carry apoor prognosis.

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

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Reptile Medicine and Surgery in Clinical Practice

Figure 8.1 Australian broad‐shelledturtle hatching (courtesy of Bob
Doneley).

Figure 8.2 Eastern water dragons immediately post‐hatching (courtesy of Bob Doneley).

Should a neonate hatch with a small volume of non‐resorbed or still externalized
yolk sac, dilute povidone iodine solution may
be dabbed on to the umbilicus and a protective wrapping placed around it (even clear
plastic wrap may suffice in the very shortterm). In cases involving more significantly
externalized yolk sacs, the extraneous portion may be ligated close to the umbilicus
and excised. The affected neonate will need
to be fed much sooner than the conspecifics,
as the nutrition provided by the yolk sac will

be reduced. The more externalized the yolksac, the poorer the prognosis (Figures 8.3 and
8.4). In these cases, the decision to use antibiotics should be made on an individual
basis. While the internal aspect of the egg issterile, the external environment is not, andyolk sac infections can be terminal. On theother hand, antibiotics given at such an earlyage may compromise the ability of the neonate to develop normal flora. Herbivorous
species that rely on bacterial assistance fordigestion are particularly at risk. Attention toReptile Paediatrics

Figure 8.3 Externalized yolk sac in Australian broad‐shelled turtle hatchling (courtesy of Bob Doneley).

Figure 8.5 Blue‐tongued lizard giving birth(courtesy of Annette Bird).

When surgical intervention (caesarean
section) is required to alleviate dystocia,
resuscitation of any delivered young is done
according to standard mammalian processes – first clearing the oral cavity of mucus
and debris, stimulating the body using gentle
stroking pressure laterally around the thorax,
and using resuscitative drugs if needed. A
Doppler probe will be required to detect thepresence of a heartbeat in reptiles, as auscultation is problematic.

­Neonatal Care
Figure 8.4 Normal umbilicus in Australian broad‐shelled turtle hatchling (courtesy of Bob Doneley).

husbandry and hygiene is critical and arguably frontline management. There is a highmortality in hatchlings with larger exteriorized yolk sacs, regardless of intervention.
Ovoviviparous/Viviparous
Neonates
Generally, dystocia is rare in species whichgive birth to live young. In the unusual eventof obstructive dystocia, the involved foetus is
usually dead. While obstructive dystocia may
be a result of deformed or oversize foetuses,
previous trauma resulting in maternal pelvic
deformity can occur. Young born with congenital anatomical defects may be more
prone to causing dystocia and less viable,
even if successfully delivered (Figure 8.5).

Maternal Factors
Although little scientific research has been
conducted in this area, it stands to reason thatwell‐nourished females are much more likely
to produce robust offspring. The shell provides
the initial calcium for the neonatal skeleton, so
the offspring of a calcium‐depleted female arelikely to have low body levels of calcium fromthe outset. While this can be addressed if identified, the practice of selling young reptiles as
early as possible can lead to exacerbation ofthese underlying nutritional issues.
Post‐Hatch/Birth Inappetence
Most reptiles do not need to eat immediately
after birth, surviving on the nutrition provided by their yolk sacs for a variable period oftime. The exact duration will vary according
to species and should be previously researched.

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The appropriate species‐specific food must be
offered but care must be taken to source size‐
appropriate items. Tiny maggots, crickets andother insects are often used for species thatare insectivorous as young animals. Hand
feeding may be required initially as neonates
may need time to develop hunting skills.
Occasionally, developmentally delayed neonates refuse to eat for substantial periods oftime. Once the yolk sac is absorbed, they progress to a catabolic state, from which recovery
is unlikely unless eating commences. It isadvisable for all anorexic neonates to have acomplete physical examination, including disease testing if at all possible. The causes can bevaried. Breeders use a number of techniques
to encourage self‐feeding, including:changing the species of food item offeredoffering a more ‘natural’ prey item●● scenting ‘abnormal’ food, such as rodents,
with the scent of more ‘natural’ prey items●● hand feeding with normal foods, including
moving or wriggling dead prey items tosimulate life●● assist feeding with baby foods or commercial veterinary convalescence foods●● force feeding.
●●●●

It is important to remember that some species
are ambush predators rather than active hunters. Those species will commonly refuse to
feed if they are feeling insecure, so an environmental audit ensuring sufficient hiding areas

is important. If force feeding is required, it must
be done extremely carefully, as damage canoccur during the process. This is a particularconcern with snakes. Animals that are not thermoregulating can suffer from maldigestion,
meaning that the ingested food can decompose
before it is digested. It is crucial to ensure thatthe animal is kept at the optimal body temperature in the postprandial phase of digestion.
In recently purchased young animals, common iatrogenic causes of inappetence include
excessively large enclosures (leading to insufficient thermoregulation and feelings of insecurity); excessive interaction or handling of the
new animal; inappropriate positioning of theenclosure in a thoroughfare (also leading to
disruption of feeding); trauma from previous
efforts to assist feed and of course inappropriate provision of hot spots and heat gradientsresulting in the animals not being able to reach
their optimum body temperature.
Thermoregulation
In the wild, neonatal reptiles are at considerable risk of predation. Sufficient and adequate
hiding areas within an enclosure allow a senseof security, which facilitates feeding. Hides
must be provided in multiple areas of theenclosure, including hot, warm and cool thermal zones, or the animals may refuse to thermoregulate in preference to staying hidden(Figure 8.6). Specific hot spots can be draped
Figure 8.6 This juvenile jungle carpet
python has toilet rolls as hides to allow
for a sense of security in the enclosure(courtesy of Bob Doneley).

Reptile Paediatrics

in artificial vines or other cover to improve
the sense of security of neonates and encourage basking. While the maximum enclosure
size possible is usually recommended for
adult animals, young reptiles housed in excessively large enclosures will often thermoregulate poorly, presumably due to insecurity.
As well as the obvious improvement toimmune function, adequate thermoregulation also facilitates the absorption of nutrients(including calcium) from the gastrointestinal
tract.
Conspecific Aggression
It is common practice to house multiple­neonates together but this often results inaggression and trauma. Some species (e.g.
bearded dragons and blue‐tongued skinks)
are notorious for this. Not only can aggression result in damage to other babies but low
level ‘bullying’ and ‘intimidation’ can also leadto delayed feeding and stunted growth for
subordinate animals. Reduced access toresources, including prime basking areas,can compromise immunity. In many cases,
paediatric reptiles do better kept individually,
although this does vary according to species.
In any case, previously traumatized young
animals should be removed from group housing and any wounds treated according to firstprinciples. It is not uncommon for bitewounds to crush the vascular supply of theskin, leading to progressive distal limb necrosis over several days. Treatment of suchwounds involves aggressive, early diagnosis
and treatment. Hot and cold poultices may
stimulate blood supply to the extremity.
Antibiotics are usually indicated. Traumatic
amputation may occur from bites to limbs ortails or may be subsequently required at alater date due to tissue necrosis.

­Examination
and Diagnostic Testing
Paediatric reptiles are usually small, which
confers particular difficulties with physicalexamination and diagnostic testing. Palpationof the body and limbs should be performed
but diagnostic sensitivity is often poor.
Specialized equipment can be used in specificinstances (for instance paediatric and neonatal stethoscopes have much smaller heads).
Ingenuity and creativity is often useful, as isinspiration acquired from other practitioners
at conferences and presentations.
Oral and cytological smears can be madefrom samples taken with tiny cotton tips.
Often, viral swabs provided by pathology
companies have particularly small tips.
Vascular access can be challenging, both dueto the mechanical difficulties of drawing
blood and the restriction in available volume
if venepuncture is successful (see Chapter 13
for venepuncture sites). Using the smallest
insulin syringe available (e.g. a 0.3 ml with a
29 g needle), it is often possible to get a small
sample. Haemodilution with lymph is notuncommon and results must be interpreted
in light of this. In the author’s opinion, a bloodsmear for haematological analysis is the mostuseful test to prioritize, with a packed cell volume/total solids being the next most beneficial parameter. Even though venepuncture
may be challenging, it is still not recommended to take blood via toe nail clipping.
Faecal analysis (floatation and direct smear)can be performed on freely passed specimens,
thus avoiding issues of size on collection.
Given these challenges, comparatively morereliance needs to be placed on anamnesis to
identify the likely aetiology of illness. A careful
history may elicit information more consistent with congenital deformity, for instance, orindicate an animal that initially appeared
healthy and then deteriorated, which may
make infection more likely. If confirmatory
testing cannot be done, the clinician must be
prepared to prepare a treatment plan based on
the most likely or most serious possibilities.

­Treatment
If there is a high index of suspicion for aparticular condition or a disease has been
confirmed, then treatment specific to thatproblem must be instituted. In most cases,

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Reptile Medicine and Surgery in Clinical Practicethe drugs used will be the same regardlessof age, although paediatric cases often
require drug dilution to be accurate. Somedrugs do not distribute or may be unstablein dilution and the practitioner must beaware of this. Compounded drugs may be
the solution to this problem. Regardless of
the underlying pathology, paediatric animals are prone to several serious secondary
conditions.
Hypothermia
A small total body size and a high surface
area to volume ratio leaves paediatric patientsat risk of hypothermia. Additionally, unwellyoung animals may not properly thermoregulate. A lack of secure hides will makethis more likely. When treating paediatricpatients, it is advisable to provide a relatively
small enclosure with a tightly controlled
thermal gradient. Water should be provided,
as insufficient humidity can worsen dehydration. Care must be taken to prevent total
body immersion in the water dish, as evaporative cooling of the patient can occur.
Paediatric patients presenting with hypothermia must be gently rewarmed, using
stages to reach preferred optimum bodytemperature. Aggressive rewarming can leadto rebound hyperthermia. As immunocompromise is often associated with an episodeof hypothermia, prophylactic antibiotics areoften indicated.
Hypoglycaemia
After the yolk sac is exhausted, paediatricanimals need to eat regularly to maintaineuglycaemia. The frequency of feeding is
mainly dictated by species, with snakes
needing the least frequent feeding.
Hyporexia and anorexia are common in
unhealthy paediatric patients and secondary
hypoglycaemia is not uncommon. Clinicalsigns can range from lethargy to an obtundeddemeanour. Tremors can be present, andanimals can even be seizuring on presentation. Hypoglycaemia can be difficult todifferentiate from viral infection, septicaemia or structural neurological disease.
A blood glucose test to confirm the diagnosis is ideal, although it is not uncommon totreat on the presumption of hypoglycaemia
rather than wait for confirmation, given the
low risk of administration of glucose and thehigh consequence of incorrectly withholding
treatment. In many situations, the bloodtaken for testing can be better used for otherparameters, such as haematological examination. The accuracy of some patient‐side
testing kits has been called into question.
Depending on the degree of hypoglycaemia,
treatment may include the administration oforal glucose supplements, the use of stomach
tubes to administer glucose and/or electrolyte solutions, or even subcutaneous injections or intravenous injections of glucose or
dextrose solutions, providing intravenous
access is possible. For oral and subcutaneous
measures to be effective, the animal must bein the preferred optimal temperature zone.
Once initially stabilized, normal assist feeding should begin, remembering that many
paediatric animals have higher dietary protein requirements than adults. Caution needs
to be exercised during assist feeding, as iatrogenic mandibular fractures can occur. The
use of metal or other hard, narrow feeding
tubes is contraindicated.
Hypocalcaemia
Young animals are generally undergoinggreat skeletal growth. This rapid growthcommonly highlights husbandry deficiencies, meaning that hypocalcaemia is a common paediatric problem (see Chapters 4, 6,
15 and 25 for further information). True
hypocalcaemia is a medical emergency, as
acute cardiac failure, seizures and death canoccur. Other common clinical signs include
depression, lethargy, generalized muscle
weakness and twitching. Patient‐side testing
can be done and is useful to gauge the severity of the deficiency and can determine theaggressiveness of treatment, with more
severe cases receiving increased treatment

Reptile Paediatrics

frequency. Treatment options range fromoral calcium/vitamin D to parenterally
administered calcium (either subcutaneously, intravenously or intracoelomically).
Prevention of hypocalcaemia can beachieved with excellent husbandry, including appropriate provision of hot spots andthermal gradient, appropriate calcium andvitamin D supplementation of food, appropriate provision of ultraviolet lighting. An
underappreciated cause of metabolic bonedisease is insecurity of the reptile leading toconstant hiding and lack of exposure to both
ultraviolet light and basking areas. In somecases, curtains over the front of the enclosure can restore a feeling of security (seeChapters 4, 6 and 25).
Dehydration
Dehydration can occur rapidly, as much froma dry environment as insufficient drinking.
Regardless of the patient’s condition, in mostcases it is crucial to have a shallow bowl of
water in the enclosure of a sick paediatric tomaintain humidity. The amount of humidity
varies according to species, with chondropythons requiring a high humidity, while species such as shingleback lizards need a muchdrier environment. Gauze swabs can be usedwithin the water dish to prevent animals
from drowning or immersing themselves inwater. Positioning water dishes close to heatsources will increase enclosure humidity.
Dehydration is rectified using oral or parenteral means. Fluid requirements must be
carefully calculated, as it is easy to cause iatrogenic overhydration.

­Anaesthesia
Most injectable and gaseous anaesthetic
agents used for adult reptiles may be used in
paediatric patients, although the delivery ofthe drugs may be more complex. Dilution of
injectable drugs to ensure an accurate dose iscommon. Insulin syringes are also useful fordelivery and measurement of these amounts.

The relative amount of damage (and therefore pain) caused by intramuscular injection
into small muscle volumes is greater in paediatric patients.
Vascular access is difficult in paediatricpatients. Intraosseous catheterization isextremely useful; however, anaesthesia must
be induced before an intraosseous catheter
can be placed. Not all drugs are appropriate
for intramedullary injection and the clinician
is advised to check before administration.
See Chapter 13 for placement of intraosseous
catheters.
Intubation can also be challenging and many
practitioners fashion ‘home‐made’ endotracheal tubes from various items including intravenous catheters to allow intubation of small
patients (Figure 8.7). Mucous blockage ofsmall tubes can occur, so intermittent positive
pressure ventilation is important. Additionally,
the percentage decrease of the airway diameter is much greater in smaller animals.

­Specific Conditions
Genetic Defects
The popularity of morphological mutations
within the reptile trade means that congenital deformities and developmental issues are
becoming more common. Unfortunately, inmany cases, the economics of producing‘designer’ traits supersedes the poor welfare
outcomes experienced by these animals. This
ethical tension needs to be resolved by thehobby. Examples include neurological deficits in jaguar carpet pythons (‘jags’) andlethal genes associated with some homozygous dominant colour traits like leucism. A
good history of the affected individual andfamily tree, as well as knowledge of the industry will help differentiate random congenital
deformity and intrinsic genetic deficits.
Infectious Diseases
Paediatric reptiles are initially reliant onmaternal factors for protection against specific diseases (via maternal antibody transfer

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Reptile Medicine and Surgery in Clinical Practice

Figure 8.7 Eastern brown snake
juvenile with endotracheal tube madefrom a 26‐guage catheter (courtesy of
Bob Doneley).

into the egg). Subsequently, appropriate husbandry should allow good general immunity.
While young reptiles can be afflicted by anyof the infectious diseases of older animals, thecourse of the disease is often more acute andmore severe. An example is adenovirus inbearded dragons, which is often unapparent
in adults; however, young dragons demonstrate a range of particular signs, including:chronic ill thrift●● stunting●● secondary
infections due to immune
suppression●● neurologic changes (tremors, star gazing,
seizuring)●● diarrhoea
and other gastrointestinal
abnormalities.
●●

See Chapter 16 for specific diseases. Given
the emerging nature of reptile viral diseases,
adequate quarantine is essential for any reptile keeper, more so those with paediatricanimals. See Chapter 5 for a more detailed
discussion of quarantine.
Substrate Ingestion
As young animals are acquiring the skills of
hunting and prehension, it is more likely thatthey will accidentally ingest substrate. For
this reason, saw shavings and wood chips are

inadvisable as substrates. Rarely, indigestible
food items may also cause gastrointestinal
obstructions.
Endoscopic gastric retrieval under anaesthesia is possible. Sand can sometimes movethrough to the colon and cause constipation,
which may be relieved using enemas.
Failure to Thrive
Some animals fail to thrive after hatching or
birth. In the wild, this is an expected occurrence and not every animal survives to adulthood. In captivity, there are emotional andfinancial reasons to have a more individualized focus. At the outset, stunted patientsshould have a full examination including
physical examination, faecal examinationand preferably haematological examination(if possible). Consideration must be given toviral testing where appropriate (e.g. adenovirus in neonatal bearded dragons).
It is likely that, in some cases, the diagnostic sensitivity of the available testing is toopoor to identify the underlying problem. It isalso likely that some of these animals are suffering from emerging pathogens that have
not yet been elucidated. Nonetheless, it islikely that paediatric patients failing to meet
normal developmental milestones may not
thrive long‐term unless excellent support

Reptile Paediatrics

and husbandry is maintained, including
attention to hygiene, assist feeding andappropriate lighting and heating for species(Annette Bird, personal communication).

­Further Reading
Johnson, J.D. (2012) Reptile and amphibian
pediatric medicine and surgery. Veterinary

Clinics North America, Exotic Animal
Practice, 15 (2), 251–264.

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9
Setting Up and Equipping a Reptile Practice
Bob Doneley, Shane Simpson, Angela M. Lennox and John Chitty­Marketing A Reptile
Practice
Introduction
The decision to start a reptile practice orincorporate reptiles into an existing practice
should, like all business decisions, be basedon research and planning detailed in a busi­
ness plan. While a reptile practice is a niche
concept it can and should be promoted likeany mainstream business entity, with bothinternal and external marketing focusing on
how you intend to advertise your interest
and willingness to see and treat reptiles andamphibians.
Internal Marketing
Internal marketing is the process of promot­
ing your services to both your staff and exist­
ing clients. It is vital that staff appreciate theservices you are able to provide and actively
discuss them with current and potential cli­ents of the practice. It may be of no surprise
to discover that many of the practice’s cur­rent clients are reptile owners; by simply
marketing to current clients the practice may
already have a reptile client base.
Providing the staff with tools to allow themto promote the practice’s services is vital, as

is developing a brand that reflects the prac­
tice’s interest in reptiles. Logos, client hand­outs, brochures, reminders, an informative
website and social media outlets such as
Facebook are all key components. In addi­tion, reception and nursing staff need to be
trained not only in handling reptile patients
but also in how to handle and answer ques­
tions from clients. Employing staff who own
reptiles or having one or two pet reptiles in
the practice waiting room can go a long way
to creating an air of confidence with thesometimes sceptical reptile owner.
External Marketing
Attracting new clients is essential should areptile practice wish to succeed. Avenues for
obtaining new clients include:
Actively encouraging current clients torefer friends and family members who own
reptiles. This can be achieved by offering
discounts and other incentives to both thecurrent and potential client.
●● Advertising: an advertising budget canform part of a marketing plan to allow
for promotion in locations such as busi­
ness directories, Google AdWords, online
forum banners and reptile‐related maga­zines. Writing articles for magazines is also
a great way of promoting your practice.
●●

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

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Reptile Medicine and Surgery in Clinical Practice

Involvement with local herpetologicalgroups. Becoming an active member byattending meetings, expos and speaking at
events will quickly result in new clients.
Reptile keepers know how hard it is to finda vet able to treat their animals and willappreciate your participation.
●● Referrals: develop relationships with local
pet stores and other veterinary clinics.
These businesses will often readily forward
clients to veterinarians who exhibit aninterest in reptiles. Ensure you updatethese contacts with the progress of referredcases to keep the lines of communication
open.
●●

­ ee Setting for the Reptile
F
Practice
In principle, fees for services for reptiles
should be similar to those for other pet­species. In well‐managed practices, veteri­narians determine prices based on one ofseveral strategies: competitive, cost‐based,variable or value‐based pricing. The com­
petitive pricing strategy recommends set­ting fees somewhere in between the middle
and the high end of local competition.
Cost‐based pricing uses a standard mark up
over the purchase prices of goods. For vari­able pricing, prices change depending on
demand or include strategies such as loyalty
programmes or wellness programmes. Value‐
based pricing aligns the price of all services
with the examination fee, which can be
determined by what the economy in thearea is expected to bear.
Regardless of strategy, most management
consultants recommend there should be nodifference between fees for reptiles andfees for more traditional pets, as veterinari­
ans in general spend the same amount oftime (and often more) during consultations
and, in many cases, have invested signifi­
cant resources into continuing education orother specialized equipment necessary totreat reptiles. Regardless, many practitioners

feel obligated to reduce fees for species seen
less frequently. Reasons that have been given
include feelings of inadequacy in terms ofveterinary competency and sympathy forowners whom the practitioner perceives may
not have funds for veterinary services.
Veterinarians who truly feel they havenothing to offer reptile owners should refrainfrom accepting them as clients. For the rest,
the veterinary visit often consists of signifi­
cant amounts of time discussing husbandry,
the actual physical examination, consultation
with books, journal or proceedings to sup­port a diagnostic plan, diagnostic testing,which usually takes more time than for morefamiliar traditional pet species, and a returnto the literature to interpret diagnostic test­
ing and to formulate and put in place a treat­ment plan. In most cases, this takes much
more time that the typical traditional pet
consultation. Many exotic pet practitioners
and practice consultants actually recom­
mend that exotic services should be priced
higher than a traditional pet examination.
Some charge more for the physical examina­tion only; others charge more for individual
items such as specialized hospitalization or
diagnostic testing.

­Measuring the Financial
Health of the Reptile
Practice
Using traditional strategies to measure prac­
tice growth and health can be applied to thereptile practice. Key performance indicators(KPIs) are standardized calculations ofquantifiable and measurable data reflecting
performance or trends occurring within abusiness that impact on achievement ofbusiness goals and objectives. They can bemeasured across a number of areas of a busi­
ness (including business performance, humanresources, marketing and the operations of thebusiness) and can be used for comparison of
performance within a business (e.g. from year
to year) or to similar businesses. A successful

Setting Up and Equipping a Reptile PracticeTable 9.1 Suggested key performance indicators (KPIs) for a reptile practice.
Category

KPI

Explanation

Financial ratio

Rates of return

Investment income or loss for a specified time period,
calculated as a percentage gain or loss on initial cost ofinvestment

Solvency

Ability of a business to meet financial obligations

Debt

Ratio of debt to assets

Inventory turnover

Frequency of sale and replacement of inventory

Receivables turnover anddebtor days

Ability of the business to collect monies owed

Income area sales

Measurement of income area (professional fees andinventory) sales as a percentage of total income

Veterinarian productivity

Sales income, annual number of transactions, active
clients, new clients, and lapsed clients, expressed as aratio to full time equivalent veterinarians

Transaction sales

Average transaction charge, professional fee averagetransaction charge, and number of transactions per active
clientTotal costs

Generally measure the relationship between total costs
and total income and can help identify where a practice
can trim costs to improve profitability

Cost centres:
Drugs and medical supplies●● Veterinary staff costs●● Support staff costs●● Pathology costs

Can be related to total income to help monitor theeffectiveness or degree of influence expenditure in theseareas has on profitability

Sales

Cost controla●●a

As a percentage of total income.

veterinary practice monitors a range of KPIs
to seek ways of improving service provisionand profitability. Improvements to veterinary
practice performance can only be made whendata are collected and interpreted using KPIs.
Veterinary business KPIs can be grouped
into three broad categories (Table 9.1). These
KPIs can be obtained, in many cases, fromveterinary practice software, bank state­ments and the practice accountant. The
practice owner or manager should measurethese indicators each month and compare toprevious months and years to monitor thepractice performance.
KPIs often include items such as client
turnover. Unlike in dog and cat practice, rep­
tile owners are much less likely to use well­ness care and do not present for routine
vaccinations. Most consultations are for sick

reptiles; if the reptile recovers, the owner isoften unlikely to return until the next illness.
Thus, certain KPIs may be less useful thanfor traditional pet practice.

­The Consultation Room
The consultation room is a key element inany veterinary practice and is no less impor­tant in the reptile practice. It serves as themain interface between the veterinarian andthe client. As such, it is important that it
sends the right messages to clients – profes­
sionalism, hygiene, competence, and confi­
dence. The room should be escape‐proof forthe eventuality of a reptile responding unex­
pectedly to handling and suddenly finding

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Reptile Medicine and Surgery in Clinical Practiceitself unrestrained. Possible escape routes
include doors, windows and drains; likely
hiding places include behind cupboards,
refrigerators, chairs and bins. All of thesefeatures should be taken into consideration
when designing or altering a room to serve asa consultation room.
The room and its fittings should be con­structed of impervious material that not only
looks professional but is also easy to clean
and disinfect between patients. Handwashingfacilities and an alcohol hand rinse add to thelevel of hygiene (and the client’s perceptionof cleanliness).
Doors should be lockable and staff should
be advised to always knock before entering.
This is particularly important when dealing
with dangerous reptiles such as venomous
snakes and large monitors. When dealing
with such animals, the display of warning
signs on the doors is an appropriate safetymeasure.
The walls of the room can be used to­display awards and certificates that attest to
the veterinarian’s knowledge and skills, andpictures or paintings that demonstrate aninterest in reptiles.
Equipment
Most of the equipment needed to practice
reptile medicine can be found in nearly all

veterinary practices. There are some addi­
tional pieces that will make the consultation
process smoother and easier. Digital scales,
capable of weighing to 1 gram, are essential
when examining a reptile. Larger scales will
be required for large patients such as large
monitors or tortoises. Easily cleaned (or dis­posable) containers are useful when weigh­ing small patients, such as hatchling pythonsor small lizards; plastic containers and card­board boxes with lids are ideal, as are washa­ble cloth bags (e.g. pillow slips).
Magnification and illumination are usefulwhen examining small patients or lesions.
Binocular loupes or ophthalmic equipment
can fill this role.
Examination of a reptile’s mouth and theadministration of oral medications are always
a challenge for the reptile veterinarian.
Mouth gags, either stainless steel or acrylic,are useful items to have in the consultation
room (Figures 9.1 and 9.2). Wooden tongue
depressors or the plunger of a syringe canmake useful substitutes. Care must be taken
to minimize or prevent damage to thepatient’s gingiva and teeth.
Reptile sexing probes can be purchased asa set in different sizes (Figure 9.3). These areuseful for identifying the sex of many snakes,
look professional and are easy to clean. They
must be used carefully, with adequate lubri­
cation, and must be disinfected after use.
Figure 9.1 Metal oral specula.

Setting Up and Equipping a Reptile Practice

Figure 9.2 Acrylic oral specula.

Figure 9.3 Reptile sexing probes.

A tape measure is useful for recording
details such as carapace length and measur­ing snakes for determination of organ loca­
tion and the investigation of lumps.
If diagnostic sampling is performed in the
consultation room a supply of sampling
equipment should be kept on hand. This
includes syringes, needles, cotton buds, ster­ile culture swabs, microscope slides, cover­slips and paediatric blood collection tubes(lithium heparin and sodium EDTA).
Medical Records
Medical records are maintained for threereasons: to preserve a database of previous

clinical findings for future reference andcomparison; to prompt the clinician’s mem­ory on details when a patient has not been
seen for weeks, months or years; and todemonstrate a clear (and defensible) thoughtprocess when the records are reviewed byanother party, whether they be another clini­cian or a court of law. They also are invalua­
ble for marketing and management purposes,
such as reminders and billing. Records
should be generated at the time of clinicalexamination or shortly afterwards, and insuch a manner that the record is regarded as
accurate and trustworthy.
Whether the record is handwritten or com­puterized, the use of a template encourages a

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Reptile Medicine and Surgery in Clinical Practicemethodical and organized approach to theclinical examination, assisting the clinician inboth organizing their thoughts and ensuringthat nothing is overlooked. After an initialrecord is created on the first visit, a separate
record should be created for each subsequent
day in hospital, revisit or visits for otherproblems. The record should also containcopies of laboratory and radiology reports orindicate where these records are held.
It is also important that records containcommunications between the client and theclinic, including recommended treatmentsthat were declined by the client, telephone
calls made by either party, cost estimates andnotification of patient progress and labora­
tory results to the client.

hospitalize these patients in optimal condi­
tions as an essential part of their therapy.
Hospitalization facilities must be plannedwith the anticipation that patients will be kept
for much longer periods than a sick bird or
mammal (in the case of an anorexic tortoise,for example, it is not unusual to hospitalize
patients for over a month). To provide optimal
therapy, the veterinarian must provide opti­
mal husbandry. Hospitalization in suboptimal
conditions will result in poor success rates.

­Facilities
The basic facilities required are:the enclosure itself
a heat source●● humidity●● light●● hiding places●● handling aids.
●●●●­Hospitalization of Reptiles
Reptiles frequently require prolonged hospi­
talization. They have a much lower metabolic
rate than birds or mammals, so their response
to both illness and treatment will be accord­
ingly slower. They are often a lot sicker thanthey initially appear and so extensive sup­portive care is often necessary to stabilize
them. They may be as difficult to medicate,especially at home. Suboptimal husbandry
practices are the primary cause of many
reptile diseases. It is therefore imperative to

The Enclosure
Reptile enclosures (Figure 9.4) must be
escape proof with tight‐fitting, lockable
doors (especially for small lizards and snakes)
and strong hinges and locks (for large lizards
and snakes). Access to the enclosure mustbe sufficient for easy capture of the patient.
Figure 9.4 Reptile hospital cage.

Setting Up and Equipping a Reptile PracticeDimensions are dependent on species need;for example, arboreal species need some
capacity to climb and hang, as this can aid
passively clearance of respiratory discharges(Figure 9.5). Non‐climbing tortoises can be
maintained in an open ‘tray’ with a thermal
gradient (Figure 9.6). Ambient heating islikely to be required to ensure lower temper­
atures are sufficient. Using old pet cages is
Figure 9.5 Climbing perches allow
arboreal species to display normal
behaviour.

Figure 9.6 Tortoise hospital enclosure.

not recommended, as disinfection is usuallyproblematic. Aquatic species are difficult to
hospitalize. They may be maintained in an
aquarium or plastic tub, which can be part‐filled with water and tilted to give a varying
depth of water, with the shallowest end
allowing the animal to leave the water. Water
quality should be monitored and, preferably,changed daily. Semi‐aquatic species, such as

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Reptile Medicine and Surgery in Clinical Practice

red‐eared sliders, may be ‘dry docked’ andkept in the same way as tortoises. In thesecases, bathing in deep water (e.g. in a plastictub) should be provided as required. Post‐
surgery patients should only be provided
with shallow bathing each day.
For practices that do not see many reptiles,
it may seem logical to use the owner’s vivar­
ium. However, it must be remembered thatmany of the disease syndromes are due to a
failure in husbandry; using an inappropriate
vivarium may not be helpful to the patient.
Heat Source
All reptiles require keeping in the ‘preferred
optimum temperature zone’. This will vary
according to species and may be altered bydisease (see Chapter 5 for more detail).
Temperatures should be monitored by a­minimum–maximum thermometer. Hyper­
thermia can be rapidly fatal, so vivaria should
never be placed in direct sunlight and theentire room should be adequately ventilated
in hot weather.
Humidity
Different species require different humidity
and gradients (see Chapter 1). Even desert
species require a humidity chamber tomimic the trapping of water under rocks: a
wet towel in a box can be used and is easilychanged each day. Humidity could also be
provided by misting regularly or allowing
evaporation from open dishes of water.
Misting is vital when hospitalizing somespecies, such as chameleons, as they will
only drink by taking droplets from the vivar­
ium walls.
Light
Full‐spectrum ultraviolet light should be
provided. This may be incorporated into theheat source or may be separate. A 12‐hour :12‐hour light–dark cycle is generally appro­
priate. The use of ultraviolet B lighting in
reptile enclosures is discussed in Chapter 6.

Hiding Places
Many reptiles are shy and benefit from aplace to hide. This may be a small box or
humidity chamber, paper or substrate. This
must be easily accessible for regular monitor­
ing through the day. Covering the front of thevivarium may also help for some nervous
individuals.
Handling Aids
While most species can be easily restrainedusing a towel, some handling aids may berequired for more aggressive species, espe­
cially snakes. These should always be kept
close to the vivarium whenever the animal ishandled. All practices seeing reptiles shouldhave the following aids:
gloves – both thick gauntlets and thinneranti‐needle stick gloves●● snake hook●● snake grabs or tongs●● snake tubes, if venomous species are being
hospitalized.
●●­Biosecurity
Many reptile pathogens are spread by directcontact or fomite. Biosecurity is therefore
paramount and all patients must be barrier
nursed (see Chapter 32). Enclosures shouldbe thoroughly cleaned and disinfected
between patients. All equipment used should
be cleaned and disinfected between uses.
Separate equipment (e.g. bath trays, bowls)
should be labelled and only used for an indi­vidual patient.

­The Surgical Suite
The surgical suite of most small animal
practices can be easily modified to cater for
reptilian patients. There are specific require­ments that will make performing surgery
safer for both the patient and operating

Setting Up and Equipping a Reptile Practicestaff, allow for a more efficient use of space,staff and time, resulting in an improved
standard of care.
Instrumentation
Most veterinary practices already have surgi­
cal instruments that could be used satisfacto­rily in reptilian patients. In addition to these,
ophthalmic instruments are useful when
operating on small patients. A basic kit for
reptile surgery may include:
small scalpel handle and blade
fine needle holders such as Olsen‐Hegar orCastroviejo●● straight and curved Halsted mosquito for­ceps and Allis tissue forceps for tissue han­dling and haemostasis●● a selection of fine forceps such as Bishop
Harmon or Debakey, as well as atrau­
matic forceps, e.g. Adson Brown tissue
forceps●● at least one pair of good quality fine scis­
sors, such as Iris (both straight and curved),
Castroviejo or strabismus scissors.
●●●●

In addition to these basic surgical instru­
ments, the surgeon may have need for:●●eye speculums, such as Barraquer orCastroviejo, which are very effective
retractors for coelomic surgery on small
reptilesFigure 9.7 Haemoclips are used toligate blood vessels, such as theovarian vasculature in this bearded
dragon.

●●bulldog clamps; these small atraumatic
clamps are useful in gastrointestinal surgery.

Other Equipment
In addition to the surgical instruments, someancillary equipment is useful, including:vascular clips: haemostasis in small
patients can problematic. The use of stain­
less steel or titanium vascular clips (e.g.
Hemoclips® and Ligaclips®) can help greatly
to reduce blood loss and surgery time
(Figure 9.7).
●● laser or radiosurgical unit: reduced swell­ing and pain at the surgery site, accurate
haemostasis and a further reduction inanaesthetic time are some of the benefitsof these modalities.
●● reuseable retractor rings (e.g. Lone Star
Retractor®): adequate surgical exposure
can be a challenge in reptiles, particularly
when performing a coeliotomy. The use ofa Lone Star Retractor will greatly improve
exposure and again reduce surgery time
(Figure 9.8).
●● magnification loupes: being able to actu­
ally see what you are performing surgery
on is obviously vital, especially with verysmall patients.
●● heating: keeping the patient warm through­out surgery and recovery is imperative fora good outcome. This can be achieved
●●

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Reptile Medicine and Surgery in Clinical Practice

Figure 9.8 Lone Star retractor in use.

through the use of heating mats, forced
warm air blankets and heat lamps.
●● consumables: using clear patient drapes,
swaged on suture needles, and sterilized
cotton buds can improve patient care andincrease the chances of a positive outcomeof surgery.

Anaesthetic Equipment
Having the correct surgical equipment isuseless if the animal cannot be safely and­adequately anaesthetized for surgery. See­
Chapter 27 for more information on anaes­
thesia in reptiles.

125

10
The Reptile Consultation
Bob Doneley and Brendan Carmel­The Appointment
Before an examination can be performed, an
appointment has to be made. This requires
an interaction between your reception staff
and a potential client, either in person or on
the telephone. Some pointers that have
proven to be successful include:
Allow up to 1 hour for a new reptile clientand 30 minutes for a regular client. Your
receptionist must be bright, friendly andcomfortable with reptiles and, above all,must exude confidence that your practice
can competently examine and treat a reptile.
●● Give the client clear instructions on what
to bring:–– a fresh faecal sample (not urates)–– a water sample from the tank of aquatic
reptiles (the client should bring at least
100 ml in a sealed bottle, without thereptile in it–– digital photographs of the enclosure–– the reptile in a suitable container, notdraped over the client’s neck or down
their shirt front. The enclosure shouldbe escape and leak proof and shouldhave supplemental heat; for example, a
hot water bottle or heat pack, to keep
the reptile warm.
●●

Ensure that the receptionist obtains exact
details of what is coming in – species, age,sex and problem. Having these details
before the client arrives allows the veterinarian to do some quick research on thehusbandry requirements and biologicalcharacteristics of any unfamiliar species.
There is nothing worse than seeing an
appointment in the scheduler that simply
says ‘Mr Jones, sick snake’.
●● Ask the client to arrive at least 10 minutes
before their appointment. If possible, e‐
mail them a new client questionnaire andask them to bring it with them already filled
in. Alternatively, have a link to a downloadable history form on your website.
●●

More information on making an appointment is contained Chapter 32. On the arrivalof the client and patient, details can be confirmed and entered into the computer database. Faecal and water samples provided by
the client can be passed to a staff member
for testing: water quality (pH, ammonia,
nitrates, and nitrites), a faecal smear and afaecal flotation. These tests can be running
while a history is taken and the reptile isbeing examined and the results available tothe veterinarian before the completion of
the consultation.

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

126

Reptile Medicine and Surgery in Clinical PracticeDiagnosis
Diagnostic
testing
Close physicalexamination
Distant physicalexamination
Clinical history
Patient’s life history

Figure 10.1 The diagnostic pyramid.

­The Diagnostic Pyramid
The process of arriving at a diagnosis can belikened to building a pyramid (Figure 10.1). A
solid base – the patient’s history – is necessary for a good start and strong support.
Layers can then be added (the physical examination and diagnostic testing) before arriving at the apex, the diagnosis. Bypassing anyof these steps leads to a shaky and unstablediagnosis. But by working on them steadily
and adding them in the right order, a solid
diagnosis can be achieved.

­Taking a History
A patient’s history can be divided into twoareas: what happened to the reptile before it
became ill, and ‘why are you here today?’.
Most health problems in reptiles are due toincorrect or poor husbandry and, without
an idea of how the reptile has been cared for,it can be difficult to determine what hasgone wrong.
By using a computerized template, the firstpart of the history can be collected by thereception or nursing staff and then reviewed
by the veterinarian at the beginning of theconsultation. As mentioned above, a history
form can be provided to the client before theconsultation for completion. A list of suggested headings for such a template areshown in Box 10.1.
The second part of the history (Why are
you here today?) can be started by thereceptionist or nurse but will need to be
explored in greater depth by the veterinarian after reviewing the first part of the history. An indication of the problem, when it
was first noticed, whether is it progressing
and what effect it is having on the animal(appetite, thirst, urination, defecation,
shedding and activity levels) needs to beascertained. It is important to know if any
other animals have been affected and, if so,
what happened to them.
Having the right tools in the consultation
room to examine a reptile is essential.
Much of the required equipment is alreadypresent in the general small animal practice,although some equipment specific for dealing with reptiles is required (see Chapter 9
for more details).

­The Physical Examination
This is the part of the consultation the owneris keenest to get to, and a mistake made bymany veterinarians is to go straight to a physical examination without first obtaining a goodhistory. The clinician must resist the temptation to open that bag or container too soon!
All animals should be weighed and theweight recorded. A set of digital scales is an
essential piece of consulting room equipment. Weighing the reptile in the bag or container before taking it out and then weighing
the bag or container after removing the reptile is the simplest means of weighing fidgety
reptiles. Recording the weight allows the clinician to calculate drug doses accurately, tomonitor response to treatment and to compare the weight against previously recorded
weights and against expected weights for thatspecies. (It is also useful to encourage clients
to weigh their reptiles regularly at home asweight loss may be the only subtle indicatorof ill health in some reptiles.)Successful reptile practice is based on asound knowledge of the biology of the commonly presented species; perhaps more sothan when dealing with other animal classes.
In clinical reptile practice, a problem‐based

The Reptile Consultation

Box 10.1 Suggested headings for a history form.
The origin of the animal: where did the client
obtain this animal and how long ago?
●● The animal’s age, sex, weight and reproductive history.
●● Are there any other reptiles in the collection? If so, where are they housed in relation
to the animal that has been presented?
●● Have there been any new arrivals? If so,where did they come from? What quarantine
procedures were followed and were any prophylactic treatments given?
●● Details of the enclosure:○○ indoor/outdoor○○ orientation (horizontal or vertical)○○ size○○ construction materials○○ cage furniture (substrate, hides; climbing
branches, water and feed dishes)○○ ventilation○○ frequency and method of cleaning.
●● Heating:○○ At what temperature is the enclosure kept?
○○ Is there a temperature gradient?
○○ How is the heat provided?
○○ How is it monitored (thermometer)?
○○ How is it controlled (thermostat)?
○○ Is the enclosure cooled during winter?
●● Humidity:○○ What is the humidity in the cage?
○○ How is it provided?
○○ How is it monitored and controlled?
●●

approach to diagnosis and treatment, outlining the commonly occurring clinical conditions, can be used (see Chapter 17). As withany species, examining normal or well animals to learn the normal is essential to detect
the abnormal. Consider inspecting reptiles atpet shops, local herpetological societies or
local zoos or wildlife parks to gain experienceand to learn what is normal.
Although the history will have somewhat
narrowed the clinician’s list of differential
diagnoses, care must be taken not to ‘jump to
the obvious’. A thorough physical examination, followed by a detailed examination of the

Ultraviolet B (UVB) lighting: how is it provided? Is there access to unfiltered sunlight?
How old are any artificial UVB sources andhow often are they changed?
●● Water (for aquatic reptiles):○○ Quality(temperature; pH; ammonia;
nitrates; nitrites; hardness).
○○ How is it filtered?
○○ Water changes (how often, how much).
○○ How is water quality monitored and how
often?
●● Feeding:○○ What with?
○○ How often?
○○ Any supplements?
○○ When was the animal last fed?
●● When did the reptile last defecate?
●● When did the reptile last shed? Were there
any difficulties with any shedding? Was any
assistance required?
●● Routine prophylactic treatments against
external and internal parasites:○○ Has anything been done?
○○ What with and how frequently?
○○ When was the last treatment?
●● Previous medical history:○○ Has this animal been unwell before?
○○ What was the problem, how was it treated,
and who treated it?
○○ How did the animal respond to thistreatment?
●●

problem area, may reveal other problems ofwhich the owner was not aware; for example,
necrotic stomatitis in a snake with skin lesions.
The physical examination should also
include sex identification. Many owners,
especially of pet reptiles (as distinct frombreeding animals) are unaware or uncertainof their reptile’s sex and seek veterinary
advice on how to identify whether their pet ismale or female. Knowing the animal’s sex is a
key element of establishing a list of differential diagnoses.
As with the examination of any species,
a systematic approach is recommended: a

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Reptile Medicine and Surgery in Clinical Practicemethodical approach to examination of thereptile will lessen the chance of a missed
diagnosis. Most reptiles resent oral examination so preferably examine the mouth last.
Disposable gloves should be worn when
examining reptiles, both for personal hygiene
and also to help to minimize the potential
transmission of disease between reptiles (e.g.
sunshinevirus in snakes).
The first step of the examination is toobserve: assess the demeanour, general alertness, posture and conformation of the reptile. This is done before picking the animalup; for example, observing a snake for any
unusual coiling, twisting motions or weakness (Figure 10.2). If the reptile appears particularly lethargic, distressed or unwell, stop
the physical examination and concentrate on
stabilizing the patient (Figure 10.3). An outline of the approach to the physical examination is provided in Box 10.2.
The physical examination of a reptile isoften unrewarding with respect to the development of a differential diagnosis list. Thereis then a resultant need for collection of diagnostic samples (see Chapter 11).

Figure 10.2 Abnormal posture andmouth breathing in a jungle carpet
python with sunshinevirus.

Figure 10.3 This juvenile frilled lizard
may benefit from supportive carebefore conducting a detailed physicalexamination.

Box 10.2 Some general notes regarding the physical examination of reptiles.
Begin with the external examination(Figure 10.4). Examine the skin, looking forabnormalities such as dysecdysis (abnormal
shedding), lumps or bumps, discolouration,
ulceration, wounds or parasites. Visuallycompare the symmetry of body parts. The
nares, eyes, mouth, cloaca and ear openings(where present) should be free from discharge, swelling or discolouration.
●● Performing a neurological examination on a
reptile can be challenging. Reptiles do not●●have a consensual light response but dohave a pupillary light response, although
this is often sluggish compared with otherspecies. Basic proprioceptive testing can be
performed in some species.
●● The reptilian eye is extremely variable inappearance. Familiarize yourself with the normal appearance of the species being examined. In snakes, the cornea is covered by theeye scale, or spectacle. (Figure 10.5) Some lizards have fused eyelids that form a spectacle

Figure 10.4 The clinical examination of this large reticulated python (Python reticulatus) with dysecdysis
is aided by keeping most of the snake in a bag, with the help of assistants.
Figure 10.5 The reptilian eye isextremely variable inappearance.

Figure 10.6 Oral examination of the pharynx of this bearded dragon revealed impaction with fibrousplant material.

as in snakes. See Chapter 2 for more details on
the anatomy of the reptilian eye.
●● The reptile mite (Ophionyssus natricis) isoften found in grooves or crevices, such as
inside the edge of the orbit, or in the gulargroove (ventral chin region) of snakes.
●● Thecloacal region should be closely
inspected. Does it appear enlarged orswollen or tender to the touch? Is there sufficient cloacal tone (akin to anal tone in
mammals)? There should not be any accumulation of faecal or other matter aroundthe cloaca.
●● Auscultation of the heart and lungs in reptiles can be problematic. Some clinicians
find the use of a wet swab or small towel as
an interface between the reptile and a stethoscope will allow some assessment of respiratory or cardiac noises. Using a Doppler ishighly recommended as a method to assessheart rate and rhythm in the consultation.
Cardiac disease is increasingly being diagnosed in reptiles. See Chapter 20 for more
information on cardiovascular diseases.
●● Palpation of the coelomic region is possible
in some reptiles.
●● The mouth should be examined last, as most
reptiles resent examination of the oral cavity, as mentioned previously (Figure 10.6).
Pigmentation of the oral cavity varies widely
between reptile species. Mucous membranes in reptiles are typically paler than in
mammals but should have some colour andFigure 10.7 The mucous membrane colour of
reptiles can be variable, from pale pink to darkly
pigmented, such as in this snake.

should not appear dry (Figure 10.7). Pay
attention to the choanae on the dorsal surface of the oral cavity; any discharge or
swelling may point towards respiratory
disease.

The Reptile Consultation

Figure 10.8 This venomous snake is‘tubed’ to allow it to be examinedsafely. Only experienced veterinarians
should examine and treat venomousor dangerous reptiles.

Venomous Reptiles
Warning: It is recommended that only experienced reptile veterinarians examine and treat
venomous species. Safety is the prime consideration. Strict handling protocols must be inplace and implemented (Figure 10.8).
Examination of the Lizard
A useful method of restraining many lizards
for examination is to place the animal in a pillowcase or bag and extract the part of the lizard that you wish to examine (for example, aleg), leaving the rest of the lizard covered. This
allows the head to be covered, keeping the lizard in the dark, which has a calming effect.
The internal organs of some small lizards
such as geckos can be visualized via transillumination, using a focal light such as an otoscope light source. Palpation of the coelomic
region in many lizards can be rewarding.
Bearded dragons, for example, can be palpated to assess the size of the caudal abdominal fat pads and females can be palpated tofeel for follicular stasis, a common concern inthese species.

be more subtle; for example, hemipenal
bulges and the presence of femoral pores inthe bearded dragon (Pogona vitticeps) andthe iguana (Iguana iguana). Even more subtle dimorphism can be seen in species suchas the blue‐tongued skink (Tiliqua scincoides) where careful measurement of certain physical characteristics (head length, tailbase width, etc.) can be used to identify thesex of this species.
Techniques used in sexually monomorphic
species include eversion of the hemipenis(‘popping’, Figure 10.9), radiology of thehemipenis with or without contrast media,

Sex Identification

Some lizards, such as the eastern water
dragon (Intellagama lesueurii lesueurii) display obvious sexual dimorphism, with themale larger and with brighter, more prominent markings than the female. Others may

Figure 10.9 Manual eversion of a hemipenis in ablue‐tongued lizard.

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Reptile Medicine and Surgery in Clinical Practicetransillumination of the tail base, ultrasound,and endoscopy (see Chapter 7 for further
detail).
Examination of the Snake
Initially, the snake should be weighed and its
movements closely observed, watching for
any unusual coiling, twisting motions or
weakness of the distal body and decreased
constriction. This can be done as a distant or
hands‐off examination for non‐venomous or
non‐fractious species, allowing the snake tomove over the consulting room table. It willusually try to find a secure point to which toanchor its tail, such as the table leg or underside of the table top. An alert snake will intermittently flick its tongue.
Palpate the entire length of the snake ventrally to feel between the ribs, assessing formasses and organ location. The snake is aconveniently linear animal and the positionof the organs can be ascertained by using linear charts according to species. For example,
the heart is located approximately 25% of thesnout–vent length and can be palpated ormonitored via a Doppler probe.
Sex Identification

Many snakes can be sexed by gently probing
one or both hemipenes sulci to determine its
length or by everting the hemipenes. Many
pythons have a vestigial spur – the remnantsof the pelvic girdle – on either side of thevent. In males, this spur is often (but notalways) noticeably larger than that of thefemale. Ultrasonic detection of ovarian­follicles is relatively simple in mature female
snakes and requires less restraint thanmany other techniques (see Chapter 7 forfurther detail).
Examination of the Chelonian
On initial examination, place the chelonian
on a flat surface, taking care to ensure that it
cannot fall. Check muscle tone and strength
as the turtle moves. Limbs should be strong
and easily retract back under the carapace.
Head and neck should also retract to resist
handling.
Chelonians should be weighed and measured (straight carapace length). Carapace
and plastron injuries and lesions are common and skin lesions may be an indication of
more serious disease, such as a systemic illness. Oral examination may be revealing inan otherwise healthy animal, although opening the mouth can be a challenge in healthy
species. Consider the use of a credit cardor guitar plectrum as a lever to open themouth. Abscesses occur frequently, especially around the eyes and ears. Oedema of
the neck and limbs, with accompanying petechial haemorrhages, may indicate septicaemia (Figure 10.10). Palpation or ballottementof the inguinal and axillary fossae can be
rewarding, for example to detect gravidity.
Placing a turtle into lukewarm water can be auseful method to detect abnormal flotation.

Figure 10.10 Petechial haemorrhages,
often an indicator of septicaemia, in a
moribund eastern long‐necked turtle(Chelodina longicollis).

The Reptile Consultation

examination has been concluded. Oncethe examination has been completed, thereptile can be returned to its carrier andthen a summary of findings can be discussedwith the client. This avoids distractions andallows the client to focus on the veterinarian. The discussion could include:
problems identified with the husbandry
and nutrition of the reptile●● problems identified during the examination●● how these problems could be linked●● a short list of possible diagnoses●● where to go to from here: radiology, haematology, biochemistry, etc.
●● likely costs of these further tests and why
the tests are needed●● the likely prognosis.
●●

Figure 10.11 A chelonian may evert its phallus
during the physical examination.

Sex Identification

Turtles and tortoises are often sexed by theshape of the shell (especially the plastron),the shape of the caudal plastron notch or by
the length of the tail. The red‐eared slider(Trachemys scripta elegans) shows a pronounced difference between the male andfemale front claws, with the claws on themales’ front legs being longer than the clawsof female turtles.
Young male tortoises may ‘flash’ their phallus (i.e. allow it to protrude from the cloaca)
when immersed in a warm bath (Figure 10.11).
Ultrasonic examination via the pre‐femoral fossa can be used in some larger tortoises
to identify ovarian follicles, as can endoscopic cystoscopy (the ovaries can be visualized through the thin bladder wall). See
Chapter 7 for further detail.

­Summary
Other than to point out lesions during theexamination, the clinician should resist
the temptation to discuss findings and conclusions with the client until the physicalIf the client declines further testing, thisshould be noted in the clinical record(and the client made aware that their decision is been recorded) and a treatment
plan outlined.

­Diagnosis
The apex of the diagnostic pyramid(Figure 10.1) is the diagnosis. In an ideal
world, this would be a single, confirmed disease or problem. In the real world, however,such a diagnosis is often only obtained by necropsy and histopathology. In the live patient,
we are often left with a short list (two to three
items) of tentative diagnoses. In this situation,
after explaining this outcome to the owner, a
final diagnosis may be achieved by observing
the patient’s response to treatment.
Keep in mind that disease is usually the
result of a combination of many factors:
environment, husbandry, nutrition andexposure to a potential pathogen. Correcting
many of these contributing factors often
results in a clinical improvement and ‘cure’,
and a final diagnosis may be obscured bythis improvement.

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11
Diagnostic Testing
Rachel E. Marschang, Frank Pasmans, Tim Hyndman, Mark Mitchell and An Martel­Introduction
Reptiles have evolved to mask their illnesses.
This method of preservation is useful to animals in the wild but can make it challenging
for veterinarians attempting to assess thehealth status of these patients. In addition,
many disease processes found in reptiles are
multifactorial and may involve husbandry
issues and multiple infectious agents. Many
infectious agents found in reptiles may only
be pathogenic in conjunction with otherissues or immune suppression. Diagnostic
testing should therefore always be interpreted together with other findings, including history, clinical signs and adjunct testing
methods. The methods used for laboratory
testing for reptiles differ from testing in
mammals. Contact your laboratory before
submitting samples in order to optimize thesamples submitted and the results obtained.

­Haematology
Haematology can be used to provide physiological information regarding the health of
reptile patients. Limitations with current
analytical equipment require veterinarians to
use manual methods of measuring blood

cells. In mammals, it is common to evaluate
erythrocytes as part of a complete bloodcount but, in reptiles, clinicians are typicallylimited to analyzing a packed cell volume.
References for packed cell volume in reptiles
are highly variable (20–40%) and should beinterpreted based on the general conditionand health of the patient. In cases where
there are concerns that erythrocyte numbers
are low (e.g., anaemia), erythrocytes can becounted (using the Unopette® system) manually or a review of the blood smear can be
performed. Typically, a subjective, ordinalscale (1–4+) is used to assess the presence ofanisocytosis and anisokaryosis from theblood smear. Immature erythrocytes have ahigher nuclear to cytoplasmic ratio thanmature cells and, using Romanowsky‐typestains, have a more basophilic cytoplasm
than mature cells. Review of the blood smear
can provide additional information regarding potential anomalies of erythrocytes(e.g., viral inclusions and blood parasites;
Figures 11.1 and 11.2).
Slide preparation for blood smears canaffect the differential count. Direct bloodsmears made using glass microscope slides
are found to be associated with significantly
higher ‘smudgeocytes’ (cells that could not be
differentiated) than other techniques such as

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

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blood smear preparation using coverslips.
Significant loss of blood cells due to incorrectslide preparation can affect the estimatedleucocyte or differential counts.
Manual leucocyte counts for reptiles are
typically performed using semi‐quantitative
methods. The first and simpler method isusing a stained blood smear (e.g. Diff‐Quikor Wright–Giemsa stain; Wright– Giemsa
staining is less likely to be associated withleucocyte degranulation). Review the slide
near the edge of the smear where the cells areevenly distributed in a monolayer. Using thehigh dry objective (400–450×), ten fields arescanned. The total number of white cells canbe divided by 10 to obtain an average, which
is multiplied by 2000 to calculate an estimated total leucocyte count (cells/μl). A differential count is then performed. A 100 or
250 cell count differential is recommended.
A second method of estimation is done using
phloxine B stain. A blood sample is mixed
with the stain and the cells are then loaded
on to a haemocytometer. The stain is used to
identify heterophils and eosinophils. Once a
differential is found, the following formula isused to estimate the leucocyte blood count:
Total leucocyte count(total haemocytometer count ) (32) 100(% heterophils and eosinophils) 100
Reptiles have similar types of white blood
cells to other non‐mammalian vertebrates,with some species specific morphologicaldifferences. Table 11.1 gives examples of theblood cells and their function.

­Biochemical Analyses

Figure 11.1 Inclusion bodies in blood cells of a boa
constrictor with inclusion body disease (courtesy of
Kim Heckers, Laboklin).

Biochemical analyses can also provide
physiological information about a reptile­
patient’s health status. Many of the same
biochemical measures in mammals are also
evaluated in reptiles; however, unlike
Figure 11.2 Haemogregarines(Karyolysis sp.) in a blood smear(stained with Hemacolor®) of the lizard
Podarcis melisellensis. The parasites arevisible inside the erythrocytes.

Diagnostic Testing

Table 11.1 Leucocytes commonly found in reptiles.
Cell typeAppearance

Function

Heterophil

Eosinophilic granules, round to
lobed nucleus

Elevated with acute inflammation(e.g., infection, trauma, neoplasia)

Lymphocyte

Agranulocyte (highnuclear : cytoplasmic ratio)

Cell‐mediated immunity
Antibody production

Monocyte

Agranulocyte (lownuclear : cytoplasmic ratio)

Chronic inflammation

AzurophilSame as monocyte, azure staining
cytoplasm

Chronic inflammation

Eosinophil

Eosinophilic or basophilic granules

Hypersensitivity, parasitaemia

Basophils

Basophilic granules

Histamine releasemammals, interpretation can be difficult(while there is only one species of dog, there
are over 9000 different species of reptile).
Many of the biochemistry references available for reptiles are based on study populations of limited size or unknown healthstatus. Because of these limitations, it is best
to develop individual patient biochemistryreferences using known disease‐free intervals for the patient (e.g. on annual healthchecks). These data can then be used in
combination with published references tobetter assess a reptile’s health status.
Sample collection and processing areimportant considerations when evaluating
biochemistries in reptiles. Haemolysis andlymph dilution can have deleterious effects
on the results. Lymph vessels are closely
associated with blood vessels and may be
accidentally sampled, diluting the blood
sample. Either serum or plasma can be used
to analyse biochemistries in reptiles; in either
case, the normal appearance of the sample
will be clear. The serum and plasma should
be removed from the cells immediately tominimize artefacts.
Glucose concentrations in reptiles arehighly variable but generally range between
2 mmol/l and 10 mmol/l (40–180 mg/dl).
Lower concentrations are more commonly
noted in large snakes, while higher concentrations are common in animals under stress.
Diabetes mellitus is rare in reptiles.

Total protein, albumin and globulins canprovide insight into the hydration, immunological and reproductive status of a reptile.
Concentrations for total protein may range
from 35 g/l to 75 g/l (3.5–7.5 mg/dl) andthere should be a positive albumin to globulin ratio. Elevated total protein and albumin
are common in dehydrated reptiles, whileelevated globulins are common in reptiles
with inflammatory disease. Protein electrophoresis is recommended to better ascertain
which proteins are elevated in these cases.
Elevated albumin concentrations in female
reptiles during the breeding season are indicative of impending egg‐laying; concurrent
elevations in calcium and phosphorus arecommon in these individuals. Albumin may
be artificially lower in some species (e.g., tortoises) because of a weakened affinity forbromocresol dye binding.
The end‐products of protein catabolism invertebrates include ammonia, uric acid andurea nitrogen. In reptiles, uric acid is generally considered the most common catabolite
to be excreted; however, in some species (e.g.
some tortoises) urea nitrogen is more common. This is important to consider, as it may
result in misclassifying a reptile’s health status. Hyperuricaemia is commonly associatedwith high‐protein diets, a recent meal, dehydration and gout. Hyperuricaemia is notcommonly observed in reptiles with renal
disease. This is because urea is excreted in

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the proximal tubules; thus, it is usuallywidespread renal disease that affects bloodconcentrations. Uric acid concentrations
are generally less than 595 μmol/l (less than
10 mg/dl) in healthy reptiles, although concentrations up to 1487 μmol/l (25 mg/dl) may
be observed in carnivorous reptiles postprandially. Urea nitrogen concentrations are
typically less than 12.5 mmol/l (less than
35 mg/dl) in chelonians. Elevations in urea
nitrogen may be associated with pre‐renal,
renal or post‐renal disease.
Sodium (125–155 mmol/l), potassium(2.5–6.0 mmol/l) and chloride (90–120 mmol/l) are the electrolytes most commonly measured in reptiles. Elevations in
sodium and chloride concentrations mostcommonly occur with dehydration; evaluating these electrolytes with total protein, albumin and packed cell volume can better define
hydration status. Elevations in potassium arecommon with haemolysis and renal disease.
Calcium and phosphorus circulate in bothbound and unbound forms. Most analysers
measure total calcium (2–3.5 mmol/l;
8–14 mg/dl) and total phosphorus (0.97–
2.26 mmol/l; 3–7 mg/dl), although some alsomeasure unbound (ionized) calcium (1.0–
1.5 mmol/l; 4–6 mg/dl). Hypocalcaemia andhyperphosphataemia are common in reptiles
with renal disease; biopsy and histopathology
are recommended for these cases to confirm
a diagnosis. Hypercalcaemia and hyperphosphataemia are common with folliculogenesis
and may be used to confirm a reptile’s sex as
female in non‐dimorphic species. Normal
calcium and phosphorous levels do not confirm that the reptile is male.
There are a number of enzymes commonly measured in biochemistry analyses,
including creatine kinase, aspartate aminotransferase, alkaline phosphatase, lactate
dehydrogenase and lactate. Few studies haveassessed tissue specificity for these enzymes;
however, only creatine kinase appears to be
tissue specific, with the highest concentrations found in skeletal, cardiac and smoothmuscles. The lack of site specificity forthese enzymes suggests that clinicians
should use caution when interpreting

results. Best results will be achieved using
biopsy and histopathology in association
with enzyme concentrations.
Bile acids are considered an importantliver function test in mammals and birds.
Reptiles can produce different types of bile
acids, limiting the value of some analysers ifthey only measure one type. Research ingreen iguanas (Iguana iguana) suggests thatelevated bile acids (greater than 70 μmol/l)are indicative of hepatic disease.

­Cytology
Cytological examination of samples canbe used to make a diagnosis or to guide aclinician to additional diagnostic tests. The
primary benefits of cytology are that it is
rapid and inexpensive, if done in‐house.
Unfortunately, this diagnostic method only
has a fair sensitivity (i.e. it is subject to false
negatives). In cases where cytology proves
limiting, biopsy and histopathology should
be considered.
Fine‐needle aspirates are commonly used
to evaluate masses, joints, fluid‐filled spaces(e.g., ascites), bone marrow or internalmasses in reptiles. Needle and syringe sizes
used for collecting the samples may vary
based on patient size but a 25‐gauge needle
and 3–6 ml syringe are commonly used forsample collection. The surface of any site
being sampled should be disinfected using
standard aseptic techniques. For externalmasses, two different fine‐needle aspiration
techniques can be used. The first techniquerequires the needle to be attached to thesyringe; the needle is inserted into the massand negative pressure is applied by pullingback on the syringe plunger. Negative pressure should be released before removing theneedle from the mass to prevent aspiration of
the sample into the syringe and the loss ofany cells. The second technique requires thatthe needle be inserted directly into the mass
(with no syringe attached). This techniqueattempts to collect ‘cores’ of cells for evaluation. In both cases, the needle needs to be
redirected through the sample multiple times

Diagnostic Testing

to maximize the collection of cells. Onceobtained, the samples should be placed onslides for staining. Ultrasound is recommended for collecting samples from within
the coelomic cavity to ensure that the appropriate site is sampled.
Stain selection should be based on the presumed differentials. The most common findings from fine‐needle aspiration and cytology
are inflammation, infection, foreign materialand cancer. Romanowsky‐type stains, such as
Diff‐Quik stains, are commonly used because
they are inexpensive, easy to prepare and canidentify many of the common findings noted
above. Gram stains are also useful for screening samples for bacteria. Direct smears prepared with saline are recommended forassessing protozoal populations.
Because reptiles are stoic in nature andmask illness, they typically present with varying stages of inflammation. Acute inflammation is often characterized by a significant
number of heterophils (greater than 75%) on
the smear. The presence of toxic heterophils(e.g., degranulation and vacuolation) is suggestive of a more aggressive response fromthe host. These slides should be screened
closely for pathogens (e.g., bacteria, fungi). If
pathogens are suspected, additional samples
should be collected and submitted for culture or polymerase chain reaction testing.
Chronic inflammation is a more common
presentation and is characterized by a mixed
population of lymphocytes, macrophages
and heterophils. These slides should also be
screened for pathogens, although otherinflammatory diseases, such as neoplasia,
should be considered. Diagnosing neoplasia
from cytological samples can be challenging.
Cells should be evaluated for the presence ofmultiple nuclei or nucleoli, the nuclear tocytoplasmic ratio and the types and densities of cells.

­Serology
Serological testing is used in reptile medicine to determine whether an animal has
been exposed to certain infectious agents. It

is important to realize that the reptile
immune system is dependent on environmental factors to function optimally.
Antibody responses to infection will dependon temperature and time of year, stress, animal age and other infections. Serology is
only capable of detecting a portion of thehumoral immune response. In many cases,
the cellular immune response may be more
important for removal of pathogens fromthe system. While a positive serological test
will provide information if an animal has
been exposed to an infectious agent (or asimilar antigen), it will not generally provide
information on the current infection statusof that animal. In these cases, paired testing
may prove more valuable. Serological testingin reptiles is not standardized and resultsfrom different laboratories may not be comparable. Contact the laboratory to determine
test methods used, antigens used, antibodies
being measured (immunoglobulin M or Y, orboth), cut‐off points and any standardization of methods. Most methods used for thedetection of antibodies against specificagents in reptiles require reagents withsomewhat limited availability, including isolates or other source of antigen, specific antibodies or cell lines. This limits these tests tolaboratories in which all of the necessary
reagents are available and increases thecosts. Here, we provide an overview of tests
commonly described in reptile medicine andtheir interpretation.
Virus or Serum Neutralization Tests
Neutralization tests measure the ability ofantibodies in serum or plasma to prevent agiven pathogen from infecting susceptible
cells. In reptiles, this method has been used
for multiple viruses including herpesviruses, adenoviruses, reoviruses and picornaviruses. It is most commonly used todetect antibodies against testudinid herpesvirus in tortoises. Since herpesviruses cause
persistent infections, any animal with
detectable antibodies against these virusesmust be considered infected, regardless ofclinical status.

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Haemagglutination
Inhibition Tests
Haemagglutination inhibition is used todetect antibodies against pathogens thatbind to and haemagglutinate red blood
cells. In reptiles, this method is used to detect
antibodies against ferlaviruses (also known
as ophidian paramyxoviruses). Ferlaviruseshave been shown to be serologically diverse
and the use of different isolates and different
cut‐off values can lead to extreme differencesin results obtained from different laboratories. It is not known whether ferlaviruses
cause persistent infections in reptiles and so
the presence of ferlavirus antibodies should
not be automatically interpreted to meanthat the animal is infected. The detection of
antibodies against viruses in healthy reptiles
should always be interpreted carefully.
Enzyme‐linked
Immunosorbent Assay
A number of enzyme‐linked immunosorbent
assays (ELISAs) for the detection of antibodies against specific pathogens have been
described for reptiles. In general, antibodies
in the sample bind to antigen. The reptile
antibodies are then detected using secondary
antibodies that target the reptile antibodies.
ELISAs are most commonly used for thedetection of antibodies against Mycoplasma
agassizii in tortoises. Since this pathogen
causes persistent infections, the detection of
antibodies is an indication of infection,
regardless of clinical status.
Molecular Diagnostics
In reptile practice, molecular diagnostics areusually used to detect the nucleic acids (DNAand RNA) of infectious agents. In the early
21st century, the technology and availabilityof molecular diagnostics has advanced at a
staggering rate. Molecular diagnostics offer anumber of advantages over traditional tests.
For example, the viability of the infectiousorganism does not need to be maintained
because the agent will not be required toreplicate in the laboratory. This has the added
advantage that molecular testing can detect
agents that have fastidious in vitro growthrequirements (e.g. arenavirus) or grow very
slowly (e.g. Mycobacteria). Finally, the detection limits of molecular testing nearly always
outperform those of more traditional tests
such as culturing. A more detailed overview
of these methods can be found in the excellent review by Johnson et al. (2007).
Polymerase Chain Reaction
In the polymerase chain reaction (PCR),
nucleic acid (DNA or RNA) specific to theinfectious agent of interest is amplified intolarge amounts of DNA. If a detectableamount of agent‐specific DNA is found, thesample is considered to be positive for thepresence of that agent. If not, the sample isconsidered negative. The interpretations ofpositive and negative PCR results, together
with recommended courses of action, arelisted in Table 11.2. Some PCR tests used toscreen reptile samples are broadly reactive
and so false positives are possible. For example, if a PCR for adenovirus was used that can
detect all known adenoviruses, it is important that the test result is validated (bysequencing) to make sure that a reptilian
adenovirus was identified and not a contaminating human adenovirus.
Traditionally, PCR has been a test that only
provides a positive or negative result. Some
more modern PCRs are able to quantify theamount of infectious agent in a sample,
referred to as real‐time or quantitative PCRs.
From the clinician’s perspective, many ofthese quantitative PCRs have limits of detection that are superior to traditional PCRs andthus represent a better test.

­Culture
Bacterial and fungal cultivation is a standard procedure in reptile diagnostics but
seldom used for viruses and parasites.
­
Advantages of culture compared over

Diagnostic Testing

Table 11.2 Interpretation of polymerase chain reaction results.
PCR result
Positive

Negative

Interpretation

Animal is infected.
orAnimal is uninfected but
sample was contaminatedwith infectious agent.

Animal is uninfected.
orAnimal is infected but:●● sample contained infectious agent in quantities
below the detection limit of the PCR●● wrong type of sample was collected (e.g. swabvs. blood)●● sample was degraded (e.g. exposure to hightemperature)●● did not have agent in that sampling space (swab,
blood) at the time of sampling e.g. intermittent
shedding of infectious agent.

Recommended
course of action

If comfortable sample
contamination did not occur,then assume animal is infected.
If there are doubts about
inter‐sample contamination,
repeat testing.

Repeat testing ensuring the correct sample istaken and that it is stored and transported to thelaboratory correctly. Multiple negative results will
increase the confidence that the animal is truly
uninfected.

molecular diagnostics are a less biased­estimate of pathogen presence and diversity,
the possibility of obtaining antimicrobial­susceptibility profiles to redirect treatment(see Chapter 14) and, in the case of novel
pathogens, detection of novel disease entities. Interpretation of mixed cultures can behampered by the bias towards organisms thatgrow well on routine culture media and thecurrently poor understanding of bacterial

and mycotic pathogens in reptile disease(Figures 11.3 and 11.4). Important pathogens
that require specific growth conditions will
be missed (e.g. intracellular bacteria thatneed cell cultures for growth such as
Chlamydiales, many mycobacteria and most
Mycoplasma spp.).
Standard techniques for bacteriology andmycology can be applied to reptile samples,with some modifications. Although many

Figure 11.3 Open intra‐oral abscesses(here in the skink Corucia zebrata)
often yield abundant growth of a large
variety of bacteria, which seriously
hampers interpretation of bacterial
cultures.

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Reptile Medicine and Surgery in Clinical Practice

Figure 11.4 Bacterial cultures
obtained from closed abscesses, suchas this large abscess in a Python
molurus are generally far easier tointerpret, often yielding abundant
growth of a limited number ofbacterial and/or fungal taxa.

reptile‐derived bacteria and fungi will growwell at typical clinical laboratory incubatortemperatures (35–37 °C), incubation of samples should ideally reflect the preferred bodytemperature of the species or temperature of
the reptile’s environment (e.g., cooler temperatures with fungi). Generally, an incubation temperature of 30 °C supports thegrowth of bacterial and mycotic reptile pathogens. Both aerobic and anaerobic culture
conditions should be used. Fungal cultures
should be incubated for at least 10 days todecrease the likelihood of false negatives.
Cultures can be identified using culture
growth characteristics and morphology,
biochemical typing, DNA sequencing (typically 16S rDNA for bacteria and internaltranscribed spacer sequencing for fungi)
or protein and peptide profiling (matrix‐
assisted laser desorption/ionization–time‐of‐flight mass spectrometry). A detailed
laboratory report should include the bacteria and fungi that were identified and (semi‐)
quantitative data regarding the organisms toallow meaningful interpretation. The following guidelines are suggested:In cases where pure and abundant cultures
are obtained from lesions, the bacteria or
fungi identified can be expected to play arole in the disease process.
●● In cases with mixed cultures (e.g. gastrointestinal, respiratory and skin samples), interpretation may be difficult. Isolation of a●●known bacterial or fungal reptile pathogen
from a lesion or site should only beconsidered as a presumptive diagnosis;­
histopathology is required to confirm the­association. Despite the publication of reptile pathogens and their pathogenic relevance, epidemiological knowledge ofbacterial (and mycotic) pathogens in reptiles
is very limited. Few bacteria and fungi havebeen shown to be primary reptile pathogens(e.g. several Mycoplasma sp., Devriesea agamarum (Figure 11.5), fungi belonging to
the family Onygenaceae; Figure 11.6).
Identification of these pathogens in a sample
from a patient with lesions consistent withthe disease syndrome should be consideredhighly suspicious. Many potentially pathogenic taxa (e.g. Salmonella sp., Aeromonassp., Pseudomonas sp.) are commonly foundin the digestive and/or respiratory tract ofhealthy reptiles. In these cases, high relative
abundance of a potentially pathogenic bacterium or fungus in a clinical sample is suggestive that it may play a role in the disease
process.
●● It is hard, if not impossible, to interpret thesignificance of bacteriological and mycological results from intestinal and faecal
reptile samples. Intestinal bacterial andmycotic pathogens, let alone microbiota
imbalances, in reptiles have been very
poorly characterized. Since the majority of
reptiles carry potential pathogens in thegut (e.g. Salmonella), the mere presence ofDiagnostic Testing

Figure 11.5 Although the cheilitis in
this collared lizard (Crotaphytus collaris)
is suggestive of an infection withDevriesea agamarum, bacterial cultures
are necessary to confirm the diagnosis.

Figure 11.6 Growth of Nannizziopsis
guarroi, isolated from a bearded
dragon (Pogona vitticeps) on
Sabouraud dextrose agar. Fungal
cultures should be incubated for atleast 10 days.

these pathogens is insufficient to draw any
sound conclusions with regard to their rolein the disease.
Overall, except for a few cases, bacterial andfungal infections in reptiles should generally
be considered to be secondary to any causethat compromises reptile defences, such asother infections (e.g. viruses, parasites),stress or inadequate husbandry. Althoughparasitological examination should form partof any clinical or post‐mortem examinationof a reptile, parasite cultivation is not routinely done.
Viral cultures are rarely used in reptile
diagnostics and generally require highly specialized laboratories. Viral cultures are sometimes considered when there is clear
indication on histopathology that there is aviral aetiology but routine tests (PCR, serology) do not return any positive results.

ReferenceJohnson, A.J., Origgi, F.C. and Wellehan, J.F.X.
(2007) Molecular Diagnostics in Infectious

Disease and Pathology of Reptiles.
CRC Press, Boca Raton, FL.

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Reptile Medicine and Surgery in Clinical Practice

Further Reading
Allender, M.C., Mitchell, M.A., Dreslik, M.J.
et al. (2008) Measuring agreement anddiscord among hemagglutination inhibition
assays against different ophidianparamyxovirus strains in the Eastern
massasauga (Sistrurus catenatus catenatus).
Journal of Zoo and Wildlife Medicine, 39 (3),358–361.
Bogan, J.E. and Mitchell, M.A. (2014)
Characterizing tissue enzyme activities in
the American alligator (Alligator
mississipiensis). Journal of Herpetological
Medicine and Surgery, 24 (3–4), 77–81.

McBride, M., Hernandez‐Divers, S.J., Koch, T.
et al. 2006. Preliminary evaluation ofpre‐ and post‐prandial 3α hydroxyl bile
acids in green iguanas. Journal of
Herpetological Medicine and Surgery, 16 (4),
129–134.
Myers, D.A., Mitchell, M.A., Fleming, G.
et al. (2008) Determining the value ofbovine albumin as a blood cell stabilizer
for pancake tortoise, Malacochersus
tornieri, blood smears. Journal of
Herpetological Medicine and Surgery,
3 (4), 95–99.

145

12
Diagnostic Imaging
Zdeněk Knotek, Shane Simpson and Paolo Martelli­Radiography
Radiography is part of the comprehensive
clinical examination of reptiles and can beused to evaluate bone structures, confirm
or rule out the presence of mineralized
eggs, identify areas of differing soft‐tissue
density, including penetrating bite wounds,
pulmonary granulomas and gastrointestinal
foreign bodies.
Sedation and Anaesthesia
Sedation or short‐acting anaesthesia is rec­ommended for box turtles, shy tortoises that
refuse to protrude from the shell, dangerous
animals, very stressed or delicate individuals
or when precise positioning is required.
Positioning
For correct radiographical interpretation,
proper positioning and restraint are manda­
tory. Practitioners are encouraged to invest
in equipment that allows the use of a hori­zontal beam. Not only is lateral recumbency
difficult (or impossible) to maintain, it islikely to be resisted by the reptile. It also
allows internal organs to move within the

coelom, complicating interpretation of radi­
ographs (Pees 2011, Raiti 2004, Silverman
et al. 2006, Wilkinson et al. 2004).
Chelonians

Three projections (dorsoventral, laterolat­
eral, and craniocaudal) can be used in che­lonians. When taking these views, patientsshould be in their natural ventral position
lying on their plastron (Pees 2011, Raiti
2004, Silverman et al. 2006, Wilkinson et al.
2004). The patient’s head and limbs should
be extended out of the shell, which can beachieved by placing the patient on an ele­
vated stand that touches the plastron only
(Figure 12.1). The lungs are superimposedover other coelom organs and difficult toassess on a dorsoventral view, although col­lapsed or over‐expanded lungs may be diag­
nosed. Better images of the lung fields canbe obtained with laterolateral and cranio­
caudal projections using a horizontal beam.
The cassette is placed vertically with theedge of the shell touching the cassette. The
centre of the beam should be aimed at thelateral scutes in the middle of the animal(laterolateral view) or the centre of the body
(craniocaudal view). The craniocaudal viewis used as a complementary projection to

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

146

Reptile Medicine and Surgery in Clinical Practice

Figure 12.1 Positioning of a tortoise for a laterolateral view x‐ray.

compare the inflation and densities of theleft and right lung. Positioning of the chelo­nian is as symmetrical as possible so thatboth sides of the lungs can be compared(Pees 2011, Raiti 2004, Silverman et al. 2006,
Wilkinson et al. 2004).
SnakesIn snakes, dorsoventral and laterolateral pro­jections are used. Individual segments of the
body should be properly identified using
radio‐opaque markers so that the same area
can be compared in an orthogonal view.
Dorsoventral projections of a coiled snake
placed on the cassette are of limited value
because of the possible movement of coelom
organs and asymmetry of spine and ribs
(Pees 2011, Raiti 2004, Silverman et al. 2006,
Wilkinson et al. 2004). When dorsoventral
projection is used, the patient is positioned
in ventral recumbency using sedation and/ortranslucent plastic tubes to keep the spine asstraight as possible. Better results are
obtained if the laterolateral projection is per­formed using a horizontal beam (Pees 2011,
Raiti 2004, Silverman et al. 2006, Wilkinson
et al. 2004).

Lizards

In lizards, the appendicular skeleton is­evaluated using dorsoventral and laterolat­eral projections, with the patient’s limbs
being as close as possible to the cassette (Pees2011, Raiti 2004, Silverman et al. 2006,
Wilkinson et al. 2004). For the laterolateralprojection, the pectoral limbs are extended
cranially and the pelvic limbs extended cau­dally. A translucent box or tube may assist in
keeping the spine straight.
Crocodilians

Crocodilians are challenging to image on
account of their large size and the presenceof osteoderms, which mask underlying struc­tures (Figure 12.2).
Exposure
Reptilian skeletal structures are less radio­paque compared with mammalian, therefore
higher milliangstrom (mA) and lower kilo­
volt (kV) values are generally recommended(Pees 2011, Raiti 2004, Silverman et al. 2006,
Wilkinson et al. 2004). While specific expo­
sure settings depend primarily on the x‐ray

Diagnostic Imaging

media may also be used to assess the sizeand position of other organs and masses(kidneys, urinary bladder or tumours; Pees
2011, Raiti 2004, Silverman et al. 2006,
Wilkinson et al. 2004). In reptiles, gastroin­
testinal passage is very slow and variable,
depending on the ambient temperature, theseason and the reptile species. It has beenreported that bowel transit time in a healthychelonian is more than three weeks.
Barium Sulphate

Figure 12.2 The presence of osteoderms incrocodilians may mask underlying structures orpathology.

system being used they generally range from
40 kV to 100 kV for 1.25–20 mA dependingon the size of the animal and whether grids
are used.

The recommended maximum dose of bar­ium sulphate is 20 ml/kg (Raiti 2004); how­ever, a dose of 5–10 ml/kg is generally
adequate. Ideally, the solution is adminis­
tered by oesophageal tube into the stomachor, in large snakes and marine turtles, as cau­dally as possible within the oesophagus(Figure 12.3). It can also be injected or mixed
into the diet for transit time studies. The
administration of barium is contraindicatedwhen the integrity of the gastrointestinal
tract wall is suspect.

Plain Radiographs
Standard examination of the patient begins
with taking plain radiographs. Data obtained
from the clinical examination and plain radi­
ographs will determine whether other special
imaging procedures are warranted. Because
organ densities may be very similar becauseof the absence of peritoneal fat, coelom
insufflation with a small volume of surgicalgrade carbon dioxide is useful in differentiat­
ing organs.
Contrast Radiology
Contrast radiology is performed primarily
to illustrate individual segments of the­gastrointestinal tract, to identify radiolucent
foreign bodies and to distinguish between
intra‐ and extraluminal masses. Contrast

Figure 12.3 A contrast study of the gastrointestinal
tract of a hawksbill turtle (Eretmochelys imbricata).

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Reptile Medicine and Surgery in Clinical Practice

Iodine‐Based Contrast Agents

Iodine compounds are the contrast media of
choice in patients with intestinal wall perfora­tion (Schumacher and Toal 2001). The rec­ommended dose of iodine‐based contrast
agents is 10 ml/kg (250 mg iodine/ml). The
advantage of these substances is a shortertransit time through the gastrointestinal
tract. As iodine‐based contrast media aregradually diluted by intestinal fluid in theintestine (they bind water), their contrast
capacity decreases in caudal segments of thegastrointestinal tract. Retrograde applicationof a contrast medium via the cloaca is used toview caudal segments of the intestine, urinary
bladder and cloaca. Iodine contrast agents are
eliminated by means of glomerular filtration,
so it is always critical to check the patient’s
hydration status and renal function.
Angiography, Excretory Nephrography

The principles of intravenous administrationof contrast agents to reptiles are the same as
in mammals; however, reliable intravenous
access is more difficult in reptiles.
Evaluation of Radiographs
Respiratory Tract

In most reptiles, the lungs are located dorsal
to the liver and extend to the dorsal wall of
the coelom. Chelonian lungs are locateddirectly beneath the carapace with the lungfield representing 30–50% of the height ofthe coelom. Most snake species have only aright lung, terminating in a caudal air sac.
The commonly kept Boidae have two lungsof similar size, with the right air sac extend­
ing more caudally. Detailed radiographic
evaluation of the lung field in reptiles is ham­
pered by the shell in chelonians and thickskin and skin derivatives in crocodiles andlizards. To properly evaluate the lung fieldof chelonians, the neck and limbs should
be fully extended. Crocodiles have two well‐developed, symmetrical and fleshy lungs
devoid of air sacs. The trachea of young croc­
odiles is straight but with age a double flex­
ure develops at the thoracic inlet. Unilaterally

collapsed lung with contralateral overexpan­
sion are not uncommonly seen after pene­
trating injuries.
Heart

The heart of most lizards is located between
the pectoral girdle and it is therefore not­easily viewed on radiographs. The heart ofmonitor lizards and crocodiles is locatedmore caudally, halfway between the pelvic
and pectoral girdles. Good visualization of
the cardiac silhouette in chameleons isachieved only when their pectoral limbs areextended cranially. The heart of chelonians ismasked by the superposition of the plastronand the carapace (dorsoventral view) and theliver and other internal organs in all views.
The heart of most snakes is located within
the cranial 15–25% of the snout–vent length(more cranial in arboreal snakes, more­caudal in sea snakes).
With notable exceptions, such as in gout(when the pericardium is filled with uricacid crystals), radiography of the heart is oflimited diagnostic significance; it is better
evaluated with other imaging modalities.
Gastrointestinal Tract

Radiographic evaluation of the gastrointesti­
nal tract is affected by the presence of gas orradio‐opaque material (Figure 12.4). In many
reptile species, a small amount of gas or smallstones in the digestive tract is generally con­sidered to be normal.
The chelonian stomach is tubular and islocated in the left cranial third of the coelom.
Accurate delineation of individual segmentsof the intestine is impossible unless they arefilled with a radiopaque material or gas.
If the location of individual organs ofsnakes is expressed as a percentage of thesnout–vent length, the stomach, small intes­
tine and colon of Boidae are located at
50–70%, 60–80% and 80%, respectively.
Certain lizard species (iguanas) have a dis­tinct caecum located in the right caudal coe­lom. The full stomach of bearded dragons iselongated and is located near the medianaxis. In chameleons, the stomach turns in aDiagnostic Imaging

Figure 12.4 The stomach of a tortoise full of stones
and pebbles due to lithophagia.

cranioventral direction and the intestine islocated in the caudal coelom.
In lizards and snakes, the triangular hepatic
shadow is distinct, with the base located on
the floor of the coelom cavity.
Urogenital Tract

Inactive ovaries and oviducts cannot be­evaluated using radiography. However, in the
reproductively active reptile, ovarian follicles
and eggs occupy a considerable amount of
the coelom, displacing other organs. Ovarianfollicles cannot be evaluated in chelonians,
although eggs are usually visible. Dependingon the stage of gestation, the skeletons of­foetuses can be radiographed in viviparous
snakes and lizards. If the radiograph shows
the spines as elongated linear formations,
it is evidence of damage of fetal membranes
and fetal death. The ability to evaluate thepresence and shape of eggs in oviparous
snakes is based on the degree of minerali­zation of eggshells. In lizards such as cha­meleons, iguanas and agamids, preovulatory

Figure 12.5 Urolith in the bladder of a green iguana(Iguana iguana).

follicles can be seen as nodular, soft‐tissue
formations located in the caudal coelom.
The major radiographical findings of theexcretory system include radiopaque uroliths
or sediment within the urinary bladder.
Uroliths are most often found in chelonians
and green iguanas (Iguana iguana; Figure 12.5).
The kidneys of boid snakes are found 65–80%of the snout–vent length, with the right kidneycranial to the left. In chameleons, the kidneys
are found cranial to the pelvis, near the verte­bral column, especially when a laterolateralprojection is used. The healthy kidneys ofgreen iguanas, agamids and numerous otherlizard species are intrapelvic and are only­visible radiographically if they are enlarged.
In monitor lizards, the kidneys are locatedcranial to the pelvis.
The hemipenes of rattlesnakes and hemib­
acula of monitor species are clearly visible onradiographs, offering a safe and accurate alter­
native for sexing these dangerous animals.

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Reptile Medicine and Surgery in Clinical Practice

Skeleton

The density of bone in reptiles is evaluatedby radiographic imaging of the ribs of snakes,
the limbs of lizards and the shell and pectoraland pelvic girdles of chelonians. Some geck­oes store calcium in specialized structures in
the cervical area, the endolymphatic sacs.
Congenital defects (lordosis, kyphosis andscoliosis) may be the consequences of prob­
lems during embryogenesis.
In young animals suffering from metabolicbone diseases, radiographs may show reduced
radio‐opacity of bones or shells and thick­ening of the long‐bone cortices. In adult­animals, these signs, as well as pathologicalfractures, may be present. Radiographic
examination of chelonians may reveal shells
with a ‘moth‐eaten’ appearance.
Fractured ribs are common in free‐living
and captive reptiles and are seldom of clinicalsignificance. Fractures of other bones takelonger to heal in reptiles compared withmammals; follow‐up radiographs should betaken at 6, 12 and 18 weeks.

­Ultrasonography
Ultrasonography is a feasible non‐invasive
diagnostic imaging modality in reptiles.
Anaesthesia is seldom necessary, although
sedation is recommended in aggressive or
dangerous (venomous) animals. Organs canbe easily visualized and differentiated bytheir specific echogenicity. Ultrasonography
is the major imaging tool for obstetrical workin reptiles, being useful in fertility assess­ment, sex identification, determination of
the number of follicles and the timing ofoviposition.
Chelonians
For chelonians, either a 7.5 MHz or 7–12
(14) MHz transducer with a small footprint isrecommended (Hochleithner and Holland
2014, Schumacher and Toal 2001). For giant
tortoises and sea turtles, frequencies of

2.5–5 MHz are recommended. The animal isheld in ventral recumbency with the feet heldaway from the table to prevent movement, oron a pedestal, as previously described. For all
but the largest species, one person can
restrain the animal while another performs
the ultrasound examination. The acoustic
windows are in the pre‐femoral fossa, thecervical region and the axilla (in soft‐shelledchelonians, the coelom can be scanned
through the plastron). An acoustic stand‐offmaterial such as a glove filled with acoustic
coupling gel or water can be used to provide
adequate contact with the skin (Hochleithnerand Holland 2014, Schumacher and Toal
2001). Soaking the patient in warm water for
approximately 20–30 minutes before investi­
gation will also improve the contact of thetransducer with the skin.
To access the cervical window, the head
and foreleg must be fully extended and pulled
to the side. This site allows examination of
the cranial coelom. The heart is imaged on
the midline in the dorsal third just caudal to
the scapulae. The ventricular and atrial walls,
atrioventricular valves and main coronary
vessels can be imaged. Blood‐flow patterns
and velocities can be measured using the col­our Doppler display and spectral analysis(Figure 12.6). The valves can be seen as highlyreflective ribbons.
The pre‐femoral window is the preferredsite for examination of the liver, gastrointesti­
nal and genitourinary tracts. In chelonians,
the liver is bi‐lobed, the right lobe is larger andthe anechoic gallbladder is attached to it. The
structure of the liver is homogenously hypo­echoic with anechoic vessels. The portal vein,
hepatic veins and the caudal vena cava can be
individually assessed. Hyperechogenicity andenlargement of the liver is seen in cases offatty liver deposition degeneration. A hetero­geneous pattern of the liver parenchyma with
anechoic areas is common with focal necrosis
or inflammation (Hochleithner and Holland
2014, Schumacher and Toal 2001). Anechoicround or oval structures can be visualized inpatients with cystic changes. The ovaries areDiagnostic Imaging

Figure 12.6 Ultrasound colour
Doppler image of a chelonian kidney.

paired, hyperechoic elongated organs attachedto the peritoneum on either side of the dorsal
midline cranial to the pelvic girdle. Ultrasoundcan penetrate the thin‐walled eggs of somespecies (e.g. red‐eared sliders) to detect theinspissated contents within retained eggs.
This technique has proved useful in determin­
ing the age of the egg and hence diagnosing
dystocia. Eggs that are in the distal tract may
be imaged through the post‐femoral fossa(between the tail and legs). The testes arelocated cranial and ventral to the kidneys,appearing uniformly echogenic and slightly
more hypoechoic than the adjacent kidneys.
The kidneys show higher echogenicity
than the liver and the fat body. Large hyper­
echoic granules may be detected in enlarged
kidneys in animals with renal disease.
Anechoic spherical structures indicate cystic
changes. The thin‐walled urinary bladder islocated ventrally in the caudal section of the
coelom. The round or oval bladder is either
anechoic or hyperechoic. Calculi can be dis­tinguished by their solid structure and the
distal shadowing of the ultrasound beam.
Pathologically, there can be eggs within theurinary bladder. In herbivores, the stomach

is small with a thin wall and the intestines areelongated and show mucosal folds.
Lizards
In small lizards, transducers with high fre­quency (10–18 MHz) are recommended. In
larger lizards (iguanas, monitors), 7.5–
12 MHz linear or convex transducers can beused; for animals heavier than 10 kg 3.5–
7.5 MHz probes are suitable (Hochleithnerand Holland 2014, Schumacher and Toal
2001). Acoustic coupling gel should beapplied to the skin and the transducer. As
with chelonians, the use of stand‐offs andwarm water baths is useful. The animal may
be scanned in either lateral or dorsal recum­
bency. Lizards may also be restrained verti­
cally with the head uppermost and theventral surface facing the scanner operator.
The limiting factors for ultrasonography inlizards are the presence of ossified scales (inTiliqua and Heloderma spp.) and ecdysis,
when the space between the layers of thecutis is filled with lymph. The atrioventricu­
lar valves and the hepatic vein extending
from the liver to the sinus venosus is imaged

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Reptile Medicine and Surgery in Clinical Practiceon the longitudinal view of the heart. The
liver is bi‐lobed, with the gallbladder situatedin the larger right lobe as an anechoic
structure. The portal vein, hepatic veins andthe caudal vena cava may be individuallyassessed. The twin fat bodies lie on eitherside, cranial to the pelvis. The echogenic pat­tern is hyperechoic compared with the liverwith a granular structure and typical hyper­
echoic septa. The gonads are cranial to thekidneys. The ovaries, containing many smallround, hypoechoic previtelline follicles, arepositioned dorsally. An ovary containing
vitelline follicles (large, up to 2.5 cm, round,
hyperechoic structures) is easily detected.
Care must be taken to differentiate poorly
calcified eggs from bowel loops by rotating
the transducer through 90 degrees: the bowel
will appear as a tube whereas the follicles or
eggs will remain spherical. The testes are
small oval structures in the dorsal coelom,
hyperechoic compared with the kidneys. The
kidneys are located within the pelvis but, incases of enlargement, the cranial pole may
extend beyond the pelvic region. The urinary
bladder, round to oval in shape, is identified
by a thin wall and anechoic contents.
SnakesSnakes can often be scanned using gentle
restraint but very active or dangerous (ven­omous) snakes require anaesthesia. A
7.5 MHz sector transducer is generally used,although small snakes may require a 10 MHz
transducer (Hochleithner and Holland 2014,
Schumacher and Toal 2001). As with otherreptiles, a stand‐off is required, although,alternatively, the patient and transducer may
be partially submerged in water to achieve an
optimal image. In larger snakes, intercostal
placement of the transducer may avoid theribs interfering with the ultrasound picture
but, in smaller snakes, acoustic shadows may
be present.
The standard procedure should start crani­ally, beginning with the heart, and end withthe cloaca (Hochleithner and Holland 2014,
Schumacher and Toal 2001). The heart islocated by visualizing the beating organ
beneath the scales ventrally at 15–25% of thesnout–vent length. In larger snakes, the atrial
ventricles and atrioventricular valves may beseen. In larger individuals, the right and left
aortic arches may be followed cranially to thecommon carotid artery. The liver in snakes islocated immediately caudal to the heart
extending to the middle of the body.
The gall bladder is extrahepatic, locatedcaudal to the empty stomach. The stomach
may be identified at the caudal edge of theliver, distinguished by its folded appearance
or the presence of food particles or fluid. The
triad of the spleen, pancreas and gall bladder(located at 50% snout–vent length) serves asa useful landmark, caudal to the liver yet cra­nial to the gonads and kidneys. The gall blad­
der appears as an anechoic focal area.
The pancreas may be seen as a less hyper­
echoic form in the group. In cases of ano­rexia, the gall bladder is often greatly enlarged
and can fill one third of the diameter of thesnake. The spleen can be visualised as a cir­cular shaped organ with higher echogenicity
than the liver.
The testes have uniform echotexture. In
larger snakes, the deferent duct may be seen
as hyperechoic parallel lines originating fromthe testis. The ovaries may be difficult tolocate in non‐cycling, young females butwith progressive breeding seasons the folli­cles become more apparent, just caudal to
the gall bladder. In mature females the­ovaries may fill a large part of the coelom.
Ovarian follicles appear as hypoechoic
spherical structures. In snakes, the eggs seemto contain two layers with the upper layer
consisting of the anechoic albumin and theinner layer is the highly echoic yolk. In vivip­
arous snakes (boid snakes, anacondas,
vipers) an embryo/foetus is seen. The kidneys
are located caudal to the gonads (the rightkidney is located cranial to the left kidney)
and are cylindrical in shape with a stacked
book appearance. On ultrasound, they show
a homogenous texture with a higher echo­
genicity than the fat body and a granulated
structure. Faecal pellets may be imaged

Diagnostic Imaging

within the large intestine. In males, theinverted hemipenes are located caudal tothe vent and can be detected as a
hyperechoic area.
Crocodilians
For diagnostic imaging, adult crocodilians
need to be sedated (midazolam) or anaesthe­tised. In young specimens, manual restraint
can be used. Crocodilians are kept in ventral
recumbency. Ultrasonography is particularly
useful in crocodilians and is strongly indi­cated for general examination and healthassessment. The heart is located centrally inthe body, below the lungs and between the
two liver lobes. Crocodilian cardiac anatomy
is unique and probably the most complex ofvertebrate hearts. The liver is bi‐lobed andtogether with the heart separates the cranialcoelom from the caudal part. The right liver
lobe is slightly larger than the left and bothcan be scanned in their entirety.
The gallbladder is centrally situated caudal
to the liver. The spleen is located almost
directly caudal to the gall bladder. Anotherimportant abdominal organ is the single fat
body. The kidneys can be very hard to iden­
tify as they are intrapelvic and consist of
inverted renal tissue folded within a fatty
stroma. The two ovaries are cranial andmedial to the kidneys and consist of flat,
Figure 12.7 Computed tomography ofa green turtle (Chelonia mydas).

folded tissue in the hatchling, small bunchedfollicles in the immature female or, in thepreovulatory stage, they may appear as
numerous large follicles filling the caudal
coelom. Testicles are elliptical in shape andsimilar in texture to those of other verte­
brates. The diameter of the intestines
increases and the thickness of the intestinal
wall decreases from duodenum to rectum.

­Computed Tomography
Computed tomography (CT) makes use ofcomputer‐processed x‐rays to produce
tomographic images (‘slices’) of the scanned
object (Figure 12.7). The x‐ray slice data is
generated using an x‐ray source that rotatesaround the object as the object passes
through the beam; x‐ray sensors are posi­tioned on the opposite side of the circle fromthe x‐ray source. Increasing the number of
sensors increases the resolution; for example
a 16‐slice scanner has 16 sensors (Kiefer andPees 2011, Wyneken 2014). The data are thenprocessed by a computer to generate images
in a number of planes (transverse, sagittaland coronal) and even three‐dimensional
reconstructions. Sedation or short‐acting
anaesthesia is recommended to prevent
movement artefacts, although chelonians
may be restrained within a sac or fixed on

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wooden blocks. Densitometry, the qualita­
tive assessment of density of tissues, isexpressed in Hounsfield units (HU; Kiefer
and Pees 2011, Wyneken 2014). As an exam­
ple, the normal densitometry of the chelo­nian shell measures 950–1300 HU but, inchelonians with metabolic bone disease, thedensitometry may measure only 350–550 HU(Kiefer and Pees 2011, Wyneken 2014).
A stomach filled with gas is easy to find but
the bowel loops are difficult to identify inthe normal animal. Enlargement of the liver
is easily detected. The densitometry of theliver decreases with fatty liver disease from
50–70 HU to –10 to –40 HU (Kiefer and Pees
2011). CT scans give detailed information
about the number, size, shape, density andposition of follicles and eggs. In mostpatients, the kidneys are easily located using
plain sagittal views, especially when enlarged.
Using plain CT, kidneys from the clinically
healthy tortoises range in density from33 HU to 42 HU. Gout often causes increased
density of the kidneys. Urine retention or
urate deposits in the reptile urinary bladder
are easy to find. In tortoises, the normal kid­
ney length is 1.7–2.7 cm and, when com­pared with the length of the endoplastron(equivalent to the breast bone), the ratio ofendoplastron to kidney is 1.37 to 1. The slow
respiratory rate permits high‐quality scans of
the typical reticular pattern of the chelonianlung. The value for density of lungs in python
is about –744 HU (Kiefer and Pees 2011).
Iodinated contrast medium (370 mg I/ml)
at a dose of 1 ml/kg, 2 ml/kg or 3 ml/kg is
injected into the jugular vein and coelom
organs are measured 1, 5, 10 and 15 minutes
post‐administration. After intravenous admi­
nistration of the contrast medium, the kidneydensity varies with the dosage given (55–62 HU for 1 ml/kg contrast medium,
58–110 HU for 2 ml/kg contrast medium and
92–93 HU for 3 ml/kg contrast medium). In
the majority of reptiles, maximum enhance­
ment may be visible immediately, while insome animals maximum enhancement is evi­
dent after 5–10 minutes (Kiefer and Pees
2011, Wyneken 2014).

­Magnetic ResonanceImaging
Magnetic resonance imaging (MRI) in rep­tiles is suitable for imaging of the respiratory
tract, liver, gastrointestinal tract, urogenitaltract and soft‐tissue masses (tumours). As an
MRI procedure takes longer than conven­tional radiography or CT examination, seda­
tion or light anaesthesia is recommended(Ludewig and Pees 2011). For MRI examina­
tion, the reptile is positioned in ventral
recumbency as symmetrically as possible(Figure 12.8). The three standard scanningplanes are used – coronal, transverse andsagittal. The most important weightings areclassified as T1 and T2. Fat tissue has a very
high signal intensity (bright), while fluids
have low signal intensity (dark) with T1‐
weighting. In contrast, in the T2‐weighting,free fluid has high signal intensity and fat has
low signal intensity (grey). T1‐weighting isused for the assessment of structures that
contain more fat, while T2‐weighting is used
for the assessment of ascites, inflammatory
exudates and effusions. Further image
enhancement can be achieved with the useof intravenous injectable paramagnetic com­pounds (via intravenous catheter). Within
20–30 minutes, it is possible to obtain suffi­
cient images to build up a complete three‐dimensional picture of the patient’s internal
structure (Ludewig and Pees 2011).

­Diagnostic Endoscopy
Endoscopy is a minimally invasive diagnostic
method for direct visual examination andantemortem biopsy. The standard equip­
ment for diagnostic endoscopy in reptiles
includes (Divers 2014):
2.7 mm diameter × 18 cm telescope, 30‐
degree forward‐oblique with 4.8 mm oper­
ating sheath●● 1.9 mm diameter × 18 cm telescope, 30‐
degree forward‐oblique with 4 mm operat­
ing sheath●●Diagnostic Imaging

Figure 12.8 Magnetic resonance imaging of a green iguana (Iguana iguana).

1.7 mm flexible grasping forceps
1.7 mm flexible biopsy forceps with double‐­
action jaws●● insufflator machine●● fluids (e.g. 0.9% sterile saline solution bagwith infusion set)●● xenon cold light source and light cable●● endovideo camera and monitor.
●●●●

Alternatively, the mobile endoscopic imaging
systems (Tele Pack® system or AIDA‐Vet®
system) can replace the need for a lightsource, cable, camera and monitor).
In most cases, animals should be sedated
or anaesthetised to achieve safe and goodquality endoscopy. If necessary, sedation canbe supplemented with local anaesthetic
blocks (Divers 2014).
Oculoscopy, otoscopy
Oculoscopy in snakes and otoscopy in lizards
are performed using similar approaches toother animals. These simple techniques
require minimal training and allow goodvisualization and magnification of the­ocular/ear structures. Sedation is requiredfor ­oculoscopy in snakes, while manual
restraint is sufficient for otoscopy in small to
medium sized lizards.
Tracheoscopy, Pulmonoscopy
In small to medium snake or lizard species,
direct endoscopy of the trachea and proximal
part of the lungs is easy to perform under
sedation, while in larger animals pulmonos­
copy (air sac endoscopy) is required to accessthe lungs and requires general anaesthesia.
Pulmonoscopy in snakes can be performed
via either a tracheal and transcutaneous
approach. For transcutaneous pulmonos­
copy, the snake is positioned in left lateralrecumbency (for examination of right air sac
and lung in all snake species) or right lateralrecumbency (for examination of the smaller
left lung in Boidae). After aseptic prepara­tion, a short incision is made in the skin on
the right side of the snake’s body, at 35–45%
along its length and parallel with the hori­zontal axis of the body. The incision is madebetween the second and third row of lateralskin scales. After incising the skin and blunt

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Reptile Medicine and Surgery in Clinical Practice

Figure 12.9 Air sac endoscopy in a python.

dissecting through the muscle and coelom
membranes, the avascular transparent wallof the air sac can be visualized. Stay sutures
are placed in the air sac wall and it is gently
perforated; the telescope is introduced anddirected cranially into the lung (Figure 12.9)
and caudally into the air sac. Some of the vis­
ceral organs can be viewed through thetransparent air sac. After selected parts of
the air sac and lungs are observed, the air sac,muscle wall and skin are closed in separate
layers (Knotek and Jekl 2015).
Oesophagoscopy and Gastroscopy
Oesophagoscopy can be performed on rep­tiles using ‘twilight’ anaesthesia (intravenous
alfaxalone or propofol), while gastroscopy
requires a surgical plane of anaesthesia. A
bag of warm sterile saline fluid is connected
via an infusion set to the port of the operat­
ing sheath. A second set, although rarely
required, can be connected to a second port,with the other end placed into a collection
bucket under the table (Divers 2014). A tele­scope (1.9 mm or 2.7 mm) with operating
sheath is gently introduced into the proximal
part of oesophagus. The saline irrigation

helps to gently dilate the oesophagus, allow­
ing the telescope to be easily directed into the
distal part of the oesophagus and the stom­ach. Flexible forceps (grasping or biopsy) are
passed through the working channel of theoperating sheath as required (Divers 2014).
Cloacoscopy–Cystoscopy,
Colonoscopy
Cloacoscopy can be performed using seda­
tion or short‐acting anaesthesia but cystos­
copy and colonoscopy require a surgicalplane of anaesthesia. Cloacoscopy is usefulfor examining the cloacal mucosa and thechelonian phallus or clitoris. Cloacoscopy
combined with cystoscopy is used in cheloni­
ans for direct visualization of the urinary
bladder and indirect visualization of the coe­lom cavity (gonads, fat, liver and intestine;
Divers 2014). The telescope with working
sheath attached is inserted into the cloaca
while placing a finger and thumb around thevent to act as a valve to control the infusion
and outflow of fluid. Flushing of the cloaca
with warm saline through the operating
sheath allows a clear view of the accessory
vesicles (Figure 12.10). The telescope isDiagnostic Imaging

telescope introduced into the coelom anddirected proximally. The telescope with theoperating sheath is then introduced anddirected into the proximal coelom.
Lizards

Figure 12.10 Cloacoscopic examination of ared‐eared slider (Trachemys scripta elegans).

gently inserted into the urinary bladder,making sure that the volume of saline infusedis controlled to prevent overfilling the bladder.
Coelioscopy
Coelioscopy is used for the examination of
the reptilian coelom and biopsy collection(Divers 2014). General anaesthesia combinedwith effective analgesia is mandatory. Lizards,
snakes and chelonians are placed in ventral,lateral or oblique (some chelonians) recum­
bency. Insufflation of the coelom with medi­
cal grade carbon dioxide (or irrigation of the
coelom with warm saline fluid), allows aclearer view of the coelom. One finger andthumb are placed around the operating
sheath and incision in the skin to form a seal,
regulating the outflow of saline or carbon
dioxide. After coelioscopy is finished, thecarbon dioxide (or saline fluid) is releasedout of the coelom through the operating
sheath, while the body wall is gently pushed.
Chelonians

Coelioscopy is performed through thepre‐femoral approach (Divers 2014). After
incising the skin and blunt dissecting the­
subcutaneous fat, the tendinous aponeurosisof the ventral and oblique abdominal mus­cles is opened, exposing the underlying coe­lom membrane. This is perforated and the

Coelioscopy is performed on lizards using a
caudolateral approach. Following the skinincision, a haemostat is used for blunt perfo­
ration of the subcutaneous tissues, including
the coelom membrane. The telescope with
operating sheath is introduced and directed
into the proximal coelom while the haemo­
stat is withdrawn.
Snakes
Coelioscopy is performed on snakes using aleft lateral approach in the caudal coelom.
The skin incision is made between the sec­
ond and third row of lateral skin scales and ahaemostat is used for blunt perforation of the
subcutaneous tissues including the coelom
membrane (Divers 2014). The telescope with
operating sheath is introduced and directed
into the proximal coelom while the haemo­
stat is withdrawn.

­Training
Diagnostic endoscopy is not an innate skill andappropriate training (with the use of training
models and cadavers) is required to obtainand maintain competency (Divers 2014).

­References
Divers, S.J. (2014) Diagnostic endoscopy. in
Reptile Medicine and Surgery, 2nd ed. (D.R.
Madder, ed.). W.B. Saunders, Philadelphia,
pp. 154–178.
Hochleithner, C. and Holland, M. (2014)
Ultrasonography, in Current Therapy in
Reptile Medicine and Surgery (D.R. Mader
and S.J. Divers, eds). Elsevier, St. Louis, MO,
pp. 107–127.

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Reptile Medicine and Surgery in Clinical Practice

Kiefer, I. and Pees, M. (2011) Computed
tomography, in Diagnostic Imaging of Exotic
Pets (M.E. Kraurwald‐Junghanns, M. Pees,
S. Reese et al., eds). Schlutersche, Hannover,pp. 358–367.
Knotek, Z. and Jekl, V. (2015) Pulmonoscopyof snakes. Veterinary Clinics of North
America Exotic Animal Practice, 18,
493–506.
Ludewig, E. and Pees, M. (2011) Magnetic
resonance imaging in Diagnostic Imaging of
Exotic Pets (M.E. Kraurwald‐Junghanns, M.
Pees, S. Reese et al., eds). Schlutersche,Hannover, pp. 368–377.
Pees, M. (2011) Reptiles, in Diagnostic Imagingof Exotic Pets M.E. Krautwald‐Junghanns,
M. Pees, S. Reese and T. Tully, eds).
Schlütersche, Hannover, pp. 309–333.
Raiti, P. (2004) Non‐invasive imaging in
BSAVA Manual of Reptiles, 2nd ed. (S.J.
Girling and P. Raiti, eds). British Small

Animal Veterinary Association, Gloucester,
pp. 87–93.
Schumacher, J. and Toal, R.L. (2001) Advanced
radiography and ultrasonography in reptiles.
Seminars in Avian and Exotic Pet Medicine,
10, 162–168.
Silvermann, S. (2006) Diagnostic imaging, in
Reptile Medicine and Surgery, 2nd ed. (D.R.
Madder, ed.). W.B. Saunders, Philadelphia,
pp. 471–489.
Wilkinson, R. Hernandez‐Divers, S.,
Lafortune, M. et al. (2004) Diagnostic
imaging techniques, in Medicine andSurgery of Tortoises and Turtles (S.
McArthur, R. Wilkinson and J. Meyer, eds).
Blackwell, Oxford, pp. 187–238.
Wyneken, J. (2014) Computed tomography
and magnetic resonance imaging, in Current
Therapy in Reptile Medicine and Surgery(D.R. Mader and S.J. Divers, eds). Elsevier,St. Louis, MO, pp. 93–106.

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13
Clinical Techniques and Supportive Care
Kimberly Vinette Herrin­General Handling
Patient knowledge and proper restraint are
key to avoiding injury. Snakes that tend tobite may be restrained in plastic restraint
tubes. Venomous snakes should be restrainedby licensed handlers using snake hooks andtubes. Lizards may bite, scratch or flick theirtails. Freshwater turtles may bite, particularly
short‐necked turtles. Long‐necked turtles
also have glands along the margin of the plastron that may discharge a strong odour whenhandled. Sea turtles may occasionally bitebut more often flap their front flippers
strongly when handled. This may cause
trauma to the handler if they are holding theturtle from the sides of the carapace. There isalso a spur on the leading edge of the front
flippers that may cut and scratch.
In addition to injuries, reptiles may naturally carry strains of Salmonella sp. that
could be shed in the faeces and be a source of
zoonotic infection. Proper hygiene, especially hand washing and dedicated enclosure
cleaning areas, is important when handlingand keeping reptiles.
An initial visual or distant examination
may reveal an immense amount of information about a reptile’s condition, including
activity, appetite, posture, excrement or any
visible signs of illness or injury. A calico bag

or pillowcase may be used to restrain reptiles
safely for radiographs or to expose a specificpart of the body through the opening.
SnakesSnakes should be supported throughout theentire length of their body, to avoid excessive
pressure on the spine, which can lead to fractures and subsequent arthritis (Figure 13.1).
For very large snakes, multiple handlers
may be required to support the snake’s
weight. Allow non‐venomous snakes to moveslowly. Nervous or aggressive snakes may be
restrained in snake tubes and may require
injectable sedation or anaesthesia for examination (e.g. alfaxalone intravenously). Oralexaminations may necessitate gently holding
the animal behind the base of the head toallow opening of the mouth by the clinician.
To restrain the head, hold the lateral cranium
behind the occiput with thumb and middle
finger, with the index finger on top of thesnake’s head.
Lizards
Most lizards may be restrained by supporting
the body. Small lizards often do not require
much restraint (particularly bearded dragons, blue‐tongued or shingle‐backed lizards)

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

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Reptile Medicine and Surgery in Clinical Practice

Figure 13.2 Restraint of a large green iguana(Iguana iguana).

holding the sides of the carapace or bys­upporting from the plastron. Smaller sea
turtles (less than 15 kg) may be restrainedby holding the cranial part of the carapace(behind the head) and caudal carapace(above tail). Larger sea turtles may require
two or more handlers.
Figure 13.1 Veiled chameleon (Chamaeleo
calyptratus) restraint. Chameleons are more
comfortable when grasping something with their feet.

while others that are more active (smaller
skinks) may be held around the pectoral girdle with the forelimbs against the body.
Remember that small skinks and geckos candrop their tails. In lizards exhibiting tailautotomy, take care not to grab them by thetail. In larger lizards (such as monitors),
restraint may be best achieved by holding thefront legs against the thorax with the hindlegs extended alongside the tail. To avoid aflicking tail interfering with examination or
diagnostics, secure the tail by restraining it
under an arm. Alternatively, flicking may be
avoided by holding the lizard away from thehandler’s body (Figure 13.2). If necessary, lizards may be wrapped in towels for restraint.
TurtlesFreshwater turtles may be restrained byholding the sides or the tail end of the carapace. Tortoises may also be restrained by

Crocodilians
Restraint varies on size and species. For crocodilians up to 0.8 m, manual restraint can be
performed with one hand holding the neck(if examining mouth) or by holding themouth closed and having the other handholding the lower body. Always be mindful of
the teeth, which are partially exposed evenwhen the jaw is closed, and the tail that maylash around. When not being examined, themouth can be taped closed. Crocodilians
between 1 m and 3 m can be restrained witha catchpole to snare around the neck and by
grabbing the tail to help stabilize and preventrolling. They may also be strapped to a
restraining board to help control movement.
The head can then be pinned and the mouth
taped closed. Larger crocodilians should
be restrained by two or three experienced
handlers and chemical restraint should beconsidered.
For some reptiles (e.g. iguanids, crocodilians), a calming effect may be achieved bysimultaneously applying gentle pressure toboth eyes to induce vasovagal response.

Clinical Techniques and Supportive Care

­Diagnostic Techniques
Blood Collection
Blood collection in reptiles can be challenging to the uninitiated practitioner. When collecting blood, take care not to contaminate
the sample with lymph fluid as this may alter
the values of the complete blood cell count(dilution) as well as some chemical parameters (total phosphorus and potassium).
SnakesIn snakes, the primary site for blood collection is the caudal tail vein. This vein runs
just below the vertebral processes. Short‐tailed snakes are slightly more challenging.
Access is via the ventral midline at a point
approximately one‐quarter to halfway along
the tail (distal to the male hemipenes or
female musk glands). Use an appropriately
sized needle and syringe at a 45–60‐degree
angle, aiming craniodorsally while maintaining gentle negative pressure. Advance
until the needle reaches the vertebral bodyand then slightly withdraw. If venepuncture
via the tail vein is unsuccessful, cardiac
puncture may be attempted. With the snakein dorsal recumbency, the heartbeat may be
visualized on the ventral aspect of snake atapproximately the cranial third of the body.
This is often easier to perform in an anaesthetized snake. In a study of repeated cardiocentesis in ball pythons, there was noevidence of clinical complications and only
minimal histological evidence of trauma
from this technique; however, there is still achance of causing some degree of haemopericardium. If the heartbeat is not readily
visible, ultrasound is a quick and simple
means of identifying the heart. The heart
can be isolated by the forefinger (cranial
aspect) and by the thumb (caudal aspect).
The approach to cardiocentesis is to enter
through the skin under the ventral scute(approximately 1 scute caudal to heart) at 45
degrees in a craniodorsal direction into theventricle. Apply pressure for up to 60 seconds after cardiocentesis.

Lizards

In lizards, the tail vein is the most common
venepuncture site. It is accessed through aventral midline approach at either a 90 or 45‐
degree angle in the craniodorsal direction.
Maintain negative pressure until the needle
reaches the vertebral body and slightly withdraw to find the ventral tail vein; redirectslightly if needed. The approach may also be
on lateral midline by angling 45–90 degrees
craniomedially towards the lateral process ofthe vertebral body. Lymph contamination
may occur from the lateral approach. Anotheroption in lizards is venepuncture of the ventral abdominal or jugular vein (Figure 13.3a,b).
TurtlesCommon venepuncture sites include thedorsal coccygeal (tail) vein, jugular vein, brachial vein and subcarapacial vein. Tortoises
and freshwater turtles often have visible jugular veins on both sides and there is little riskof lymph contamination. The dorsal coccygeal vein can be accessed at the cranial aspectof the tail by aiming cranioventrally at a
45–90‐degree approach from the dorsal midline of the tail, maintaining some negative
pressure. The subcarapacial venous sinus canbe accessed if the head is retracted by bending the needle and approaching midline
behind the head where the carapace and skinmeet. The needle is advanced in a caudodorsal direction toward the vertebra. Maintainslight negative pressure and redirect slightly
if needed. In larger tortoises, the brachialvein may be accessed via the caudal aspect of
the forelimb. In sea turtles, the supravertebral sinus is a common collection site andcan be accessed by advancing the needle oneither side of the nuchal crest approximately
2–4 cm behind the skull and directed toward
the vertebra (Figure 13.3c). The external jugular vein is another site that can be accessedwith the head extended. The needle isadvanced at approximately 45 degrees(around one‐third of the distance laterally
from the spine and around one‐third of the
distance from the carapace to the skull).
Ultrasound is useful in locating this site.

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Reptile Medicine and Surgery in Clinical Practice

(a)

(b)

(c)

Figure 13.3 Blood collection from the ventral tail vein of (a) a shingleback lizard; (b) a green iguana; (c) Bloodcollection from the supravertebral sinus in a green turtle.

Crocodilians

The supravertebral venous sinus may beaccessed in crocodilians through a 90‐degree
dorsal midline approach directly behindthe occiput. Advance slowly with negative
pressure to avoid deep penetration that
could lead to spinal trauma. Alternatively,
the ventral tail vein may be used (as described
for lizards).
Blood Handling
Lithium heparin is the anticoagulant ofchoice for reptile blood. Fresh slides should
be prepared before placing the sample inheparin, as there is less clumping of leucocytes and thrombocytes, leading to an
improved differential count. Samples may be
stored at 4 °C for up to 24 hours. If there is adelay in testing, packed cell volume and total
protein should be run in‐house and the bloodsmear fixed in methanol (estimated leucocyte count and differential). Blood for biochemical analysis should be separated.
As a general rule, the amount of blood volume that may be removed is between 0.5%
and 0.8% of the body weight in lizards, snakes,
chelonians and 0.3–0.5% in crocodilians.
Occasionally, because of the patient’s size,
the sample may be too small for routine biochemical analysis; however, in most cases,
packed cell volume, total protein and bloodsmear (differential cell count, check for haemoparasites) can still be analyzed. Small
plastic sample tubes (e.g. 0.8 ml tubes) areavailable commercially. In some laboratories
a full blood count (manual method) andchemistry can be performed on as little as
0.2 ml of whole blood.
A typical chemistry panel for reptiles may
include total protein, albumin, glucose, uricacid, aspartate aminotransferase, creatine

Clinical Techniques and Supportive Carekinase, calcium and phosphorous. Special
tests may require serum for analysis anddetails may be obtained from reference laboratories. If excess plasma or serum has beencollected, it may be frozen at –20 °C or preferably –80 °C freezer in cryovials and banked
for later use.
Microbiology
Fungal and bacterial diseases are often diagnosed in reptiles. Sampling sites will varydepending on the condition. Microbiology,
including both bacterial and fungal cultures,
may be useful tools in diagnosing reptile conditions. Good sample technique and sterile
collection of samples is important. Samplingof the skin by deep scrapings or biopsy is recommended to exclude the possibility of environmental contamination.
Fluid‐filled structures may be aspirated
and submitted in a sterile container for cytology and culture/sensitivity. In some cases,
tissue biopsies may yield the greatest information. Tissue biopsies may be submitted
directly in a sterile container with sterile
saline. Biopsies may be split in half with onepart frozen or submitted for culture and theother half placed in 10% buffered formalin
for histopathology.
If viral testing is indicated, contact the reference laboratory for specific viral culture ormolecular testing advice (e.g. sunshinevirus,
adenovirus). Blood culture may be indicatedin cases of sepsis. Skin should be sterilized
and a blood sample taken using a sterile technique. Aerobic and anaerobic cultures may
be carried out on as little as 0.5 ml of blood.
Cytology

Cytology may be very useful diagnostic toolin assessing lesion aetiology. Slides should bedried and fixed in methanol in preparation
for Diff‐Quik staining. Diff‐Quik is the mostcommonly used stain, however some clinicians recommend a modified Giemsa technique (Pappenheim method: May‐Grünwald
plus Giemsa–Romanowsky staining). If bacterial or fungal pathology is suspected, slides

should be heat fixed in preparation for Gram
staining. A Ziehl–Neesen stain can be added
to either type of preparation to assess theslide for acid‐fast bacteria.
Parasitology

Faecal samples can be collected opportunistically and are often a valuable diagnostic
tool in a sick reptile. Faecal samples may be
infrequent or even absent, owing to feeding
patterns or anorexia. Repeat faecal examinations may be helpful to monitor parasite burdens or catch eggs of species that shedintermittently. The practitioner should befamiliar with gastrointestinal helminths andwhich protozoa and amoebae are parasitic
and which are natural, beneficial fauna. Keepin mind that pseuodoparasites (parasites ofprey items) may also pass through reptile faeces and should not be interpreted as pathogenic. Wet preparations are used to detectflagellates, ciliates, larvae and amoeba. If
amoebae are detected, Lugol’s iodine canhelp highlight their structure. For animals
that have died, necropsy should reveal theactual parasite burden, which may not bereflected in the egg counts.
External parasites include ticks (usuallyreadily visible), mites (often hidden underscales, use magnification to view) and leeches
on aquatic species. A thorough external
examination should be carried out. Myiasis(maggot infestation) may also be seen in
debilitated reptiles. For sample identification, ectoparasites may be collected in 70%
ethanol and submitted to laboratory if further identification is required.

­Treatment Techniques
Heating
Reptiles are ectothermic, generally requiring
an external heat source to maintain bodytemperature. The preferred optimum temperature range should be known for patientsthat are in care to allow for best healing andrecovery (see Chapters 1 and 2). Effort should

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be made in hospital enclosures to provide
reptiles with their complete temperature
range, allowing the reptile to choose its preferred temperature. Refer to Chapter 6 forfurther details on heating.
Lighting
Most reptiles require some degree of ultraviolet B light (wavelength 290–320 nm) for
vitamin D3 synthesis. Vitamin D3 is required
to absorb dietary calcium and subsequent
prevention of nutritional metabolic bone­disease. An ultraviolet B gradient may allow
reptiles to regulate their exposure and lamps
may be set to a timer to provide the appropriate amount of ultraviolet light. In species that
can absorb oral vitamin D3, short‐term hospital stays may not require ultraviolet lighting if they are supplemented with oralvitamin D3 and calcium. Refer to Chapter 6
for further details on lighting.
Fluid Therapy
Assessment of dehydration and fluid deficit
may be difficult in reptiles. Some indicators
include skin turgor, sunken eyes and thickmucus in the mouth. Understanding how fluids are obtained is critical for each species, asmany do not drink directly (e.g. chameleons
lick water droplets off their face and require
misting). Recommended daily fluid therapy
doses range from 10 ml/kg/day to 40 ml/kg/
day. Calculation of daily fluid therapy(Table 13.1) has also been estimated at 15 ml/
kg for large reptiles and up to 25 ml/kg forsmall reptiles (author’s preference).
Recommended routes and management of
fluid therapy include oral, subcutaneous,
intracoelomic, intravenous, intraosseous andcloacal. Fluids should be administered orally
if the animal is less than 5% dehydrated and iscapable of absorbing oral fluids (no vomiting,ileus or diarrhoea). Administer by syringe or
stomach tube (red rubber catheter measured
to distal oesophagus or stomach). Whenpassing a stomach tube, use a soft spatula toopen the mouth to avoid damaging the teethor the beak (turtles). A bite block may be useful in chelonians as they tend to bite soft
feeding tubes. Avoid the glottis, which is at
the base of the tongue. Fluids should be pre‐warmed and the volume delivered should be
no more than 3% of the body weight at a time.
During gavage, identify the glottis and stop if
the stomach overfills and fluid starts to backup. Fluid therapy may need to be divided into
several treatments if this occurs.
The subcutaneous space may also be used
if dehydration is less than 5%. Administer atbody temperature. The subcutaneous spaceis limited in reptiles and subcutaneous fluid
administration may cause trauma in lizards
with tight or fragile skin. In lizards, accessareas include the lateral body wall or over thescapulae (Figure 13.4); in snakes, the paravertebral space; in chelonians, the axillary or
inguinal regions; this route is rarely used incrocodilians.
The intracoelomic route is recommended
for more dehydrated cases, as it offers rapid
administration of larger volumes of fluid andthe coelom has good fluid absorption. In chelonians, inject in the ventrocaudal coelomic
cavity to avoid the lungs and other internalorgans. In lizards and snakes, the injection
may be given with the patient in dorsal
recumbency to move the viscera and lungs
away, injecting the fluids intracoelomically inthe caudal third of the body. Alternatively,
lizards may be tilted on their side, which may
be less distressing. Aspirate before giving
intracoelomic fluids to ensure that the needle
has not entered the lungs or a viscus. This
may also be performed via a catheter placedin the pre‐femoral fossa to help to avoid needle trauma. The intracoelomic route allows
large volumes of fluids to be administered at
the one time. Beware of overhydration, as
exceeding coelomic absorption levels will
reduce the capacity of the lungs to expand
due to iatrogenic ascites.
The intravenous route is the best route for
rapid fluid administration, especially in reptiles
that are more than 8% dehydrated. Intravenous
fluid administration typically requires cut‐
down surgery for catheter placement.

Clinical Techniques and Supportive Care

Table 13.1 Fluid therapy.
Administration
Solution

Dose

Frequency

RouteComments

PO

Oral fluid therapy, anorexia

Oral electrolyte

10–20 ml/kg

q24h prn

Crystalloids:

10–30 ml/kg

q24h prn

Dose depends on patientdehydration and ongoing losses

Non‐lactate sodium
chloride (0.45%)

PO, SC, IV, IC,
EpiCe, IO prn

Hypertonic dehydration; can mix
with other crystalloid solutions

Sodiumchloride (0.9%)

SC, IV, IO, IC,
EpiCe prn

Hyperkalaemia, hypercalcaemia,
hypochloraemic metabolic
alkalosis; can mix with othercrystalloid solutions

Dextrose(2.5%, 5.0%)

PO, SC, IV, IC,
EpiCe, IO

Fluid therapy, hyperkalaemia; canmix 5% dextrose with othercrystalloid solutions in equal partsif patient is hypoglycaemic

Lactated Ringer’s
solutionSC, IV, IO, IC,
EpiCe(chelonians)

Fluid replacement, prevention ofaminoglycoside nephrotoxicity; canuse EpiCe in chelonians; avoid
using with hepatic insufficiency

Ringer’s solution
for reptiles

SC, IV, IO, IC,
EpiCe(chelonians)

Hypertonic dehydration or
prevention of aminoglycoside
nephrotoxicity; can use epiCe inchelonians
Formula:1 part LRS, 2 parts 2.5%
dextrose/0.45% saline
1 part LRS, 1 part 5% dextrose,
1 part 0.9% saline

EpiCe, epicoelemic; IC, intracoelomic; IO, intraosseous; IV, intravenous; PO, oral; prn, as needed; q24h, every
24 hours; SC, subcutaneously.
Sources: Carpenter et al. (2014), Carpenter (2013), Funk and Diethelm (2006), Mader and Rudloff (2006),
Kirchgessner (2009), Gibbons (2009), Jarchow (1988).

Figure 13.4 Subcutaneous fluid
administration to a double‐crested
basilisk (Basiliscus plumifrons).

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The intraosseous route is useful when
rapid absorption is needed and intravenous
access is limited or unavailable. Intraosseous
catheters may be used in lizards and small
crocodilians. They may also be placed in tortoises but with some difficulty. In lizards,
placement is in the distal femur or tibial
crest. Aseptic technique is imperative andlocal anaesthesia should be used over thetibial crest to numb the periosteum. With
the leg in flexion, a spinal needle with stylet
is advanced into the tibial plateau, anterior
to the joint capsule and manipulated into themarrow cavity. Once placed, the stylet isremoved and the needle secured. Placement
must be confirmed by radiography as theneedle may deviate out of the tibial medullary cavity. Catheter placement may also be
carried out in the distal femur by entering
the anterior surface of the metaphysis.
Intraosseous catheters are useful for constant rate infusion since the marrow has limited space and is not suitable for bolus fluid
administration (Figure 13.5a,b).
Cloacal absorption of fluids may be beneficial on a routine basis (daily bathing) and for
mild dehydration but should not be considered a replacement for fluid therapy.

(a)Nutritional Support
Nutritional support for the hospitalized reptile can be challenging. Attempts should bemade to provide the species specific diet.
Sick, hyporexic reptiles will often be reluctant
to eat their normal diet. Many wild reptiles
placed in captivity, particularly chelonians,
are often reluctant to eat and may require
supplemental feeding. Dehydration is common in sick reptiles and proper hydration
should be established prior to supplemental
feeding.
Standard metabolic rate (SMR) for reptiles
is 32 (BW0.75), measured in kilocalories (kcal)
per day, where BW is body weight in kilograms (a 1‐kg animal has an SMR of approximately 32 kcal/day). SMR in reptiles is only
25–35% of estimated values for mammals(personal communication, Michelle Shaw).
In reptiles, daily intake is calculated as 1.1–4
times SMR, so a 1‐kg animal requires
35–128 kcal/day. This amount may decreaseduring fasting and with less activity and/or
lower ambient temperatures or may increase
with more activity, reproduction, growth andprotein synthesis required for healing. If theanimal is in good condition, give approximately 75–100% of daily estimated calories(b)

Figures 13.5 (a,b) Correct positioning of an intraosseous catheter in a lace monitor (Varanus varius).

Clinical Techniques and Supportive Care

Table 13.2 Percentage energy requirements for reptile dietary classifications.
Protein (%)(range)Fat (%)(range)Carbohydrate(%)

Carnivorous (snakes, crocodiles, some lizards, juvenile
aquatic turtles)

50 (25–60)

45 (30–60)

5Omnivorous (adult aquatic turtles, tortoises, some lizards)

25 (20–40)

2550

Herbivorous (some tortoises, iguanas)

20

5

75

Dietary type

Source: Donoghue (2006).

to a hospitalized patient. If the reptile is ina debilitated condition, start with 40–75%
and increase gradually so as to not cause
gastrointestinal upsets (Donoghue 2006).
For example, a 300‐g bearded dragon would
have an SMR of approximately 13 kcal/day
and daily requirements would range from
14–52 kcal depending on the considerations
listed here.
Carnivorous reptiles have a higher protein
requirement than omnivorous reptiles. Some
species alter their diet as they age, usually
becoming less carnivorous (aquatic turtles
and bearded dragons). Herbivores tend tohave diets higher in carbohydrates (Donoghue2006). Table 13.2 gives the energy requirements for reptile dietary classifications.
There are several commercial critical carediets available for gavage feeding in hospital,
including a variety of commercial diets covering the nutritional range of carnivorous(including insectivorous), omnivorous andherbivorous reptiles. Some of the products
used are human nutritional support products. When deciding when to feed the hospitalized reptile, it is important to understandthe feeding frequency of the species in care.
Nutritional Delivery
Reptiles that are not eating on their own but
are still alert may tolerate assist feeding by
gently opening the mouth with a soft spatulaand inserting food items that the reptile caneasily swallow. If feeding whole prey, ensurethat the prey is dead. If the reptile is difficult

to assist feed, gavage feeding may benecessary.
Soft, flexible feeding tubes (e.g. red rubber
catheter) or steel feeding needles can be used
to deliver liquid or puréed diets. The tube
should extend to the distal oesophagus or
stomach. The practitioner can visually place
the well‐lubricated tube past the glottis toensure that it enters the oesophagus. A bite
block or speculum may be used to protect
the reptile from biting on the feeding tube.
When delivering soft food through the tube,
identify the glottis during the process toensure that food does not back up andbecome aspirated (Figure 13.6). Regurgitation
could be a concern if the meal is too large. If
it is tolerated by the patient, consider dividing the daily calorie requirement into twodaily feeds.
Additional oil (e.g. olive oil) may be added
to boost energy intake, particularly if the volume is restricted during assisted feeding(personal communication, Shaw).
Oesophagostomy Tube Support

Oesophagostomy tubes are useful for nutritional support in anorexic chelonians thatcannot or will not eat. Chelonians are often
difficult to assist feed due to their long necks
and resistance to mouth opening relative toother reptiles. An oesophagostomy tube canbe easily placed in chelonians in debilitatedcondition using local anaesthesia or they may
require general anaesthesia if they are more
active. See Chapter 28 for a description of thetechnique.

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Reptile Medicine and Surgery in Clinical Practice

Figure 13.6 Gavage feeding adouble‐crested basilisk (Basiliscus
plumifrons).

Liquid enteral nutrition is often requiredand can be made up from prepared sources
or natural food items. Commercial criticalcare diets exist for herbivorous, omnivorousand carnivorous reptiles. In addition, humannutritional support products have also been
useful for recovery from long‐term anorexia,
and may be mixed with vegetables or fruits
for herbivores.
Respiratory Support
Assess respiratory rate and effort in the reptile patient. If the reptile is dyspnoeic, place itin an oxygen chamber for support. If it is sufficiently moribund and dyspneic, the reptile
may need to be intubated and oxygen supplied through assisted ventilation, making
sure the trachea is clear first. Once stabilized,
diagnosis of the underlying respiratory condition may be assessed, including use of
pulmonoscopy.
In instances of tracheal obstruction insnakes, saccular lung cannulation can be performed by transcutaneously accessing the airsacs to allow ventilation of the snake.
Through a skin incision, the air sac may beaccessed through blunt dissection of theintercostal muscles, allowing a tube to beplaced through a small incision into the caudal aspect of the saccular lung (air sac). Thishas been performed successfully in ball and
Burmese pythons with minimal damage tothe surrounding tissue.

Administering Medications
The most common medication routes
include: oral, subcutaneous, intramuscular,
intravenous, intracoelomic and intraosseous.
Oral and Parenteral Dosing

Oral treatment may be given in the food andmay be flavoured to avoid rejection. Gavage/tube feeding is another option for chelonians,
snakes and lizards but care is needed to avoid
damaging the mouth by repeated manipulation. Chelonians also tolerate oesophagostomy
tubes. Crocodilians are typically treated infood. In some animals, such as bearded dragons, simply dripping measured amounts of liquid medication into the mouth is successful.
Parenteral dosing is often more effective
than oral dosing in reptiles. Injection techniques may vary slightly in different species
but should always be performed using sterile
technique. With parenteral administration,
there is evidence that some drugs removed byrenal excretion or hepatic metabolism may bepartially eliminated by the first‐pass effect.
When possible, subcutaneous or intramuscular injections may be given in the cranial half ofthe body, except in cases where a specific drug
has been proven to be acceptable for caudal
administration (e.g. carbenicillin, gentamicin).
Subcutaneous Dosing

Subcutaneous space is limited in reptiles andis poorly vascularized, therefore having variable absorption. In lizards, the lateral bodyClinical Techniques and Supportive Carewall or scapular area is often used; in chelonians, the axillary and inguinal areas are preferred; in snakes, the paravertebral space; incrocodilians, this route is rarely used.
Intramuscular Dosing

This is a common route of drug administration as it has rapid uptake and distribution. A
common injection site is in the forelimbs.
Some drugs are irritating when given intramuscularly and may cause pain and inflammation at the injection site. Enrofloxacin
50 mg/ml may cause muscle necrosis andsloughing when given in large volumes at fullstrength but may be diluted to 25 mg/ml withsterile water at a ratio of one to one to alleviate this problem. Avoid injecting into small
muscle masses if possible, particularly insmall animals, as this may impair mobility.
Rotate injection sites if ongoing treatments
are required.
Intravenous Dosing

The intravenous route has rapid uptake anddistribution but may pose some difficultywith access in a debilitated patient. If a catheter is in place, intravenous drug administration is accessible and should be used. It is thebest route for drug administration if a patientis dehydrated and hypothermic. Dehydration
should be corrected prior to administrationof any organotoxic drugs (e.g. gentamicin,
nonsteroidal anti‐inflammatory drugs).
Intraosseous Dosing

The intraosseous route is adequate fordrug administration if access is available but
only if the drugs have no known adverse
marrow effects.
Intracoelomic Dosing
The intracoelomic route is a rare route fordrug administration, although it is very goodfor fluid administration. For many drugs, theintracoelomic route is recommended only if
all other routes are unavailable as absorption
across coelomic membranes may be variable.

Maintaining Vascular AccessOnce vascular access is achieved (which canbe difficult), intravenous catheters can be
secured in many reptilian species. Reptile
skin is thick and tough and requires aseptic
surgical cut‐down technique for catheter
placement. This is best performed in heavily
sedated or anaesthetized animals but may be
performed in emergency situations withmoribund animals and local anaesthesia.
Consider analgesia for pain relief.
Lizards
The typical site for intravenous catheter
placement is the cephalic vein on the medial
to lateral forelimb. A transverse cut‐down
can be performed with the incision running
perpendicular to the vein. Dissect down tovein through subcutaneous tissue to place
the catheter. Secure the catheter into the veinwith tape or glue and bandage for protection.
The jugular vein is also an option but is usually more difficult to access.
Chelonians
In tortoises and semi‐aquatic turtles, the left
and right jugular veins are used for intravenous catheters. Note that the right jugular
may be larger than the left. The jugular vein
may be visualized starting at the tympanic
membrane and extending caudally. In somecases, a skin incision may not be necessary.
With thicker skin, a small nick in the skin near
the jugular vein will allow access to the vein.
Catheter placement should be near the cranial
third of the neck. The catheter should be flexible and its length should be one‐third of theneck length to compensate for neck flexion
and retraction. The catheter may be sutured
or glued in place (no bandage is necessary).
In sea turtles, the external jugular vein is
fairly accessible through cut‐down and dissection technique.
SnakesThe left or right jugular vein is the intravenous
catheter site for snakes. Placement is 9–10 ventral scales cranial to the heart. With the snake

169

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Reptile Medicine and Surgery in Clinical Practicein dorsal recumbency, an incision is madebetween the first and second rows of dorsal
scales (just above the ventral scales). The rectus
abdominis muscle needs to be bluntly dissected
to reveal the jugular vein (medial to ribs). Oncethe catheter (largest bore possible) is inserted, it
may be sutured in place.
Blood Transfusion
The literature is scant regarding whole bloodtransfusions in reptiles but reptile practitioners do perform transfusions. Anaemia may bechronic or acute. Acute anaemia from acuteblood loss is typically an indication for transfusion if the overall blood loss exceeds 20%.
Packed cell volume and total protein of therecipient are critical in determining the needfor a transfusion. Normal reptile packed cellvolume ranges are typically between 20% and
40% and total protein levels of 3–8 g/dl. In ananaemic reptile, packed cell volume may drop
quite low (less than 10%) and the patient
should be monitored closely. Many reptiles
may be able to cope with anaemia and will
recover with supportive care. However, clinicalsigns such as weakness and lethargy are good
indicators of when a transfusion is warranted.
Whole blood from a healthy conspecific(not to exceed 0.8% of the body weight of thedonor) can be collected aseptically in anticoagulant. The anticoagulant commonly used
is heparin at 5–10 units/ml of blood. If available, acid citrate dextrose solution can also
be used at a ratio of one to nine with blood.
Blood must be collected with strict aseptic
technique and should be used within six
hours of collection as red blood cells lose
viability over time, especially in heparin,
which lacks preservatives. Blood should be
stored cooled and then warmed prior toadministration.
Whole blood may be administered to therecipient via the intravenous or intraosseousroute. Use a large gauge intravenous or butterfly catheter to prevent red blood cell haemolysis and platelet clumping. This may bedifficult in snakes and the transfusion may
instead be given via the intracoelomic route.

The blood should be warmed to 25–30 °C
and may be given by syringe at a rate of
5–10 ml/kg/hour. In shocked patients, 20 ml/
kg/hour is recommended. Monitor for signsof circulatory overload, particularly in small
reptiles. A positive response to transfusion isoften noted within two hours.
Note that a slide agglutination test can be
performed on patients with a history of previous transfusions.
While filters (80 µm pore) have previously
been recommended for clot and debris
removal, one report recommended not using
a standard Millipore filter as large reptilian
erythrocytes would not pass through.
Bandaging and Wound
Management
There are a variety of bandage materials available for use in reptiles. Small open wounds
may be cleaned and dressed with topical­antibiotic if infected (e.g. acute cadexomer
iodine powder) covered in hydrocolloid
paste to maintain moisture (e.g. DuoDERM®;
Figure 13.7). The same principle may be
applied to larger wounds with an additional
secondary dressing. Change bandaging as
needed; typically every two to three days as
the wound is monitored. Some practitioners
recommend suturing bandage material to theskin. Wound healing typically progresses similar to that of other animals but at a slower
rate. Do note that in snakes, bandages are difficult to maintain because of their body shape.
Enemas
Impaction due to constipation or obstipation
may be seen in some reptiles. Adequate
hydration status should be maintained andfluid correction often resolves constipation.
If not, warm water enemas given per cloaca
may be performed. Red rubber catheters
may be gently advanced and warm water
instilled into the lower intestine. Alternatively,
a mixture of 50% lubricant and 50% warm
water at a rate of 1–3 ml/100 g body weight
may be used.

Clinical Techniques and Supportive Care

Figure 13.7 The use of DuoDERM®/
Iodosorb® in a shell fracture repair onan eastern long‐necked turtle.

­Acknowledgements
Taronga Zoo Wildlife Hospital: Michelle
Shaw, nutritionist, Paul Thompson, laboratory manager, and the nurses and Reptile

Division keepers for assistance with thischapter, and Robert Johnson.

Reference
Donoghue, S. (2006) Nutrition, in Reptile
Medicine and Surgery, 2nd ed. (D. Mader,ed.), Saunders Elsevier, St Louis, MO,
pp. 251–298.

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Barten, S.L. (2006) Lizards, in Reptile Medicine
and Surgery, 2nd ed. (D. Mader, ed.),Saunders Elsevier, St Louis, MO, pp. 59–77.
Barten, S.L. and Fleming, G.J. (2014) Current
herpetologic husbandry and products, inCurrent Therapy in Reptile Medicine andSurgery (D.R. Mader and S.J. Divers, eds).
Elsevier Saunders, St Louis, MO, pp. 2–12.
Boyer, T.H. and Boyer, D.M. (2006) Turtles,
tortoises and terrapins, in Reptile Medicine
and Surgery, 2nd ed. (D. Mader, ed.),Saunders Elsevier, St Louis, MO, pp. 78–99.
Campbell, T.W. (2006) Clinical pathology of
reptiles, in Reptile Medicine and Surgery,2nd ed. (D. Mader, ed.), Saunders Elsevier,
St Louis, MO, pp. 453–470.
Campbell, T.W. (2014) Clinical pathology, in
Current Therapy in Reptile Medicine

and Surgery (D.R. Mader and S.J. Divers,
eds). Elsevier Saunders, St Louis, MO,
pp. 70–92.
Campbell, T.W. (2006) Hemoparasites, in
Reptile Medicine and Surgery, 2nd ed.
(D. Mader, ed.), Saunders Elsevier, St Louis,
MO, pp. 801–805.
Carpenter, J.W. (2013) Reptiles, in Exotic
Animal Formulary, 4th ed. (J.W. Carpenterand C.J. Marion, eds.), Elsevier Saunders,
St Louis, MO, pp. 116–121.
Carpenter, J.W., Klaphake, E. and Gibbons,
P.M. (2014) Reptiles, in Current Therapy in
Reptile Medicine and Surgery (D.R. Mader
and S.J. Divers, eds). Elsevier Saunders,
St Louis, MO, pp. 70–92.
Cooper, J.E. (2006) Dermatology, in Reptile
Medicine and Surgery, 2nd ed. (D. Mader,

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DeVoe, R.S. (2015)Lacertilia (lizards, skinks,
geckos) and Amphisbaenids (worm lizards),
in Zoo and Wild Animal Medicine (M.E.
Fowler and R.E. Miller, eds) Volume 8,
Elsevier Saunders, St Louis, MO,pp. 52–60.
Flanagan, J.P. (2015) Chelonians (turtles,
tortoises), in Zoo and Wild Animal Medicine(M.E. Fowler and R.E. Miller, eds) Volume 8,
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Funk R.S. and Diethelm, G. (2006) Reptile
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St Louis, MO, pp. 1119–1139.
Gibbons, P.M. (2009) Critical care nutrition
and fluid therapy in reptiles. Proceedings ofthe 15th Annual International Veterinary
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Gibbons, P.M. (2014) Therapeutics, in Current
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Gibbons, P. M., Klaphake, E. and Carpenter,
J. W. (2013) Reptiles, in Exotic Animal
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Marion), Elsevier Saunders, St Louis, MO,
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Greiner, E.C. and Mader, D.R. (2006)
Parasitology, in Reptile Medicine andSurgery, 2nd ed. (D. Mader, ed.), Saunders
Elsevier, St Louis, MO, pp. 343–364.
Hernandez‐Divers, S.J. (2006) Diagnostic
techniques, in Reptile Medicine and Surgery,2nd ed. (D. Mader, ed.), Saunders Elsevier,
St Louis, MO, pp. 490–532.
Holz, P., Barker I.K., Burger, J.P. et al. (1997)
The effect of the renal portal system on
pharmacokinetic parameters in the red‐
eared slider (Trachemys scripta elegans).
Journal of Zoo and Wildlife Medicine, 28 (4),386–393.

Innis, C. (2008) Zoo Med 2008: Reptile
Medicine. Tufts Open Courseware, Tufts
University. http://ocw.tufts.edu/Content/60/
lecturenotes/843397 (accessed 5 June 2017).
Innis, C., Papich, M., and Young, D. (2007)
Pharmacokinetics of metronidazole in the
red‐eared slider turtle (Trachemys scripta
elegans) after single intracoelomic injection.
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Isaza, R. and Jacobson, E.R. (2013)
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cardiocentesis in ball pythons (Python
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patient, in Exotic Animals (E.T. Jacobson and
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Kirchgessner, M. and Mitchell, M.A. (2009)
Chelonians, in Manual of Exotic Pet Practice(M.A. Mitchell and T.N. Tully Jr, eds). Elsevier
Saunders, St Louis, MO, pp. 207–249.
Knotková, Z., Doubek, Z., Knotek, Z. andHajková, P. (2002) Blood cell morphology
and plasma biochemistry in Russian
tortoises (Agrionemys horsfieldi). Acta
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Lane, T. (2006) Crocodilians, in Reptile Medicine
and Surgery, 2nd ed. (D. Mader, ed.), Saunders
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Lock, B.A., and Wellehan, J. (2015) Ophidia(snakes), in Zoo and Wild Animal Medicine(M.E. Fowler and R.E. Miller, eds) Volume 8,
Elsevier Saunders, St Louis, MO, pp. 60–74.
Mader, D.R. (2006) Medical care of seaturtles:
medicine and surgery, in Reptile Medicine andSurgery, 2nd ed. (D. Mader, ed.), Saunders
Elsevier, St Louis, MO, pp. 977–1000.
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(2009) Saccular lung cannulation in a ballpython (Python regius) to treat a tracheal
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D.R. (2006) Microbiology: fungal andbacterial diseases of reptiles, in Reptile
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Schumacher, J. and Mans, C. (2014)
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MO, pp. 134–153.
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Elsevier, St Louis, MO, pp. 442–452.
Stacy, N. I., Alleman, A.R. and Sayler, K.A.
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14
Reptile Pharmacology
Tim Hyndman­Introduction
Primum non nocere (First, do no harm)
Post hoc ergo propter hoc (After this,
therefore, because of this; He was sick,he is now well, and therefore the treatment cured him)
These two Latin phrases eloquently summa­
rize the guiding principles of drug therapy inall species. First, the goal of all veterinarians
when administering therapy to animals is not
to cause harm. Second, it is important thatthe veterinarian understands that the resolu­
tion of a clinical disease was not necessarily
because of the therapy they administered. To
automatically assume that it was can result inself‐fulfilling prophecies, and not scientificevidence, justifying therapeutic decisions.
These teachings are especially pertinent toreptile drug therapy because the veterinarian
only has limited information to guide theirdecisions as to how they employ their drug
armamentarium for an incredibly diverse
group of species. Despite these challenges,
the veterinarian is already well trained toapply their knowledge of pharmacology tothese remarkable animals.
The reader is reminded that the drug for­mulary found in Appendix 1 of this bookprovides information specific to individual
drugs (e.g. doses) and so serves as acomplement to the discussion presented inthis chapter. Box 14.1 outlines 10 rules toremember when treating reptiles with drugs.

­Administration of Drugs
for Reptiles
The clinician should know what species (orat least what family) of reptile has been pre­sented to them. This will then allow helpfulhusbandry recommendations to be made.
The second fundamental piece of informa­tion that should be established before any
drug therapy starts is an accurate diagnosis.
It is accepted that delaying supportive ther­apy until all diagnostic tests have been com­pleted can compromise the animal’s welfare.
It is also accepted that treatment trials canprovide valuable information about under­
lying disease processes but, nevertheless,determining a definitive diagnosis should
always remain the goal of the veterinarian,as it will direct the clinician to the mostappropriate treatment modality.
All reptiles are ectothermic and each spe­
cies has a natural preference for a specificrange of ambient temperatures they will seek
to regulate their body temperature. This isreferred to as the preferred optimal body tem­
perature or the preferred optimal temperaturezone. The assumption is made that a reptile

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

176

Reptile Medicine and Surgery in Clinical PracticeBox 14.1 Ten rules to remember when treating reptiles with drugs.
1) Ensure that the owner has provided
informed consent for the therapy you
would like to instigate. The vast majority ofdrugs administered to reptiles are not registered for them.
2) Do not use macrocyclic lactones in turtles
and tortoises. Great care should also be
exercised when considering these drugs forcrocodilians, skinks and indigo snakes.
3) Be kind and compassionate to your reptilian patients. Our capacity to interpret painand distress in reptiles is limited. Assume
that reptiles require the same levels of analgesia afforded to companion mammals.
4) Husbandry can always be improved.
Improved husbandry is unfailingly the best
medicine.
5) Ensure that each reptilian patient is kept attheir preferred optimal body temperatureduring drug therapy. This should mean that

drug absorption, distribution, metabolism
and elimination will be as reliable aspossible.
6) Courses of medication will generally need
to be longer in reptiles than mammals.
7) ‘Baytril® (enrofloxacin) deficiency’ is not adiagnosis. Reptile patients deserve ourbest efforts to reach a correct diagnosis.
8) Avoid serial injections of enrofloxacin into
the muscle and subcutaneously. This practice is painful and is associated with tissue
necrosis and abscess formation.
9) Intramuscular injections should be
injected into the front half (e.g. forelimbs)
of reptiles. This may avoid first pass renal
clearance of some drugs.
10) There is very little justification to use corticosteroids in reptiles. Nonsteroidal anti‐
inflammatory drugs will nearly always
represent a better option.

will function optimally at their preferred
optimal body temperature. It is therefore
also assumed that if a reptile is held at its pre­ferred optimal body temperature, any drugs
that are administered to it will be absorbed,
distributed, metabolized and eliminated asreliably as possible (see also Chapter 2).
Once a drug has been selected for therapy
and the animal has been provided with its
preferred optimal temperature zone, a routeof administration needs to be chosen. The
most reliable ways to deliver a drug to theblood are by intravenous or intracardiac
injection. For intravenous injections, the ven­
tral tail vein is usually chosen for snakes andlizards but for turtles and tortoises the dorsal
tail vein, jugular vein, occipital sinus, subcar­
apacial sinus and brachial vein can be tried(see Chapter 13). Intravenous injections canbe very challenging in reptiles. Injections
directly into the heart are typically reserved
for the administration of euthanasia solutionsin anaesthetized or heavily sedated patients.
Injections administered into the muscle
and the subcutaneous tissue are two common

routes of drug administration for reptiles.
Larger boluses can be administered under theskin rather than into the muscle and espe­
cially large volumes should be injected into
multiple sites (see Chapter 13). For snakes,
back (epaxial) muscles are usually chosen for
intramuscular injections but, for turtles, tor­
toises and lizards, the front limb is usuallychosen. There is debate as to whether drugs
should be preferentially injected into the cra­nial half of reptiles. Reptiles have a uniquevascular system and part of it, the renal portal
system, means that venous drainage from thecaudal half of the animal may be delivered
directly to the kidney before returning to theheart. For drugs that are primarily eliminatedby the renal tubules (e.g. beta‐lactam antibi­
otics), this may mean that some of the admin­
istered drug is extracted by the kidney before
it can be distributed throughout the body.
This may have clinical consequences if thisresults in blood drug concentrations becom­ing subtherapeutic. Obviously, the clinicalconsequences of injecting drugs into the cau­dal half of reptiles have not been quantified

Reptile Pharmacology

for every drug in every species. Consideringthat it is rarely more difficult to inject a reptile
in the cranial half of the body compared withthe caudal half of the body, injections into thecranial half of the body are encouraged. It
should also be noted that intravenous injec­
tions into the tail vein may also result in drugs
being delivered directly the kidney.
Injecting drugs into the body cavities ofreptiles (the coelomic cavity) cannot be rec­ommended because of the risk of lacerating
the alimentary tract, highly vascular organs
and the reproductive tract, especially infemales during their breeding seasons. The
inadvertent injection of drug into the lumenof the alimentary tract may decrease drug
absorption.
Drugs can be administered directly into
the alimentary tract of reptiles. This can be
through instilling drug into the mouth,
depositing it lower down into the oesopha­
gus or stomach or even by inserting the drug
into the reptile’s food item. This last method
is sometimes used for venomous or other­wise dangerous reptiles and, although it rep­resents a safe method of drug administration,
drug absorption will likely be unpredictable.
Some drugs are administered directly on to
the skin of reptiles. As a generalization, it
should be assumed that this route of admin­
istration is only suitable for those drugs being
used for a topical effect; for example, fortreating external parasite burdens such asmite infestations. Due care should still be
exercised as systemic toxicity has been asso­
ciated with topical drug administration in
reptiles (e.g. pyrethroids).

­Drug Compounding
Drug compounding is defined as the manip­
ulation of a drug to form a medicine. It is
typically performed by compounding phar­macists or veterinarians and is done extem­
poraneously (ad hoc) to meet the medical
needs of an individual patient. Owing to thelimited arsenal of drugs that are registeredfor use in reptiles, it can be tempting toobtain medicines from compounding phar­macists. By this means, specific drug concen­
trations can be obtained, drugs can be
combined into ‘polypills’, particular palatants(flavours) can be added to drugs and, often,
this can be done at a cheaper price than if theclinician were to purchase registered drugs.
These advantages may be partially or totallyoffset by a number of disadvantages, namely
the unproven safety, efficacy, manufacturing
standards and stability for the particular
medication being sought. In one study on
two concentrations of compounded oral doxy­cycline, 33 mg/ml and 167 mg/ml, the doxy­cycline was found to be stable for between 7
and 14 days, at both room temperature andwhen stored in a refrigerator (Papich et al.
2013). The compounding pharmacist had
assigned an expiry date of 28 days to thesetwo preparations.
It is prudent to be cautious about com­pounded drugs. This caution should extend
especially to low‐concentration medications(e.g. drugs presented in microgram amounts),
those intended for injection and those asso­
ciated with claims of systemic absorption
following their application to the skin(transdermals).

­Antibiotic Therapy
Antibiotic resistance is emerging and spread­ing more rapidly than ever. Compounding thisresistance, new antibiotics are arriving tomarket at their slowest rates ever. This meansthat antibiotics should be used sparingly andappropriately. Once the decision has been
made to administer an antibiotic (or antibiot­ics), the dose and dosing interval must be con­sidered carefully. The duration of the antibiotic
course should be decided during therapy.
Which Antibiotic(s) Should
be Used?
A bacterial culture and sensitivity continues
to be the gold standard for determining thebacteria present in a clinical sample and for

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Reptile Medicine and Surgery in Clinical Practice

predicting which antibiotic(s) will have in
vivo efficacy against the cultured bacterium.
If possible, culture and sensitivity should beordered in parallel with cytology or histopa­
thology. These pathology tests can provide
further insights into the significance of thebacteria that has been cultured. For example,
seeing Gram‐negative rods within hetero­phils and monocytes would support that aculture result of Escherichia coli was signifi­
cant. The added benefit of cytology and his­
topathology is that non‐bacterial causes of
disease can be investigated (e.g. neoplasia,
fungal infections).
In the absence of culture and sensitivity,
the clinician is forced to make a clinicaljudgement as to whether they consider there
is a bacterial infection at all, and which bac­teria are involved. As a starting guide,
Pseudomonas and Aeromonas are commonly
isolated from ulcerative stomatitis, pneumo­
nia, cutaneous lesions and septicaemias.
Serratia is commonly isolated from bitewounds and other cutaneous lesions.
Mycobacteria can be isolated (and/or
detected by special stains) in cutaneous
lesions and in septic reptiles. Providencia canbe an opportunistic pathogen of the mouthand Klebsiella can be associated with ocular
infections and pneumonia. Salmonella andEscherichia are associated with gut infec­
tions. It is not surprising then that empiri­cally selected antibiotics should have goodefficacy against Gram‐negative bacteria.
Some empirical antibiotic choices for a selec­tion of common reptile presentations arelisted in Table 14.1.
A culture and sensitivity result predicts sus­
ceptibility but if the antibiotic does not reachthe site of infection because of decreased bloodflow to that area (e.g. the core of an abscess),antibiotic efficacy will be diminished. This is
one of the reasons why the surgical treat­ment of reptilian abscesses is so important.
Antibiotics such as fluoroquinolones andmacrolides will concentrate in abscesses
while sulphonamides are inactivated in puru­
lent environments. For slow‐growing bacteria,
the beta‐lactams are expected to havediminished activity because these antibiotics
are dependent on bacterial replication to beeffective. The aminoglycosides have no activity
against anaerobic bacteria.
What Dose and Dose Interval
Should be Used?
The dose of an antibiotic should not be astatic number that is independent of the clin­
ical case. Rather than ‘What is the dose rate
for antibiotic X?’, the clinician is encouraged
to tailor their dose to suit the clinical presen­tation. Therefore, the question of ‘What doseshould I choose for this case?’ is far more rel­evant. It is naïve to assume that all bacterial
infections will respond equally to the same
dose of a particular antibiotic.
Broad generalizations can still be madeabout dose selection, and the recommenda­
tions are strongly linked to the particularclass of antibiotic. For dose (concentration)‐
dependent antibiotics, such as the fluoroqui­
nolones, aminoglycosides, metronidazole
and azithromycin, higher doses result in
improved efficacy. For time‐dependent anti­
biotics such as the beta‐lactams and the mac­
rolides (except azithromycin), the efficacy of
the antibiotic is enhanced by prolonging thelength of time that the plasma concentration
exceeds the susceptibility of the bacterium(e.g. the minimum inhibitory concentration).
For these drugs, increasing the dose fre­quency is the best way of improving drug
efficacy. The tetracyclines and the sulphona­mides do not fit neatly into either of thesecategories. A practical example would be toconsider increasing the dose rate of enroflox­acin from 10 mg/kg once daily to 20 mg/kg
once daily if you were targeting a bacteriumthat was harder to kill (e.g. Pseudomonas).
Similarly, administering the typical 20 mg/kg
dose of ceftazidime at a higher dose fre­quency (e.g. every 48 hours compared withevery 72 hours) should result in improved
drug efficacy for this commonly usedbeta‐lactam.
The sensitivity profile presented as part ofa culture and sensitivity report is derived

Table 14.1 Treatment recommendations for specific conditions.
Disease process

Anti‐infective options

Other drugs

Comments

Abscess: subspectactular
abscesses, internal abscesses

Bacterial: ceftazidime, ceftiofur

NSAIDsSurgery is nearly always more important
than medical therapy.
Topical ocular preparations areinappropriate for reptiles with undamaged
spectacles; e.g. all snakes and most geckos.

Alimentary: periodontal
disease, diarrhoea,
regurgitation

Bacterial: ceftazidime, ceftiofur
Fungal: nystatin, itraconazole
Coccidia: toltrazuril, ponazuril, potentiatedsulphonamides
Cryptosporidium: paromomycin
Flagellates: metronidazole
Nematodes: fenbendazole, ivermectina

NSAIDsFluid therapy, especially if
diarrhoea and stomatitis (notdrinking)

Beware of zoonotic potential of
salmonella.

NeurologicalProtozoal (rare): metronidazole, potentiatedsulphonamides

Drug therapy may not help (e.g. viral
NSAIDsinfections) and so may need to consider
Calcium for hypocalcaemia
euthanasia.
Glucose for hypoglycaemia
Fluid therapy to hasten eliminationof toxins

Reproductive: egg binding(dystocia), prolapse

Bacterial/prophylactic: ceftazidime, ceftiofur

Some eggs can be manually passed and so
NSAIDsCalcium and fluid therapy for many drug therapy may not be needed.
dystocias (see Chapter 22 for more Many cases will be surgical.
medical options)

Respiratory: upper and lower
respiratory disease

Bacterial: ceftiofur, ceftazidime, piperacillin
Mycoplasma: enrofloxacin, macrolides (e.g.
azithromycin, tylosin)
Fungal: itraconazole, voriconazole
Protozoal: potentiated sulphonamides,
toltrazuril
Herpesvirus: acyclovir
Helminth: ivermectina

NSAIDsVitamin A in turtles and tortoises
with swollen eyelids

Ensure that humidity is correct.

(Continued )Table 14.1 (Continued)
Disease process

Anti‐infective options

Other drugs

Comments

SepsisBacterial: amoxicillin/clavulanate and either
ceftazidime or ceftiofur

NSAIDsFluid therapy

Aggressively look for underlying cause

NSAIDsMixed bacterial/fungal: topical silver
Skin/shell: thermal burns,
Fluid therapy, especially for burns
trauma (cage mate, dog attack, sulfadiazine, chlorhexidine, iodine or
clotrimazole; systemic ceftiofur, ceftazidime
motor vehicle)
Fungal: itraconazole, voriconazole
Tapeworm: praziquantel
Ectoparasites: topical ivermectin,a fipronil andpyrethroids

Neoplasias are not uncommon
Adequate humidity is important foraddressing shedding problems. Drugtherapy rarely needed
Regular substrate changes are very
important for ectoparasite management
Tapeworm cysts should be surgicallyresecteda
Do not use the macrocyclic lactones in turtles, tortoises, indigo snakes, crocodilians or skinks. Toxicity is treated with fluid therapy.
NSAID, nonsteroidal anti‐inflammatory drugs.

Reptile Pharmacology

from interactions between the cultured­bacterium and standardized concentrationsof each antibiotic. The corollary to this is that
if a sensitivity profile returns with a lot of‘resistants’, a dose‐dependent antibiotic, forexample, may still be effective if a very highdose is chosen. Obviously, the adverse‐effectprofile of the drug must also be considered.
What Antibiotic Course Duration
Should be Used?
There are numerous factors that should beconsidered when choosing the duration of an
antibiotic course. The idea that an antibiotic
course for a reptile should always extend for
14, 21 or 28 days is overly simplistic. For
every antibiotic course that is started, themost common scenarios that the clinician
will face are ‘It’s not working’ and ‘This is
working really well, but how long do I go for?’.
With ‘It’s not working’, be prepared to change
the plan. The definition of a fool is someone
who does the same thing over and over
expecting a different outcome. The clinician
is strongly encouraged to revisit diagnostics.
It is acceptable to change to a new antibiotic
if the decision was directed by recent culture
and sensitivity results. However, it is rare thatchanging from one empirically selected anti­
biotic to another one will provide a morefavourable outcome.
When asked ‘This is working really well,
but how long do I go for?’, try to have a check­point in mind that you see as an indicatorthat the patient has ‘turned the corner’. At
this checkpoint, consider administering anantibiotic for a short while longer (e.g.
4–­5 days, but using common sense as you
reflect on the progression of recovery). The‘turned the corner’ checkpoint may be that the
animal is now eating, walking, perching, sup­porting their own body weight, has defecatedor passed urates for the first time since being
hospitalized. An important exception to thisgeneralization about stopping an antibiotic
course involves the treatment of some chelo­nian shell infections. These infections typi­cally require months of antibiotic therapy.

­Antifungals
Fungal infections in reptiles occur most com­monly on the skin. They are most often sec­
ondary to thermal burns or trauma and so
specific treatment of the fungal infection
should always occur in parallel to addressing
the underlying problem, which will often be
related to husbandry. Some fungal infections
can be primary diseases (e.g. yellow fungus
disease in dragons; see Chapter 16). These
infections are usually treated topically withbroad‐spectrum antimicrobial creams such as
silver sulfadiazine or with antifungal creams
such as clotrimazole. Some fungal infections
are treated systemically with terbinafine or
antifungal azoles such as itraconazole or vori­conazole. Antifungal courses vary in lengthfrom a couple of weeks to many weeks.
Systemic fungal infections in reptiles are rare.

­Antivirals
Our understanding of viral infections in rep­tiles is still very limited. Some infections canhave no signs of disease (e.g. some adenovirus
infections), while others can be highly infec­
tious and pathogenic (e.g. some ferlavirus
outbreaks). This creates a challenge for theclinician as to how these infections should bemanaged. These viruses can usually only be
avoided through good biosecurity, as com­
mercially available vaccines do not exist. The
most extensively studied antivirals in reptiles
are all purine analogues (acyclovir, ganciclo­
vir and valacyclovir) and they have been asso­
ciated with varying degrees of success intreating herpesvirus infections in tortoises.
For some iridoviral infections, increasing
the ambient temperature has been trialled.
With this method, the animal is kept at anelevated temperature where viral replicationis reduced. This can have animal welfare
implications for the reptile and so this treat­ment should only be considered as a lastresort, and only in heat‐tolerant species.
Sadly, for many reptiles clinically affected byviral infections, treatment is often palliative

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Reptile Medicine and Surgery in Clinical Practice(e.g. nonsteroidal anti‐inflammatory drugs)
and sometimes euthanasia is the most suita­
ble option.

­Antiparasitics
Reptiles can be infested (often simultane­
ously) with a suite of parasites that cover abroad range of taxonomic groupings, mostcommonly nematodes, protozoa and a selec­tion of external parasites (see Chapter 31).
The majority of antiparasitics used in reptiles
for internal helminths are administeredorally and these include the benzimidazoles(e.g. fenbendazole) and the macrocyclic lac­tones (e.g. ivermectin, moxidectin). Boththese drug classes are capable of causing tox­
icity under certain situations. The benzimi­
dazoles have been associated with toxicity ofthe bone marrow (myelosuppression), intes­
tinal epithelium, liver and fetuses, especiallyat higher doses given for longer periods (e.g.
fenbendazole 100 mg/kg every 24 hours for
3 days with food or even 25 mg/kg as a single
dose). It is important that only modern doserecommendations are followed for the benzi­
midazoles. Ivermectin has been associatedwith dose‐dependent toxicity in a number ofchelonian species (Teare and Bush 1983). It issuspected that the mechanism of toxicity issimilar to that seen in susceptible dog breeds,
where there is a deficiency in the P‐glycopro­tein pumps at the blood–brain barrier thatwould ordinarily prevent toxic concentra­
tions in the brain. Toxic effects are predomi­
nantly neuromotor (e.g. paresis). The entire
group of macrocyclic lactones should be
avoided in turtles and tortoises.
Coccidiosis is a common infestation of
reptiles, especially dragons, that can be very
difficult to treat. Toltrazuril and its metabo­lite ponazuril are both coccidiocidal andhave been shown to be effective in eliminat­
ing organism shedding. However, not all
studies support these findings and longer‐term studies that include post‐mortem­histological examinations are needed. The
sulphonamides have also been used for thisindication but similar reservations about
drug efficacy need to be made. The ownershould be informed about the difficulty intreating these infestations.
The drug paromomycin has been used for
cryptosporidiosis but successful drug ther­apy is usually temporary. This parasite isnotoriously difficult to treat.
Studies on topical imidacloprid–moxidectin
and emodepside–praziquantel have revealed
encouraging signs of efficacy against nema­
todes. Safety studies of these drugs in reptiles
are lacking, so the use of these topical drugs
should only occur following informed ownerconsent.
Topical antiparasitics are most commonlyused for treating mite infestations in snakes.
Ivermectin diluted in tap water, fipronil
spray (not spot on) and the synthetic pyre­throids have all been used with success.
Careful monitoring is required as neurologi­
cal adverse effects have been observed withall three drugs.

­Anti‐Inflammatories
and Analgesics
It can be very difficult to detect pain in
reptiles but, despite this, it should be­assumed that whatever causes pain in a
mammal will cause similar levels of pain in
reptiles. The corollary to this assumption
is that inflammation in reptiles will be asso­
ciated with pain and we assume that it can beattenuated by anti‐inflammatory medica­
tions. Inflammatory pain can be caused byvarious noxious stimuli: thermal (e.g. ther­mal burns), mechanical (e.g. cage‐matetrauma) and chemical (e.g. proinflammatory
mediators secondary to infectious pro­
cesses). It is typically treated with non‐steroi­
dal anti‐inflammatory drugs (NSAIDs).
Although controlled clinical trials are lacking
that compare the efficacy and safety of the
NSAIDs in reptiles, meloxicam is the NSAID
that is preferred by a number of reptile
practitioners. There have been recent phar­macokinetic studies that have assessed theReptile Pharmacology

plasma concentrations of meloxicam follow­
ing the administration of standard doses,
usually 0.1–0.2 mg/kg (Divers et al. 2010; Laiet al. 2015; Uney et al. 2016). Plasma concen­
trations associated with analgesia in mam­mals were found in green iguanas but not in
loggerhead sea turtles or red‐eared sliders.
The opioids represent a vitally importantclass of analgesics. Excepting euthanasia,
they represent the most powerful method of
pain relief available from a systemicallyadministered drug. Furthermore, they gener­
ally have minimal effects on the cardiovascu­
lar system. Traditionally, their use in reptiles
has been based on extrapolations from avian
dosing. However, since the early 2000s, theresults of a number of experiments on theefficacy of opioids in reptiles have been pub­lished. The opioids morphine (1–5 mg/kg
subcutaneously or intramuscularly every
24 hours) and methadone (3–5 mg/kg subcu­
taneously or intramuscularly every 24 hours)
and the opioid‐like drug tramadol (5–10 mg/
kg orally every 48–72 hours) have shown thebest results in the few reptile species tested.
The results of testing butorphanol andbuprenorphine have been disappointing.
There are insufficient data to be able torecommend the use of corticosteroids asanti‐inflammatories and analgesics, andsimilarly, the efficacy of other analgesics­
such amantadine, gabapentin, ketamine andalpha‐2 agonists has not been properly sub­stantiated. An excellent summary of clinicalanalgesia in reptiles is provided by Sladky
and Mans (2012).

As mentioned earlier in this chapter, it canbe difficult to assess pain (and therefore
analgesia) in reptiles. This does not meanthat the clinician should not attempt to doit. There are number of signs that reptiles
can be display as manifestations of pain.
Examples include aggression, decreased
movement, guarding parts of their bodies
and decreased intake of food and water.
These signs are obviously non‐specific topain but improvement in these signs should
be viewed favourably.

­Learning More
The reader interested in learning more about
reptile pharmacology and drug therapy isreferred to the overview written by Mitchell(2006) and for a review of published litera­ture on reptilian therapeutics, the workby Gibbons (2014) is recommended.
Recommended reptile formularies can befound in Appendix 1 of this book and in themost recent edition of the Exotic Animal
Formulary (Carpenter 2012). Information
about drug stability and drug interactions
can be found in product inserts (dossiers)
and the veterinary drug formularies by
Papich (2015) and Plumb (2015). For objec­
tive information about drug compounding
produced by veterinary advocacy groups,
the reader is referred to the guidelines pro­
duced by the American Veterinary Medical
Association and the Australian Veterinary
Association.

References
Carpenter, J.W. (2012) Exotic Animal
Formulary, 4th ed. Elsevier Saunders,
St Louis, MO.
Divers, S.J., Papich, M., McBride, M. et al.
(2010). Pharmacokinetics of meloxicam
following intravenous and oral
administration in green iguanas (Iguana
iguana). American Journal of Veterinary
Research,. 71 (11), 1277–1283.

Gibbons P. (2014) Therapeutics, inCurrent Therapy in Reptile Medicine
and Surgery (D. Mader and S. Divers,
eds). Elsevier, St. Louis, MO,
pp. 57–69.
Mitchell, M. (2006) Therapeutics, in
Reptile Medicine and Surgery, 2nd ed.
(D. Mader, ed.). Elsevier, St. Louis, MO,
pp. 631–664.

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Reptile Medicine and Surgery in Clinical Practice

Lai, R.O., Di Bello, A., Soloperto, S. et al.
(2015). Pharmacokinetic behavior of
meloxicam in loggerhead sea turtles(Caretta caretta) after intramuscular andIntravenous administration. Journal of
Wildlife Diseases, 51 (2), 509–512.
Papich, M.G. (2015) Saunders Handbookof Veterinary Drugs: Small and Large
Animal, 4th ed. Elsevier Saunders,
St. Louis, MO.
Papich, M.G., Davidson, G.S. and Fortier, L.A.
(2013) Doxycycline concentration over timeafter storage in a compounded veterinary
preparation. Journal of the American
Veterinary Medical Association, 242,
1674–1678.

Plumb, D. (2015) Plumb’s Veterinary Drug
Handbook, 8th ed. Wiley‐Blackwell,
Oxford, 2015.
Sladky, K.K. and Mans, C. (2012) Clinicalanalgesia in reptiles. Journal of Exotic Pet
Medicine, 21, 158–167.
Teare, J. and Bush, M. (1983) Toxicity andefficacy of ivermectin in chelonians. Journalof the American Veterinary Medical
Association, 183, 1195–1197.
Uney, K., Altan, F., Aboubakr, M. et al. (2016).
Pharmacokinetics of meloxicam in red‐
eared slider turtles (Trachemys scripta
elegans) after single intravenous andintramuscular injections. American Journalof Veterinary Research, 77 (5), 439–444.

Further Reading
American Veterinary Medical Association.
Compounding. https://www.avma.org/KB/
Resources/Reference/Pages/Compounding.
aspx. 2016 (accessed 5 June 2017).
Australian Veterinary Association. Guidelines
for the Preparation and Use of Compounded
Pharmaceuticals. http://www.ava.com.au/
newsarticle/guidelines‐prescribing‐and‐using‐compounded‐medicines (accessed 5
June 2017).

Svendsen, O., Kok, L. and Lauritzenã, B.
(2007) Nociception after intraperitoneal
injection of a sodium pentobarbitone
formulation with and without lidocaine
in rats quantified by expression ofneuronal c‐fos in the spinal cord: apreliminary study. Laboratory Animals,
41, 197–203.

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15
Nutritional and Metabolic Diseases
Brendan Carmel and Robert Johnson­Metabolic Bone Disease
The term ‘metabolic bone disease’ is not asingle disease entity but rather a term used
to describe a collection of medical disordersthat affect the integrity and function ofbones (see Chapter 25 for further discussion). Nonetheless, the term metabolic bonedisease is used in this chapter as a broadphrase to cover the complex disease.
Metabolic bone diseases likely comprise themost common disease conditions affecting
captive reptiles.
Previously the forms of metabolic bonedisease linked to improper diet, inadequate
exposure to ultraviolet lighting or kidney
dysfunction have been termed fibrous
nutritional metabolic disease, osteodystrophy, nutritional secondary hyperparathyroidism (NSHP), osteodystrophia fibrosa,
osteomalacia, renal osteodystrophy andrickets. There are other synonyms. For the
purpose of this discussion, and for clarity,
the general term metabolic bone disease
will be used and will concentrate on thecommon forms of disease seen in captive
reptiles.
The aetiology of metabolic bone disease
is typically nutritional environmental or
renal.

CausesThe predominant causes of metabolic bonedisease in reptiles are prolonged deficiency
of dietary calcium or vitamin D3, an imbalance of the calcium–phosphorus ratio in thediet (usually an excess of phosphorus), inadequate exposure to UVB radiation of appropriate wavelength or a lack of a suitabletemperature zone (Figure 15.1).
Metabolic bone disease is most common inlizards and turtles. The condition is uncommon to rare in snakes as they usually eat
whole food items and are more likely toreceive and absorb adequate dietary levels of
calcium and vitamin D3. Note than many
reptiles that actively bask (heliothermic) may
not have developed mechanisms to absorb or
store dietary forms of vitamin D3, relying on
the pathways described in this chapter toproduce active vitamin D3 via UVB light.
Vitamin D Synthesis
In reptiles, UVB of the wavelength 290–
315 nm reacts with the reptile skin and provitamin precursors are converted to previtamin
D3. The previtamin D3 is then converted
to vitamin D3 (cholecalciferol) via temperature‐dependent isomerization (Hedley

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

186

Reptile Medicine and Surgery in Clinical Practice

Pathogenesis

Figure 15.1 A free living central bearded dragon(Pogona vitticeps) basking. Metabolic bone disease
only occurs in captive reptiles.

2012a). This is an important point: adequate
temperature (via a basking zone in the reptile
enclosure) is required for vitamin D3 synthesis to occur. Cholecalciferol is metabolized
via renal and hepatic pathways to the active
form of vitamin D3, calcitriol (1,25‐DHCC).
Calcitriol is required for absorption of calcium from the intestinal tract.
Captive animals may not have adequate
exposure to UVB due to several factors, suchas ultraviolet light not passing through Perspex
or glass, inadequate ultraviolet lighting in thevivarium or infrequent replacement of ultraviolet globes: ultraviolet output diminishes withtime (see Chapter 6 for more details).
To summarise: the most common causesof metabolic bone disease in captive reptiles
are inadequate ultraviolet light, inadequate
dietary calcium, an inappropriate calcium
to phosphorous ratio and inadequate temperature zone (the reptile needs to be at an
appropriate temperature to absorb ultraviolet light).

Homeostatic mechanisms work to maintaina constant blood calcium level, which isessential for normal function of cells. Any
reduction in the blood calcium level frommetabolic bone disease triggers production of parathyroid hormone. Parathyroid
hormone stimulates an increase in blood­calcium levels by increasing bone resorption, renal tubular reabsorption of calcium
and phosphate excretion in the urine.
Parathyroid hormone also stimulates theformation of calcitriol (1,25‐DHCC), which
in turn increases the absorption of intestinal calcium.
If insufficient calcium is available fromthe diet, calcium is resorbed from thebones to compensate. With a prolonged
deficiency, the resultant osteopenia weakens the bones leading to rickets (young
animals) or osteomalacia (adult animal).
Susceptible reptile groups include most
diurnal species: agamids (dragons), skinks,
turtles, iguanas, varanids (monitors) andchameleons (Figure 15.2). Young, actively
growing reptiles, mature, reproductively
active females and herbivorous and insectivorous species are particularly prone todeveloping metabolic bone disease, (insectivorous species due to the difficulty ofproviding an appropriate captive diet withthe right balance of calcium).
Clinical metabolic bone disease is uncommon in adult reptiles, which have a lesser
demand for calcium, the exception being
breeding females. Reptiles fed on a whole‐animal diet, such as most snakes, are unlikely
to exhibit clinical metabolic bone disease, as
the diet likely provides adequate vitamin D
and calcium. Subclinical disease may be present, although no studies have investigatedthis theory.
Clinical Signs
Common clinical signs include weakness,musculoskeletal deformities, anorexia, poor
growth or weight loss, abnormal shellNutritional and Metabolic Diseases

Figure 15.2 Severe stunting, bone loss
and rubber jaw in a juvenile lacemonitor (Varanus varius).

Figure 15.3 Kyphosis,
lordosis in an easternblue‐tongued skink(Tiliqua scincoides).

Figure 15.4 Spinal deformity in acentral bearded dragon (Pogona
vitticeps) with metabolic bone disease.

growth in chelonians, paresis/paralysis andtremors. Other more specific signs may
include an inability to walk, hyperreflexia,
hypermetria, tetany, seizures; lordosis,
kyphosis, scoliosis, pathological fracturesand stunted growth (rostral ‘rounding’, smallhead); prolapse of the cloaca, colon, hemipenis, oviduct or tongue (occurring in Old
World chameleons; Figures 15.3 and 15.4).
Fibrous osteodystrophy is common in green

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Reptile Medicine and Surgery in Clinical Practice

Figure 15.5 Rubber jaw in a juvenile
central bearded dragon (Pogona
vitticeps).

Figure 15.6 Rubber jaw in a juvenile
pygmy bearded dragon (Pogona
henrylawsoni).

iguanas, manifesting as a thickness andswelling of the long bones and mandible.
Demineralization of bony tissue may lead tosofter, more pliable bones, particularly themandible (Figures 15.5 and 15.6). Bloating
and decreased gastrointestinal motility may
also occur. It has been suggested that metabolic bone disease may be a factor in spinal
osteopathy (proliferative spinal osteoathropathy; see Chapter 25).
Differential Diagnosis
Other disease processes which may result insimilar clinical signs include renal metabolicbone disease (RMBD), spinal osteopathy(proliferative spinal osteoathropathy), osteomyelitis, trauma, sepsis, neoplasia, toxins/
poisons, other vitamin/mineral deficiency orexcess, and osteomalacia.
Diagnosis
Metabolic bone disease is strongly suspected in many cases based on clinical­history (diet and husbandry in particular)
and physical examination. Whole‐bodyradiographs often confirm suspicions, withcharacteristic changes of decreased bone­density, pathological fractures (often ‘folding’ fractures; Figure 15.7 and 15.8), bending and distortion of bones and increased

Nutritional and Metabolic Diseases

Figure 15.7 Pathological fracture of the femur in an
adult perentie (Varanus giganteus).

and uneven cortical widening due to fibrous
osteodystrophy.
Clinical pathology results may be normal,
as the reptile will try to keep calcium
levels within normal range. Reptiles with­renal metabolic bone disease are typically
hypocalcaemic and have high phosphorus
levels. Ionized calcium is a more accurate
representation of physiologically active calcium, although normal ranges are available
for very few species.
Treatment
Stabilize the patient and treat life‐threatening signs first. Long‐term treatment is usually required for many weeks to months,
during which time husbandry deficiencies
can be addressed. An early assessment of
the client and their commitment is required.
Euthanasia may be recommended for

Figure 15.8 Spinal deformity of the caudal lumbar
spine and tibia and fibula fracture in a central
bearded dragon (Pogona vitticeps) with metabolicbone disease.

patients where there is little chance of success or when dealing with a client who is notdedicated.
Initial Treatment

Warm the patient and provide the preferred
optimal temperature zone for the species toallow the patient to thermoregulate andachieve its preferred body temperature.
Commence nutritional support and give
fluid therapy if required. Analgesia is indicated in most cases as metabolic bone disease is thought to be a painful condition.
If signs of hypocalcaemia, such as tremors,
seizures or tetany, are present, give calcium
gluconate intramuscularly until the signs
have abated. Provide appropriate lighting(see Chapter 6). Once stabilized, oral calcium
supplementation (calcium glubionate) andVitamin D3 should be provided. See
Appendix 1 for dose rates.

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Reptile Medicine and Surgery in Clinical PracticeLong‐term Treatment

Husbandry improvements should be madeto ensure adequate exposure to UVB light(see Chapter 6) and the opportunity to thermoregulate within the species’ preferred
optimal temperature zone. A diet with suitable levels of vitamins D2, D3 and calcium
should be provided. Specific attention should
also be paid to the management of chronic
pain associated with secondary conditions
such as degenerative joint disease.
Prognosis
The prognosis will vary according to thechronicity and severity of clinical signs.
Ideally early identification and treatment ofclinical signs will prevent or at least lessen
bony changes, such as fibrous osteodystrophy
and pathological fractures, paralysis or prolapse carry a graver prognosis. Malocclusion
secondary to fibrous dystrophy may also
occur, leading to dysphagia and weakness.

­Renal Secondary
Hyperparathyroidism
Causes
Causes of renal secondary hyperparathyroidism (RSHP) include dehydration, a high‐protein diet, hypervitaminosis D, toxins andprimary renal disease.
Pathogenesis
In cases of chronic renal insufficiency,
decreased filtration of phosphate occurs,
leading to hyperphosphataemia. In thehealthy animal, parathyroid hormone
promotes renal hydroxylation of 25‐­hydroxycholecalciferol to form calcitriol,
the most active form of vitamin D. However,hyperphosphataemia has a negative effecton hydroxylation in renal tubular cells anddecreases calcitriol production, leading to
RSHP and osteodystrophy.

Diagnosis
A blood calcium to phosphorus ratio ofless than one is a reliable diagnostic indicator of renal disease in reptiles.
Hypoproteinaemia is also a common finding in lizards with metabolic bone disease,particularly green iguanas. Hyperuricaemia
is not commonly observed in reptiles withrenal disease (discussed in Chapter 11).
Differential diagnoses of RSHP include
NSHP, hypertrophic osteopathy andosteomyelitis.
Treatment
Treatment of RSHP is mostly supportive, as
the prognosis is poor in most cases.
Supportive care is instituted as for metabolic bone disease. See Chapter 13 for
information on fluid therapy. Phosphatebinders such as aluminium hydroxide or
calcium carbonate and chitosan may beof some use in helping to control
hyperphosphataemia.
Reptiles with renal disease may present
with concurrent illness such as gut impaction, preovulatory follicular stasis or gout(see Chapter 23 for more detail). The
underlying renal disease may not beapparent initially and the practitioner isadvised to ensure that a diagnostic workup
is performed to detect any concurrent
illness.

­Obesity
Pathogenesis
Obesity is not uncommon in captive reptiles
yet it may go undiagnosed by both veterinarians and owners. Sedentary captive reptiles
are often fed high‐fat diets and are fed too
much and too often, resulting in energy
intake significantly higher than energy
expenditure (Figure 15.9). A thorough clinicalexamination of the patient and evaluation ofNutritional and Metabolic Diseases

Figure 15.9 Obese captive frilled
lizard (Chlamydosaurus kingii).

Figure 15.10 Large intracoelomic fat
pads and hepatic lipidosis in obese
central bearded dragon (Pogona
vitticeps).

the captive diet and clinical history may indicate obvious signs of obesity. Excess intracoelomic fat will typically result in obvious
coelomic distension (Figure 15.10). Someobese reptiles will have excessive fat stores insubcutaneous tissues or internal organs withresultant derangements, such as hepatic lipidosis. Clinical pathology may point towards
organ dysfunction from fatty change andbiopsy of affected organs. Other possible consequences of obesity include dystocia anddecreased lifespan.

Treatment
Treatment of a reptile with obesity centres on
ensuring that the animal is provided with adequate amounts and correct types of feed toenable safe weight loss. This is best undertaken
slowly while monitoring the patient and evaluating clinical parameters. Specific treatment isrequired for any obesity related illnesses, suchas hepatic lipidosis (see Chapter 19).
Prevention is aimed at educating clients
regarding appropriate diets for captive animals and feeding frequency (Figure 15.11).

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Reptile Medicine and Surgery in Clinical Practice

Figure 15.11 Treating an obese reptile is best undertaken by closely monitoring and a diet aimed at providing
slow weight loss (courtesy of Brendan Carmel).

The nutritional requirements and metabolic
rate of an individual reptile will vary, depending on many factors, such as sex, reproductive status, seasonal cycles and the vivarium
environment (temperature gradient, humidity etc.; see Chapter 4 for further details ofnutritional requirements). The effect of brumation, or lack thereof, on nutritional statusof captive reptiles is unknown.
Although there is a lack of specific nutritional requirements for many captive reptiles, some general recommendations can bemade to help to prevent obesity. Regularweighing of the reptile is a simple and effective method of monitoring condition. Some
captive species have average body weights
recorded and these can be consulted. Educate
owners that captive reptiles lead predominantly a sedentary lifestyle, undergoing very
little exercise, and are often fed food items
high in fat. Owners should record the typeand amount of food offered and its frequency
and relate the diet fed to the natural diet ofthe species concerned. Overfeeding may be
prevented in many cases by simply reducing
the feeding frequency; for example, offeringa thawed rat to an adult snake every two to
three weeks rather than weekly. Carnivores
should be fed lean prey, herbivores should be
fed a diet high in fibre and insectivores
should be offered food items low in fat.
For example, mealworm (Tenebrio molitor)

larvae contain a much higher fat content
than the adult mealworm beetle and would
be best avoided or restricted as a food item
for a bearded dragon.
It is not known whether increasing exercise will have a positive effect on an obese
reptile or how practical this would be to initiate. Changing the habitat to encourage natural hunting, such as hiding food items andproviding scent trails to follow, will help to
encourage some reptiles to exercise.

­Hypovitaminosis A
Pathogenesis
Hypovitaminosis A results from a diet lacking in vitamin A precursors/provitamins(carotenoids) and/or vitamin A (retinol, retinal and retinoic acid). It may take many
months for a vitamin A deficiency to develop,
as the liver can store vitamin A for long periods. Vitamin A is involved in many processes,
including maintaining normal epithelial tissue. Hypovitaminosis A is most commonly
seen in aquatic or semi‐aquatic turtles; forexample, the red‐eared slider (Trachemys
scripta elegans) and box turtles (Terrapenespp.), insectivorous reptiles (e.g. chameleons
and geckos), young or reproductively active
female lizards or turtles and crocodilians.

Nutritional and Metabolic Diseases

Herbivorous reptiles can endogenously
synthesize vitamin A from dietary carotenoids. Vitamin A deficiency is uncommon torare in these species, as many plants containhigh amounts of carotenoids. Hypovitaminosis
A would probably only occur if the animal
were anorexic for several months. Vitamin A
deficiency is also uncommon in carnivorous
snakes fed whole prey items.
Clinical signs
Clinical signs can be non‐specific but are typically related to the squamous metaplasia that
occurs as a result of the deficiency, with theHarderian and lacrimal glands often affected.
Classic signs in aquatic turtles and chameleons are swollen and closed eyelids. Other
possible signs include blepharitis, blepharoedema, blepharitis, conjunctivitis, blindness
from retinal damage, nasal discharge and respiratory disease. Nonspecific signs such as
stomatitis, dysecdysis, stunted growth, anorexia and lethargy may also be present.
Diagnosis
Diagnosis is usually achieved by taking agood clinical history and conducting a thorough physical examination. Confirmation
can be difficult, as vitamin A levels cannot be
evaluated via blood sampling. Plasma retinol,
one of the biologically active compounds ofvitamin A, could be of use but interpretation
can be challenging. Liver biopsy may be considered with hepatic vitamin A levels for carnivorous reptiles found to be greater than
1000 iu/g and are likely much less in herbivorous reptiles. Biopsy requires surgery, endoscopy or ultrasound‐guided sampling andmay not be practical in small reptiles.
Response to therapy is often used to confirm
the diagnosis. A full blood screen is advised
to look for underlying issues.

via supplementation for weeks to months.
Any debris acclimated in the conjunctival
sacs is removed and the eyes flushed withsaline. Dose rates for vitamin A are
mostly extrapolated from mammalian studies or from anecdotal reports. Oral supplementation is not necessarily safer as
over‐­supplementation can occur regardlessof the route of administration. Clinicalimprovements can take up to several weeks,
depending on severity (see Hypervitaminosis
A section for toxic effects of overdosing).
Some reported dose rates for vitamin A in
reptiles are given in Appendix 1 in this book.
Prevention
Prevention of hypovitaminosis A centres
around providing an appropriate diet for the
species. Feed carnivorous or omnivorous
reptiles whole prey items such as rodents orwhole fish. Commercial pellets are suitable
for some species, such as aquatic turtle pellets. Invertebrates contain a low amount ofvitamin A, so should be gut loaded anddusted with a supplement that contains vitamin A. Wild‐caught invertebrates can be ofexcellent nutritional value, especially if partof the natural diet of the species. Herbivorous
reptiles are unlikely to be vitamin A deficientif they are fed a broad‐based diet of vegetables, as they are able to synthesize vitamin A
from dietary carotenoids.

­Hypervitaminosis A
CausesHypervitaminosis A is almost always causedby overzealous treatment with vitamin A,
especially parenteral forms, but it can also
occur if excessive amounts of raw liver are fed.

Treatment

Clinical signs

Treatment involves addressing any secondary issues, such as bacterial infections, andcorrecting the vitamin A deficiency, typically

Clinical signs are typically skin lesions,with characteristic flaking of skin, ulceration, blistering or sloughing seen. Secondary

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Reptile Medicine and Surgery in Clinical Practice

infections are common and depression,lethargy, anorexia and dehydration may­
also be seen.
Treatment
Treatment is based on supportive care,treating secondary infections if present,­
providing fluid therapy and assisted feeding
where required, together with analgesia.
Recovery may be prolonged.
Prevention
Prevent by avoiding vitamin A administration unless indicated (by evaluating thediet and patient). Do not give vitamin A athigh doses or for prolonged periods. Notethat herbivorous reptiles are extremely
unlikely to develop hypovitaminosis A
unless they are anorexic for long periods,
so avoid administration of vitamin A tothese species unless a vitamin A deficiency
is confirmed.

­Thiamine Deficiency
Thiamine, or vitamin B1, is a water‐soluble
vitamin part of the B complex required by
all living organisms but only synthesized inbacteria, fungi and plants. All animals must
therefore obtain thiamine from their diet.
Cause
Captive reptiles fed a large percentage ofthawed fish are prone to thiamine deficiency.
A slow thaw will result in a build‐up of thethiaminase. The enzyme is not destroyed by
the freezing process and depletes the thiamine present in the fish. Thiamine deficiency
may also occur in herbivorous reptiles; forexample, if the multivitamin supplement islacking in thiamine, as thiamine is highlylabile and may undergo rapid deterioration if
the supplement is not used in a timely fashion or is stored incorrectly.

Clinical signs
Signs of thiamine deficiency relate to resultant nerve degeneration and neuropathy andtypically include neurological signs suchas tremors, incoordination, opisthotonus
and torticollis. Diagnosis is typically basedon the clinical history and clinical signs.
Confirmation of the disease is via demonstrating the characteristic histopathologicalchanges in the nervous system. Captive species of reptiles more likely to develop thiamine deficiency include semiaquatic turtles
and crocodilians fed primarily a fish diet.
Treatment
Treatment is via administration of thiamine
50–100 mg/kg intramuscularly, subcutaneously or orally once daily or administering avitamin B complex formulation which contains thiamine (Mans and Braun 2014). For
crocodilians, thiamine can be administeredin 30 g/kg of fish orally.

­Postprandial Cardiac
Hypertrophy in Pythons
Oxygen consumption by carnivorous reptiles
increases enormously after they have eaten alarge meal, to meet metabolic demands, andthis places an extra load on the cardiovascularsystem. In the Burmese python (Python molurus) an extraordinarily rapid 40% increasein ventricular muscle mass occurs 48 hours
after feeding, mainly due to increased gene
expression of muscle‐contractile proteins(Andersen 2005).

­Hyperglycaemia in Bearded
Dragons
Persistent hyperglycaemia associated withgastric neuroendocrine carcinoma in bearded
dragons has been reported. Affected lizards
may have a chronic history of anorexia, weightNutritional and Metabolic Diseases

loss, depression and melaena. The neoplastic
cells secrete somatostatin, inhibiting insulin
release, which results in hyperglycaemia.
Coelomic ultrasound may reveal the primary

tumour in the stomach wall and metastases in
the liver. The prognosis is poor and the diagnosis is often only confirmed at necropsy.

References
Hedley, J. (2012a) Metabolic bone disease
in reptiles: part 1. Companion Animal,
17 (6), 52–54.

Mans, C. and Braun, J. (2014) Update oncommon nutritional disorders of captive
reptiles. Veterinary Clinics of North America
Exotic Animals, 17, 369–395.

Further Reading
Andersen, J.B., Rourke, B.C., Caiozzo, V.J. et al.
(2005). Physiology: postprandial cardiac
hypertrophy in pythons. Nature, 434 (7029),
37–38.
Carpenter, J.W. (2012) Exotic Animal
Formulary, 4th ed. Elsevier Saunders,
St Louis, MO.
Divers, S.J. and Cooper, J.E. (2000) Reptile
hepatic lipidosis. Seminars in Avian andExotic Pet Medicine, 9 (3), 153–164.
Frye, F.L. (1991) Common pathologic lesions
and disease processes, in Biomedical andSurgical Aspects of Captive Reptile
Husbandry, 2nd ed. Krieger, Malabar, FL,
pp. 529–617.
Hedley, J. (2012b) Metabolic bone disease in
reptiles: part 2. Companion Animal, 17 (7),38–41.
Lyons, J.A., Newman, S.J., Greenacre, C.B. andDunlap, J. (2010) A gastric neuroendocrine
carcinoma expressing somatostatin in abearded dragon (Pogona vitticeps). Journalof Veterinary Diagnostic Investigation,
22 (2), 316–320.
Mader, D.R. (2006) Metabolic bone diseases, in
Reptile Medicine and Surgery, 2nd ed.
(S.J. Divers and D.R. Mader, eds). Elsevier
Saunders, St Louis, MO, pp. 841–851.
Ritter, J.M., Garner, M.M., Chilton, J.A. et al.
(2009) Gastric neuroendocrine carcinomas
in bearded dragons (Pogona vitticeps).
Veterinary Pathology Online, 200946 (6), 1109–1116.
Simpson, M. (2006) Hepatic lipidosis in a
black‐headed python (Aspiditesmelanocephalus). Veterinary Clinics ofNorth America Exotic Animals, 9, 589–598.
Wright, K.M. and Whitaker, B.R. (2001)
Nutritional disorders, in Amphibian
Medicine and Captive Husbandry(K.M. Wright and B.R. Whitaker, eds)
Krieger, Malabar, FL. pp. 73–87.

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16
Infectious Diseases and Immunology
Tim Hyndman and Rachel E. Marschang­Introduction
The collective knowledge of the infectious
diseases of reptiles has been rapidly expanding in the last few years. Major breakthroughs
have become commonplace. We now findourselves in a golden age of new agent discovery and, as never before, we can detect awide range of infectious agents with extraordinary sensitivity. Despite this, significant
gaps still exist in our knowledge of infectious
agents regarding routes of infection, pathogenicity, pathogenesis, treatment methods
and prognoses. In spite of these limitations,however, several generalizations can still bemade. It should be assumed that husbandry
has played a part in all disease processes in
reptiles. Inadequate husbandry will increase
the susceptibility of reptiles to infection byviruses, bacteria, fungi and parasites. Mixed
infections are commonplace in reptiles andthe clinician should always be hesitant toconclude that a single aetiological agent is toblame for any disease process. The lack ofdetailed knowledge of the biology for manyof these agents makes interpreting test resultsdifficult. For example, a negative test result
for an infectious agent should not be automatically interpreted to mean the animal isuninfected because it is often unknown how
reliably that organism will be present in thepart of the animal that was sampled. This

overview is presented according to the­anatomical location of the primary clinicalcomplaint. Tables 16.1 and 16.2 provide
summaries of the infectious diseases coveredin this section and also serve to direct thereader to the relevant section of text.

­Upper Respiratory Tract
Rhinitis and upper respiratory tract illness
is most commonly seen in chelonians. In
tortoises,
mycoplasma,particularly
Mycoplasma agassizii, is one of the mostimportant causes of upper respiratory tract
disease. Infected animals can develop palpebral oedema, ­conjunctivitis and rhinitis,
although subclinical infections are also frequently reported. Infected animals remain
persistently infected and may experience
periods of recurring disease. These animals
can shed mycoplasma, especially when they
have nasal discharge (Figure 16.1).
Mycoplasma have been repeatedly detected
in aquatic turtles and sporadically reported
in squamate reptiles, although their association with disease in those animals is not wellunderstood. Testing for mycoplasma in chelonians is generally via polymerase chain
reaction (PCR) using nasal lavages or oralswabs. In tortoises, detection of antibodies
by enzyme‐linked immunosorbent assay

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

Table 16.1 List of infectious agents mentioned in this chapter and clinically relevant information.1
Diagnostic test
System mostcommonly affected2

Treatment

Pathogenicity3

Infectivity4

Live animal

Serology5

Alimentary, liver >lower respiratory >neurological0, +1, +++, ++PCR: cloacal
swab

Virus
PCR: intestine,
neutralization liver

Neurological, >lower respiratory,
upper
alimentary > skin,liver, blood

1

0, + , ++, +++Neurological, >upper alimentary+, ++1

Erythrocytic
necrosis

Blood: > systemic

1

Ferlavirus8

Infectious agent

Dead animal6

Environment7

Host

Other
considerations

Difficult

None–

RoutineNone–

Viruses:
Adenovirus

Histology: liver,intestine
PCR:
oesophageal
swab, whole
blood. Direct
examination or
IHC of whole
blood/buffy coat
smear

None

++

PCR: oral‐cloacal swab

None

PCR: brain

RoutineNone–0, + , ++0

Cytology: bloodsmear
PCR: blood

None

Histopathology,
PCR: blood,
liver

RoutineNone (increase
ambient
temperature)

Probablytransmitted byarthropods

Lower respiratory >neurological0, +, ++1, ++++++PCR: lung wash,oral‐cloacal
swab

HI

PCR: lung > gut,
liver, kidney,
brain

RoutineNone–

Herpesvirus

Upper alimentary,
upper respiratory >skin/shell, liver,neurological0, +, ++, +++*++

PCR: oral swab,
lesions

PCR: tongue,Virus
neutralization liver, brain,(some strains) lesions

RoutineAciclovir,
ganciclovir,
supportive
therapy

Infectivity
dependent onhost species andvirus strain;causes latent
infections

Invertebrate
iridoviruses

Skin0*, +, ++0, +PCR: skin biopsy None

RoutineNone–

Arenavirus/
inclusion bodydiseaseBornavirus+

PCR:
brain > liver,kidneyHistology:
brain > liver,kidneyPCR: skin, liverDiagnostic test
Infectious agent

System mostcommonly affected2

Nidovirus/
coronavirus

Lower respiratory >upper alimentary+, ++*, +++Picornavirus9

Skin/shell, upper
respiratory, kidney

Poxvirus

Treatment
Dead animal

Environment7

Host

Other
considerations

PCR: lungRoutine

None

–

Virus
PCR and/or
neutralization virus isolation:
tongue,oesophagus,
intestine,
trachea > othertissues

Difficult

None–

Cytology, PCR:
skin

None

Histopathology,
PCR: skinRoutineNone–++, +++

PCR: oral swab,
blood

None

PCR: liver,intestine,
kidney, skinRoutineNone, increase
ambient
temperature–?

PCR: oral‐cloacal swab

Virus
PCR: lung, gut,
neutralization kidney > brain

Difficult

None–

Neurological > lower 0, +, ++*, +++respiratory, upper
alimentary, skin,
blood

++

PCR: oral‐cloacal swab

None

PCR:
brain > kidney,lung

RoutineNone–

Skin, blood

0*, +, ++, ++++PCR: Blood

ELISA

PCR: blood

RoutineNone

Arbovirus,
highlypathogenic incrocodilians,
zoonotic

Lower respiratory,
liver > heart+*, ++?

PCR: tracheal
wash, lesions

None

PCR: lesions,lung, liver

RoutineSystemic
antibiotics

Some species
are zoonotic

Pathogenicity

3

Infectivity

4

Live animal

Serology++

PCR: lung wash,oral‐cloacal
swab

None

0, +, ++*, +++++PCR and/or
virus isolation:oral swab

Skin+*, ++*+, ++Ranavirus

Upper respiratory,
upper alimentary,
liver, skin

0, +, ++*, +++Reovirus

Lower
respiratory > upper
alimentary,alimentary, liver,neurological0, +*, ++SunshinevirusWest Nile virus

5

6Bacteria:
Chlamydia(Continued )Table 16.1 (Continued)
Diagnostic test

Treatment

System mostcommonly affected2

Pathogenicity3

Infectivity4

Live animal

Serology5

Dead animal6

Environment7

Host

Devriesea
agamarum

Skin > systemic

0, +*, +++Culture: skinscrapings, oral
swabs

ELISA

Culture: skinRoutineCeftiofur 5 mg/kg –IM for at least
12 days

Mycobacterium

Lower respiratory,
liver > skin/shell,
spleen,neurological > allother systems

0, +*, ++, +++0, +PCR, culture,cytology with
acid‐fast
staining: lesions

None

PCR, culture,
histopathology
with acid‐faststaining: lesions

Difficult

None–

Mycoplasma

Upperrespiratory > lower
respiratory

0, +, ++*+, ++*

PCR: nasal
lavage > oral
swab

ELISA

Nasal cavity

RoutineSystemic andlocal (nasal flush)
antibiotics(especiallyfluoroquinolones(enrofloxacin),macrolides(clarithromycin)
andtetracyclines);
increased
ambient
temperature

Animals canremainpersistently
infected despite
therapy+, +++Culture,cytology, PCR:
oral‐cloacal
swabs, liverbiopsyNone

Histology,
culture, PCR:
material fromlesions

RoutineNystatin,terbinafine–

Infectious agent

Otherconsiderations

Fungi:
Chamaeleomyces Liver, upper
granulomatis
alimentary, skin,systemicDiagnostic test

Treatment

System mostcommonly affected2

Pathogenicity

Infectivity

Live animal

Serology

Dead animal

Environment7

Host

Other
considerations

Nannizziopsis
spp./ yellow
fungus disease

Skin, liver+, ++*, +++++Cytology,
culture, PCR:
skin scrapings,
skin biopsy

None

Histopathology,
culture, PCR:skin

RoutineVoriconazole–

Ophidiomyces
ophiodiicola

Skin++, +++++

Cytology,
culture, PCR:
skin scrapings,
skin biopsy

None

Histopathology,
culture, PCR:skin

RoutineTreatment as for
Nannizziopsis
spp. can beattempted–

Yeasts (Candida
spp.)

Alimentary0, +, ++

0, +Culture: cloacal
swabs, faeces

None

Culture:intestine(interpretation
with associatedhistology)

RoutineNystatin,probiotics

Common in theenvironment
and ascommensals

Acanthamoeba(protozoan)

Neurological,
alimentary

0*, ++++

Faecal exam:
unstained,
iodine stained

None

Histopathology:
brain

Steam, heat

Treatment as for
Entamoeba
invadens can beattempted. No
standard
treatment
reported

Intestinal forms
non‐pathogenic;
neurologicalform only
detectable post
mortemCholeoimeria
spp. (protozoan)

Liver+, ++*++

Floatation:
faecesNone

Histopathology:
liver

Difficult–Some success
reported withtoltrazuril in
combination withclindamycin over
several days

Coccidia (e.g.
Isospora spp.)(protozoan)

Alimentary0, +*, ++++Microscopy,Nonefloatation: faeces

Microscopy,
floatation:
intestinal
content

Difficult

Toltrazuril,
hygieneInfectious agent

3

4

5

6

Parasites:–(Continued )Table 16.1 (Continued)
Diagnostic test

Treatment

System mostcommonly affected2

Pathogenicity

Infectivity

Live animal

Serology

Dead animal

Environment7

Host

Cryptosporidium
spp. (protozoan)

Alimentary++*, +++++PCR (andsequencing),
microscopy,
ELISA: faeces,
gastric lavage(snakes), slime
from surface ofregurgitatedfood items(snakes)

None

Histopathology,
PCR (andsequencing):
stomach(snakes),
intestine(lizards)

Difficult

Paromomycin,
hygieneTreatment does
not eliminate
the organism

Entamoeba
invadens(protozoan)

Alimentary > liver,kidney+, ++, +++*++

Microscopy,
iodine staining:
faecesNone

Histopathology:
intestine

Steam, heat

Metronidazole,paromomycin,
increased
ambient
temperature,
hygiene–Hexamita parva(protozoan)

Kidney < alimentary

0*, +, ++, +++++Microscopy:
faeces, urine

None

Histopathology:
kidneyRoutineMetronidazole–

Intranuclear
coccidiosis of
tortoises(protozoan)

Alimentary, upper
respiratory, liver, allother systems+, ++*, +++++PCR: nasal
lavage, oral‐cloacal swab

None

PCR: Intestine,
liver, kidney,pancreas >other tissues

Difficult

Toltrazuril,
increased
ambient
temperature–

Ophionyssus
natricis (mite)

Skin

+, ++

+++

Visualization on
skin

None

Visualization on
skin

Difficult

Ivermectin,
fipronil,pyrethroid

Environmental
treatment isessential

Oxyurids(nematode)

Alimentary

0*, +, ++++Faecalexamination,
floatation

None

Microscopy:
intestinal
content

DifficultFenbendazole,
hygienePentastomid(arthropod)

Lower
respiratory > skin

0*, +, ++, +++0Endoscopy,
radiography,
faecalexamination

None

Histopathology:
lung, gut, skinnodulesRoutinePhysical removal,
macrocyclic
lactoneSome species
are zoonotic.
Drug treatment
can sometimes
cause more
harm than good
due to therelease of
antigens fromkilled adultpentastomids

Strongylids, e.g.
Kalicephalus
spp. (nematode)

Alimentary0, +*, ++++Faecalexamination,
floatation

None

DifficultFenbendazole,
hygiene–Spirometra(tapeworm)

Liver, skin,alimentary

0, +*

0

Faecalexamination,
floatation, skin

None

DifficultPraziquantel andsurgical removalof skin nodules–

Infectious agent

3

4

5

6

Microscopy:
intestinal
content andOtherconsiderations

food items(snakes)1

Entamoeba
invadens(protozoan)

Alimentary > liver,kidney+, ++, +++*++

Microscopy,
iodine staining:
faecesNone

Histopathology:
intestine

Steam, heat

Metronidazole,paromomycin,
increased
ambient
temperature,
hygiene–Hexamita parva(protozoan)

Kidney < alimentary

0*, +, ++, +++++Microscopy:
faeces, urine

None

Histopathology:
kidneyRoutineMetronidazole–

Intranuclear
coccidiosis of
tortoises(protozoan)

Alimentary, upper
respiratory, liver, allother systems+, ++*, +++++PCR: nasal
lavage, oral‐cloacal swab

None

PCR: Intestine,
liver, kidney,pancreas >other tissues

Difficult

Toltrazuril,
increased
ambient
temperature–

Ophionyssus
natricis (mite)

Skin

+, ++

+++

Visualization on
skin

None

Visualization on
skin

Difficult

Ivermectin,
fipronil,pyrethroid

Environmental
treatment isessential

Oxyurids(nematode)

Alimentary

0*, +, ++++Faecalexamination,
floatation

None

Microscopy:
intestinal
content

DifficultFenbendazole,
hygienePentastomid(arthropod)

Lower
respiratory > skin

0*, +, ++, +++0Endoscopy,
radiography,
faecalexamination

None

Histopathology:
lung, gut, skinnodulesRoutinePhysical removal,
macrocyclic
lactoneSome species
are zoonotic.
Drug treatment
can sometimes
cause more
harm than good
due to therelease of
antigens fromkilled adultpentastomids

Strongylids, e.g.
Kalicephalus
spp. (nematode)

Alimentary0, +*, ++++Faecalexamination,
floatation

None

DifficultFenbendazole,
hygiene–Spirometra(tapeworm)

Liver, skin,alimentary

0, +*

0

Faecalexamination,
floatation, skin
swellings

None

DifficultPraziquantel andsurgical removalof skin nodules–

Microscopy:
intestinal
content andskin swelling

Controlled studies do not exist to support or refute much of this information. In these situations, the information provided has been based on anecdotal accounts or has been extrapolated
from first principles knowledge of the biology of these infectious agents.
System(s) most commonly affected; section of chapter to consult.
3
Most common presentation: 0 subclinical, + mild, ++ moderate, +++ severe, * most common.
4
Infectivity to conspecifics in captive environment: 0 non‐infectious,? unknown, + low, ++ moderate, +++ high.
5
Sample is always plasma or serum. Many of these serological tests are not widely available.
6
Test for agent in dead animal; priority samples. A complete set of samples should be collected from all necropsies but extra attention should be paid to the organs listed.
7
Routine treatment: household disinfectants; difficult: specialized disinfectants (Virkon, F10, bleach)
8
Formerly ophidian paramyxovirus.
9‘Topivirus’, virus ‘x’).
ELISA, enzyme‐linked immunosorbent assay; HI, haemagglutination inhibition; IHC, immunohistochemistry; IM, intramuscularly.
2

Table 16.2 Agents most commonly implicated as primary disease of each system in chelonians, lizards and snakes.1

1

System affected

ChelonianLizardSnake

Upper respiratory tract (rhinitis)

Mycoplasma, TINC,
herpesvirus–

Nidovirus

Lower respiratory tract (pneumonia)––

Ferlavirus, nidovirus, arenavirus/IBD, pentastomids

Upper alimentary tract (glossitis andstomatitis)

Herpesvirus, ranavirus

Chamaeleomyces

Nidovirus, arenavirus/inclusion body disease

Alimentary tract (obstipation,
diarrhoea, vomiting, regurgitation)–

Adenovirus, coccidia,
cryptosporidia

Entamoeba invadens, strongylids

Liver

Herpesvirus, ranavirus

Adenovirus, choleoeimeria

Arenavirus/IBD

Neurological system

Herpesvirus

Adenovirus

Arenavirus/IBD, bornavirus, Sunshinevirus, ferlavirus

Skin/shell

Herpesvirus, picornavirus

Nannizziopsis spp., Devriesea
agamarum, mites

Ophionyssus natricis, Ophidiomyces ophiodiicola

Kidney/urinary tract

Picornavirus, Hexamita
parva

–

–

Blood

–

–

Arenavirus/IBD

Summaries of each agent are presented in Table 16.1. Secondary and tertiary causes of diseases, such as most bacterial and fungal infections, are not included in this table but
will still often need to be treated.
IBD, inclusion body disease.

Infectious Diseases and Immunology­Lower Respiratory Tract

Figure 16.1 A spur‐thighed tortoise (Testudo graeca)
with nasal discharge indicative of rhinitis. This isoften caused by infections with mycoplasma in
tortoises but can also be associated withpicornavirus or herpesvirus infections, as well as
intranuclear coccidia.

(ELISA) can be helpful in detecting persistently infected animals (see Chapter 11).
Ranaviruses have also been associated withrhinitis in tortoises but these viruses canalso infect other reptiles, including aquatic
turtles and various species of squamate reptiles. Ranavirus‐infected animals may beanorectic and lethargic and may develop
conjunctivitis, stomatitis, hepatitis, enteritis
and pneumonia. Ranaviruses can be transmitted between reptile species and families,
and even between reptiles, amphibians andfish. In live animals, ranavirus infections
are generally diagnosed by testing oral swabs
by PCR. In box turtles, blood can be usedfor virus detection. Picornaviruses have also
been described as a possible cause of rhinitis in tortoises (see Skin/Shell Disease).
Herpesviruses have been known to cause
rhinitis in tortoises (see Upper Alimentary
Tract Disease). Intranuclear coccidia havebeen described as a cause of rhinitis invarious tortoise species (see Alimentary­
Tract Disease). A multitude of different­bacteria can be involved in upper respiratory tract disease in reptiles. In general,these are involved in multifactorial disease
processes.

The infectious causes of lower respiratory
tract disease seen in reptile practice include
viruses, bacteria, fungi and parasites. Diseaseof this system is common in all reptile
species.
Ferlaviruses were previously reported in
the literature as ‘reptilian’ or ‘ophidian’ paramyxoviruses. Ferlaviruses are seen far morecommonly in snakes than lizards and chelonians. Clinically, infection can be characterized by dyspnoea, sometimes with open‐mouth
breathing, and oral secretions that are sometimes bloody (Figure 16.2). Nonrespiratory
signs of disease, such as neurological signs,
are also seen. It should be assumed that thevirus can be transmitted from one snake toanother through aerosols, so individual caging in the same room is not expected toform a barrier to infection. Current testingfor this virus is through serology and PCR.
Serological testing on a single blood sample
can only inform on exposure to the virus.
PCR testing on lung washes or combinedoral–cloacal swabs is recommended. A positive result confirms the presence of infection
and it should be assumed that clinicallyaffected animals will not recover from infection and represent a source of infection forother animals.
Reoviruses have been detected in reptiles,
mainly snakes and lizards, with respiratory
disease but also in the presence of nonrespiratory clinical signs such as glossitis,
papillomas, sudden death, enteropathy,­
hepatopathy and neurological disease. Theseviruses have also been detected in theabsence of any clinical disease. Testing combined oral–cloacal swabs for these viruses by
PCR is recommended.
In 2014, a novel nidovirus in the coronavirus family was detected. The virus was
detected in the lungs of ball pythons (Python
regius) with severe respiratory disease.
Closely related viruses were subsequently
detected in similarly affected snakes (manywith stomatitis) in Europe and early indications suggest the virus is relatively common.

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Reptile Medicine and Surgery in Clinical Practice

Figure 16.2 This ball python (Python
regius) was infected with a ferlavirus
and had small amounts of bloody
mucous in the oral cavity as well as
hyperaemia of the oral mucous
membranes.

Transmission is expected to be through aerosols. PCR testing of pulmonary washes andoral swabs is recommended (Figure 16.3).
Inclusion body disease (IBD), which isprobably caused by arenaviruses, has been
associated with respiratory disease in snakes,
as has sunshinevirus. These two viruses arecovered in more detail in the section on neurological disease.
The vast majority of bacteria recoveredfrom respiratory samples in animals with respiratory disease will either be commensals,
playing no part in the disease process of thatanimal, or secondary pathogens. Two bacteriathat can act as primary respiratory p­ athogens
are worth mentioning, however. Chlamydia
and mycobacteria have been associated with
granulomatous disease in a number of tissues
in a variety of reptile species. It is recommended that testing for these two agents isdone using PCR and sequencing, especiallyconsidering that certain species are zoonotic.
Pentastomids are arthropods with worm‐
like or leech‐like appearances. These parasites can create severe damage to the lungs
and some species are zoonotic (Chapter 31).

Figure 16.3 Tracheal washes can beused for the detection of manydifferent pathogens of the lower
respiratory tract. Tracheal wash fluid isoften cloudy or flocculated in animals
with lower respiratory tract infections.
Fluid can be examined microscopicallyfor cells, bacteria and fungi, can beused for isolation of bacteria and fungiand can be used for detection ofvarious viruses, including ferlavirus
and nidovirus.

Infectious Diseases and Immunology­Upper Alimentary Tract
Various severities of stomatitis are regularly
observed in reptiles, especially tortoises, inassociation with various infectious diseases.
Herpesvirus infections are frequently associated with severe, necrotizing stomatitis andglossitis, especially in tortoises (Figure 16.4).
Affected tortoises are generally lethargic andanorectic. Chronically infected animals may
also develop neurological signs and the upperand lower respiratory tracts, the alimentarytract and the liver may all be affected. The
severity of disease, morbidity, and mortality
depend on both the tortoise species and thevirus strain. Diagnosis of acute infections
should be by virus detection methods. PCRof oral swabs with material from the baseof the tongue is recommended. Serologicaltesting has also been described for sometortoise herpesviruses. Tortoise species thatare resistant to disease, such as spur‐thighed
tortoises (Testudo graeca), are more likely
to develop detectable antibody titres.
Herpesviruses cause persistent latent infections and so any animal that survives infection or has antibodies against a herpesvirus
must be considered a carrier. Herpesvirus

infections with similar clinical signs have also
been infrequently described in various lizard
species. Reoviruses have also been described
as a cause of stomatitis in tortoises and canalso be diagnosed by virus detection (isolation in cell culture or PCR) from oral swabs.
For more information, see the section on
lower respiratory tract disease. Ranaviruseshave been described in association withupper alimentary tract disease, mostly in turtles and tortoises but also in squamates. In
animals with stomatitis, oral swabs can also
be used for diagnosis. For more information,
see the section on upper respiratory tract
disease. In boas and pythons, IBD is frequently associated with a therapy resistantstomatitis, especially in boas. For more
information on IBD and arenavirus infections, see the section on neurological disease.
Nidoviruses have been described as a causeof pneumonia in pythons. A number ofaffected animals have also had stomatitis (seeLower Respiratory Tract section).
Multiple bacteria have been associatedwith upper digestive tract disease in various
reptiles but most of these must be consideredfacultative pathogens that can belong to thenormal flora of reptiles.

­Lower Alimentary Tract

Figure 16.4 A Hermann’s tortoise (Testudo
hermanni) with sever diphtheroid‐necrotizing
glossitis as a result of a herpesvirus infection.

Multiple infectious agents have been associated with various signs of alimentary tract
disease (obstipation, diarrhoea, vomiting andregurgitation). While various parasites are
particularly important in diseases of this system, a number of viruses, fungi and bacteria
have also been associated with disease.
Adenoviruses are most commonly found inlizards and snakes. Bearded dragons appear
to be frequently infected. These viruses aremostly found in the liver and intestine of
infected animals, where they can cause
necrosis. Clinical signs associated with infection are variable and range from lethargy,
anorexia, failure to thrive and wasting to neurological signs such as head tilt, opisthotonus
and circling, as well as pneumonia, stomatitis

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Reptile Medicine and Surgery in Clinical Practiceand dermatitis. Chelonians have been
increasingly reported with adenovirus infections. In this host, there appears to be a strong
correlation between the genera of adenovirus
and the clinical signs. Consequently, infectedchelonians may be asymptomatic or they may
be affected by severe disease with high rates
of mortality. Testing cloacal swabs by PCR
is the preferred method.
Bacterial and fungal infections of thealimentary tract can be very difficult to­diagnose since the normal flora in reptiles
can include multiple potential pathogens.
Malnutrition, particularly a diet high infruits, can result in dysbioses, such as yeast
proliferations, that can lead to diarrhoea.
This is most common in tortoises.
Multiple protozoal infections of the gastrointestinal tract have been described, someassociated with severe clinical disease, whilein other cases the infected animals may beclinically healthy. Many flagellates (e.g. trypanosomes, trichomonas, tritrichomonas andhexamita) are commonly detected in reptiles
and are only associated with disease in thecase of high parasite burdens or as secondary
causes of disease.
Infections with the protozoan Entamoeba
invadens have mostly been described in association with clinical disease in snakes andcarnivorous lizards, while infections in herbivorous tortoises are often incidental. Mixing
species in collections can lead to transmission
and severe disease, and even death, in susceptible species. Clinical signs include anorexia,
wasting, dysentery with mucus or blood in
the faeces, vomiting and a firm swelling of the
body from large intestine inflammation. E.
invadens can also affect the liver and kidney.
Affected animals often die relatively shortly
after clinical signs are observed. Infection is via
oral ingestion of cysts, which are resistant toinactivation or disinfection in the environment. Diagnosis is by direct examination of
faeces and may be aided by iodine staining.
Detection in necropsy tissues of affected animals is more reliable.
Coccidia (e.g. Isospora spp.) are often aproblem in lizards in captivity. These have a
direct lifecycle and can lead to high parasiteburdens with corresponding clinical disease,particularly diarrhoea and anorexia.
Diagnosis is by detection of oocytes in faecal
material via floatation.
Intranuclear coccidia (tortoise intranuclear coccidiosis) is an important cause of
disease in tortoises and box turtles and areassociated with significant morbidity andmortality. Clinical signs associated with
infection can include rhinitis, lethargy, wasting, dyspnoea and, in some cases, skinlesions. Tortoise intranuclear coccidiosis canbe diagnosed by PCR and is most commonly
found in the intestine, pancreas, liver andkidney. In live animals, it can be detected incloacal swabs and nasal lavages.
Cryptosporidiosis,
causedby
Cryptosporidium serpentis and C. saurophilum, is an important cause of gastrointestinal
disease in lizards and snakes. C. saurophilum
causes an intestinal infection in lizards, leading to anorexia, wasting, lethargy, and deathand has most often been described in leopard
geckos. C. serpentis infection in snakes is
associated with gastric dysplasia or hyperplasia with swelling of the stomach region of thebody, regurgitation, and wasting. Diagnosis isby direct examination (with acid‐fast staining), ELISA or PCR of faeces, mucous fromregurgitated food items, gastric lavages or
gastric biopsies. Since most methods candetect a range of cryptosporidia, including
those of prey mammals, it is important to
identify the cryptosporidium species, which
is best done by sequencing PCR products.
There are many nematode parasites that
can infect reptiles including strongylids, oxyurids and ascarids. Most will only cause disease of the alimentary tract when highnumbers are present. Clinical disease generally includes anorexia and weight loss (seeChapter 31).

­Liver Disease
Liver disease is relatively common in reptiles
with many infectious agents, including
viruses, bacteria, fungi and parasites capableof infecting the liver. Adenoviruses can cause

Infectious Diseases and Immunology

liver damage and often also affect the alimentary tract. These are described in more detailin the section on the lower alimentary tract.
Herpesviruses also commonly affect the liver,
especially in aquatic turtles (see the section
on the upper alimentary tract for details).
The liver is one of the tissues most often
infected by ranaviruses in many different
reptile species. For more details see the section on the upper respiratory tract. In
pythons, and especially boas, IBD is often
associated with inclusions in hepatocytes,
although these inclusions have not been
associated with a specific pathology. IBD is
discussed in more detail in the section onneurological disease.
Many bacteria have been detected in association with liver pathology. In general, theseare facultative pathogens that can often
belong to the normal bacterial flora of theseanimals and cause liver pathology following
immune suppression or sepsis. Chlamydia(see Lower Respiratory Tract section) andvarious fungi have also been associated with
granulomatous lesions in the liver, including
members of the family Onygenaceae (e.g.
Nanniziiopsis spp., see section on skin andshell disease for more information). The fungus Chamaeleomyces granulomatis has beenreported in association with liver lesions inchameleons in several cases and can be diagnosed in oral and cloacal swabs and liverbiopsies by cultivation, PCR and cytology.
Multiple protozoan parasites can infectand damage the liver. The main text on thesecan be found in the section on the lower alimentary tract. In many cases, very high numbers of protozoa in the alimentary tract canlead to dissemination of these parasites into
the liver. Entamoebae can also infect the liver,as can intranuclear coccidia in chelonians(see Chapter 19). Choloeimeria spp. are coccidian parasites with a direct lifecycle that
can infect the bile ducts of lizards and snakes.
Infection can lead to bile duct obstruction
and hepatomegaly. Affected animals may beanorectic and lethargic and infection canlead to death of the animal. Diagnosis is via
detection of sporulated oocysts in faeces(floatation). Helminths (e.g. the spargana of

Spirometra tapeworms) and nematodes that
wander through the body can also affect theliver and cause damage.

­Neurological Disease
A number of infectious agents have been
associated with neurological disease in reptiles, most of which are described in snakes. It
must be stressed that for many of these neurological diseases, negative results of live‐animal testing using minimally invasive samples,such as oral–cloacal swabs, can be misleading, as the agent will often be localized to thenervous system. This stresses the importanceof collecting fresh samples from the nervous
system during necropsy that are suitable formolecular testing, not just formalin‐fixed tissues for histological examination.
IBD is an enigmatic disease that has been
described in snakes and has neurologicalsigns as its most common presentation.
Traditionally, it has been diagnosed following
the histological detection of numerous large
intracytoplasmic eosinophilic inclusion bodies in a number of tissues (Figure 16.5).
Following the groundbreaking work by
Stenglein et al. (2012), it is now strongly suspected that arenaviruses cause this disease.
However, it is still unknown what factors drive
an arenaviral infection into a case of IBD,
whether other agents can cause IBD and what
factors are necessary for IBD to manifest itself
into clinically detectable disease. IBD is foundin pythons and boas and, anecdotally, pythons
tend to develop clinical disease faster thanboas. Testing oesophageal swabs and whole
blood for arenavirus by PCR is probably thebest test but cytological evaluation of blood orbuffy coat smears is also valuable. Submitting
oesophageal swabs for cytological examination and collecting liver biopsies for histological evaluation can also be considered. In live
animals, the detection of arenavirus and inclusions is occurring more commonly in boas
than pythons. It is recommended the clinician
consults the most current literature on thisdisease, as new knowledge may suggest alternative testing recommendations.

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Reptile Medicine and Surgery in Clinical Practice

Figure 16.5 Multiple eosinophilic
intracytoplasmic inclusion bodies in
the pancreas of a boa constrictor withinclusion body disease (haematoxylin
and eosin stain, 1000×; courtesy Kim
Heckers, Laboklin).

Figure 16.6 A jungle carpet python(Morelia spilota cheynei) with abnormal
mouth gaping and incoordination,
which could have been infected witha range of neurological infectious
agents; for example, arenavirus/
inclusion body disease, ferlavirus or,in this particular case, sunshinevirus(courtesy of Bob Doneley).

In 2012, a novel paramyxo‐like virus was
described in Australian pythons, which wereprimarily affected with neurological signs,
but respiratory signs and non‐specific signsof disease, such as lethargy and regurgitation,
were also seen (Figure 16.6). The virus wasnamed sunshinevirus after the geographicalorigin of the first isolate. It has been detected
in a wide range of python species. Verticaltransmission has been demonstrated andchronically infected animals have also been
identified. Testing of combined oral–cloacal
swabs by PCR is recommended.

The role of reptilian bornaviruses had been
undefined for many years but, in Australia, anumber of neurologically affected pythons
have been found to be infected with highly
divergent bornaviruses, many with neurohistopathology that is consistent with bornavirus infection in other species. Testing of
combined oral–cloacal swabs by PCR is recommended. It is expected that this infection
will become more significant as more information is obtained.
Ferlaviruses, adenoviruses and reoviruseshave all been associated with neurologicalInfectious Diseases and Immunology

disease in reptiles, mostly snakes, and aredescribed in more detail elsewhere in thischapter.
Bacterial infections of the neurological­system are occasionally seen. Spinal osteopathies of bacterial origin (often secondary
to skin trauma) can manifest as paresis andfollowing sepsis, brain abscessation canoccur. Also, multisystemic granulomatous
disease (e.g. mycobacterium) can invade thecentral nervous system.
Parasitic causes of neurological disease
include acanthamoebic meningoencephalitis
and toxoplasmosis. It is suspected that acanthamoeba infections originate from water
bowls and live animal testing for this parasite
is very difficult, as infection is usually localized to the nervous system.

­Skin and Shell Diseases
A number of related fungi have increasingly
been shown to be important primary pathogens in squamate reptiles. First describedas the Chrysosporium anamorph of
Nannizziopsis vriesii in bearded dragons,
similar pathogens have now been found in
multiple species of lizards, including bearded
dragons, iguanas, geckos and chameleons.
Related fungi (Ophidiomyces ophidiodiicola)
are considered an emerging pathogen insnakes causing severe disease and mortality
in wild snakes in North America. Similar
pathogens have also been described in crocodilians. Disease in bearded dragons has beencalled yellow fungus disease. Lesions consisting of yellow to brown crusts are often foundon the head, but can also be found on otherparts of the body, and infected animals candevelop systemic disease. Diagnosis is by PCRor isolation of fungi using skin scrapings orbiopsies as samples. Cytological or histological detection of fungi is also used diagnostically but this cannot identify the fungus to thelevel of species. Other fungi have also been
described in association with skin lesions in
reptiles, but are often secondary pathogens.
Without cytological or histological evidenceof tissue invasion or active inflammatory
responses to the fungi, the role of any detectedfungi will remain speculative.
Picornaviruses have been associated withsoftening of the carapace in young tortoises,
especially spur‐thighed tortoises (Testudo
graeca), probably as a result of kidney damage. Adult tortoises may be inapparent carriers or may develop various clinical signs,
including rhinitis and ascites. Persistent
carriers are common. Diagnosis is by virus
isolation or PCR detection using oral swabs.
Antibodies can be detected by virus neutralization tests.
Other viruses have also been associatedwith skin lesions in reptiles, including ranaviruses in lizards (Figure 16.7; see Upper
Respiratory Tract section). Invertebrate iridoviruses, found commonly in insects sold as
food items in the pet trade, have also been
associated with skin lesions in insectivorous
lizards in some cases. Papilloma‐like lesions
have been repeatedly described in various
reptile species and have been associatedwith papilloma‐like, reo‐like and herpes‐likeviruses. Diagnosis is generally by skin biopsies and electron microscopic detection ofvirus. In sea turtles, herpesviruses have been
associated with fibropapillomatosis and thisis a cause of severe disease in several species
throughout the world. Diagnosis in thesecases is possible via PCR using tissue lesions.
In crocodilians, poxviruses and herpesviruses have been associated with skin lesions
in various species and can be diagnosed byhistology or PCR using skin scrapings fromlesions. West Nile virus has also been associated with skin lesions in infected alligators.
This virus can also cause systemic disease
and death in crocodilians and is zoonotic.
Many different bacteria have been associated with skin lesions in reptiles, mostly
associated with poor hygiene and other husbandry issues. Examples include ulcerative
shell disease of chelonians such as septicaemic cutaneous ulcerative disease in freshwater turtles. The bacteria that are involved
are often secondary pathogens, and culture
and sensitivity can help to guide treatment.

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Reptile Medicine and Surgery in Clinical Practice

(a)

(b)

(c)

Figure 16.7 Skin alterations observed in ranavirus‐infected green anoles (Anolis carolinensis; Stöhr et al. 2013).

The bacterium Devriesea agamarum has
been shown to be a primary pathogen causing skin lesions (primarily around the mouth)
and in some cases systemic disease and deathin agamid lizards, particularly Uromasytx
species. Other reptile species (e.g. bearded
dragons) can carry the bacterium as part oftheir normal oral flora. Diagnosis is by isolation from skin swabs or scrapings and fromoral swabs.
Numerous ectoparasites can affect reptiles
and severe infestations can cause dermatitis.
Haematophagous parasites can also weaken
the animals, if they are present in large numbers. Mites are common in captive reptiles.
The most common mite is the snake mite,

Ophionyssus natricis, which can infest lizards
as well as snakes (see Chapter 31 for details).

­Kidney and Urinary
Tract Disease
Many infectious diseases of the kidney associated with bacterial infections have been
described. These are generally secondary toother issues that either directly affect kidney
function or the immune system of the affectedanimal. Picornaviruses in tortoises are believed
to cause primary kidney disease, leading tovarious clinical signs including softening of thecarapace in young animals (see Skin and Shell

Infectious Diseases and Immunology

Diseases). The flagellate Hexamita parva generally infects the gastrointestinal tract of chelonians without causing disease but, in young
and immunocompromised animals, it can
infect the kidney and cause nephritis anddeath. Detection of h
­ examites in faecal material is not necessarily indicative of kidney
infection, and detection in urine, which can beslimy, should be attempted.

­Blood Disease
Multiple infectious agents can cause inclusion body formation in blood cells and somecan cause disease, including anaemia. Viruses
known to cause inclusion bodies in erythrocytes include iridoviruses such as erythrocytic necrosis virus. These have most often
been described in wild‐caught reptiles in various parts of the world. Infections can cause
anaemia and systemic disease in animals kept
at suboptimal temperatures. Diagnosis is byvisualization of inclusions in peripheral red
blood cells followed by PCR to specifically
identify the virus. IBD and sunshinevirus
have also been shown to cause inclusions inerythrocytes and leucocytes of infectedsnakes, particularly boas (see Neurological
Disease).
A number of endoparasites are capable ofinfecting erythrocytes, including trypanosomes and haemogregarines (e.g. Hepatozoonspp.).These generally require an invertebratevector for transmission and are therefore
found mostly in wild‐caught reptiles. Diagnosis
is by microscopic examination of stained bloodsmears.

­Formulating a Plan
The biology of an infectious agent needs to becarefully considered once it has been definitively detected in a reptile. Several factors
should be considered: pathogenicity, infectivity, host treatment, environmental treatment
and other miscellaneous considerations.

Underlying the response to every diagnosis of
an infectious agent should be a review of thehusbandry of the animal(s) and, as mentioned
earlier in this chapter, it should not be automatically assumed that the collection isaffected by a single infectious agent as mixed
infections are more common than single
infections.
The pathogenicity of an organism is one of
the most fundamental factors to consider. If
an organism is not pathogenic or, even more
pertinently, is actually beneficial to the healthof the animal, any further management considerations, besides husbandry improvements, will often be unnecessary. There isevidence that pinworms play a supportiverole in the digestive health of lizards.
Conversely, ferlaviral outbreaks have been
associated with mass mortalities and affectedcollections should be managed promptly andassertively. Euthanasia should be considered
on welfare grounds for animals with highly
pathogenic infectious disease that cannot beeffectively managed.
Some infectious agents of reptiles arehighly infectious, others are less infectiousbut, for most, the level of infectivity is
unknown. Perhaps the best example of infectivity is provided by mites in snakes.
Infestations in individual animals should beinterpreted to mean that mites are widespread and therefore disinfection and treatment should be thorough. In contrast, thelifecycle of pentastomids means that single
animals that were infected in the wild will
not be infectious to their conspecifics in
captivity.
Whether an animal is treated or not
depends on a number of other factors: pathogenicity, infectivity, the value of the animalcompared with the cost of treatment, ownerconsent, compliance concerns, drug toxicity
and so on. For many agents, host treatments
are not available. This is commonly the casefor viral infections. For other infections, suchas many intestinal nematodes, treatment of
the infected animal will form the cornerstoneof controlling the infectious disease.

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Reptile Medicine and Surgery in Clinical Practice

The treatment of the environment also
needs to be considered, requiring soundknowledge of the stability of the agent outside the host and how likely there will be significant loads of infectious agent present. For
most instances, switching to nonparticulate
substrates such as newspaper, changing thesubstrate often (sometimes daily) and using
typical household disinfectants will be sufficient to address environmental contamination. For situations like mite infestations,more specific products, such as topical ivermectin, fipronil or pyrethroids, will beneeded. Some infectious agents are remarkably resistant to disinfection. This includes
nonenveloped viruses such as adenoviruses
and reoviruses, cryptosporidium and bacterial spores. More specialized disinfectants
such as biguanide–quaternary ammonium
combinations (F10SC veterinary disinfectant) and peroxygen compound–surfactant–organic acid combinations (Virkon® S) should
be used according to the label instructions
that correspond to the most resistant agents.
It is important to remember these substances
may be highly toxic to reptiles, so thoroughrinsing with clean water is necessary to avoid
contact with animals. Replacement of porous(wooden) enclosures with non‐porous (plastic) enclosures may need to be considered.
Following the definitive diagnosis of an
infectious agent, there are a number of otherconsiderations, such as whether there is azoonotic potential for the agent (e.g. somemycobacteria, pentastomids) and whether
the animal is a loved pet in a single‐animal
household or in a large breeding collection.
These considerations influence the management decision making process.
For both large and small collections, closing the collection should be considered, so
no animals are introduced or released fromthe collection for a time. Confidence to reopen a collection should come from multiple
negative test results from surviving animals.
Once the decision has been made to reopena collection, strict biosecurity should beobserved, including appropriate quarantining. There is growing evidence that someanimals infected with certain infectious

agents (e.g. sunshinevirus, tortoise picornaviruses) can remain asymptomatic for years.
It cannot therefore be guaranteed that an
asymptomatic animal that has been in quarantine for three months, six months, one
year or even several years will be free of all
pathogenic organisms. Because of this, it isstrongly recommended that diagnostic testing should be performed during a quarantine period that is as long as is practicallypossible. The value of the individual animalin quarantine should be measured against
the value to the collection when determining
what testing will be performed on an animal
while in quarantine. It is recommended
that faecal samples are examined for parasites and PCR testing is performed on appropriate samples for the microbes of the most­relevance to the local area. For agents known
to cause persistent infections ­(herpesviruses,
Mycoplasma and picornaviruses), serological testing should be considered as well.
Testing should be repeated at least once.

­Undiscovered Infectious
AgentsThis chapter has focuses on significant
known infectious agents of reptiles. There isno question that there are many more to bediscovered and that the overwhelming
majority of these will be in animals that are
first presented to private practitioners. The
authors would like to embolden the readers
to pursue interesting and atypical cases. It is
recommended they make enquiries to findtheir nearest colleague that has the capacity(and motivation) to discover new agents andinvestigate the nature of these infections.
Collaborations like these will always be worth
more than any research grant.

­Immunology
The immune system of reptiles is poorly
understood. Nonspecific barriers such as
skin form the first layer of defence from

Infectious Diseases and Immunology

foreign materials. Nonspecific innate mechanisms such as the complement cascade
serve as the second layer of defence and,
finally, the adaptive immune system, madeup of the components of humoral (antibody)immunity and cell‐mediated immunity, provides antigen‐specific responses. Although
this system is said to be similar among allvertebrates, the components of the reptilian
immune system have not been comprehensively defined in any species and it is likelythat there are significant differences
between taxa. In reptiles, the immune
responses mounted against foreign antigens
have not been fully mapped but it is suspected reptiles rely on nonspecific immunological defences more than mammals.
However, virus neutralization assays forherpesviruses, ferlaviruses and adenoviruses prove that reptiles can produce
humoral responses that can prevent in vitro
infections. Information on the specific cell‐
mediated immune responses (e.g. cytotoxic
cells) that reptiles produce is extremely
sparse and incomplete. It is plausible thatcell‐mediated immune responses represent
significant defensive mechanisms for reptiles and so results of humoral testing should

be carefully interpreted. More specificinformation on the serological testing that isused in reptiles can be found in Chapter 11.
It is broadly accepted that the innate andadaptive arms of the reptilian immune system function optimally at that animal’s preferred optimal body temperature. Many
reptiles are kept at suboptimal temperaturesand so, often by simply warming them up,
great improvements in their immunologicaldefences can occur.

­Reviews
For readers interested in more detailed overviews of the viral infections of reptiles, thereviews by Marschang (2011, 2014) are recommended. For an excellent review on thefungal infections of reptiles, the work by Paré
(2014) should be read. For bacteriology andparasitology, the reviews by Paré at al. (2006)
and Greiner and Mader (2006), respectively,
are excellent. The most comprehensive
review of all infectious diseases of reptiles
was compiled by Jacobson (2007) and thistext serves as an outstanding reference.

References
Greiner, E.C. and Mader, D.R. (2006)
Parasitology in Reptile Medicine andSurgery, 2nd ed. Elsevier Saunders, St. Louis,
MO, pp. 343–364.
Jacobson, E.R. (2007) Infectious Diseases andPathology of Reptiles. CRC Press, Boca Raton, FL.
Marschang, R.E. (2011) Viruses infecting
reptiles. Viruses, 3 (11), 2087–2126.
Marschang, R.E. (2014) Clinical virology, in
Current Therapy in Reptile Medicine andSurgery, (D. Mader and S. Divers, eds).
Elsevier Saunders, St. Louis, MO,
pp. 32–52.
Paré, J.A. (2014) Update on fungal infections in
reptiles, in Current Therapy in Reptile

Medicine and Surgery, (D. Mader and
S. Divers, eds). Elsevier Saunders, St. Louis,
MO, pp. 53–56.
Paré, J.A. and Sigler, L., Rosenthal, K.L. andMader, D.R. (2006) Microbiology: fungal andbacterial diseases of reptiles, in Reptile Medicine
and Surgery, 2nd ed. (D.R. Mader, ed.). Elsevier
Saunders, St. Louis, MO, pp. 217–238.
Stenglein, M.D., Sanders, C., Kistler, A.L. et al.
(2012) Identification, characterization, andin vitro culture of highly divergent
arenaviruses from boa constrictors andannulated tree boas: candidate etiologicalagents for snake inclusion body disease.
MBio, 3 (4), e00180‐12.

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Further Reading
Hyndman, T.H., Shilton, C.M. and Marschang,
R.E. (2013) Paramyxoviruses in reptiles:
a review. Veterinary Microbiology, 165 (3),200–213.
Jacobson, E.R., Brown, M.B., Wendland, L.D.
et al. (2014) Mycoplasmosis and upper
respiratory tract disease of tortoises: areview and update. Veterinary Journal, 201(3), 257–264.
Miller, D.L., Pessier, A.P., Hick, P. andWhittington, R.J. (2015) Comparative

pathology of ranaviruses and diagnostic
techniques, in Ranaviruses: Lethal
Pathogens of Ectothermic Vertebrates(M.J. Gray and V.G. Chinchar, eds).
Springer, Vienna, pp. 171–208.
Stöhr, A.C, Blahak, S., Heckers, K.O. et al.
(2013) Ranavirus infections associated withskin lesions in lizards. Veterinary Research,
44, 84.

217

17
Differential Diagnoses: A Problem‐Based Approach
Helen McCracken, Brendan Carmel, John Chitty, Bob Doneley, Robert Johnson,
Angela M. Lennox, Deborah Monks and Annabelle Olsson­Introduction
The following lists provide a guide to the­differential diagnoses of the most common
presenting signs of disease in the four major
reptile taxa: snakes, lizards, chelonians andcrocodilians. Note that the lists include cir­
cumstances where the presenting sign repre­
sents a normal state for that group of reptiles.
They also include the husbandry errors thatwill cause or predispose to these presenting
signs. The lists are intended to give the­clinician a starting point for the diagnostic
process and should not be considered
exhaustive.

­Snakes
Anorexia●●

Normal:–– Before and during ecdysis.
–– Hatchling snakes.
–– Reproduction – gravid or brooding
female, mating male.

–– Decreased appetite associated with sea­sonal decreases in photoperiod andambient temperatures.
–– ‘Shy feeders’ – these are snakes that pre­fer to feed while hidden and therefore
refuse food offered in full view of thecarer.
●● Husbandry:–– Suboptimal environmental temperature
management, so cannot reach or main­
tain optimal body temperature forfeeding.
–– Inappropriate photoperiod cycle, affect­
ing stimulus to feed.
–– Maladaptation to new environment.
–– Environmental stress from enclosure
mates.
–– Stress from increased frequency or
duration of handling, including for
management of a health:.
–– Disturbances in environment outside
the enclosure.
–– Inadequate cage furniture to enablenormal behaviour, such as basking, hid­ing, climbing, burrowing.
–– Inappropriate food item.

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

218

Reptile Medicine and Surgery in Clinical Practice

Health:–– Systemic infections including arenavirus(inclusion body disease) reported inpythons and boas, ferlavirus (ophidianparamyxovirus), reported in all snake
families, predominantly in viperids andsunshinevirus, a paramyxovirus reported
mainly in Australian pythons.
–– Antifungal drug toxicity (amphotericin
B, griseofulvin, ketoconazole).
–– Toxicosis from ingestion of rodent killed
by rodenticide.
–– Visual deficit, including due tocataracts.
–– Tongue or tongue sheath infection ortrauma resulting in loss of olfactory
function.
–– Occluded nares.
–– Pneumonia.
–– Stomatitis or oesophagitis or gastroen­
teritis.
–– Gastrointestinal tract parasites.
–– Gastrointestinal neoplasia.
–– Gastrointestinal
obstruction(see‘Regurgitation’).
–– Extra‐intestinal inflammation or infec­
tion, neoplasia and other disease,including gout, hepatic lipidosis andother hepatopathies.
–– Dystocia.
–– Multiple rib fractures in constricting
species (pythons and boas).
–– Pain.
●● Weight loss–– All causes of anorexia as above.
●● Health:–– Cardiac dysfunction.
–– Maldigestion or malabsorption (to date,no precise aetiologies are recognized forthese:).
–– Nephropathy.
●●

Distended Coelom
Normal:–– Gravid female.
●● Husbandry:–– Obesity due to overfeeding and inactiv­
ity; common in black‐headed pythons●●(Aspidites melanocephalus) and royal orball pythons (Python regius).
●● Health:–– Coelomitis.
–– Ascites.
–– Faecal impaction.
–– Dystocia.
Weakness, Decreased Muscle Tone,
Lethargy, Reluctance to Move,
Loose or Absent Coiling in Pythons
Husbandry:–– Inappropriately low or high environ­mental temperature.
●● Health:–– Non‐specific sign seen with many
­disease processes, often coupled withanorexia.
–– Dehydration.
–– Systemic disease, including septicae­
mia, viral infection (ferlavirus, arenavi­
rus, sunshinevirus).
–– Heavy external or internal parasiteburden.
–– Neoplasia of any system.
–– Toxicoses, including organophosphateand carbamate insecticides, alcohol.
–– Visual deficits, including due to cataracts.
–– Head or spinal trauma.
–– Renal insufficiency.
–– Pain.
–– Early manifestation of all causes ofneurological signs listed.
–– Haemorrhage.
–– Anaemia.
–– Visceral gout.
●●

Increased Activity
Normal:–– Preparing for ecdysis.
–– Mate‐seeking behaviour.
–– Gravid snake seeking nesting site.
●● Husbandry:–– Inappropriately high environmental
temperature.
–– Inadequate or inappropriate retreat
areas or cage furniture.
–– Environmental disturbance.
●●Differential Diagnoses: A Problem‐Based Approach●●

Other:–– Hunger or thirst.
–– Mite infestation.

Increased Time Spent Basking
Normal:–– Gravid female.
–– Behavioural thermoregulation to opti­
mize postprandial digestion.
●● Husbandry:–– Decreased ambient temperature.
●● Ill health.
●●

Increased Time Spent Soaking
In Water Bowl
Normal:–– Preparing for ecdysis.
●● Husbandry:–– Environment inappropriately dry or hot.
–– Mite infestation.

–– Inappropriately low environmental
temperature–– Lack of suitable cage furniture to initi­
ate or assist shedding●● Health:–– Malnutrition, dehydration, debilitation.
–– Concurrent illness.
–– Bacterial or fungal skin infection.
–– Mite or tick infestation.
–– Previous skin scarring from burn ortrauma.
Dysecdysis: Increased Frequencyof Sloughing●●●●

Dull, Dry, Pale or Discoloured Skin
Normal:–– Prior to ecdysis.
–– Stretched, pale skin over the mid‐bodybulge in a recently fed snake.
●● Husbandry:–– Inappropriately low environmental
humidity.
●● Health:–– Fungal dermatitis (focal skin discolour­
ation).
–– Scar at site of previous trauma or sur­gery (pale, smooth skin without scales).
–– Injection site of tissue irritant drug (e.g.
enrofloxacin).
●●

Dysecdysis (abnormal shedding):
fully or partially retained slough●●

Husbandry:–– Inappropriately low environmental
humidity–– Failure to provide adequate water bodyfor soaking (required by some species)

Health:–– Bacterial or fungal skin infection.
–– Mite or tick infestation.
–– Burns.
–– Hyperthyroidism.

Skin Hyperkeratosis, Granulomas,
Proliferative Nodules, Papules,
Pustules, Blisters, Ulceration
Husbandry:–– Inappropriately high environmental
humidity, wet substrate, poor environ­mental hygiene (all predispose to bac­terial or fungal dermatitis).
●● Health:–– ‘Blister disease’ caused by bacterial
or fungal infection (fluid‐filled skin­vesicles most commonly involving theventral scales).
–– Infection with Chrysosporium anamo­
rph of Nannizziopsis vriesii (CANV)
fungus.
–– Other bacterial or fungal dermatitis.
–– Sunshinevirus infection (blisters anddermatitis).
–– Nematodes, including Kalicephalus spp(blisters, pustules that rupture to form
ulcers).
–– Thermal burns (blisters, crusting,ulcers, full thickness loss of epidermis).
–– Chemical burn from contact with­concentrated disinfectants e.g. sodium
hypochlorite.
●●

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Reptile Medicine and Surgery in Clinical Practice

Skin Abrasions, Thickening,
Disruption
Husbandry:–– Mite or tick infestation.
●● Trauma:–– Stress‐related rostral abrasion.
–– Traumatic wound (including bite fromprey or enclosure mate).
–– Scar at site of previous trauma or surgery.
●●

Cutaneous and Subcutaneous
Swellings
Iatrogenic:–– Subcutaneous microchip (snakes are
typically chipped caudolateral to theskull or craniolateral to the cloaca)–– Injection site reaction.
●● Health:–– Subcutaneous abscess or granuloma(due to ectoparasite attachment, punc­
ture wound, foreign body, injection site,poor environmental hygiene).
–– Soft tissue infection, abscess or granu­
loma as sequela of adjacent spinal osteo­
myelitis lesion.
–– Subcutaneous nematodes (visible under
the skin).
–– Sparganosis (only in snakes that haveconsumed frogs or reptiles; lesions mostcommonly occur in the caudal half ofthe body).
–– Skin neoplasia.
–– Subcutaneous lipomas (most common
in colubrids).
–– Bony swellings from focal vertebral
osteomyelitis.
–– Rib fractures.
●●

Eyes: Colour Change, Opaque or
Dry Spectacle
Normal:–– Opaque spectacle associated with pre‐ecdysis (normal).
●● Husbandry:–– Spectacle abrasion from constant facerubbing against solid objects due to●●peri‐ocular mites, dysecdysis or dry skincaused by low humidity.
●● Health:–– Spectacle retention following ecdysis.
–– Indented spectacle due to previous caseof retention.
–– Spectacle trauma or ulceration follow­
ing incorrect treatment of retention.
–– Bacterial or fungal infection of eye orspectacle, including as extension fromadjacent skin infection.
–– Subspectacular infection or abscess –most cases occur from ascending
infection via the nasolacrimal duct sec­
ondary to stomatitis or respiratory tract
infection.
–– Traumatic full or partial loss ofspectacle.
–– Exposure keratitis following iatrogenic
spectacle loss.
–– Cataract.
Eye or Spectacle Distension
Spectacle:–– Subspectacular infection or abscess(most cases occur from ascending infec­
tion via the nasolacrimal duct second­
ary to stomatitis or respiratory tract
infection).
–– Subspectacular fluid accumulation due
to blocked nasolacrimal duct (‘pseu­
dobuphthalmos’).
●● Globe:–– Bacterial or fungal ocular infection(panophthalmitis) – most commonlyfrom trauma.
–– Ocular neoplasia.
–– Traumatic eye injury.
–– Glaucoma (including secondary tocataract).
●●

Periocular Swelling●●

Health:–– Periocular cellulitis or abscess.
–– Periocular mites or ticks.
–– Trauma.

Differential Diagnoses: A Problem‐Based Approach

Oral, Nasal and Choanal Discharge,
Excessive Salivation, Mouth Gaping,
Wheezing, Stridor, Dyspnoea
Nares and nasal cavity:–– Normal transient partial obstruction ofnares during ecdysis, producing awheezing sound.
–– Stomatitis (exudate or saliva may enter
the choana, producing nasal discharge).
–– Complete or partial obstruction ofnares by retained slough (mouth gaping,wheezing).
●● Respiratory tract:–– Obstruction of glottis by oral cavity for­eign body or lesion, including abscess,neoplasia.
–– Rhinitis.
–– Pneumonia (may present with nasal­discharge and/or exudate from glottis inoral cavity).
–– Aspiration pneumonia due to inexpert
assist feeding or administration of oral
medication.
–– Water aspiration (near‐drowning),
including in snakes unattended while
soaking in buckets of water.
●● Toxins:–– Organophosphate, carbamate, pyre­thrin and pyrethroid insecticide toxi­
cosis (salivation, respiratory secretions,dyspnoea).
–– Toxicosis from ingestion of rodent killed
by anticoagulant rodenticide (dyspnoea).
–– Inhaled irritants, including fumes of
disinfectants and other chemicals.
●● Systemic viral infections including ferlavi­rus (blood in oral cavity, stridor, dyspnoea),sunshinevirus and arenavirus (clear, vis­
cous oral discharge, dyspnoea).

–– Electrocution (petechiation only).
–– Stomatitis (bacterial or fungal).
–– Stress‐related rostral abrasions – may
extend deeply into oral tissues.

●●

Gingival Inflammation,
Ulceration, Petechiation,
Exudation, Tooth Loss●●

Health:–– Hyperthermia.
–– Septicaemia (petechiation only).
–– Organophosphate toxicity.

Tongue Lesions●●

Health:–– Bacterial or fungal infection of tongue
or tongue sheath (erythema, ulceration,
exudation).
–– Inability to protrude tongue due toadhesions within tongue sheath as
sequela of trauma or infection.

Oral Mucous Membrane Colour
White to very pale pink:–– normal for most species.
●● Pale green:–– Hepatic disease.
–– Cholecystitis.
–– Bile duct obstruction.
–– Haemolysis.
●●

Facial or Cephalic Swelling
Infectious diseases:–– Cephalic cellulitis as sequela of bacterial
stomatitis.
–– ‘Facial disfiguration syndrome’ caused
by Ophidiomyces ophiodiicola infection.
–– Venom gland abscess.
–– Abscess of other facial tissues, including
due to puncture wound, ectoparasite
attachment.
–– Osteomyelitis (bacterial, fungal).
●● Trauma:–– Fracture or soft tissue wound, including
due to cage‐mate trauma or bite fromprey item.
●● Bone or soft tissue neoplasia.
●● Sialocoele.
●●

Regurgitation, Vomiting●●

Husbandry:–– Suboptimal environmental temperature
following feeding.

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Reptile Medicine and Surgery in Clinical Practice–– Handling or other environmental stresses
within 24–48 hours after feeding.
–– Overfeeding.
–– Inappropriate food item or inappropri­ate preparation of food item.
●● Infection:–– Systemic viral disease (arenavirus,
sunshinevirus).
–– Bacterial or fungal gastroenteritis.
●● Parasites:–– Cryptosporidium spp. hypertrophic gas­
tritis (most commonly seen in ­colubrids,
elapids and viperids).
–– Other gastrointestinal parasites (nota­
bly cestodes, ascarids, Entamoeba spp.).
●● Gastrointestinal obstruction:–– Ingested foreign body (snakes will
eat objects with the odour or remains ofprey items on them (e.g. substrate mate­rial, mouse trap), neoplasia, ­granuloma,
intussusception or faecal impaction.
–– Extraintestinal lesion.
●● Hepatopathy.
Diarrhoea
Normal:–– Viperids produce semi‐liquid faeces
compared with other snake species.
●● Husbandry:–– Maldigestion and bacterial overgrowth
due to suboptimal environmental
temperature.
–– Overfeeding.
–– Recent diet change.
●● Infection:–– Ferlavirus (mucoid diarrhoea, malodor­
ous stools).
–– Bacterial or fungal enteritis or colitis(including salmonellosis).
–– Protozoal enteritis or colitis (notably
Entamoeba spp., flagellates).
–– Infestation with Strongyloides spp.,
hookworms or ascarids.
●● Dysbiosis following antibiotic therapy orsystemic illness.

–– Dehydration due to low humidity envi­
ronment or inappropriate delivery ofdrinking water.
–– Insufficient exercise.
–– Inappropriate food items (e.g. long‐haired rodents).
–– Incidental ingestion of enclosure sub­strate (pebbles, gravel, sand, bark).
●● Health:–– Gastrointestinal obstruction:○○ intraluminal(intussusception, neo­plasia, foreign body).
○○ Extraluminal (e.g. dystocia).
Mid‐Body Swelling
Normal:–– Recently consumed food in stomach.
●● Health:–– Cryptosporidium spp. hypertrophic
gastritis (most commonly seen in colu­
brids, elapids and viperids).
–– Gastric abscess or granuloma.
–– Gastric neoplasia.
–– Gastric foreign body.
●●●●

Constipation, Reduced Faecal Output●●

Husbandry:–– Suboptimal environmental temperature.

Other Palpable or Visible Internal
Swellings (Figure 17.1)
Reproductive tract:–– Folliculogenesis and atretic follicles.
–– Gravid female.
–– Oophoritis or salpingitis.
–– Dystocia.
–– Retained unfertilised eggs (‘slugs’).
●● Cardiac:–– Cardiomegaly (cardiomyopathy or peri­
cardial effusion).
●● Gastrointestinal tract:–– Ingested foreign body.
–– Intestinal intussusception.
–– Faecal impaction.
–– Solid urate masses in colon.
●● Generalized:–– Abscess or granuloma of any internalorgan or coelomic cavity, including
Mycobacteria spp. infection.
–– Neoplasia or cyst of any internal organ
or coelomic cavity.
●●

BOIDAES

ELAPIDAEVIPERIDAE(n = 7)s-c: 99.6 ± 46.5 cm(n = 6)s-c: 81.3 ± 33.8 cm

Position of organ relative to snout-cloaca length

0
.04
.08
.12
.16
.20
.24
.28
.32
.36
.40
.44
.48
.52
.56
.60
.64
.68
.72
.76
.80
.84
.88
.92
.96
C 1.00

COLUBRIDAE(n = 31)(n = 5)s-c: 141.8 ± 70.4 cm s-c: 121.9 ± 14.1 cm

BOIDAE= boas and pythons
COLUBRIDAE = rear-fanged snakes
ELAPIDAE= front-fanged snakes
VIPERIDAE= cobras and vipers
LEGENDs-c: snout - cloaca
length expressed
as x ± s.d.
Heart
Right lung
Liver
StomachGonadsKidneys
R Right side
L Left side
S Snout
C Cloaca
R

L

R

L

R

L

R

L

N.B.
Heart is located in the midline, not on the right-hand side as suggested
in these graphs.

S

0
.04
.08
.12
.16
.20
.24
.28
.32
.36
.40
.44
.48
.52
.56
.60
.64
.68
.72
.76
.80
.84
.88
.92
.96
C 1.00Children’s
PythonDiamond &CarpetPythons

Scrub
Pythons(n = 11)s-c: 76.5 ± 22.4 cm(n = 13)s-c: 160.2 ± 29.7 cm(n = 5)s-c: 276.5 ± 30.7 cm

LEGENDs-c: snout - cloaca
length expressed
as x ± s.d.
Heart
Right lung
Liver
StomachGonadsKidneys
R Right side
L Left side
S Snout
C Cloaca
R

L

R

L

R

L

1. The sample size given (n) represents the total number of specimens examined foreach species or family. The sample size for some mesurements is slightly less than
this total because in a small number of specimens examined, some organs could not
be measured due to pathological change.
2. The posterior pole of lung represented is the point of junction between alveolar lungand membranous air sac.

Figure 17.1 Identification of the location of internal organs in snakes by determining the distance from thesnout, expressed as a percentage of snout–vent length (McCracken 1994).

224

Reptile Medicine and Surgery in Clinical Practice–– Inflammatory swelling of any internalorgan.
–– Steatitis.
–– Gall bladder distension due to bile ductobstruction or bacterial or coccidial
cholecystitis.
–– Omphalitis (in hatchlings).
Diffuse Distension, Firmness orPuffiness in Caudal Halfof Body Cavity
Reproductive:–– Folliculogenesis.
–– Gravid female.
–– Oophoritis or salpingitis.
–– Dystocia.
●● Intestinal:–– Ferlavirus (gaseous bowel distension).
–– Coelomitis (including yolk‐related).
–– Steatitis.
–– Protozoal colitis (Entamoeba spp. or
flagellates).
–– Intestinal or caecocolic neoplasia.
–– Faecal impaction.
–– Solid urate masses in colon or cloaca.
●●

Swelling of the Cloaca or
Hemipenal Region●●

Health:–– Protozoal colitis–– Bacterial or protozoal cloacitis.
–– Hemipenal pocket infection.
–– Hemipenal trauma.
–– Mating trauma in female.
–– Oedema of cloacal mucosa secondary totenesmus due to faecal impaction ordystocia.
–– Paracloacal gland infection.

Prolapse from cloaca●●

Cloaca:–– Generalized weakness (prolapsed cloaca,colon, bladder, oviduct or hemipenes).
–– Humid environment – predisposes toprolapse of cloacal tissue and terminalcolon (most commonly in juvenile green
pythons).

Intestinal:–– Gastrointestinal tract: parasitism, gas­
troenteritis, cloacitis or gut obstruction
by faecal impaction, intussusception,neoplasia (prolapsed cloaca, colon).
–– Extraluminal gastrointestinal blockage,
including neoplasia, abscesses (pro­lapsed cloaca, colon).
●● Reproductive:–– Dystocia (prolapsed cloaca, oviduct).
–– Prolapsed hemipenes, following probing
for sex identification, traction during
copulation, spinal injury, or contamina­tion with substrate material or straining
due to any of the causes listed.
●●

Discoloured Urates
Yellow:–– normal variation of the usual white or
cream urates●● Green (biliverdinuria):–– Chronic anorexia or starvation.
–– Hepatic disease.
–– Cholecystitis.
–– Bile duct obstruction.
–– Haemolysis.
●● Bloody:–– Haemorrhage or inflammation of thekidneys, colon or cloaca.
–– Passage of abnormally hard faeces,causing blood streaking on surface ofboth faecal and urate masses.
–– Following manual palpation to resolve
faecal impaction or egg retention.
●●

Gravid Female not Commencing
or Completing Parturition or
Oviposition
Normal:–– Primigravid female.
●● Husbandry and nutritional:–– Environmental temperature or humid­
ity not species appropriate.
–– Failure to provide suitable nest site.
–– Disturbance of parturition by cage mateor external stimulus.
–– Obesity due to overfeeding.
–– Malnutrition.
●●Differential Diagnoses: A Problem‐Based Approach–– Dehydration.
–– Lack of fitness in chronically inactive
snake.
●● Health:–– Obstructive dystocia due to oversizedor malformed egg or foetus, crushed
egg, dead foetus, or pathology external
to reproductive tract.
Salpingitis●●

Health:–– Spinal disease.
–– General debilitation due to other dis­ease process.

Vertebral Swellings
and Spondylosis●●

Health:–– Vertebral osteomyelitis (generally focal).
–– Bone neoplasia.
–– Vertebral trauma.
–– Proliferative spinal osteopathy (generally
multifocal or diffuse, causing segmented
fusion of adjacent affected vertebrae).
–– Intervertebral articular gout.

Tail Necrosis, Missing Tail Tip●●

Health:–– Trauma, or within two weeks of ventral
caudal vein venepuncture (most likely
due to iatrogenic vascular damage).
–– Dysecdysis (tourniquet effect).
–– Necrotising dermatitis.
–– Spinal osteomyelitis.

Paralysis
CNS lesions:–– Viral infections, including arenavirus,
ferlavirus (flaccid paralysis).
–– Other central nervous system infections,bacterial, fungal, viral or parasitic.
●● Spinal lesions:–– Vertebral osteomyelitis.
–– Bone neoplasia.
–– Spinal trauma, including from handling,crushing by enclosure furniture.
●●–– Pathological fracture (including as sequelaof proliferative spinal osteopathy).
●● Faecal impaction.
●● Electrocution (flaccid paralysis).
Neurological Signs, Including
Muscle Fasciculation,
Incoordination, Ataxia, Writhing,
Star‐Gazing, Head Tilt,
Opisthotonus, Convulsions
Nutritional:–– Thiamine deficiency (notably in snakes
fed frozen fish without vitamin B1
supplementation).
–– Metabolic disease, including hypogly­
caemia, hypocalcaemia.
●● Toxicosis:–– Organophosphate, carbamate, pyre­thrin and pyrethroid insecticide toxicity(ataxia, muscle fasciculation).
–– Drug toxicity, including metronida­zole, ivermectin and aminoglycosideantibiotics.
–– Ingestion of disinfectants, including
iodine.
–– Ingestion of and exposure to fumes ofhousehold chemicals, including paintsolvents, ethylene glycol.
–– Plant toxicity, including cedar shavings.
●● Central nervous system disease:–– Head or body trauma.
–– Bacterial and mycotic encephalitis(including micro‐abscesses secondary
to septicaemia).
–– Viral encephalitis including arenavirus,
ferlavirus, sunshinevirus and bornavi­rus (reported mainly in pythons).
–– Parasitic infections (including brain
abscess due to Entamoeba invadens).
–– Meningoencephalitis
duetoAcanthamoeba spp.
●● Liver disease:–– Hepatic lipidosis.
–– Hepatic encephalopathy.
●● Renal failure and visceral gout.
●● Disseminated infection or septicaemia.
●● Electrocution (convulsions).
●● Pain.
●●

225

226

Reptile Medicine and Surgery in Clinical Practice

Loss of Righting Reflex, Abnormal
Body Position and Movement,
Inability to Strike at Prey
Normal:–– Gravid females frequently rest in dorsal
recumbency.
–– Rolling and resting in dorsal recum­
bency may be normal behaviours forsome individuals.
●● Spinal disease:–– Vertebral or spinal cord disease (infec­
tion, neoplasia, trauma).
–– Proliferative spinal osteopathy (may causevertebral fusion and hence segmental
rigidity, kinking or abnormal posture).
–– Congenital spinal deformities (lordosis,
kyphosis, scoliosis).
●● Thiamine deficiency (notably in snakes
fed frozen fish without vitamin B1
supplementation).
●● Organophosphate, carbamate, pyrethrin
and pyrethroid insecticide.
●● Systemic viral infections, including ferlavi­rus, arenavirus, sunshinevirus.
●● Pneumonia (abnormal posture).
●● Any cause of general debilitation.
●●

Sudden Death
Husbandry:–– Hyperthermia from inappropriately
high environmental temperature (e.g.
thermostat failure or exposure to direct
sunlight without opportunity to seek
cooler area).
●● Health:–– Failure of carer to detect earlier signs ofchronic illness.
–– Systemic infections including septicae­
mia and ferlavirus.
–– Leukaemia.
–– Organ failure (e.g. visceral gout).
–– Toxicities.
●● Envenomation by cage mate.
●● Toxicities including bufotoxin from inges­
tion of a cane toad.
●● Trauma.
●● Electrocution.
●● Haemorrhage.
●● Shock.
●●­Lizards
Anorexia
Normal:–– Gravid female.
–– Males during breeding season.
–– Decreased appetite associated with sea­sonal decreases in photoperiod andambient temperatures.
–– ‘Shy feeders’ – individuals that prefer tofeed while hidden and therefore refuse
food offered in full view of the carer.
●● Husbandry:–– Suboptimal environmental temperature
management.
–– Lack of ultraviolet light or inappropriate
photoperiod cycle, affecting stimulus
to feed.
–– Maladaptation to new environment.
–– Stress from increased frequency or
duration of handling, including for
management of a health.
–– Disturbances in environment outside
the enclosure.
–– Inadequate cage furniture to enablenormal behaviour (e.g. basking, hiding,climbing).
–– Inappropriate food items (e.g. live
insects are preferred over dead ones).
–– Environmental stress from enclosure
mates.
●● Health:–– Metastatic soft tissue mineralisation due
to excessive vitamin D supplementation.
–– Systemic infections including adenovi­
rus (mainly in young bearded dragons).
–– Rodenticide toxicity, either primary fromingestion of bait pellets (herbivorous
species) or secondary from ingestion ofbaited rodent (carnivorous species).
–– Sensual deprivation (e.g. loss of sight –cataracts, corneal lipidosis) or smell(severe upper respiratory tract infection).
–– Periodontal disease (agamids, chame­leons).
–– Lesion of tongue sheath (monitors andchameleons) and tongue (all species) –affect food prehension.
–– Gastrointestinal tract infections, para­sites, neoplasia or obstruction.
●●Differential Diagnoses: A Problem‐Based Approach–– Hepatopathy (including hepatic lipidosis).
–– Nephropathy.
–– Dystocia.
–– Preovulatory follicular stasis.
–– Pain.
–– Visceral gout.
Weight Loss
All causes of anorexia as above.
Husbandry:–– Dominance of food source or otherresources by enclosure mate, together
with the effects of hierarchical stress –may predispose to disease.
–– Malnutrition due to insufficient foodquantity or inappropriate food items.
●● Health:–– Neoplasia of any system.
–– Coccidiosis due to Isospora amphiboluri(young bearded dragons, frequently as
co‐infection with adenovirus).
–– Cryptosporidial enteritis or gastritis.
–– Maldigestion or malabsorption – todate, no precise aetiologies are recog­
nised for these problems.
●●●●Distended Coelom
Reproductive:–– Gravid female.
–– Preovulatory follicular stasis.
–– Post‐ovulatory follicular stasis.
–– Dystocia.
●● Other:–– Obesity (common in blue‐tongue
lizards, bearded dragons and leopard­
geckos fat is stored in paired ovoid fat
bodies in the caudal coelom).
–– Organomegaly (e.g. neoplasia, hepatic
lipidosis).
–– Coelomitis (including yolk coelomitis,
most common in bearded dragons andgreen iguanas).
–– Ascites (including from hypoproteinae­
mia due to anorexia, malnutrition, mal­digestion, malabsorption, parasitism,hepatopathy, nephropathy).
–– Pneumocoelom due to ruptured lung(s).
–– Faecal impaction.
●●

Lethargy, Weakness, Depression
Normal:–– Gravid female.
●● Husbandry:–– Inappropriately low or high environ­mental temperature.
–– Inappropriate light type or photoperiod
cycle affecting activity levels.
–– Inadequate cage furniture to enablenormal behaviour (e.g. basking, hiding,climbing).
–– Social stress from enclosure mates.
–– Hypocalcaemia due to chronic nutri­tional secondary hyperparathyroidism(NSHP) caused by dietary calcium or
phosphorus imbalance and/or inade­quate exposure to ultraviolet B light.
●● Health:–– Non‐specific sign seen with many disease
processes, often coupled with anorexia.
–– Hypocalcaemia due to renal secondary
hyperparathyroidism (RSHP).
–– Dehydration.
–– Systemic infection including septicae­
mia and adenovirus (mainly in young
bearded dragons).
–– Heavy external or internal parasiteburden.
–– Neoplasia of any system.
–– Visual deficits, including due to cata­
racts, corneal lipidosis.
–– Renal failure (common in green iguanas).
–– Dystocia.
–– Preovulatory follicular stasis.
–– Vertebral and long‐bone weakness andfractures as a result of NSHP or RSHP.
–– Pain.
–– Early manifestation of all causes of neu­
rological signs listed.
–– Haemorrhage.
–– Anaemia.
–– Visceral gout.
●●Dull, Dry, Pale or Discoloured Skin●●

Normal:–– Prior to normal ecdysis (geckos only
dull, pale skin).
–– During normal ecdysis (flaky, peelingskin as most lizards shed piecemeal).

227

228

Reptile Medicine and Surgery in Clinical Practice–– Behavioural or environmental skin col­our change due to activation of chroma­
tophores (normal in some species,
including chameleons, anoles).
●● Husbandry:–– Stress‐induced skin colour change(fine black dots over whole body) due toactivation of chromatophores in somespecies, including chameleons, geckos,
iguanas (common with handling).
–– Inappropriately low environmental
humidity.
●● Health:–– Fungal dermatitis, notably with
Chrysosporium
anamorphofNannizziopsis vriesii (CANV) (focal
skin discolouration).
–– Scar at sites of previous trauma or sur­gery (pale, smooth skin without scales).
–– Site of injection of irritating substance,
especially enrofloxacin.
Dysecdysis (Abnormal Shedding):
Fully or Partially Retained Slough
Husbandry:–– Inappropriately low environmental
humidity.
–– Failure to provide adequate water bodyfor soaking (required by some species).
–– Inappropriately low environmental
temperature.
–– Lack of suitable cage furniture to initi­
ate or assist shedding.
●● Health:–– Malnutrition, dehydration or debilitation.
–– Hypovitaminosis A (chameleons).
–– Concurrent illness.
–– Bacterial or fungal skin infection.
–– Mite or tick infestation.
–– Previous skin scarring from burn ortrauma.
●●Dysecdysis: Increased Frequencyof Sloughing●●

Health:–– Bacterial or fungal skin infection.
–– Mite or tick infestation.
–– Burns.
–– Hyperthyroidism.

Skin Hyperkeratosis, Granulomas,
Proliferative Nodules, Papules,
Pustules, Blisters, Ulceration
Husbandry:–– Inappropriately high environmental
humidity, wet substrate, poor environ­mental hygiene (all predispose to bacte­rial or fungal dermatitis).
–– Burns, including from contact with aheat lamp, wire mesh heated by an adja­
cent lamp or pieces of hot glass from alamp shattered when spayed with water(blisters, crusting, ulcers, full thickness
loss of epidermis).
–– Chemical burn from contact with con­centrated disinfectants (e.g. sodium
hypochlorite).
●● Health:–– ’Blister disease’ (fluid‐filled skin vesi­cles) caused by bacterial or fungal
infection.
–– Infection with CANV (‘yellow fungus
disease’ of bearded dragons causes coa­lescing necrotic hyperkeratotic epider­mis on head, limbs, body).
–– Dermatophilosis(nodular
hyperkeratosis).
–– Other bacterial or fungal dermatitis.
●●

Skin Abrasions, Thickening,
Disruption
Mite or tick infestation.
Scar at site of previous trauma or surgery.
●● Stress‐related rostral abrasion.
●● Traumatic wound (including bite fromenclosure mate).
●●●●

Cutaneous and Subcutaneous
Swellings●●

Normal:–– Subcutaneous microchip (lizards are
typically chipped in the inguinal area,
just cranial to the thigh).
–– Hemipenal bulge (normal, associatedwith onset of sexual maturity and breed­ing season).
–– Swollen hemipenal pockets due to semi­
nal plugs.

Differential Diagnoses: A Problem‐Based Approach●●

Health:–– Hemipenal pockets distended withretained slough, generally due to low
environmental humidity.
–– Subcutaneous abscess or granuloma(due to ectoparasite attachment, puncture
wound, foreign body, injection site, poor
environmental hygiene, dermatophilosis).
–– Soft tissue infection, abscess or granu­
loma as sequela of adjacent osteomyeli­
tis lesion (most commonly of the digitsof blue‐tongue and shingleback lizards
and mandible or maxilla of agamids andchameleons).
–– Cellulitis.
–– Subcutaneous nematodes and filaroidparasites.
–– Skin neoplasia.
–– Pseudoaneurysm or dissecting aneu­
rysm in bearded dragons (fluctuant tofirm subcutaneous swelling on the dor­solateral neck just caudal to the skull).
–– Impacted pores of secretory pre‐femo­
ral or perianal glands (generally due tosuboptimal humidity).
–– Periarticular gout.
–– Injection site reaction.

Overgrown or Misshapen Nails●●

Health:–– Inadequate exercise and opportunity towear nails, including climbing, digging,access to substrates of varying hardness
or roughness.
–– Sequela to paronychia.
–– Chronic abnormal weight bearing due
to injury, limb loss or degenerative joint
disease.

Opaque or Dry Spectacle (inGeckos and other Lizard Species
with Spectacles)
Normal:–– Opaque spectacle associated with
pre‐ecdysis.
●● Husbandry:–– Spectacle abrasion from constant facerubbing against solid objects due to●●periocular mites, dysecdysis or dry skincaused by low humidity.
–– Spectacle retention following ecdysis(occurs less commonly than in snakes
because geckos regularly lick theirspectacles).
●● Health:–– Indented spectacle due to previous caseof retention.
–– Spectacle trauma or ulceration follow­
ing incorrect treatment of retention.
–– Traumatic full or partial loss ofspectacle.
Eyes: Colour Change, Opacities
Normal:–– Arcus lipoides corneae (normal age‐
related change in monitors): partly or
fully circumferential band of corneal
opacity at limbus.
●● Health:–– Bacterial or fungal keratitis or corneal
ulcer, including as extension from adja­
cent skin infection.
–– Keratitis or corneal ulcer due to trauma,
foreign body or chemical exposure (e.g.
hypochlorite bleach).
–– Exposure keratitis following iatrogenic
spectacle loss (in species with spectacles).
–– Subspectacular infection or abscess (inspecies with spectacles).
–– Corneal lipidosis.
–– Cataract.
●●

Eye or Spectacle Distension●●

Health:–– Bacterial or fungal ocular infection(panophthalmitis), most commonlyfrom trauma.
–– Subspectacular infection or abscess (inspecies with spectacles most cases
occur from ascending infection via thenasolacrimal duct secondary to stoma­
titis or respiratory tract infection,
including with Trichomonas spp.).
–– Ocular neoplasia.
–– Traumatic eye injury.
–– Subspectacular fluid accumulation
due to blocked nasolacrimal duct

229

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Reptile Medicine and Surgery in Clinical Practice(in species with spectacles; ‘pseu­
dobuphthalmos’).
–– Glaucoma (including secondary tocataract).
Blepharoedema, Blepharospasm,
Ocular Discharge, Periocular
Swelling●●

Health:–– Restraint behind the head may cause
blepharoedema due to engorgement of
periocular venous sinuses.
–– Hypovitaminosis A (chameleons, anoles).
–– Subcutaneous cellulitis or abscess –most commonly from trauma.
–– Bacterial or fungal conjunctivitis,
including from ascending infection via
the nasolacrimal duct secondary to sto­
matitis or respiratory tract infection.
–– Periorbital abscess, including as sequelaof upper respiratory tract infection.
–– Periocular mites or ticks.
–– Periocular viral papillomas.
–– Ocular or periocular neoplasia, includ­ing squamous cell carcinoma in bearded
dragons.
–– Ocular or periocular trauma.
–– Eyelid burns from heat lamp.
–– Conjunctival or subpalpebral foreign
body, most commonly substrate material.
–– Cardiomegaly, pericardial effusion ormass in the pectoral region (causes
bilateral periocular swelling likely due
to partial occlusion of the venous returnand lymph flow).

Ear Swelling●●

Health:–– Abscess (bacterial, fungal).
–– Ectoparasites – mites, ticks.
–– Neoplasia.

Nasal Discharge, Excessive Salivation,
Open Mouth Breathing, Dyspnoea●●

Normal:–– Nasal salt gland secretions (clear liquidor dry white powder) in some species,

including green iguana, shingleback
lizard.
–– Inspiration or expiration in some spe­
cies (including agamids) is exaggerated,
may be mistaken for dyspnoea.
–– Transient partial obstruction of nares
during ecdysis, producing wheezingsound (normal).
●● Husbandry:–– Open mouth ‘panting’ for thermoregu­
lation (normal, but may indicate
inappropriately high environmental­
temperature)●● Health:–– Complete or partial obstruction of nares
by retained slough.
–– Toxins:○○ organophosphate, carbamate, pyre­thrin and pyrethroid insecticide toxic­
ity (salivation, respiratory secretions,dyspnoea);○○ anticoagulant
rodenticide toxicity,either primary from ingestion of baitpellets by herbivorous species or sec­
ondary from ingestion of baited rodent
by carnivorous species (dyspnoea);○○ epistaxis due to haemorrhage frommetastatic soft tissue mineralisation
caused by excessive vitamin D supple­
mentation;○○ inhaled irritants, including pollen
and fumes of disinfectants and otherchemicals.
–– Oral abnormalities○○ stomatitis (bacterial, fungal) – exu­
date or saliva may enter the choana,
producing nasal discharge;○○ obstruction of glottis by oral cavity
foreign body or lesion, including
abscess, neoplasia.
–– Nasal:○○ infectious upper respiratory tract
infection of unknown aetiology,
including in juvenile blue‐tongue­lizards and ‘bobtail flu’ of shingle­
back lizards (nasal or oral discharge,
epiphora, sneezing, dyspnoea);○○ rhinitis or sinusitis (bacterial, viral,fungal).

Differential Diagnoses: A Problem‐Based Approach–– Lower respiratory tract disease:○○ intracoelomic
disease (including
ascites, coelomitis, neoplasia, masses)
may impede normal lung expansion,
resulting in dyspnoea;○○ pneumonia (bacterial, fungal, viral, par­asitic), including ferlavirus infection;○○ neoplasia, primary tumour or lungmetastasis;○○ pulmonary oedema due to cardiac or
hepatic disease;○○ aspiration pneumonia due to inexpert
assist feeding or administration oforal medication;○○ water
aspiration (near‐drowning),
including in lizards unattended while
soaking in buckets of water.
Oral Discharge, Salivation, Gingival
Inflammation, Recession, Ulceration,
Hyperplasia or Exudation●●

Health:–– Stomatitis (bacterial, fungal, viral).
–– Chronic exposure gingivitis and ptyal­
ism – due to traumatic lip defects ordeformed mandibles or maxillae due to
NSHP.
–– Periodontal disease in agamids, chame­leons (includes gingival erythema, swell­ing, recession, ulceration, hyperplasia,
exudation, mainly at the bone‐gingiva
junction).
–– Focal gingival infection following trau­
matic dental loss or fracture.
–– Oral neoplasia – may be ulcerated.
–– Stress‐related rostral abrasion – may
extend deeply into oral tissues.
–– Pneumonia (bacterial, fungal, parasitic) –may present with exudate from glottis inoral cavity.
–– Organophosphate, carbamate, pyre­thrin and pyrethroid insecticide toxicity(salivation).

Dental Loss, Plaque or Calculus●●

Normal:–– Pleurodont species (skinks, geckos,
iguanas, monitors): occasional missing

or shedding tooth – normal continuous
tooth replacement that occurs through­out life in these species.
–– Acrodont species (agamids, chamele­ons): absence of teeth in all dental
arcades – normal in aged individuals, as
the teeth of these species progressively
wear with age and are not replaced.
●● Health:–– Periodontal disease in agamids, chame­leons (supragingival plaque and calcu­
lus, exposure of subgingival bone ofmandibles or maxillae due to gingival
recession, focal erosion and pitting of
exposed subgingival bone).
–– Loose teeth in pleurodonts due to mandi­
ble or maxilla pathology caused by NSHP.
–– Trauma including from biting hard
objects such as oral specula – transient
tooth loss in pleurodonts, fractured
teeth in acrodonts.
Tongue lesions●●

Health:–– Flaccid paralysis in chameleons (tongue
droops from mouth, cannot be pro­pelled for feeding) ‐ common early signof hypocalcaemia due to NSHP or
RSHP.
–– Bacterial or fungal infection of tongueof all species and tongue sheath of mon­itors, chameleons (erythema, ulcera­tion, exudation).
–– Inability to protrude tongue (monitors,
chameleons) due to adhesions within
tongue sheath as sequela of trauma or
infection.

Oral Mucous Membrane Colour●●

Normal:–– White to pale pink: normal for most
species.
–– Yellow‐orange: normal for somebearded dragons and chameleons.
–– Dark purple to jet black: normal for somemonitors, geckos and chameleons.
–– Dark pink: normal for some monitors.

231

232

Reptile Medicine and Surgery in Clinical Practice●●

Health:–– Erythema (generalised or focal): perio­
dontal disease (agamids, chameleons);
stomatitis.
–– Cyanosis: indicative of severe respira­tory compromise.
–– Green (biliverdinaemia): pre‐hepatic,
hepatic or post‐hepatic disease.

Facial or Jaw Swellings, Deformities●●

Health:–– Swollen or misshapen mandibles (‘rub­
ber jaw’) due to fibrous osteodystrophy
from NSHP.
–– Malocclusion, including overshot andundershot jaw, due to fibrous osteodys­
trophy from NSHP.
–– Subcutaneous abscess adjacent to osteo­
myelitis lesion of mandible or maxilla asa sequela of periodontal disease (aga­mids, chameleons).
–– Abscess of temporal gland of chamele­ons (positioned at the commissure of
the mouth).
–– Abscess of other facial tissues, including
due to puncture wound, ectoparasite
attachment.
–– Cellulitis.
–– Fracture or soft tissue wound, including
due to cage‐mate trauma or bite fromprey item.
–– Osteomyelitis (bacterial, fungal).
–– Bone or soft tissue neoplasia.
–– Gout.
–– Sialocoele.

Diarrhoea●●

Husbandry:–– Maldigestion and bacterial overgrowth
due to suboptimal environmental
temperature.
–– Sudden diet change (mostly affects her­bivorous lizards).
–– Inappropriate diet for herbivorous
lizards, including excessive fruit and­insufficient fibre, fermented fruit orvegetables, selectivity for fruit.

–– Inappropriate diet for carnivorous­lizards, including dog food, meat partsand products instead of whole prey
items.
–– Overfeeding.
●● Health:–– Bacterial or fungal enteritis or colitis(including salmonellosis).
–– Protozoal enteritis or colitis (including
coccidia,
Cryptosporidium
spp.,
Entamoeba spp., flagellates).
–– Infestation with hookworms, ascarids,
strongyles.
–– Dysbiosis following antibiotic therapy
or systemic disease.
–– Polyuria, producing semi‐liquid faeces
due to mixing with urine.
Constipation, Reduced Faecal Output
Husbandry:–– Suboptimal environmental tempera­ture, hence cannot reach or maintain
optimal body temperature for normal
gastrointestinal function.
–– Dehydration due to low humidity envi­
ronment or inappropriate delivery ofdrinking water (e.g. some lizards will
only drink from a spray bottle, or fromdroplets on leaves).
–– Insufficient exercise.
–– Insufficient fibre in diet of herbivores oromnivores.
–– Inappropriate food items (e.g. long‐haired rodents, insects with heavy
exoskeletons).
–– Overfeeding of beetle larvae (‘meal­
worms’) due to excess of indigestible
chitin.
–– Ingestion of enclosure substrate (peb­bles, gravel, sand, bark).
●● Health:–– Poor muscle tone and intestinal stasis due
to hypocalcaemia from NSHP or RSHP.
–– Gut obstruction (e.g. intussusception,neoplasia).
–– Extraluminal gastrointestinal blockage(e.g. cystic calculi, dystocia).
–– Spinal neuropathy.
●●Differential Diagnoses: A Problem‐Based Approach

Palpable or Visible Internal Swellings
Normal:–– Gravid female; egg bulges may be visible
through body wall.
●● Health:–– Abscess or granuloma of any internalorgan or coelomic cavity, including
Mycobacteria spp. infection.
–– Inflammatory swelling of any internalorgan.
–– Neoplasia of any internal organ.
–– Ingested foreign body.
–– Faecal impaction.
–– Solid urate mass in colon.
–– Dystocia.
●●

Swelling of the Cloaca or
Hemipenal Region
Health:–– Increased production of hemipenal
plugs due to hypovitaminosis A(chameleons).
–– Bacterial or protozoal cloacitis.
–– Hemipenal pocket infection.
●● Trauma:–– Hemipenal trauma.
–– Mating trauma in female.
–– Oedema of cloacal mucosa secondary totenesmus due to faecal impaction ordystocia.
●●

Prolapse from Cloaca
General:–– Poor muscle tone, intestinal stasis andbloating due to hypocalcaemia from
NSHP or RSHP (prolapse of cloaca,colon).
–– Generalized weakness (prolapsed cloaca,colon, bladder, oviduct or hemipene).
–– Increased intracoelomic pressure due tocoelomic distension (prolapsed cloaca,colon, bladder or oviduct).
●● Gastrointestinal:–– Tenesmus due to parasitism, gastroen­
teritis, cloacitis or gut obstruction
by faecal impaction, intussusception,neoplasia (prolapsed cloaca, colon).
●●–– Straining due to extraluminal gastroin­
testinal blockage, including by tumour,abscess (prolapsed cloaca, colon).
●● Urinary:–– Straining due to bacterial cystitis, cystic
calculi (prolapsed cloaca, bladder, colon).
●● Reproductive:–– Straining due to dystocia (prolapsed
cloaca, oviduct).
–– Prolapsed hemipenes, due to traction
during copulation, bite wounds fromcage mates, spinal injury, contamination
with substrate material, poor muscle
tone from NSHP or straining due to anyof the causes listed above.
Discoloured Urates
Normal:–– Yellow: normal variation of the usual
white or cream urates.
●● Health:–– Green (biliverdinuria): chronic anorexia
or starvation; hepatic disease; cholecys­
titis; bile duct obstruction; haemolysis.
–– Including frank blood: haemorrhage or
inflammation of the kidneys, colon or
cloaca; passage of abnormally hard fae­
ces, causing blood streaking on surface
of both faecal and urate masses; follow­
ing manual palpation to resolve faecal
impaction or egg retention.
●●

Gravid Female not Commencing
or Completing Parturition or
Oviposition●●

Husbandry:–– Environmental temperature or humid­
ity not species appropriate.
–– Failure to provide suitable nest site,
including adequately deep substrate forburying of eggs.
–– Disturbance of parturition by cage mateor external stimulus.
–– Obesity due to overfeeding.
–– Malnutrition.
–– Exhaustion mid‐lay due to poor fitness
in chronically inactive lizard.

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Reptile Medicine and Surgery in Clinical Practice●●

Health:–– Hypocalcaemia, including due tochronic NSHP or RSHP.
–– General debilitation due to other dis­ease process, including systemic illness,dehydration, NSHP or RSHP.
–– Obstructive dystocia due to:○○ oversized or malformed egg or foetus,
crushed egg, dead foetus;○○ pathology external to reproductive
tract (e.g. cystic calculi, narrowed pel­
vic canal following fracture).
–– Salpingitis.
–– Preovulatory follicular stasis (these ani­mals appear to be gravid).
–– Pelvic or spinal trauma.

Limb or Vertebral Swellings●●

Health:–– Bilaterally symmetrical swollen thighs
due to fibrous osteodystrophy of thefemoral diaphysis as a result of NSHP
or RSHP.
–– Focal osteomyelitis of long‐bone orvertebra due to trauma, spread from­adjacent soft tissue infection or haema­
togenous spread.
–– Bone neoplasia.
–– Traumatic fractures, luxations and soft
tissue injuries, including from handlingand bites from cage mates.
–– Pathological long‐bone or vertebral
fractures due to NSHP or RSHP.
–– Septic arthritis.
–– Articular and periarticular gout (radio­
lucent uric acid deposits in and aroundjoints).
–– Hypertrophic osteopathy (hypertrophic
pulmonary osteoarthropathy).

Missing Digits or Tail Tip,
Swellings, Constrictions
Normal:–– Partial tail loss and regrowth due todefensive autotomy (normal in many
iguanas, skinks and geckos).
●● Husbandry:–– Slough retention on digits and tail tip
due to low environmental humidity●●

resulting in tourniquet effect and avas­
cular necrosis.
●● Health:–– Bacterial or fungal infection of digits
due to poor environmental hygiene,
overcrowding or trauma (digital swell­ing and loss due to osteolysis).
–– Cage‐mate trauma.
–– Avascular necrosis of distal tail, digits
due to crushing injury (caught in cagedoor, under rock).
–– Avascular necrosis of distal tail within
two weeks of ventral caudal vein
venepuncture (most likely due to iatro­
genic vascular damage).
Lameness●●

Health:–– Osteomyelitis.
–– Septic arthritis.
–– Bone neoplasia.
–– Traumatic fractures, luxations and soft‐
tissue injuries, including from handlingand bites from cage mates.
–– Pathological long‐bone or vertebral
fractures due to NSHP or RSHP.
–– Penetrating foreign body, plantar sur­face of foot.
–– Foot abrasion or ulceration due to con­tact with or pacing on rough substrate.
–– Degenerative joint disease.
–– Hypertrophic osteopathy.
–– Articular and periarticular gout.
–– Pseudogout (radiopaque calcium depos­
its in joints).

Gait and Posture Abnormalities●●

Health:–– Prone resting posture with ventrum notraised off substrate and limbs splayed
from trunk, due to NSHP (agamids)(normal posture is with the limbs sup­porting the body, raising it at least partly
off the substrate).
–– Ambulation with weight bearing on
carpi and tarsi instead of on toes or feet,
due to NSHP (iguanas).
–– Ossifying spondylosis, causing segmen­
tal fusion of adjacent vertebrae.

Differential Diagnoses: A Problem‐Based Approach

Paresis, Paralysis
Neurological:–– Adenovirus infections (mainly in juve­
nile bearded dragons).
–– Central nervous system infection, bac­terial or fungal or viral or parasitic.
–– Electrocution (flaccid paralysis).
●● Spinal:–– Pathological vertebral fracture or col­lapse due to NSHP or RSHP.
–– Spinal trauma, including from handling,crushing by enclosure furniture, bitesfrom cage mates.
–– Spinal osteomyelitis or abscess.
–– Bone neoplasia.
●● Other:–– Renomegaly.
–– Faecal impaction.
–– Dystocia.
●●

Neurological Signs, Including
Opisthotonus, Head Tilt, Circling,
Ataxia, Muscle Fasciculation,
Convulsions
Nutritional:–– Hypocalcaemia (causes muscle fascicu­
lation and tetany mainly seen in con­junction with chronic NSHP).
–– Hypoglycaemia.
–– Thiamine deficiency (in lizards with ahigh proportion of un‐supplemented
frozen fish or vegetables in their diets).
–– Biotin deficiency (in lizards with a highproportion of unsupplemented raw eggs
in their diets).
●● Toxins:–– Toxicoses from contact with insecti­
cides (organophosphates, carbamates,
pyrethrins and pyrethroids).
–– Toxicoses from ingesting Photinus­fireflies (bearded dragons), snails killed
by bait (blue‐tongued lizards) or canetoads.
–– Drugs, including metronidazole, iver­mectin, and aminoglycoside antibiotics.
–– Ingestion of marijuana.
–– Ingestion of nicotine in tobacco.
–– Ingestion of disinfectants including iodine.
●●–– Ingestion of and exposure to fumes ofhousehold chemicals including paintsolvents, ethylene glycol.
–– Ingestion of plant toxins including cedar
shavings, lilies.
●● Other:–– Head or body trauma.
–– Bacterial and mycotic encephalitis(including micro‐abscesses secondary
to septicaemia).
–– Adenovirus (mainly in young bearded
dragons).
–– Pain.
–– Electrocution (convulsions).
–– Visceral gout.
Sudden Death
Husbandry:–– Hyperthermia from inappropriately
high environmental temperature (e.g.
thermostat failure or exposure to direct
sunlight without opportunity to seek acooler area).
–– Failure of carer to detect earlier signs ofchronic illness.
●● Health:–– Systemic infections including septicae­
mia and adenovirus (mainly in young
bearded dragons); toxicoses fromingesting Photinus fireflies (bearded
dragons), cane toads, nicotine or cyano­genic glycosides in seeds of apples,cherries, peaches and plums.
–– Aneurysm rupture (most commonly inbearded dragons).
–– Trauma.
–– Electrocution.
–– Haemorrhage.
–– Shock.
–– Organ failure (e.g. visceral gout).
●●­Chelonians
Anorexia●●

Normal:–– Females during folliculogenesis, ovula­tion, oviposition.

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Reptile Medicine and Surgery in Clinical Practice–– Males during breeding season.
–– Decreased appetite associated withseasonal decreases in photoperiod andambient temperatures.
●● Husbandry:–– Suboptimal environmental temperature
management, so cannot reach or main­
tain optimal body temperature for feed­
ing – this includes failure to insulate
animals from overnight decreases inambient temperature in colder seasons.
–– Inappropriate photoperiod cycle, affect­
ing stimulus to feed.
–– Inappropriate humidity (too wet or
too dry), affecting general health.
–– ‘Post‐hibernation anorexia’ (land tor­
toises); multifactorial as sequela of incor­
rect hibernation management, including
lengthy period of deprivation of heat,
light, food and water.
–– Maladaptation to new environment.
–– Environmental stress from enclosure
mates.
–– Stress from increased frequency or
duration of handling, including for
management of a health problem.
–– Disturbances in environment outside
the enclosure.
–– Inadequate cage furniture to enablenormal behaviour (e.g. basking, swim­
ming, hiding).
–– Inappropriate food items (e.g. lettuce
to a freshwater turtle; meat to a her­bivorous land turtle).
●● Health:–– Hypovitaminosis A (mainly freshwater
turtles).
–– Metabolic disease, including hypocal­
caemia, dehydration.
–– Infection, neoplasia or organ failure ofany system.
–– Sensory deprivation (e.g. loss of sight –cataracts, corneal lipidosis, frost injury)
or smell (severe upper respiratory tract
infection).
–– Gastrointestinal parasites, notably
Entamoeba spp., Hexamita spp.
–– Gastrointestinal tract infections, neo­plasia or obstruction.

–– Dystocia.
–– Follicular stasis.
–– Pain.
–– Visceral gout.
Weight Loss
All causes of anorexia as above.
Husbandry:–– Suboptimal environmental temperature,so cannot reach or maintain optimal
body temperature for digestion – note
comment about overnight temperaturesin Anorexia section.
–– Dominance of food source or otherresources by tank or enclosure mate.
–– Malnutrition due to insufficient foodquantity or inappropriate food items.
●● Health:–– Maldigestion or malabsorption – todate, no precise aetiologies are recog­
nised for these: problems.
–– Endoparasites including amoeba, coc­
cidia, Cryptosporidium spp., Hexamita
spp., nematodes.
–– Foreign body ingestion, generally mis­taken for food items, including plastic
bags, fishing tackle, coins (mainly
marine turtles).
●●●●Distended Coelom (Bulging
Inguinal Fossae)
Normal:–– Gravid female.
●● Husbandry:–– Obesity due to inactivity and overfeed­ing (e.g. high‐protein diet fed to omniv­
orous species; common in Emyduraspp.).
–– Gastrointestinal bloating due to abnor­
mal fermentation, including from sub­optimal environmental temperature,
inappropriate diet.
●● Health:–– Obesity due to hypothyroidism (anec­
dotal reports in giant tortoises due to
low iodine or high goitrogen diets).
–– Ascites (see list of causes below).
●●Differential Diagnoses: A Problem‐Based Approach–– Coelomitis (including yolk coelomitis).
–– Enlargement of any coelomic organ(e.g. neoplasia, granulomas, hepatic
lipidosis).
–– Cystic calculi (land tortoises).
–– Dystocia.
–– Follicular stasis.
Ascites, Subcutaneous Oedema●●

Health:–– Myxoedema due to hypothyroidism(anecdotal reports in giant tortoises due
to low iodine or high goitrogen diets).
–– Renal failure due to hypovitaminosis A(axillary and inguinal oedema).
–– Systemic infection, including as a resultof poor water hygiene.
–– Ranavirus infection (land tortoises andfreshwater turtles) – severe subcutane­
ous cervical oedema.
–– Picornavirus
infection(land
tortoises) – ascites.
–– Herpesvirus infection (land tortoises) –cervical oedema.
–– Herpesvirus (freshwater turtles) – sub­cutaneous oedema, mainly of limbs.
–– Hypoproteinaemia due to anorexia, mal­nutrition, maldigestion, malabsorption,parasitism, hepatopathy, nephropathy.
–– Congestive heart failure or circulatory
failure.
–– Excessive fluid therapy.

Lethargy, Weakness or Depression
Normal:–– Gravid female.
●● Husbandry:–– Inappropriately low environmental
temperature, resulting in suboptimal
activity.
–– Hypothermia due to lack of opportunity
to thermoregulate to a higher body
­temperature (e.g. by basking) at timesof sudden drop in environmental
temperature.
–– Hyperthermia due to lack of opportu­
nity to thermoregulate to a lower bodytemperature (e.g. by soaking in water,entering shade) at times of high envi­
ronmental temperature.
–– Inappropriate light type or photoperiod
cycle, affecting activity levels.
●● Health:–– Hypocalcaemia due to chronic nutri­tional secondary hyperparathyroidism,
NSHP, caused by dietary calcium or
phosphorus imbalance and/or inade­quate exposure to ultraviolet B light.
–– Hypocalcaemia due to renal secondary
hyperparathyroidism (RSHP).
–– Hypovitaminosis A (mainly freshwater
turtles).
–– Nonspecific sign seen with many dis­ease processes, often coupled withanorexia.
–– Metabolic
disease,includingdehydration.
–– Systemic infection including septicae­
mia, viral disease.
–– Heavy parasite burden, notably
Entamoeba spp., Hexamita spp.
–– Neoplasia of any system.
–– Toxicoses, including exposure to insec­
ticides, inappropriate drugs or dosages.
–– Visual deficits, including due to cata­
racts, corneal lipidosis, frost injury.
–– Foreign body ingestion, generally mis­taken for food items, including plastic
bags, fishing tackle, coins, (mainly
marine turtles).
–– Dystocia.
–– Follicular stasis.
–– Anaemia.

●●

Inability to Submerge (Freshwaterand Marine Turtles)
Husbandry:–– Inappropriately low environmental
temperature, resulting in suboptimal
activity and hence inability to divenormally.
●● Health:–– Weakness due to emaciation or any sys­
temic illness, resulting in inability todive normally.
●●

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Reptile Medicine and Surgery in Clinical Practice–– Pneumonia (bacterial or fungal).
–– Lung, eye, trachea disease due toherpesvirus (green sea turtles) –­bronchopneumonia.
–– Pneumocoelom (air free in coelom), due
to lung trauma.
–– Gastrointestinal bloating due to abnor­
mal fermentation, including from sub­optimal environmental temperature,
inappropriate diet.
–– Bloat due to gas‐producing gastrointes­
tinal infection.
–– Ileus due to intestinal impaction or
obstruction (including ingested plasticbags in marine turtles), resulting in gas
distension of bowel.
–– Spinal trauma, resulting inability to divenormally.
Uneven Floating (Freshwaterand Marine Turtles)
Normal:–– Gravidity (does not occur in all gravid
chelonians).
●● Health:–– Any unilateral internal mass, including
abscesses, granulomas, tumours, mak­ing one side of the body heavier thanthe other.
–– Pneumonia or lung abscess, or granu­
loma, making one lung less inflated thenthe other (may occur as sequela of lunginjury and contamination associatedwith carapace fracture).
–– Asymmetric gas production (bloat),making one side of the body more­buoyant than the other.
–– Dystocia.
●●

Dry, Sloughing or Discoloured Skin
Normal:–– Ecdysis (flaky, peeling skin as cheloni­
ans shed piecemeal).
●● Husbandry:–– Abnormal shedding (increased or
decreased), mainly in axillary and ingui­
nal fossae, due to suboptimal environ­mental temperature or humidity.
●●–– Dry skin due to inappropriately low
environmental humidity or unsuitablewater body (freshwater turtles).
●● Health:–– Hypovitaminosis A (mainly freshwater
turtles) – hyperkeratosis.
–– Hypervitaminosis A (iatrogenic) – ini­
tially dry, flaky skin, then blisters,
mainly on neck and limbs, progressing
to necrotizing dermatitis and full thick­ness epidermal sloughing.
–– Deep bacterial or fungal infection –may cause full thickness epidermal
sloughing.
–– Scar at sites of previous trauma or sur­gery (de‐pigmented skin).
–– Burns (thermal, chemical) – may cause
full thickness epidermal sloughing.
Skin Erythema or Petechiae●●

Health:–– Hypovitaminosis A (mainly freshwater
turtles).
–– Septicaemia.
–– Burns.

Skin Abrasions or Ulcerations●●

Health:–– Septicaemic cutaneous ulcerative disease,caused by bacteria, including Citrobacter
freundii and Pseudomonas spp. (freshwa­
ter turtles) – skin ulceration, sloughing,
septicaemia, dehydration.
–– Other ulcerative bacterial or fungal der­matitis, including due to unsuitably highwetness or humidity (land tortoises),poor water hygiene or pool overcrowd­
ing (freshwater turtles).
–– Grey‐patch disease due to herpesvirus
infection (young green sea turtles) –epizootic of small circular papularlesions that coalesce into patches, thenbecome ulcerated or necrotizing.
–– Trauma – bites on feet and neck fromtank mates (freshwater turtles) and rats
during hibernation (land tortoises).

Differential Diagnoses: A Problem‐Based Approach–– Abrasions, mainly on plantar surface offeet from contact with rough substrate(e.g. concrete pools, freshwater turtles).
–– Burns (thermal, chemical).
Cutaneous and Subcutaneous
Swellings
Normal:–– Subcutaneous microchip (chelonians are
typically chipped in the inguinal fossa).
●● Health:–– Subcutaneous abscess or granuloma(due to ectoparasite attachment, punc­
ture wound, foreign body, injection site,poor environmental hygiene) – notably
on feet and neck in freshwater turtles
due to bites from tank mates.
–– Soft‐tissue infection or abscess, or gran­uloma, as sequela of adjacent osteomy­
elitis lesion.
–– Mycobacterial or fungal infection (nod­ular skin lesions).
–– Cellulitis.
–– Attached ectoparasites, including ticks,
mites and leeches.
–– Myiasis due to botflies (mostly box tur­tles, mainly on neck, proximal limbs,
axillary and inguinal fossae).
–– Fibropapillomas due to herpesvirus(common in green sea turtles also seen
in other marine turtle species).
–– Other skin neoplasia, including epider­mal papillomas.
–– Scar at sites of previous trauma or sur­gery (focal skin thickening).
–– Periarticular gout.
–– Injection site reaction.
●●

Shell Fractures and Wounds●●

Health:–– Pathological fracture due to NSHP or
RSHP.
–– Trauma, including motor vehicle, bitewounds from predators, garden tools,
lawnmowers, falls (including being
dropped), crush injury (including by
enclosure rocks).

Soft Shell
Normal:–– Hatchlings and juveniles of many spe­
cies (normally have soft shells).
–– Softshell turtles, pancake tortoises (nor­mally have soft shells).
–– Box turtles (have hinged plastrons that
may be mistaken as soft shells).
●● Health:–– NSHP (uniformly soft, ‘bendy’ shell).
–– Bacterial or fungal infections – focal
areas of soft shell, hyperaemia, fibrinon­
ecrotic debris (‘shell rot’).
–– Picornavirus (land tortoises) – soften­
ing of carapace in young animals.
●●

Shell Deformity●●

Health:–– NSHP (distorted shell).
–– Trauma, including by heat, causing pre­mature closure of shell growth plate(s).
–– Congenital deformity (mostly due toinappropriate incubation conditions).

Pyramidal Carapace
Husbandry:–– Possibly overly rapid growth in juveniles
due to overfeeding or excess dietary
protein.
●● Health:–– NSHP (due to fibrous osteodystrophy).
●●

Shell Epidermis (Scute)
Discolouration, Flaking,Thickening
Normal:–– Ecdysis (scutes are shed, one by one,from the carapace and plastron of somespecies).
–– Green algal growth on surface of scutes
in freshwater turtles.
●● Husbandry:–– Dysecdysis (retained slough) due tosuboptimal environment, including
inadequate thermal management.
●●

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Reptile Medicine and Surgery in Clinical Practice●●

Health:–– Dysecdysis (increased frequency ofsloughing) due to rapid growth, scuteinfections, hypo‐ or hypervitaminosis A.
–– Bacterial infection of dermal bone,causing fluid accumulation underscutes, creating pale foci.
–– Dermal bone (white) exposed by loss ofoverlying epidermal scute, including
due to abrasions and other trauma.
–– Pitted or thickened scutes at sites ofprevious infection or trauma.
–– Scar at site of previous trauma or­surgery (pale).

Shell Epidermis Erythema,
Petechiae●●

Health:–– Bacterial or fungal lesions secondary tobite wounds, other trauma (includingfrom abrasive substrates), inadequate
environmental temperature manage­
ment, poor water quality.
–– Septicaemia (diffuse erythema of
scutes).

Shell Epidermis Ulceration,
Abscessation●●

Health:–– Ulcerative shell disease of freshwater
turtles, generally bacterial, may progress
to septicaemia and death (septicaemic
cutaneous ulcerative disease) – gener­
ally occurs as a result of suboptimal
husbandry including inappropriately
low water and/or basking site tempera­ture, poor water hygiene, tank mateaggression and stress due to tankovercrowding.
–– Other bacterial or fungal infection, aka‘shell rot’ (freshwater turtles, land
tortoises).
–– Trauma, including bite wounds fromother turtles, predators (such as domes­
tic dog).
–– Burns.
–– Frost‐induced necrosis.

Shell Epidermis Masses●●

Health:–– Fibropapillomas due to herpesvirus(common in green sea turtles also seen
in other marine turtle species).

Overgrown or Misshapen
Beak, Toenails
Normal:–– Long nails on hind limbs in females ofsome species for nest digging (normal).
–– Long nails on fore limbs in males ofsome species for mating (normal).
●● Husbandry:–– Overgrown toenails due to inadequate
exercise and opportunity to wear nails,
including digging, access to substrates
of varying hardness or roughness.
–– Overgrown rhamphotheca (upper jaw)
due to lack of exposure to hard or abra­
sive foodstuffs (land tortoises).
–– Possibly overly rapid growth in juveniles
due to overfeeding or excess dietary
protein.
●● Health:–– Overdevelopment of rhamphotheca due
to NSHP (fibrous osteodystrophy).
–– Sequela of paronychia.
–– Chronic abnormal weight bearing due
to injury or limb loss, or degenerative
joint disease.
●●

Eyes: Colour Changes, Opacities
Normal:–– Arcus lipoides corneae (normal age‐
related change) – partly or fully circum­
ferential band of corneal opacity at
limbus.
●● Health:–– Keratitis or corneal ulcer due to bacte­rial, fungal or viral infection.
–– Lung, eye, trachea disease due to her­
pesvirus (green sea turtles) – caseous
keratitis, corneal ulceration.
–– Corneal fibropapillomas due to herpes­
virus (common in green sea turtles also
seen in other marine turtle species).
●●Differential Diagnoses: A Problem‐Based Approach–– Keratitis or corneal ulcer due to trauma,
foreign body or chemical exposure (e.g.
hypochlorite bleach).
–– Lens opacity, hyphaema from frost
damage due to hibernation outdoors intemperatures less than 0 degrees C(land tortoises).
–– Corneal scarring post keratitis, frost
damage.
–– Corneal lipidosis.
–– Cataract.

Ranavirus infection (land tortoises,
freshwater turtles) – conjunctivitis.
○○ Picornavirus
infection(land
tortoises) – conjunctivitis.
○○ Herpesvirus
infection(land
tortoises) – conjunctivitis.
○○ Lung, eye, trachea disease due toherpesvirus (green sea turtles) –­­keratitis, conjunctivitis.
○○ Tortoise poxvirus (land tortoises) –periocular papular skin lesions.
–– Neoplasia:○○ Ocular or periocular neoplasia.
○○ Periocular fibropapillomas due to her­
pesvirus (common in green sea turtles
also seen in other MT species).
○○

Exophthalmia●●

Health:–– Retrobulbar abscess or tumour.
–– Trauma.
–– Bilateral exophthalmia occurs with gen­eralized oedema or vascular obstruction.

Blepharoedema, Blepharospasm,
Conjunctivitis, Ocular Discharge●●

Health:–– Physical problems:○○ Restraint behind the head may cause
blepharoedema due to engorgementof periocular venous sinuses.
○○ Ocular or periocular trauma (eyelid
trauma common in freshwater turtles
from feeding frenzies).
○○ Conjunctival or subpalpebral foreign
body, including dust, sand, pollen.
–– Nutritional:○○ Hypovitaminosis A (mainly freshwa­
ter turtles) – palpebral oedema, case­ous exudate underneath eyelids,
blindness, nasal or ocular discharge.
○○ Inflammatory.
○○ Keratitis, corneal ulcer or panoph­thalmitis.
–– Infectious:○○ Bacterial
or fungal conjunctivitis,
including from ascending infection
via the nasolacrimal duct secondary
to stomatitis or upper respiratory
tract infection.
○○ Mycoplasma spp. upper respiratory
tract infection – blepharoedema, con­junctivitis, ocular discharge.

Loss of Vision
Health:–– Lens opacity, hyphaema, possible reti­
nal injury from frost damage (due tohibernation outdoors in temperaturesless than 0 degrees C (land tortoises).
–– Corneal opacity, including lipidosis.
–– Cataracts.
●● Nutritional:–– Hypovitaminosis A.
●● Neoplasia:–– Corneal or periocular fibropapillomas
due to herpesvirus (common in green
sea turtles but also seen in other marine
turtle species).
●●

Tympanic Membrane Bulge●●

Health:–– Middle ear infection or abscess (com­mon in box turtles also seen in otherfreshwater turtle and land tortoise
species).
–– Neoplasia.

Oral Inflammation, Ulceration,
Abscessation●●

Nutritional:–– Hypovitaminosis A.
–– Hypovitaminosis C.

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Reptile Medicine and Surgery in Clinical Practice

Infectious:–– Bacterial or fungal stomatitis.
–– Ranavirus infection (land tortoises, fresh­water turtles) – stomatitis, tracheitis.
–– Picornavirus infection (land tortoises) –diphtheroid necrotising stomatitis–– Herpesvirus infection (land tortoises) –diphtheroid necrotizing stomatitis,
pharyngitis, glossitis, tracheitis (whiteplaque lesions).
–– lung, eye, trachea disease due to her­
pesvirus (green sea turtles) – diphthe­roid necrotizing stomatitis (mainly
periglottal), pharyngitis, tracheitis.
–– Loggerhead orocutaneous herpesvirus(loggerhead sea turtles) – ulcers, case­ous plaques.
●● Physical:–– Chemical irritation, including from eat­ing certain plants, household chemicals.
–– Penetration injuries or abrasions fromfood items (e.g. prickly branches).
–– Inflammation as sequela of food rem­nant putrefaction when chelonians are
not fasted before winter hibernation.
●●

Oral Mucous Membrane Colour
Pallor–– During hibernation (normal).
–– Inappropriately low environmental
temperature.
–– Anaemia.
–– Cardiovascular disease.
●● Erythema (generalized or focal):–– Septicaemia.
–– Stomatitis.
●● Cyanosis:–– Severe respiratory compromise.
●● Green (biliverdinaemia):–– Pre‐hepatic, hepatic or post hepaticdisease.
●●Nasal or Oral Discharge, Nares
Lesions●●

Nutritional:–– Hypovitaminosis A can predispose to
secondary nasal sinus infections (mainly
freshwater turtles).

Infection:–– Ranavirus infection (land tortoises,
freshwater turtles).
–– Picornavirus infection (land tortoises).
–– Lung, eye, trachea disease due toherpesvirus (green sea turtles) –­bronchopneumonia.
–– Herpesvirus infection (land tortoises)(mostly accompanied by whitish oral
plaques) – rhinitis, pneumonia.
–– Mycoplasma spp. upper respiratory
tract infection (land tortoises; notaccompanied by oral lesions).
–– Other upper respiratory tract infections(viral, bacterial, fungal).
●● Physical:–– Excessive salivation, including due tostomatitis (saliva may enter the choana,
producing nasal discharge).
–– Focal erosion or depigmentation ofnares due to chronic upper respiratory
tract disease.
–– Inhaled irritants, including pollen andfumes of disinfectants and otherchemicals.
–– Foreign body, including grass seeds inupper respiratory tract or pharynx.
●●

Tracheal Discharge●●

Infection:–– Pneumonia, bacterial, fungal, viral or
protozoal, often secondary to chroni­
cally low environmental temperature.
–– Herpesvirus infection (land tortoises) –tracheitis.
–– Lung, eye, trachea disease due to her­
pesvirus (green sea turtles) – tracheitis.
–– Loggerhead genital–respiratory herpesvi­rus (loggerhead sea turtles) – tracheitis.

Dyspnoea, Abnormal Respiratory
SoundsNutritional:–– Hypovitaminosis A.
●● Infection:–– Pneumonia, bacterial, fungal or para­
sitic, often secondary to chronically low
environmental temperature.
●●Differential Diagnoses: A Problem‐Based Approach–– Upper respiratory tract infection due
to Ranavirus (land tortoises, fresh­water turtles), Mycoplasma spp. (landtortoises), other bacteria, viruses orfungi.
–– Lung, eye, trachea disease due toherpesvirus (green sea turtles) –­bronchopneumonia.
●● Physical:–– Neoplasia, primary tumour or lungmetastasis.
–– Inhaled irritants, including pollen,chemicals.
–– Near drowning, including from head,limb or full body entrapment in fishingnets (marine turtles), pool furniture,
uncovered drains or filters.
–– Aspirated foreign bodies, including
grass seeds.
–– Aspiration pneumonia due to inexpert
assist feeding or administration of oral
medication.
Regurgitation or Vomiting
Husbandry:–– Suboptimal environmental temperature
following feeding.
–– Excessive handling within 24–48 hours
after feeding.
–– Overfeeding.
●● Infection:–– Septicaemia.
–– Bacterial or fungal gastroenteritis.
–– Gastrointestinal parasitism.
●● Physical:–– Gastrointestinal obstruction due toingested foreign body, gastrointestinal
neoplasia, granuloma, intussusception
or faecal impaction.
–– Gastrointestinal obstruction due toextraintestinal lesion.
●●

Diarrhoea●●

Normal:–– Semi‐liquid faeces due to mixing withlarge volume of urine.

Husbandry:–– Maldigestion and bacterial overgrowth
due to suboptimal environmental
temperature.
–– Inappropriate diet, including fermented
fruit or vegetables; selectivity for fruit.
–– Overfeeding.
●● Infection:–– Bacterial or fungal enteritis or colitis,
including salmonellosis.
–– Parasitic enteritis or colitis, notably due
to Entamoeba or Hexamita spp.
–– Dysbiosis following antibiotic therapy
or systemic disease.
●●

Constipation or Reduced
Faecal Output
Husbandry:–– Suboptimal environmental temperature,so cannot reach or maintain optimal
body temperature for normal gastroin­
testinal function.
–– Dehydration due to low humidity envi­
ronment, inadequate pool or failure toprovide water ad libitum.
–– Insufficient exercise.
–– Ingestion of enclosure substrate (peb­bles, gravel, sand, bark).
–– Impaction with the chitinous and shellparts of prey (as sequela to ileus in wild
marine turtles in rehabilitation care).
●● Health:–– Gastrointestinal obstruction (e.g. intus­
susception, neoplasia).
–– Extraluminal gastrointestinal blockage(e.g. cystic calculi, dystocia).
–– Spinal neuropathy.
●●

Coelomic Masses Palpable or
Visible at Inguinal Fossae
Normal:–– Folliculogenesis and atretic follicles.
–– Gravid female.
●● Health:–– Abscess or granuloma of internalorgan or coelomic cavity, including
Mycobacteria spp. infection.
●●

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Reptile Medicine and Surgery in Clinical Practice–– Neoplasia or cyst of internal organ or
coelomic cavity.
–– Inflammatory swelling of internal organ.
–– Faecal impaction.
–– Intussusception.
–– Cystic calculi.
–– Dystocia.
–– Retained unfertilized eggs (slugs).

dehydration, hypokalaemia, hypocal­
caemia from NSHP and RSHP.
–– Coelomic distension, including due toobesity, causing prolapse by increased
intracoelomic pressure.
–– Tenesmus due to parasitism, gastroenteri­tis, cloacitis or gut obstruction by faecal
impaction, intussusception, neoplasia.
–– Straining due to extraluminal gas­
tointestinal blockage, including by
tumour, abscess, cystic calculi.
–– Mating injuries, including forced sepa­
ration during copulation–– Other trauma, including contaminationof erect, protruded phallus with substratematerial and bites from cage mates.
–– Excessive libido (phallus becomes swol­
len and cannot retract).
–– Spinal injury.

Cloacal Swelling●●

Health:–– Bacterial or protozoal cloacitis.
–– Myiasis, often as sequela of faecal soil­
ing, diarrhoea (land tortoises).
–– Penile trauma.
–– Mating trauma in female.
–– Oedema of cloacal mucosa secondary totenesmus due to faecal impaction ordystocia.

Bleeding From Cloaca●●

Health:–– Trauma, including phallus laceration, mat­ing trauma in both males and females.
–– Haemorrhage from gastrointestinal
tract, urogenital tract or cloaca due toinfection, parasitism, neoplasia.
–– Cystic calculi (land tortoises).
–– Dystocia.

Prolapse of Other Organs from Cloaca(May be Urinary Bladder,
Oviduct, Colon or Cloaca)●●

Intracloacal and Pericloacal
Ulceration●●

Health:–– Loggerhead genital‐respiratory herpes­
virus (loggerhead sea turtles), including
ulcers at base of phallus.

Phallic Prolapse (Large Pink, Purple,
Tan or Black Mass with
Spade‐Shaped Tip)
Normal:–– Penile erection in male, retracts withinseveral hours (normal).
●● Health:–– Inability to retract and retain phallus due
to generalized weakness or poor muscle
tone, including from systemic illness,●●

Health:–– Poor muscle tone due to hypocalcaemia
from NSHP or RSHP.
–– Generalized weakness, including due
to systemic illness, dehydration,
hypokalaemia.
–– Coelomic distension, including due toobesity, causing prolapse by increased
intracoelomic pressure.
–– Tenesmus due to parasitism, gastroen­
teritis, cloacitis or gut obstruction by
faecal impaction, intussusception, neo­plasia (prolapsed cloaca, colon).
–– Straining due to extraluminal gastroin­
testinal blockage, including by tumour,abscess.
–– Straining due to oviposition, dystocia,
salpingitis.
–– Straining due to any other cause includ­ing dyspnoea, cystic calculi.

Gravid Female not Commencing orCompleting Oviposition●●

Husbandry:–– Environmental temperature, humidity
or lighting not species appropriate.

Differential Diagnoses: A Problem‐Based Approach–– Failure to provide suitable nest site,
including adequately deep substrate forburying of eggs.
–– Competition for nest sites by enclosure
mates.
–– Disturbance of parturition by cage‐mateaggression or external stimulus.
●● Health:–– Obesity, poor fitness.
–– Hypocalcaemia, including due tochronic NSHP or RSHP.
–– General debilitation due to other dis­ease process, including systemic illness,dehydration, NSHP or RSHP.
–– Obstructive dystocia due to oversized,
malformed or crushed egg(s).
–– Obstructive dystocia due to pathology
external to reproductive tract (e.g. cystic
calculi, narrowed pelvic canal following
fracture).
–– Ectopic egg(s), in coelom, urinary blad­der, colon, pelvis.
–– Reproductive tract infection.
–– Pain or neurological deficits due to pel­vic, spinal or shell trauma.

–– Trauma, including fractures, luxations,cruciate ligament injury in land
tortoises.
–– Degenerative joint disease.
–– Periarticular or articular gout.
–– Pseudogout.
Missing Digits or Tail Tip●●

Lameness, Gait Abnormalities●●

Swollen limbs●●

Health:–– Fibrous osteodystrophy due to NSHP or
RSHP, resulting in thickened bone shafts.
–– Focal osteomyelitis due to trauma,
spread from adjacent soft tissue infec­
tion or haematogenous spread.
–– Bone neoplasia.
–– Traumatic fractures.
–– Pathological fractures due to NSHP or
RSHP.
–– Limb oedema or necrosis following
entanglement (mainly marine turtles).
–– Limb oedema or necrosis from frost
damage due to hibernation outdoors intemperatures less than 0 degrees C (landtortoises).

Joint Swelling●●

Health:–– Septic arthritis.
–– Periarticular abscess.
–– Osteomyelitis.

Health:–– Avascular necrosis of digits as sequelaof bacterial or fungal osteolysis due topoor environmental hygiene, over­crowding, trauma.
–– Avascular necrosis of distal tail, digits
following crushing injury (e.g. caught
under rock), frost injury.
–– Cage or tank‐mate trauma.

Health:–– Osteomyelitis.
–– Septic arthritis.
–– Bone neoplasia.
–– Traumatic fractures, luxations and soft
tissue injuries, including from being
dropped, crushed, bites from enclosure
mates, bites from rats during hibernation.
–– Pathological long‐bone or vertebral
fractures due to NSHP or RSHP (signs
include inability to raise the body off theground).
–– Penetrating foreign body, plantar sur­face of foot.
–– Foot abrasions or ulcerations due to con­tact with or pacing on rough substrate.
–– Degenerative joint disease.
–– Articular and periarticular gout.
–– Cystic calculi.
–– Dystocia.

Paresis or paralysis
Normal:–– Gravidity or oviposition (may present
with hind limb paresis).
●● Health:–– Herpesvirus infection (land tortoises).
–– Other systemic illness.
●●

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Reptile Medicine and Surgery in Clinical Practice–– Faecal impaction.
–– Toxicosis from the products of ingesta
putrefaction when chelonians areallowed to chill following feeding or are
not fasted before hibernation.
–– Renomegaly.
–– Cystic calculi.
–– Dystocia (egg retention).
–– Follicular stasis.
–– Spinal osteomyelitis or abscess.
–– Bone neoplasia.
–– Pathological vertebral fracture or col­lapse due to NSHP, RSHP.
–– Spinal trauma, including from being
dropped, crushed by enclosure furni­ture, carapace injury.
–– Central nervous system infection, bac­terial, fungal, viral or parasitic.
–– Ivermectin toxicity (causes depression,paralysis, coma, death in chelonians).
–– Visceral or intervertebral gout.
–– Electrocution (flaccid paralysis).
–– Iatrogenic spinal cord compression fol­lowing injection of fluids or medication
into dorsal tail vein (occurs occasionally).
Neurological Signs Including
Ataxia, Hypermetric Gait, Circling,
Convulsions●●

Health:–– Sequela of hibernation outdoors in tem­
peratures less than 0 degrees C, hyper­
thermia or near drowning (possibly due
to hypoxia‐induced cerebral oedema or
cerebellar injury).
–– Thiamine deficiency (in animals with ahigh proportion of unsupplemented
frozen fish or vegetables in their diets).
–– Metabolic disease, including hypogly­
caemia, hypocalcaemia.
–– Septicaemia.
–– Herpesvirus infection (land tortoises).
–– Toxicosis from contact with insecticides(organophosphates, carbamates, pyre­thrins and pyrethroids).
–– Drug toxicity, including ivermectin,
metronidazole and aminoglycosideantibiotics.

–– Ingestion of toxic compounds, inclu­
ding pesticide residues on food,­marijuana, nicotine in tobacco, disin­fectants including iodine, snail orrodent bait.
–– Ingestion of plant toxins including cedar
shavings, lilies, oak leaves.
–– Ingestion of and exposure to fumes ofhousehold chemicals including paintsolvents, ethylene glycol.
–– Otitis media or ear abscess.
–– Joint luxation (ataxia, hypermetric gait).
–– Bacterial and mycotic encephalitis(including micro‐abscesses secondary
to septicaemia).
–– Central nervous system trauma or
neoplasia.
–– Hepatic encephalopathy.
–– Pain.
–– Electrocution.
–– Visceral gout.
Sudden Death
Husbandry:–– Hyperthermia (from inappropriately
high environmental temperature (e.g.
thermostat failure or exposure to direct
sunlight without opportunity to seek acooler area).
–– Failure of carer to detect earlier signs ofchronic illness.
●● Health:–– Systemic
infections,
including
septicaemia.
–– Ingestion of toxic compounds, includ­ing nicotine, cyanogenic glycosides inseeds of apples, cherries, peaches andplums (land tortoises).
–– Ivermectin toxicity (this drug should
not be used in chelonians).
–– Trauma.
–– Drowning, including from entrapment
in fishing nets (marine turtles), pool
furniture, uncovered drains or filters.
–– Electrocution.
–– Haemorrhage.
–– Shock.
–– Organ failure (e.g. visceral gout).
●●Differential Diagnoses: A Problem‐Based Approach­Crocodilians

Weight Loss, Suboptimal Growth Rate

Anorexia●●

Husbandry:–– Suboptimal environmental temperature
management, so cannot reach optimal
body temperature for feeding.
–– Inappropriate photoperiod cycle, affect­
ing stimulus to feed.
–– Insufficient exposure to ultraviolet light.
–– Maladaptation to new environment.
–– Environmental stress from enclosure
mates.
–– Stress from increased frequency or
duration of handling, including for
management of a health problem.
–– Disturbances in environment outside
the enclosure.
–– Inadequate enclosure design to enablenormal behaviour (e.g. basking, hiding).
●● Health:–– Systemic infections, including viral(herpes virus, adenovirus), bacterial(consider Salmonella, Mycobacteria andChlamydia spp., as well as opportunists
such as Pseudomonas and Aeromonasspp.), mycotic (particularly Fusariumspp.), parasitic (especially Coccidia spp.
in hatchlings and yearlings).
–– Pneumonia.
–– Bacterial
orfungalstomatitis,
oesophagitis or gastroenteritis.
–– Gastrointestinal tract parasites.
–– Gastrointestinal neoplasia.
–– Gastrointestinal obstruction (see listof causes under Vomiting or
Regurgitation).
–– Hepatopathy,
includinghepatic
lipidosis.
–– Extraintestinal inflammation or infec­
tion, neoplasia and other disease,including gout.
–– Steatitis and fat necrosis due to vitamin
E deficiency (in animals with a high pro­portion of frozen fish in their diet, as thevitamin E in fish is depleted duringfreezing, in its action as an antioxidantof polyunsaturated fatty acids).
●●

All causes of anorexia as above.
Husbandry:–– Suboptimal environmental tempera­ture, so cannot reach or maintain opti­
mal body temperature for digestion.
–– ‘Runting’ of some individuals housed ina group, likely due to competition for
food, hierarchical stress – may predis­
pose to disease.
–– Malnutrition due to insufficient foodquantity or inappropriate food items.
●● Health:–– Neoplasia.
–– Cardiac dysfunction.
–– Mycobacterial infection (causes intes­
tinal wall thickening, maldigestion,
malabsorption).
–– Other causes of malabsorption and/or
maldigestion.
–– Nephropathy.
–– Pain.
●●Distended coelom
Normal:–– Gravid female.
–– Recent large meal.
●● Health:–– Obesity due to inactivity and overfeed­
ing, including dominant animal ingest­
ing extra food.
–– Anasarca due to hypovitaminosis
A (occurs when animals are not fed
whole prey, without vitamin A
supplementation).
–– Ascites.
–– Coelomitis.
–– Neoplasia of any coelomic organ,
including lymphosarcoma.
–– Yolk sac retention in hatchlings, may
include inspissation from secondary
infection.
●●

Changes in Behaviour●●

Normal:–– Posturing, vocalization, head and tailslapping (normal breeding ritual).

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Reptile Medicine and Surgery in Clinical Practice–– Intraspecific aggression – breeding,territorial.
●● Husbandry:–– Intraspecific aggression due to over­crowding.
–– Stress associated with relocation.
–– Hypo‐ or hyperthermia.
Increased Time Spent Basking
Normal:–– Gravid female.
–– Behavioural thermoregulation to opti­
mize postprandial digestion.
●● Husbandry:–– Decreased ambient temperature.
–– Decreased water temperature (coldshock).
–– Most causes of ill health.
●● Health:–– Pneumonia.
●●

Increased Time Spent Submergedin Water●●

Husbandry:–– Environment inappropriately dry or
hot.
–– Stress, lack of hides.
–– Dominant animal in enclosure occupy­
ing basking space.

Inability to Submerge, Floating
Just Below Surface
Normal:–– Resting or observation position.
●● Health:–– Gas accumulation due to gut obstruc­tion by ingested foreign body, enteric orcolonic fibrosis or adhesions as sequel
to infection, including with West Nilevirus.
–– Gas accumulation associated with gas­
trointestinal infection or empty gastro­
intestinal tract.
–– Interdigital subcutaneous emphysema
or oedema in hatchlings (bubble
foot’ – unknown aetiology).
●●

Abnormal Swimming Motion, Posture●●

Health:–– Pneumonia (see list of causes under
Mouth Gaping) – swimming in circles
or tilted to one side.
–– Encephalitis (causes in NeurologicalSigns section) – head tilt, swimming incircles.

Skin Discolouration (Generalized
or Focal)Normal:–– White or patchy pigmentation (leucis­tic) – normal pigment variation due torecessive leucism gene.
–– Scar tissue from previous trauma,including propeller injuries, bites orrake marks from conspecifics.
●● Health:–– Septicaemia (pink or red discolouration
especially seen on ventral scales).
–– Dermatophilus spp. infection (brownspot disease) – red or brown lesions,mostly between scales, mostly on theventral skin.
–– Chlamydia spp. infection.
–– Lymphohistiocytic proliferative syn­drome of alligators (PIX disease) –multifocal superficial dermal lesions(1–2 mm diameter), grey or red discol­ouration, mostly on the ventral mandib­ular, abdominal and tail scales (occurs
in association with West Nile virus
infection).
–– Sooty accumulations on skin, caused byunidentified Trematode sp.
●●

Skin Hyperkeratosis, Granulomas,
Proliferative Nodules, Papules,
Pustules, Blisters, Ulceration
Husbandry:–– Poor environmental hygiene, including
poor water quality management, predis­
poses to microbial dermatitis.
●● Health:–– Dermatophilus spp. infection – red orbrown lesions, mostly between scales ofthe ventral skin, may include ulceration.
●●Differential Diagnoses: A Problem‐Based Approach–– Erysipelothrix insidiosa infection.
–– Other bacterial dermatoses, mainly sec­
ondary to viral or fungal infections.
–– Dermatomycoses,
includingChrysosporium, Paecilomyces, andFusarium spp. and Candida albicans.
–– Interdigital subcutaneous emphysema
or oedema (bubble foot – aetiology
unknown) – Trichophyton or otherfungi may be cultured from lesions.
–– Herpesvirus infection (saltwater croco­
diles) – crusty lesions on abdominal skin.
–– Pox virus infection – white, grey, yellow
or brown, circumscribed, raised, crusty
foci of dermal necrosis (1–8 mm diam­eter) on head, jaws, eyelids, neck, limbs,
trunk, which may coalesce and ulcerate(may occur as epizootic infection).
–– Scars from healed pox virus dermal necro­
sis lesions – may cause skin ­contraction,
deforming the head and mandible.
–– Capillaria crocodilus skin lesions –zigzag shaped ‘worm trail’.
–– Pododermatitis, including due to
Trichophyton spp. – hyperkeratosis,
chronic proliferative lesions.

due to nutritional or renal secondary
hyperparathyroidism (NSHP, RSHP).
–– Rib fractures.
–– Subcutaneous abscesses, including sec­
ondary to traumatic wounds.
–– Bonyswellings
due
to
focal
osteomyelitis.
–– Soft tissue infection, abscess or granu­
loma as sequela of adjacent osteomyeli­
tis lesion.
–– Omphalitis in hatchlings, including due
to Aeromonas infection – swelling atsite of yolk sac attachment on mid ven­
tral body wall.
–– External yolk sac in hatchlings – due topremature hatching.
Eye Distension, Discharge,
Conjunctival Swelling●●

Skin Abrasions, Thickening, Disruption●●

Husbandry:–– Burns (including from contact with heatlamps or occasionally with electrostun­ning equipment).
–– Traumatic wounds, including bites fromenclosure mates, fish hooks, entangle­
ment injuries – may become secondar­
ily infected, producing abscesses ordraining sinuses.
–– Stress‐related rostral abrasions.
–– Scar tissue from previous trauma,including propeller injuries, bites orrake marks from conspecifics.

Cutaneous and Subcutaneous Swellings●●

Health:–– Hypovitaminosis E – painful, swollen
subcutaneous nodules due to steatitis,
fat necrosis.
–– Excessive fibrocartilage deposition
around long‐bone or facial fractures

Health:–– Eye trauma, including ocular rupture.
–– Blepharoconjunctivitis due to Chlamydia
spp. infection – swollen eyelids, fibrinous
discharge (typically seen as epizootics inyoung farmed crocodilians).
–– Opportunistic bacterial or fungal ocular
infection.
–– Ophthalmia, including due to pox virus
with secondary bacterial infection(Streptococcus, Aeromonas spp.) – peri­
ocular dermatitis, purulent or caseous
ocular discharge, palpebral adhesions,hypopyon, uveitis.

Mouth Gaping
Normal:–– Basking position (aids in thermoregula­tion).
●● Health:–– Nasal disc and or or maxillary obstruc­tion or injury.
●●

Gingival or Oral Inflammation,
Ulceration, Petechiation, Exudation●●

Health:–– Hyperthermia.
–– Hypovitaminosis A – nodular tongue
lesions due to glandular squamous

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Reptile Medicine and Surgery in Clinical Practicemetaplasia and hyperkeratosis (affectedanimals may also have similar pathologyof the renal tubules).
–– Trauma, including puncture wounds
from conspecific bites, fish hooks.
–– Electrocution (petechiation only).
–– Septicaemia (petechiation only).
–– Organophosphate toxicity.
–– Bacterial stomatitis.
–– Pharyngitis due to Chlamydia spp.
infection – accumulation of fibrin in theoropharynx and on the gular valve, may
obstruct airway (typically seen as epizo­
otics in young farmed crocodilians.
–– Dermatophilus spp. infection – focal,
proliferative lesions.
–– Fungal infections, including Candida
spp.
–– Pox virus infection – proliferative,
crusty, white, grey, yellow or brownlesions on the tongue, palate, gingivae.
–– Stomatitis, including due to Aeromonas,
West Nile virus infection.

–– Pharyngitis due to Chlamydia spp.
infection – accumulation of fibrin in theoropharynx and on the gular valve, may
obstruct airway (typically seen as epizo­
otics in young farmed crocodilians).
–– Pneumonia due to Mycoplasma spp. –signs also include white ocular discharge,
lethargy, weakness, paresis, oedema(facial, periocular, cervical, limbs).
–– Pneumonia due to other bacteria,
including
Staphylococcus
aureus,Pasturella multocida, Pseudomonas,
Aeromonas spp.
–– Fungal pneumonia, including due toPaecilomyces, Fusarium, Aspergillus,
Candida, Cephalosporium spp.
–– Parasitic lung lesions, including due topentastomids.
–– Granulomas and neoplasia of the upperand lower respiratory tracts.
Vomiting, Regurgitation(Uncommon)●●

Tooth Loss or Damage
Normal:–– Normal attrition (replaced regularly
throughout life).
–– Extreme age (absence of complete
dentition).
●● Health:–– Trauma (inconsequential).
●●

Dyspnoea, Tachypnoea, Nasal
Discharge
Husbandry:–– Near drowning during capture, trapping
or accidental net entanglement.
●● Health:–– Aspiration pneumonia due to basihyoid
valve malfunction, mostly in animals
with generalized weakness from under­
lying illness.
–– Rhinitis, pharyngitis, mainly bacterial,
fungal.
●●Health:–– Bacterial or fungal gastroenteritis,
including due to Candida spp.
–– Gastrointestinal obstruction due toingested foreign bodies, including coins,polyvinylchloride pipe, components ofthe pool filtration or water treatment
system.
–– Gastrointestinal obstruction due toneoplasia, granuloma, intussusception,
torsion or faecal impaction–– Gastrointestinal obstruction due toextraintestinal lesion.
–– Hepatopathy.

Diarrhoea (Including Mucoid,
Haemorrhagic)●●

Health:–– Adenovirus enteritis, with secondary
infections as detailed below.
–– Bacterial enteritis in hatchlings, includ­ing due to Salmonella, Aeromonas spp.,
often as sequela of adenovirus infection.

Differential Diagnoses: A Problem‐Based Approach–– Coccidial enteritis due to Eimeria,
Isospora spp. (often occurs together
with Aeromonas infections as sequela ofadenovirus infection.
Cloacal Swelling●●

Health:–– Bacterial or protozoal cloacitis.
–– Oedema of cloacal mucosa secondary totenesmus due to faecal impaction ordystocia.
–– Phallic trauma.
–– Paracloacal gland infection.

Prolapse from Cloaca●●

Health:–– Cloacal mucosa, gut, phallus or oviductdue to generalized weakness, cloacitis,
trauma.
–– Intestine due to parasitism or gut
obstruction (faecal impaction, intussus­
ception, neoplasia).
–– Oviduct, generally postpartum.
–– Phallus, generally post‐mating or fol­lowing trauma.

Gravid Female not Commencing orCompleting Oviposition
Normal:–– Primigravid female.
●● Husbandry:–– Failure to provide appropriate environ­mental conditions, including suitable
nest site.
–– Disturbance of parturition by enclosure
mate or external stimulus.
–– Malnutrition.
–– Obesity.
●● Health:–– Exhaustion mid‐lay due to poor fitness
in chronically inactive crocodile.
–– General debilitation due to other dis­ease process.
–– Dehydration.
●●–– Obstructive dystocia due to oversizedor malformed egg or pathology external
to reproductive tract.
–– Salpingitis.
Musculoskeletal Deformities,
Swelling and Pain
Normal:–– Scute removal (routine marking method
in farmed animals and in biological sur­veys of free‐ranging animals).
●● Health:–– Congenital spinal deformities, including
lordosis, kyphosis, scoliosis, due to egg
incubation at inappropriately hightemperatures.
–– Congenital deformities, including spina
bifida, scoliosis, hydrocephalus, limb
abnormalities, possibly due to maternal
vitamin E deficiency.
–– Rubbery jaw, non‐union long‐bonefractures, skeletal demineralization,
kyphoscoliosis, excessive fibrocartilage
deposition, translucent teeth, due to
RSHP or NSHP (from vitamin D, cal­cium and phosphorus imbalance,
including inadequate exposure to ultra­
violet B light).
–– Traumatic fractures, amputation (tailtip, limbs), luxations and soft tissue
injuries, mainly from conspecificaggression.
–– Lactic acidosis or rhabdomyolysis asso­
ciated with excessive exertion (fighting,mating, capture).
–– Polyarthritis due to Mycoplasma infec­
tion and secondary to systemic bacterial
infection.
–– Polyarticular gout.
●●

Necrosis or loss of tail, digits●●

Health:–– Avascular necrosis due to trauma.
–– Digital necrosis and sloughing due topox virus.

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Reptile Medicine and Surgery in Clinical Practice–– Necrotizing dermatitis.
–– Spinal osteomyelitis.

–– Heavy metal toxicity, including zinc,lead, mercury from ingestion of prey
items killed with lead shot and metallic
objects, including coins.
–– Drug toxicity including metronidazole,ivermectin and streptomycin.
–– Head or body trauma.
–– Electrocutionorelectrostunning(convulsions).
–– Hepatic encephalopathy, including due
to hepatic lipidosis.
–– Renal failure and gout.
–– Pain.

Paralysis●●

Health:–– Pathological fracture (including as
sequela of NSHP, RSHP, proliferative
spinal osteopathy).
–– Electrocution or electrostunning (flac­
cid paralysis).
–– Vertebral trauma.
–– Vertebral osteomyelitis.

Neurological Signs Including
Weakness, Lethargy, Muscle
Tremors, Incoordination, Ataxia,
Star‐Gazing, Head Tilt,
Opisthotonus, Convulsions●●

Health:–– Thiamine deficiency (in animals fed fro­zen fish as a high proportion of their diet,without vitamin B1 supplementation, due
to the action of thiaminases in the fish) ‐weakness, ataxia, muscle tremors, coma.
–– Septicaemia.
–– Hypoglycaemia, mostly as sequela ofstress (notably from handling andrestraint) or septicaemia (notably
Salmonella, Aeromonas spp.) – muscle
tremors, loss of righting reflex,
mydriasis.
–– Bacterial and mycotic encephalitis(including micro‐abscesses secondary
to septicaemia).
–– West Nile virus infection – head tilt,
swimming in circles, muscle tremors,
opisthotonus, weakness, lethargy (mainly
occurs as epizootic in juveniles).
–– Chemical toxicity, including by iodine
disinfectants and organophosphate or
carbamate insecticides (predominantly
in hatchlings).

Sudden Death
Husbandry:–– Hyperthermia (from inappropriately
high environmental temperature (e.g.
thermostat failure or exposure to direct
sunlight without opportunity to seek acooler area).
–– Cold shock (especially in hatchling
farmed crocodiles).
–– Stress response to handling (cause ofdeath includes hypoglycaemia, see
Health, but is not always understood).
–– Failure of carer to detect earlier signs of
illness.
●● Health:–– Septicaemia.
–– Hypoglycaemia, mostly as sequela ofstress (notably from handling andrestraint) or septicaemia (notably
Salmonella, Aeromonas spp.).
–– Trauma, including aggression fromenclosure mates.
–– Drowning during capture, trapping or
entanglement in fishing nets, pool
furniture.
–– Electrocution.
–– Haemorrhage.
–– Shock.
–– Organ failure (e.g. visceral gout).
●●Differential Diagnoses: A Problem‐Based Approach­Further Reading
DeVoe, R. (2015) Lacertilia (lizards, skinks,
geckos) and amphisbaenids (worm lizards),
in Fowler’s Zoo and Wild Animal Medicine(M.E. Fowler and R.E. Miller, eds), Elsevier
Saunders, St Louis, MO, Volume 8,
pp. 52–60.
Flanagan, J. (2015) Chelonians (turtles,
tortoises), in Fowler’s Zoo and Wild Animal
Medicine (M.E. Fowler and R.E. Miller, eds),
Elsevier Saunders, St Louis, MO, Volume 8,
pp. 27–38.
Fleming, G. and Fontenot, D. (2015) Crocodilia(crocodiles, alligators, caiman, gharial), in
Fowler’s Zoo and Wild Animal Medicine(M.E. Fowler and R.E. Miller, eds), Elsevier
Saunders, St Louis, MO, Volume 8,
pp. 38–49.
Funk, R., Barten, S., Boyer, T. and Nevarez, J.
(2006) Differential diagnoses by symptoms,
in Reptile Medicine and Surgery, 2nd ed.,(D.R. Mader, ed.), Saunders Elsevier,
St Louis, MO, pp. 675–714.
Lock, B. and Wellehan, J. (2015) Ophidia(snakes), in Fowler’s Zoo and Wild Animal
Medicine (M.E. Fowler and R.E. Miller, eds),
Elsevier Saunders, St Louis, MO, Volume 8,
pp. 60–74.

Marschang, R. (2014) Clinical virology, in
Current Therapy in Reptile Medicine andSurgery (D.R. Mader and S.J. Divers, eds).
Elsevier Saunders, St Louis, MO, pp. 32–52.
McArthur, S., Wilkinson, R. and Meyer, J., eds(2004) Medicine and Surgery of Tortoises
and Turtles. Blackwell Publishing, Oxford.
McCracken, H. (1994) Husbandry and diseasesof captive reptiles, in Wildlife, Post
Graduate Committee in Veterinary Science,
University of Sydney, Sydney, pp. 461–546.
Paré, J. (2014) Update on fungal infections in
reptiles, in Current Therapy in Reptile
Medicine and Surgery (D.R. Mader and
S.J. Divers, eds), Elsevier Saunders, St Louis,
MO, pp. 53–56.
Reavill, D. and Griffin, C. (2014) Common
pathology and diseases seen in pet store
reptiles, in Current Therapy in
Reptile Medicine and Surgery (D.R. Mader
and S.J. Divers, eds). Elsevier Saunders,
St Louis, MO, pp. 13–19.
Wyneken, J., Mader, D., Weber, E. and Merigo,
C. (2006) Medical care of sea turtles, in
Reptile Medicine and Surgery, 2nd ed.
(D.R. Mader, ed.). Saunders Elsevier,
St Louis, MO, pp. 972–1007.

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18
Disorders of the Integument
Linda Vogelnest

Anatomy and Physiology
See Chapter 2 for a review of anatomy andphysiology of the integument.
Key Points
The skin is composed of two layers:
1) Epidermis.
●● Keratinizing continually renewing epithelial layer that is episodically shedthroughout life (ecdysis).
●● Modified into scales in many body
regions with the stratum corneum containing hard beta‐keratins unique tobirds and reptiles.
●● Scales
vary in appearance (smooth,keeled), arrangement (tightly abutting,overlapping) and size (small, large sheets,
called scutes) and are joined together bysofter hinged regions, where the stratum
corneum contains softer alpha‐keratins,
to enable flexibility.
2) Dermis.
●● Anchored firmly to the overlying epidermis; consists of connective tissue (collagen, elastin and ground substance),
blood vessels, lymphatics, nerves and, in

contrast to mammals, no hair follicles
and very few glands.
●● Also contains some unique features,
including chromatophore pigment cells(which, in addition to melanocytes in theepidermis, influence external colour andalso impart ability to colour change), andosteoderms (bone deposits). Some osteoderms support overlying scales orscutes (chelonians, blue‐tongued andbearded lizards) and others support body
regions (ventral abdominal region ofmost lizards and crocodilians).
●● It provides physical protection against dehydration, trauma, external pathogens, ultraviolet radiation.
●● Skin also includes specialized display anddefence structures in some species (e.g.
spines, horns, keels and rattles).
●● The appearance of the skin reflects general
health status.
●● The skin is frequently impacted by suboptimal environmental conditions and/or
nutrition.
●● Figure 18.1 shows examples of variation in
reptilian epidermal colour and texture.

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

256

Reptile Medicine and Surgery in Clinical Practice

(a)

(b)

(c)

(d)

Figure 18.1 Examples of variation in reptilian epidermal colour and texture (courtesy of Larry Vogelnest,
Taronga Zoo, Sydney Australia): (a) centralian carpet python; (b) scales on a black‐headed python;(c) freshwater crocodile; (d) knob‐tailed gecko.

­ pproach to Reptilian Skin
A
DiseaseSkin disease is one of the most common rea­sons that captive reptiles will be presented toveterinarians. Since a variety of different
causal factors can produce similar clinicalappearance, a sound approach to manage­
ment is an invaluable clinical tool. As for der­matoses in any animal species, aiming toconfirm a diagnosis or at least to narrow
down to the most likely differentials will ena­
ble more successful treatment and manage­
ment strategies for reptilian skin disease. A
step‐wise approach maximizes efficiency:
gathering and collating clues from the his­
tory and clinical examination findings to for­mulate a preliminary prioritised differential
diagnosis list and then choosing diagnostic
tests and/or management plans accordingly.

Step 1: History Taking
Taking a history is the critical first step in asound diagnostic approach to any dermato­sis. As husbandry plays a central role in many
reptilian dermatoses, collecting details on
the cage or enclosure environment and cur­rent husbandry and feeding practices is vital(see Chapter 10 for more details). Metabolism,
and thus development of disease, is notably
slower than for mammals.
Step 2: Clinical Examination
Although many diseases with contrasting
aetiology can produce similar clinical lesions,lesions can provide useful clues to suggest
the more likely differentials, especially when
considered together with history and test
results. Primary lesions (e.g. vesicles, pap­ules) are more useful clues and sampling sites

Disorders of the Integument

Figure 18.2 Adhesive tape impression
with purple filamentous dermatophyte
hyphae on pale blue keratinocytes(400× magnification; 40× lens).

than secondary lesions (e.g. ulcers). It is
important to examine all body systems, assystemic illness will commonly have cutane­
ous manifestation (see Chapter 10).
Step 3: Diagnostic Testing
Diagnostic testing is ideally guided by a list of
the most likely differentials based on colla­tion of history and clinical examination
details. This enables the most appropriate
tests to be initially chosen (see Chapters 11
12 for more detailed information). Common
tests of value for reptilian dermatoses
include:skin cytology
skin scrapings●● skin biopsies●● microbial culture●● polymerase chain reaction testing.

adhesive tape impressions (dry lesions;stained: no fixative)
Performed by pressing an approximately
5 cm strip of 18 mm wide adhesive tapefirmly on to lesional skin (Figure 18.2).
Examine unstained for mites or stained forbacteria and fungi (e.g. Diff Quik or meth­ylene blue placed on the glass slide under
the tape and stain smeared out with a tis­sue wiped over the tape).
●● fine‐needle aspirates (nodules or swelling;
Diff Quik stain)●●

A 23–21 g needle and 5–10 ml syringe
are used to collect a sample using negative
pressure. The aspirated sample is forcefully
sprayed on to a glass slide for staining as
per impression smears.

●●●●

Skin Cytology

Skin cytology is frequently indicated to eval­uate for common bacterial and fungal infec­
tions, mites, and cell types (inflammatory,
neoplastic):●●

impression smears (moist lesions; Diff
Quik® stain)
Performed by pressing a glass slide firmly
on to lesional skin.

Skin cytology:
Bacteria:
The presence of numerous bacteria on sur­face samples will mostly reflect surface
overgrowth and not necessarily infection.
Intracellular bacteria (within heterophils)
are more consistent with infection, withbacilli more commonly opportunistic in
reptiles.
●● Fungi:
Pathogenic fungi include environmental
opportunists such as a range of moulds(e.g. Penicillium, Aspergillus, Fusarium),
●●

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Reptile Medicine and Surgery in Clinical Practice

Chrysosporium spp. (e.g. Chrysosporium
anamorph of Nannizziopsis vriesii, CANV)
or dermatophytes (e.g. Trichophyton terrestre). These moulds produce fungal
hyphae within tissues: scattered surface
spores can be normal surface contami­
nants, while the presence of fungal hyphaewith tissue invasion and associated inflam­mation confirms infection.
●● Mites:
Tape impressions are useful for evaluating
for superficial mites; large body areas canbe sampled simply. Tape samples can be
stretched gently on to a glass slide andexamined without staining.
Skin Scrapings

Skin scrapings can be useful for detecting
mites but are often more difficult to perform
on body regions with scales. All mites in rep­tiles are surface dwellers, so adhesive tapesampling that is readily performed on all skinregions including under lifted scales may be
preferable.
Skin Biopsies

Skin biopsies can be collected under local
anaesthesia using 2% xylocaine or lidocaine,with elliptical or excisional samples typicallyideal. Punch biopsies can be collected fromsoft skin but not from areas with large scales.
General anaesthesia is required for collectionof shell biopsies from chelonians.
Microbial Culture

Microbial culture for bacteria or fungi should
ideally be performed from fine‐needle aspi­
rates of mass lesions or from sterile tissue
biopsies. For very superficial lesions, skinsurface swabs can be collected after gentle
surface cleaning with sterile saline but results
may be difficult to interpret due to skin sur­face flora and contaminants.
Polymerase Chain Reaction

Polymerase chain reaction (PCR) testing isideally performed from sterile tissue biopsy
samples for most pathogens. Isolation fromsurface swabs does not confirm a role in dis­ease for environmental organisms (e.g. many
mycobacteria, Flavobacterium spp.).
Step 4: Collation of History, ClinicalExamination and Diagnostic Test
Results
Ensuring that the diagnostic test results
make sense in light of the history and clinicalfindings is a vital last step in the diagnostic
approach that is sometimes overlooked. If adiagnosis is not initially achieved, a review of
all case details is important. Basic tests mayneed repeating if there are conflicting or
unclear initial results, prior to considerationof additional testing.

­Common Dermatoses
Diseases within this chapter are groupedbased on the common clinical lesions they
produce, with the important caveat that dis­eases will present with less characteristic
lesions at times. Use this ‘lesional clustering’of diseases as a guide only. Clinical lesions
can provide helpful diagnostic clues but may
also be misleading, so should not be consid­
ered in isolation from history and diagnostic
test results.

­Dermatoses Characterized
by Abnormal Scaling or
Colour Change
Abnormal or excessive scaling (sometimes
called hyperkeratosis) and shedding abnor­
malities (dysecdysis) occur commonly andreflect changes to the outer epidermal layerswith disruption of the normal keratinisation
process. The major causes are suboptimal
husbandry factors (environmental condi­
tions and nutrition), often in combination
with surface skin infections. Focal colourchanges, including erythema, altered pig­mentation and petechiae/ecchymoses, areoften important hallmarks for developing
systemic and/or cutaneous infections.

Disorders of the Integument

Dysecdysis
Dysecdysis refers to abnormal shedding ofskin and is common in snakes and some liz­ards (e.g. bearded dragon). All healthy rep­tiles periodically shed their outer keratinizedepidermal layers (ecdysis, see Chapter 2).
Ecdysis takes approximately 14 days in lizards
and snakes, during which time their appetiteand behaviour may alter. Young growing
snakes and lizards may shed every five to six
weeks and adult snakes three or four times ayear. Dysecdysis is usually associated with
suboptimal environmental conditions andoften one or more other contributing factors.
Aetiology

Low environmental humidity and low ambi­
ent temperature are considered the mostimportant causal factors. Scars from previous
wounds, a lack of appropriate substrates forrubbing and mite infections may also predis­
pose. Systemic factors are important consid­
erations, including any cause of dehydration,
nutritional factors (e.g. hypovitaminosis A)
and causes of immobility. Hyperthyroidism isreported to cause increased frequency of ecd­
ysis (every 1–2 weeks) in older snakes.
Clinical signs

Retained sheets of shed skin are most com­
mon in snakes, either as localized (e.g. spec­
tacles) or generalized forms, and some lizards(mostly localized; e.g. digits, spectacles, dor­sal spine and tail). In lizards, normal frag­mented sheets of shedding skin will be clear
and flexible, while retained skin will bedarker and dry (Figure 18.3). Chelonians areoccasionally affected (typically localized tothe digits). Circumferentially unshed por­tions of skin can form constricting rings
around extremities (digits, tails), resulting inavascular necrosis. Unshed spectacles, pro­ducing a wrinkly or cloudy appearance to theeyes, can result in ocular disease.
Treatment

Affected individuals should be placed in acontainer of lukewarm water, where they
can submerge but retain their head out of

Figure 18.3 Dysecdysis and mite infestation in ablue‐tongued lizard (courtesy of Larry Vogelnest,
Taronga Zoo, Sydney, Australia).

water, for up to two hours daily for two to
three days. Abrasive materials (e.g. wet tow­els) should be provided in the enclosure forrubbing against and also may be used withcare to gently tease away persistent skinafter soaking. Artificial tears applied several
times daily can be useful to soften retained
spectacles. A moist cotton bud can thenfacilitate gentle removal of the retained
spectacle. It is important to address anyother contributing factors or diseases (e.g.
diet, mites). If necrosis of extremities has
occurred, the affected areas should be
amputated (Figure 18.4).
Prevention and Control

Optimizing environmental conditions is ofmajor importance. Raising environmental
humidity and/or temperature is often
needed (e.g. for most snakes 50–60% humid­
ity is ideal). Desert lizards (e.g. collared liz­ards, desert iguanas, horned lizards, thicktailed or leopard geckos) require low humid­
ity and access to a moist area (e.g. plastic tub
containing damp moss, cotton wool, or
paper towels). Rocks and logs should be­provided to rub against. See Chapter 5 fora more detailed discussion of vivarium
requirements.

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Reptile Medicine and Surgery in Clinical Practice

Figure 18.4 Dysecdysis and resultant
avascular necrosis of the affected limb
in a blue‐tongued lizard (courtesy of
Larry Vogelnest, Taronga Zoo, Sydney,
Australia).

Key Points to Note about Dysecdysis
Typically occurs due to low humidity and/or ambient temperature, with or withoutcomplicating factors including previous
scars, mites, and systemic illness.
●● Treatment revolves around soaking and providing gently abrasive surfaces and addressing any other compounding factors.
●● Prevention involves optimal enclosure
environments.
●●

Infections
Ectoparasites
Aetiology Ophionyssus natricis is a shiny

black blood‐sucking mite, with a two‐ tothree‐week lifecycle. It is the mostimportant ectoparasite found on snakes
and also occurs less frequently on a range oflizards, chelonians and crocodilians.
Female mites live for up to 40 days, during
which time they lay up to 80 eggs in dark,
damp, warm niches within enclosures. A
variety of other mites may also infectreptiles (see Chapter 31 for more details).
Mites are contagious to other reptiles
and occasionally people. Environmental
parasites such as trombiculid mites(chiggers), ticks and leeches may also feed
on reptiles.

Irregular shedding cycles/
dysecdysis and pruritic behaviour areclassical. Mites can be seen collecting inskin folds, including the gular fold (ventralneck) and legs, and inside the orbital rim(Figure 18.5). Anaemia may occur withsevere infestations.

Clinical Signs

Diagnosis requires direct obser­
vation of mites (visible as minute moving dark
spots) and microscopic identification fromadhesive tape impressions.

Diagnosis

Ivermectin and fipronil sprayare commonly used. Thorough cleaning of
the environment will help to hasten a
response; eggs and mites may be foundaround water bowls. Pyrethrins andsynthetic pyrethroids (e.g. permethrin) canbe used in the environment and on snakes,
and may be most suitable for large
collections. See Appendix 1, Formulary, formore information.

Treatment

Key Points for Mite Treatment
All animals need treatment.
Treat and disinfect the enclosure.
●● Treat for adequate length of time: at least
four to six weeks.
●●●●

Disorders of the Integument

Figure 18.5 Mites visible inside theorbital rim (courtesy of Brendan
Carmel).

Fungal Infections

1) Yellow fungus disease
Aetiology: CANV is now thought to be an
obligate reptile pathogen. It is a kerat­
ophilic fungal species distinct from der­matophytes that may have previously
been incorrectly labelled as a range of fila­
mentous fungal infections, including
Trichophyton spp. infections. An environ­mental source of this organism has notbeen determined, although infection has
been linked to substandard husbandry
and diet. Fresh food (e.g. crickets) or car­rier animals may be sources of infection.
Zoonosis has been reported, mostly inimmunocompromised people, and conta­
gion occurs to other reptiles. CANV has
been isolated from captive reptiles in
Asia, Australia, Europe and North
America. The nomenclature and taxon­
omy of this fungus is currently underreview.
Clinical signs: bearded dragons andchameleons most commonly affected but
also a variety of lizards, snakes and salt­
water crocodiles. Typically, multifocal
severe yellow scaling, progressing toregions of ulceration, necrosis, crusting
and less commonly nodules. Necrotic
black areas of skin with surrounding
crusts are more typical in chameleons.
Infections tend to expand from a central

point, and may progress to systemic infec­
tion, which can be fatal.
Diagnosis: histopathology, fungal cul­
ture and PCR testing are considered idealfor diagnosis, with PCR testing suggested
as the most sensitive for detecting organ­
isms; however, false positives may occur
unless combined with histopathology
showing fungal hyphae within in tissue.
Fungal culture also confirms the presenceof the organism but it can be difficult toculture (limited growth above 37 °C).
Screening blood tests and evaluation forsystemic disease are also indicated.
Treatment: optimal antifungal therapies
in reptiles have not been not determined
and treatment has been ineffective insome cases. Combination topical and sys­
temic antifungals are recommended.
Ketoconazole has been used successfully(green iguanas) but it is no longer manu­
factured for humans. It has been super­
seded by safer efficacious alternatives(e.g. itraconazole, terbinafine, voricona­
zole; see Appendix 1 for dose rates, etc.).
Raising the environmental temperature to
between 37–39 °C may help during treat­ment if the affected reptile species cantolerate these temperatures.
2) Superficial fungal infections
Dermatophyte infections, such as
Trichophyton terrestre, occur in lizards

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Reptile Medicine and Surgery in Clinical Practice(e.g. blue‐tongued lizard) and can resultin dysecdysis and resultant avascularnecrosis and sloughing of digits or feet
(Rose 2005). Surface infections with otherenvironmental fungi may initially pro­
duce focal scaling regions or yellow,
orange or brown lichenified skin in snakes
and lizards. They will frequently progress
to ulcers and necrosis or nodular granulo­
mas if not diagnosed and treated early.
See moist erythematous dermatoses, fun­gal infections for details. A variety of
CANV‐related Chrysosporium species
has been reported as an emerging causesof ulcerative and nodular dermatoses in arange of reptiles, including iguanas,
bearded dragons and rattlesnakes.
Bacterial Infections

1) Petechiae/ecchymoses
Discrete lesions of haemorrhage occur inchelonians and less commonly in otherreptiles, associated with septicaemia.
Affected reptiles are often weak, withpoor body tone. Urgent aggressive antibi­
otic therapy, fluid‐therapy, heating andsupport are required, but the prognosis is
guarded.
2) Superficial bacterial infections
Aetiology: the Gram‐positive rod‐shaped
coryneform bacterium Devriesea agamarum is an emerging cause of disease incaptive desert lizards. It is part of the nor­mal oral flora in some lizards (e.g. bearded
dragons) and survives well in the environ­ment in humid sand, water and shed crusts.
Clinical signs: severe scaling of the lip
margins (e.g. cheilitis in spiny tailed liz­ards) or trunkal areas. Concurrent septi­
caemia is reported.
Treatment: third‐generation cephalo­
sporins (e.g. ceftiofur or ceftazidime),with or without topical chlorhexidine
0.1% baths, are reported as efficacious.
Viral Infections

Viral skin infections are rare in pet reptiles
and occasional in wild reptiles, associatedwith reptile‐specific and mammalian oravian‐associated viruses. Both host and viralfactors appear important in establishment ofdisease, and concurrent infections with mul­
tiple infectious agents, including multiple
viruses, are recognized.
1) Poxvirus infections
Pox infections have been described incrocodilians (many species), lizards (tegu)
and the Hermann tortoise. Multiple cir­cular grey or white macules, papules orbrownish wart‐like lesions occur, morecommonly on the face. Lesions tend toself‐resolve in three to four months.
2) Herpesvirus infections
Herpesvirus is linked to small circular tocoalescing papular grey lesions (greypatch disease) in young green sea turtles,
with epizootic outbreaks in summer
linked to high water temperatures, over­crowding and organic pollution. Electron
microscopy has confirmed herpesvirus
involvement. Herpesvirus has also been
linked to more exudative cutaneous
plaques in sea turtles and subcutaneous
oedema in tortoises, both in association
with signs of systemic illness.
3) Sunshinevirus infection
Sunshinevirus, a paramyxovirus seen inAustralian pythons, has been associatedwith blisters on the skin of several pythons.
Hypovitaminosis A
Aetiology

Low levels of vitamin A in the diet, typically
due to an all‐meat diet, is a common cause of
disease in chelonians (especially captive raised
aquatic turtles), and also occurs in lizards.
Clinical Signs

Chemosis and blepharoedema of eyes is classi­
cal in chelonians. Dysecdysis, scaling or
abscesses also occur in chelonians and lizards.
Diagnosis

Consistent clinical signs and history are usu­
ally diagnostic. Biopsy reveals hyperkeratosis
and squamous metaplasia in the absence of
infectious agents.

Disorders of the Integument

Treatment

Oral supplementation of Vitamin A is
required; cautious incremental dosing isadvised. Parental forms of Vitamin A should
be used with caution as they can result in
hypervitaminosis A (causing dry scaly skinprogressing to widespread necrosis andsloughing of soft skin; see Appendix 1).
Vitamin A levels must also be increased in
the base diet.
Prevention and Control

Ensure that the animal has a supply of foods
high in vitamin A, such as dark yellow vege­
tables (pumpkin/winter squash), and dark
leafy green vegetables.
Beak and Claw Overgrowth
Beak and claw overgrowth occurs in cheloni­ans, associated with a lack of sufficient abra­
sive substrates or foods, excessive dietary
proteins or nutritional osteodystrophy injuveniles. Treatment involves trimming
excessive growth (in stages when the over­growth is severe), dietary changes and hardfood items such as cuttlefish.

­Moist Erythematous,
Vesicular, Erosive/
Ulcerative and Necrotic
Dermatoses
Suboptimal or inappropriate husbandry anddiet is the most common underlying cause ofmoist erythematous, vesicular, erosive/ulcer­
ative and necrotic dermatoses (see Chapters
4 and 5 for more information).
Environmental Factors
Traumatic Lesions

Skin abrasions occur in lizards, often on the
rostral head but also on extremities, due torubbing or repetitive pushing behaviour on
abrasive surfaces. Wounds in snakes may
occur from live prey. Cage‐mate injuries arealso common. General wound care princi­
ples apply. Bandaging can be helpful for large
wounds.
Thermal or Chemical Burns

Thermal burns occur most frequently fromdirect contact with heat sources and mimic
infectious causes of similar lesions. Carefulplacement, adjustment and protection fromheat sources is the key. Heat sources are best
located along the sides of tank rather than on
the floor and should be screened to prevent
direct contact. Chemical burns occur lessfrequently, associated with cleaning products
used on enclosures. Treatment of both issimilar, using the same principals as for
mammals, including debridement of necrotic
areas, wound care and dressings when theburns are severe. Silver sulfadiazine 1%
cream can be helpful. Healing may lead toscarring, which may in turn interfere withnormal ecdysis.
Infections
Bacterial Infections

1) Superficial bacterial infections
Bacterial infections are very common
causes and complications of reptile der­matoses, most typically causing erosive toulcerative lesions. In snakes initial lesions
with some infections are fluid‐filled vesi­
cles (blister disease).
Aetiology: Most bacteria are Gram‐neg­
ative environmental opportunists, invad­
ing when skin is damaged or weakened
from other causes. In particular, they areassociated with inadequate husbandry,
especially high local humidity (particu­
larly moist bedding or sub‐floor heating),
low environmental temperatures, poorcleaning of environment and poor water
quality. Skin trauma and/or poor nutri­tion are often concurrent.
●● Lizards and snakes:–– Aetiology: Aeromonas, Pseudomonas,
Citrobacter, Escherichia coli, Klebsiella, Proteus, Salmonella, Serratia,

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Reptile Medicine and Surgery in Clinical PracticeFlavobacterium, Morganella, Neisseria spp. all reported. Less frequently
reported are Gram‐positive bacteria,
including Staphylococcus, Streptococcus, Dermatophilus congolensis
or anaerobes including Bacteroides,
Fusobacterium, Clostridium spp.
–– Clinical signs: moist, exudative anderythematous lesions on the ven­trum are most typical, with fluid‐
filled vesicles prominent in snakes,
which may progress to crusts andulceration.
●● Chelonians:–– Aetiology: Aeromonas, Citrobacterand Beneckia chitinovora are mostcommonly implicated.
–– Clinical signs include superficial shellerosions progressing to ulceration
and are common in aquatic cheloni­ans, often with a surrounding rim of
hyperpigmentation. Deep abscesses
may penetrate the full shell thick­ness. Ulcerative dermatitis of thefeet, associated with Pseudomonas
spp. has been reported in a captive
breeding programme for westernswamp tortoises.
Diagnosis: Consistent history, clinicalsigns and cytology (impression smears:
heterophils, macrophages; intracellularbacteria: typically rods) supports involve­
ment of bacteria. Bacterial culture canindicate causal species; pure growths are
more supportive of a causal role.
Treatment: Correction of substandard
husbandry is paramount; particularly
providing dry bedding (e.g. newspaper) or
improving water quality. Aquatic species
may benefit from temporary restriction ofwater access to one hour twice daily.
Surgical debridement is required toremove necrotic areas, repeated daily
until resolving. For superficial lesions,twice daily soaks in chlorhexidine (2–3%
solution for superficial lesions, avoiding
contact with eyes and mucous mem­branes; 0.5% solution for deeper lesions)or povidone iodine 5–10% solution. Silver

sulfadiazine 1% cream or manuka honeycan be helpful to limit infection andencourage healing. For deep lesions, sys­
temic antibiotics are often required, ide­
ally based on culture and sensitivity
testing; enrofloxacin, cefotaxime or cef­
tazidime may be useful initial empiricalchoices while awaiting culture results.
Treatment should continue for a mini­
mum of three to four weeks, until one to
two weeks beyond complete clinical reso­
lution. In deep lesions in chelonians, radi­
ographs can be helpful for initialassessment to determine the depth of
involvement and to guide prognosis.
2) Systemic bacterial infections
Septicaemic cutaneous ulcerative disease(shell rot) occurs in aquatic chelonians,
particularly soft‐shelled turtles. Bacterial
septicaemia in other reptilian species may
also produce skin lesions.
Aetiology:
Citrobacter
freundii,
Beneckea chitinovora, Aeromonas hydrophilia and Serratia spp. are most com­monly implicated, although otherGram‐negative bacteria can be involved.
Beneckea chitinovora may be carried bycrustaceans given as a food source.
Clinical signs: ulceration of the plas­tron, carapace and skin (irregular, case­ated, crateriform ulcers), together withsystemic signs (anorexia, lethargy).
Petechiae and ecchymoses occur com­monly in chelonians with bacterial
septicaemia.
Diagnosis: Consistent history, clinicalsigns (cutaneous and systemic signs) andcytology (impression smears: heterophils,bacterial rods) is suggestive. Bacterial cul­
ture of commonly implicated bacteria
helps to confirm a causal role; blood cul­tures are suggested as ideal when septi­
caemia suspected.
Treatment: The prognosis is guarded
but can be successful with surgicaldebridement, antibiotics based on culture
and sensitivity testing, supportive careand shell support with fibreglass and resin
if the destruction is extensive.

Disorders of the Integument

Fungal Infections

Fungal infections are less frequent than bac­terial infections and typically occur following
injury and skin maceration. They may be
more difficult to treat when established.
Mixed bacterial and fungal infections arecommon. In aquatic chelonians, deep infec­
tions involving bone are reported. A range ofopportunistic fungal may be involved.
Aspergillus, Basidiobolus, Beauveria,
Geotrichium, Mucor, Saprolegnia, Candida,
Fusarium,
Trichosporon,
Trichoderma,
Penicillium, Paecilomyces and Oospora spp. arereported. In aquatic and semi‐aquatic turtles,
the incidence of fungal infections may relate towater pH, as growth of most fungi is inhibited if
the water pH is less than 6.5. CANV is
responsible for yellow fungus disease, which isprimarily seen in the bearded dragon (seeDermatoses Characterised by Abnormal
Scaling or Colour Change section for details).
Unlike other fungi, this appears to be a primarypathogen, and is contagious.

Aetiology

Scaly yellow, orange or brownlesions occur most typically on the lateraland ventral scales in snakes and lizards andmay progress to ulcers, necrosis or nodules.
In chelonians, exudative, erythematous
ulcers and crusts are most common andfluffy or scaly white growths occasional.

Clinical signs

Consistent history, clinical signs
and cytology (impression smears: heterophils,
macrophages, fungal elements) can besuggestive, with histopathology required for
confirmation and fungal culture ideal toguide therapy. The major differentials arethermal or chemical burns, bacterial
infections and dysecdysis. A Wood’s lamp is
generally not useful for reptilian fungal
infections. It will fluoresce a subset ofMicrosporum canis dermatophytes only,
which is a rare pathogen in reptiles. It will
not detect other fungal species.

Diagnosis

Topical antimicrobials (chlorhex­
idine, 2–3% solution or povidone iodine,

Treatment

5–10% solution) or antifungals (miconazole,
ketoconazole, nystatin) can be effective. Deeplesions require debridement and may require
systemic antifungals. Oral itraconazole has
been used in spiny lizards (23.5 mg/kg) and acorn snake (1.5 mg/kg every 36 hours).
Nutritional Factors
Hypovitaminosis E from high‐fat diets is
implicated in ulcerative, necrotic lesions
related to underlying steatitis; reported morecommonly in obese monitor lizards.
Hypervitaminosis A occurs subsequent to
subcutaneous administration of concen­
trated Vitamin A and causes focal to general­ized necrosis and ulceration.

­ apular and Swollen orP
Nodular Dermatoses
Infections
Bacterial Infections

1) Abscesses
Abscesses may develop due to traumatic
implantation or haematogenous spread of
infectious agents and may be multifacto­
rial in origin. They mostly occur becauseof trauma, bite wounds or at injection
sites in chelonians. Wounds from live
prey in snakes or following previous epi­
sodes of septicaemia also occur. Abscesses
are common in lizards, typically associ­ated with underlying husbandry issues.
Aetiology:
Bacteria – common isolates include
Pseudomonas, Proteus, Aeromonas,
Serratia, Providencia, Escherichia coli,
Citrobacter, Salmonella, Serratia,
Streptococcus and Neisseria spp., andCorynbeacterium pyogenes; occasion­
ally mycobacteria or anaerobes (e.g.
Bacteroides, Clostridium, Fusobacterium,
Peptostreptococcus).
●● Secondary
nutritional hyperparathy­
roidism is multifactorial and can be
●●

265

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Reptile Medicine and Surgery in Clinical Practiceattributed to a calcium/phosphorus
dietary imbalance, lack of ultraviolet B
exposure or vitamin D3, or poor hus­
bandry. It more frequent in lizards andchelonians (see Chapter 15).
Clinical signs: localized soft to firmwell‐demarcated nodules, typically insubcutaneous location and more often on
the head and extremities, containing thickcaseous exudate (reptilian heterophilscannot form liquid purulent material).
May ulcerate when very large and may
involve deeper structures such as tendon
sheaths, dental arcades, joints and bones.
Diagnosis is usually straightforward,
based on typical lesions with caseous con­tents. Cytology of abscess contents canguide probable causal organisms, withbacterial culture (ideally of tissue; e.g.
fibrous capsule) required for identifica­tion. Radiographs are important to screen
for deeper invasion in larger lesions.
Treatment: full surgical excision is ideal.
Wounds will often heal readily without
suturing (Paré 2003) or may be sutured
closed. Systemic antibiotics may berequired for larger lesions not readily
excisable, ideally based on culture andsensitivity testing. A third‐generation
cephalosporin (e.g. cefotaxime or ceftazi­dime), which has good efficacy against

Gram‐negative bacteria, may be a useful
initial empirical choice.
2) Intermandibular cellulitis
A diffuse swelling of the lower jaw andthroat occurs as a manifestation of acutesevere sepsis in snakes, most typicallyassociatedwith
PseudomonasorAeromonas infection. Urgent aggressive
antibiotic therapy, fluid therapy, heating
and supportive care are required.
3) Dermatophilus congolensis
Aetiology: Dermatophilus congolensis isa facultatively anaerobic Gram‐positive
filamentous moisture‐loving bacteriumthat survives for at least short periods oftime in the environment, allowing it toreadily transfer to other animals orhumans. Lizards (bearded dragons, mar­bled lizards, green iguanas and chamele­ons), and crocodiles are most frequently
infected following minor skin trauma (e.g.
tick bites, skin abrasions) in association
with moist conditions.
Clinical signs: initial scaling, erythemaand necrosis may develop into subcutane­
ous nodules.
Diagnosis is usually straightforward basedon clinical signs and cytology, with the char­acteristic appearance of filamentous zoo­
spores lined up in double chains, with a‘railway track’ appearance (Figure 18.6).

Figure 18.6 Adhesive tape impression
with parallel rows of deep blue‐
staining Dermatophilus zoosporesamong nucleated and anucleate
keratinocytes and scant degenerate
neutrophils (upper right) (1000×
magnification; oil immersion field).

Disorders of the Integument

Histopathology may be required to con­firm some cases. Bacterial culture canbe difficult and slow due to fastidious
requirements.
Treatment: removal of crusted lesions,
excision of abscesses, drying the environ­ment and potentially systemic antibiot­
ics (penicillin, amikacin) are effective.
Topical povidone iodine (5–10%) or chlo­rhexidine (2–3%) can be helpful for sur­face regions.
Mycobacterial Infections

Subcutaneous nodules are reported rarely inchelonians and there is one report in a boa
constrictor.
Fungal Infections

Fungal abscesses are less common than bac­terial. They are typically associated withhigh humidity, low temperatures, poor
nutrition, concurrent disease and opportun­
istic pathogens.
Aetiology Aspergillus,
Basidiobolus,
Geotrichium, Mucor, Saprolegnia, Candida,
Fusarium, Trichosporon, Trichoderma, Penicillium, Paecilomyces, Oospora, Trichophyton.
Clinical signs

systemic signs.

Nodules with or without

Consistent history, clinical signs
and cytology (impression smears; heterophils,
macrophages and may see fungal hyphae) aresuggestive. Fungal culture (tissue samples)and histopathology is confirmatory.

Diagnosis

Complete surgical excision ofabscesses can be curative. Ketoconazole
20–30 mg/kg once daily for two to fourweeks has been effective in snakes but is
no longer commercially available (seecomments on treatment of scaling andmoist fungal infections). Itraconazole has
been used in lizards. Topical dilute povidone
iodine (10%) has been used for superficial
lesions.

Treatment

Viral infections
Papillomas Squamous papillomas, attributed

to papillomaviruses, have been reported inbearded dragons, green lizards and a numberof chelonians, including Bolivian side‐necked
turtles. Lesions vary from small white to grey,raised, spherical papules to nodules thatcoalesce and may ulcerate. Papillomavirus
has been detected by electron microscopy.
Lesions have been reported to self‐resolve.
Papillomatous
nodules are reported commonly in green
turtles, other species of marine turtles andgreen lizards. Histologically, they are benign
fibroepithelial tumours. Species‐specificherpesviruses have been incriminated as thecausative agent; they have been sequenced by
PCR testing but virus particles have not been
seen on electron microscopy studies andother viruses demonstrated in some cases
may play a contributory role. Multiple
verrucous epidermal proliferations occur on
the neck, head and thighs; particularly in soft
skin including flippers, neck, chin, inguinal
and axillary regions and tail base. Fibromas
can also develop in multiple internal organs
including the lungs, kidneys, liver andintestines. Wide surgical excision isrecommended.

Cutaneous fibropapillomatosis

Poxviruses have been detected incrocodiles, tortoises and other reptiles withskin lesions: in caimans (grey or whitelesions), Nile crocodiles (brown macules towart‐like lesions), a Hermann’s tortoise(papular periocular lesions) and a tegu lizard(brown papules).

Poxvirus

Most notably linked tooutbreaks of morbidity and mortality in fish
and amphibians, Ranavirus infections arealso reported occasionally in chelonians,
lizards and snakes. Lesions include ulcerated
papules (1–4 mm diameter) with overlying
yellow‐grey crusting, severe subcutaneous
oedema in association with oral erosions,
ulceration and systemic illness and nodules.
Transmission between several reptilian

Ranaviruses

267

268

Reptile Medicine and Surgery in Clinical Practicespecies can occur and the virus can survive
long periods in water at low temperatures.
Most viral lesions require electron
microscopy studies for confirmation. PCR
has been used for diagnosis of ranaviruses.
Treatment by surgical excision (whenpossible) is often the treatment of choice,although some lesions may self‐resolve.
Parasites

The larvae of Dracunculus spp. (free living inwater) and Filarioidea (transmitted byarthropods) occasionally cause papular to
nodular/draining lesions in wild‐caught
snakes and lizards, particularly chameleons
and agamas.
Neoplasia
Nodular lesions, with or without overlying
ulceration, may be neoplastic. Fibrosarcomas
are reported as the most common neoplasm insnakes, developing in the intermandibular
subcutaneous region most frequently, withpotential metastasis to internal organs.
Lipomas, liposarcomas, infiltrative lipomas,
squamous cell carcinoma, melanomas, myxo­
sarcoma, lymphoma and chromatophoroma
are all reported in snakes, chelonians and liz­ards. A mast cell tumour requiring periodic
acid–Schiff staining to detect granules and dif­ferentiate from fibrosarcomas is also reported.
Squamous cell carcinoma, melanoma andliposarcomas are reported in lizards.

­Miscellaneous Dermatoses
Nutritional Osteodystrophy
Inadequate diets with long‐term deficiency
of calcium or excess of phosphorus or lack ofvitamin D3 and exposure to ultraviolet light
can results in metabolic bone disease, char­acterized by either failure to mineralize agrowing skeleton or demineralization of amature skeleton (see Chapter 15).
Clinical Signs

Soft misshapen shells occur in chelonians,
with upturned marginal scutes, irregularscutes, small shells or central sagging.
Abnormal posture is characteristic in lizards,
due to soft misshapen bones. Pathologicalfractures can occur.
Diagnosis

Visual inspection and palpation, together
with radiographs, reveal reduced bone andshell density. Serum calcium and phosphorus
levels are typically normal.
Treatment

The diet must be corrected, including a twoto one ratio of calcium to phosphorus andultraviolet light provided through exposure
to sunlight or a broad spectrum artificial
light within 60 cm of the reptile and without
any filtration through glass or plastic. Severe
deformities are not readily treated.

Appendix 18.1 Bacterial Species Involved in Reptilian Dermatoses
Presentation

Species

Clinical lesions

Common bacterial species

Major differentials

Treatment

Superficial

Chelonians(shell rot)

Shell (plastron)
ulceration, loose scutes;
hyperpigmented rim
Moist, exudative,
erythema, oedema mostcommonly, or vesicles,
crusts, ulcers (mostcommonly in snakes;
frequently on ventrum)Gram‐negative opportunists: e.g.
Aeromonas, Citrobacter, Beneckia
chitinovora
Gram‐negative opportunists: e.g.
Aeromonas, Citrobacter, Pseudomonas,
Escherichia coli, Klebsiella, Proteus,
Salmonella, Serratia, Flavobacterium,
Morganella, Neisseria
Aeromonas or Pseudomonas spp. mostcommonly associated with vesicles
Actinobacillus, Arizona, Pseudomonas,
Corynebacterium, Dermatophilus,
Edwardsiella, Enterobacter,
Flavobacterium, Flavomonas,
Morganella, Salmonella, Serratia,
Staphylococcus
Devriesea agamarum

Thermal orchemical burns,
fungal infection

Reduce humidity, raise temperature,and improve cage sanitation,
particularly bedding/water quality.
Superficial: chlorhexidine soaks
twice daily.
Deep: systemic antibiotics (culture
and sensitivity), 3–4 weeks minimum

Fungal infection

Above: ceftiofur 5 mg/kg once dailyfor 2–3 weeks (Hellebuyck et al.
2009)

Snakes (bacterial
dermatitis,
blister disease)

Lizards (bacterial
dermatitis,
blister disease)

Deep

Desert dwelling
lizards e.g. spiny
tailed lizards

Cheilitis, trunkal scaling

All, especiallybearded dragons,
turtles andshinglebacks
Chelonians(abscesses)

Exudative, non‐healing
bite wounds

Mixed

All of the above

Larger enclosures; reduce stocking
density?

Localized soft to firmswellings, well‐defined
capsules, with thickcaseous exudate

Neoplasia, fungal
infection,
hypovitaminosis A

Surgical excision of entire abscess if
possible

Aquatic turtles(SCUD)

Crateriform ulcers onshell and skin; systemic
illness

Gram‐negative opportunists:
Pseudomonas, Proteus, Aeromonas,
Serratia, Providencia, E. coli,
Citrobacter, Salmonella, Corynebacteria
Gram‐positives: Streptococcus, Neisseria
Citrobacter freundii most commonly;
other Gram‐negative bacteria

Fungal infection

Surgical debridement, antibiotics(culture and sensitivity), supportive
care, shell support

SCUD, septicaemic cutaneous ulcerative diseaseAppendix 18.2 Common Dermatoses in Reptiles and Drug Contraindications

1
2

Environmental/
Multifactorial

ReptileBacterial

FungalParasitic

Nutritional/endocrine

Chelonians

Superficial to deep
ulcers/necrosis:
shell rot, abscesses

Superficial scaling/
necrosis, abscesses–

Dysecdysis
Hypovitaminosis A:
scaly, lichenified skin; Thermal burns
abscesses

SnakesSuperficial to deep:
erythema, oedema,
ulcers, necrosis:
blister disease

Yellow‐brownlichenified skin,scaling, necrosis,
abscesses

Mites (Ophionyssus Hyper‐ thyroidism:
increased frequency
natricis,of ecdysis
Trombiculids):
pruritus, dysecdysis

Dysecdysis

Lizards

Cheilitis in Agamids(e.g. spiny tailed
lizard)Yellow‐brown,lichenified scaly skin,abscesses; yellow
fungus disease (e.g.
bearded dragon,chameleon); deep
nodules, systemic
illness–
Mites (e.g.
Hirstiella spp.,
Ophinonyssus
acertinus):
pruritus, dysecdysis

Dysecdysis (less SCC, melanoma, Systemic aminoglycosides:2
common than in lipoma
neomycin, gentamicin,
snakes)streptomycin, kanamycin
Skinks: ivermectin1

Contraindicated.
Use with care.

Neoplastic

Drugs

Lipoma, SCC,
melanoma

Ivermectin1
Injectable Vitamin A2

Fibrosarcoma

Systemic aminoglycosides:2
neomycin, gentamicin,
streptomycin, kanamycin
Indigo snakes: ivermectin1

Disorders of the Integument

References
Hellebuyck, T., Pasmans. F, Haesebrouck F. andMartel, A. (2009) Designing a successful
antimicrobial treatment against Devriesea
agamarum infections in lizards. Veterinary
Microbiology, 139, 189–192
Paré, J.A. (2003) Reptile dermatology, inProceedings of the North American
Veterinary Conference, Small Animal andExotics, Orlando, Florida, USA, 18–22
January, 2003, pp. 1223–1224.
Rose, K. (2005) Reptiles, in Common Diseasesof Urban Wildlife (Australian Registry of
Wildlife Health). Zoological Parks Board of
New South Wales, http://arwh.org/
common‐diseases/reptiles (accessed
26 June 2017).

Further Reading
De Voe, R., Geissler, K., Elmore, S. et al. (2004).
Ranavirus‐associated morbidity and mortality
in a group of captive eastern box turtles(Terrapene Carolina Carolina). Journal of Zoo
and Wildlife Medicine, 35 (4), 534–543.
Goodman, G. (2007) Common dermatoses in
reptiles. In Practice, 29, 288–293.
Harkewicz, K. (2002) Dermatologic problemsof reptiles. Seminars in Avian and Exotic Pet
Medicine, 11 (3), 151–161.
Hatt, J.M. (2010) Dermatologic problems in
reptiles, in Proceedings of the 35th Small
Animal Veterinary Association Congress,
Geneva, Switzerland, June 2–5 2010,
pp. 131–133, http://www.vin.com/apputil/content/defaultadv1.aspx?pId=11310&meta=
Generic&id=4516323 (accessed 8 June 2017).
Hoppman, E. and Barron, H. (2007)
Dermatology in reptiles. Journal of Exotic
Pet Medicine, 16 (4), 210–224.
Johnson, R., Sangster, C.R., Sigler, L. et al.
(2011) Deep fungal dermatitis caused by the
Chrysosporium anamorph of Nannizziopsis
vriesii in captive coastal bearded dragons(Pogona barbata). Australian Veterinary
Journal, 89 (12), 515–519.
Latney, L. and Wellehan, J. (2013) Selected
emerging infectious diseases of squamata.
Veterinary Clinics of North America Exotic
Animal Practice, 16, 319–338.
Literak, I. et al. (2010). Herpesvirus‐associatedpapillomatosis in a green lizard. Journal of
Wildlife Diseases 46 (1), 257–261.
Lukac, M., Robesova, B., Majlathova, V. et al.
(2013) Findings of Devriesea agamarum

associated infections in spiny‐tailed lizards(Uromastyx sp.) in Croatia. Journal of Zoo
and Wildlife Medicine, 44 (2), 430–434.
Maas, A. (2013) Vesicular, ulcerative, andnecrotic dermatitis of reptiles. Veterinary
Clinics of North America Exotic Animal
Practice, 16, 737–755.
Marschang, R. (2011) Review: viruses infecting
reptiles. Viruses, 3, 2087–2126.
Mitchell, M. and Walden, M. (2013)
Chrysosporium anamorph Nannizziopsis
vriesii. An emerging fungal pathogen of captive
and wild reptiles. Veterinary Clinics of North
America Exotic Animal Practice, 16, 659–668.
Nazir, J., Spengler, M. and Marschang, R.E.
(2012) Environmental persistence ofamphibian and reptilian ranaviruses.
Diseases of Aquatic Organisms, 98, 177–184.
Palmeiro, B. and Roberts, H. (2013) Clinicalapproach to dermatologic disease in exotic
animals. Veterinary Clinics of North America
Exotic Animal Practice, 16, 523–577.
Reavill, D. and Schmidt, R. (2009) Review:
pathology of the reptile integument.
Proceedings of the Association of Reptilianand Amphibian Veterinarians. pp. 93–106.
White, S., Bourdeau, P., Bruet, V. et al. (2011)
Reptiles with dermatological lesions: aretrospective study of 301 cases at two university
veterinary teaching hospitals (1992–2008).
Veterinary Dermatology, 22, 150–161.
Wyneken, J. and Mader, D. (2009) Review:
reptilian dermatology. Proceedings of the
Association of Reptilian and Amphibian
Veterinarians. pp. 83‐87.

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19
Diseases of the Gastrointestinal System
Robert Johnson and Bob Doneley

Anatomy and Physiology
The reptilian gastrointestinal system is grossly
similar to mammals, with significant physiological differences. See Chapter 2 for more
information on the anatomy and physiology ofthe gastrointestinal tract.
Key Points
Food intake and rate of digestion are determined by reptile size and metabolic rate.
●● Snakes can swallow large prey items becauseof the unique anatomy of their jaws. The
quadrate, maxillary and palatopterygoidarches are movable, while the rami of thelower jaw are connected at the symphysis bya very extensible elastic ligament.
●● Acidic enzymatic stomach secretions help toprevent the putrefaction of large meals. The
rate of gastric emptying is dependent on the●●­Stomatitis and Dental
DiseaseAlso known as mouth rot or canker, stomati­
tis is a necro‐inflammatory condition of themouth. The presence of purulent exudate on
the glottis may lead to respiratory disease.

body temperature of the reptile and themeal size.
●● Unlike mammals, the structure of the pancreas in the reptile is not always homogeneous. Variable secretions of pancreatic enzymes
have been reported. In most snakes, thespleen and pancreas are closely joined to form
the one organ mass, the splenopancreas.
●● The gall bladder is located within the liver
mass of Chelonia and lizards but is distinct
from and caudal to the liver in snakes.
●● Some species have specialized intestinal
structures to aid digestion; for example, thegreen iguana (Iguana iguana) has a large
sacculated colon to facilitate the fermentation of complex carbohydrates.
●● The cloaca serves as a common exit chamber for the urinary, digestive and reproductive tracts. The slit‐like exit is the vent.

Aetiology
Predisposing factors for stomatitis include
anatomy, diet and immunosuppression.
Agamid lizards and Old World chameleons
have acrodont teeth (attached to the alveolar
ridge of the mandibular and maxillary bones
with no sockets or roots) anchored in place

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

274

Reptile Medicine and Surgery in Clinical Practiceby a thin gum line along the lateral surface of
the alveolar ridge. When this fragile gum tis­sue recedes or is damaged, the periosteum
becomes desiccated and damaged, allowing
bacteria to invade the underlying bone caus­
ing lysis and osteomyelitis. Inappropriate
diet (e.g. feeding soft foods such as fruit andcanned diets, lack of abrasive foods such as
insect exoskeletons) can lead to the accumu­
lation of plaque on the teeth, calculus, peri­odontal disease and gum recession. Tooth
loss and osteomyelitis may result.
Immunosuppression is often associatedwith poor husbandry (e.g. suboptimal tem­
perature and poor hygiene in the enclosure).
This may change the bacterial populationin the mouth from predominantly Gram‐
positive flora to Gram‐negative populations(e.g. Pseudomonas, Aeromonas, Citrobacter,Enterobacter, Eschericia coli and Salmonella).
These bacteria can become invasive following
injury (e.g. striking at objects, bite wounds
from live prey items) or primary viral infec­
tions (e.g. herpesvirus in tortoises).
Clinical Signs and PhysicalExamination Findings
Animals affected with stomatitis may be pre­sented for inappetance (although often inter­
ested in feeding), halitosis (often severe),
bleeding from the mouth and ptyalism. Theremay be discharge (purulent or mucoid) fromthe nares. Some animals will be presented formouth breathing or respiratory noise; caremust be taken to distinguish stomatitis from
respiratory infections (remembering thatthey may be concurrent). In chronic casesthat have progressed to osteomyelitis, there
may be swelling of the bone and soft tissuesof the jaw.
Careful examination of the mouth can beachieved by firstly reflecting the lips and thenopening the mouth gently with a speculum.
Care must be taken to avoid further trauma
to an already painful mouth, and so metal
specula are not recommended.
Diagnosis and Categorization
Diagnosis is usually made on clinical signs.
Stomatitis may be graded as:
Early – mild gingival swelling, pinpoint
haemorrhages on the gums, and salivation(Figure 19.1).
●● Moderate – swollen gums, calculus accu­
mulation, mild gingival recession andoccasional pockets or plaques of purulentmaterial.
●● Severe – abscessation and exposure ofunderlying bone. Occasionally there will bea generalized tissue infection and swellingof the whole head and neck (Figure 19.2).
●●

Figure 19.1 Early stomatitis in a carpet
python.

Diseases of the Gastrointestinal System

Figure 19.2 Sublingual abscess in a
carpet python.

Culture and sensitivity can be used to iden­
tify the pathogenic organisms involved andto determine the most appropriate antimi­
crobial agent for treatment. Since mixed
infections are common, both aerobic andanaerobic cultures should be taken. A sterile
preparation should be performed over thesite to be sampled and a sterile scalpel or nee­dle should be used to collect a deep culture
sample. Caution must be taken when inter­preting the culture results, as it can be diffi­
cult to distinguish between pathogens andnormal oral flora.
Biopsy of bone or associated soft tissue
may be useful as a method for clarifying
the disease process (e.g. distinguishinginflammation from neoplasia) or to identify
pathogenic organisms not recoverable on
culture.
Radiographic assessment of the mouth isusually unrewarding, owing to the superim­
position of other skull bones, but it may
detect osteomyelitis and determine its
extent. With the advent of digital radiogra­
phy and the availability of intraoral plates
providing better resolution lytic lesions canbe more clearly identified. Other modalities
such as computed tomography and mag­netic resonance imaging may be useful indetecting lesions not visible in radiographs(see Chapter 12).

Treatment
Treatment is often determined by the sever­
ity of the condition. Common to all treat­ments is attention to and improvement ofhusbandry. A small increase in the enclosure
temperature above the reptile’s preferredbody temperature may facilitate an improved
immune response. The enclosure substrateshould be changed to newspaper or paper,and changed daily, and regular and effective
disinfection carried out. Assisted feeding
may be necessary in some cases, usually bystomach tube, as forced feeding of prey items
may be painful. See Chapter 13 for moredetailed information. Clean water bowls andfresh water daily are also recommended.
Early cases of stomatitis may respond to
improvements in husbandry and the applica­tion of suitable topical nonsteroidal ophthal­mic antibiotics or oral chlorhexidine‐basedgels. Mild cases may require injectable ororal antibiotics and, if present, gentle
debridement of purulent material or perio­
dontal pockets. Severe cases will require sur­gical debridement, fluid therapy andanalgesia. Haematology and biochemical
screening is recommended in these cases todetermine the severity of the infection and tolook for any underlying disease processes.
Euthanasia may be necessary in severe cases.

275

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Reptile Medicine and Surgery in Clinical Practice

Periodontal disease in agamids and chame­leons will require dental scaling, debride­
ment of necrotic gingiva and bone, andsometimes tooth removal. Many of thesepatients will require stabilization prior toaggressive dental therapy, including rehydra­tion, assisted feeding and a broad‐spectrum
antibiotic regimen. Owing to the high inci­
dence of mixed bacterial infections and theseverity of osteomyelitis, a combination of
two antimicrobials is recommended initially(e.g. enrofloxacin/amikacin and ceftazidime/metronidazole). This antibiotic regimen may
be started while waiting for culture and sen­sitivity test results and, if osteomyelitis ispresent, may have to be continued for three
to six months.

­Mandibular and Maxillary
Fractures
Mandibular and maxillary fractures are notuncommon in lizards and chelonians follow­
ing trauma. They may also be secondary toosteomyelitis associated with stomatitis or
osteopenia resulting from metabolic bonedisease. Maxillary fractures may extend into
the hard palate, warranting careful examina­tion of this area.
As well as antibiotic and analgesic therapy,
mandibular fractures in small to medium
sized lizards can often be stabilized bymoulding a suitable sized wire to the shape ofthe jaw and fixing it to the skin with a suitablecyanoacrylate adhesive. This external fixa­
tion can be replaced as required until thebone heals. If necessary, an oesophagostomy
tube can be placed to facilitate feeding while
the fracture heals. This is performed undergeneral anaesthesia by choosing an exit sitebehind the head and infiltrating the area withlocal anaesthetic. After surgically preparing
the site, a long curved haemostat is intro­
duced through the mouth and the tip ispushed laterally against the exit site withenough pressure to displace any blood ves­
sels. A small scalpel blade is used to cut down

on to the tip of the haemostats while they areforced through the oesophageal mucosa andoverlying tissues. Once the haemostats arethrough the skin, the handle is opened justenough to grasp the oesophagostomy tube
(usually a soft silicon or red rubber catheter)
and the haemostat with tube attached iswithdrawn through the mouth. The tube tip
is then redirected back into the mouth anddown the oesophagus to a premeasured
length so that the tip is in the lumen of thereptile’s stomach. A purse‐string suture isplaced around the incision and tube to seal
off the incision, and a Chinese finger‐trap
suture is used to secure the tube to the skin.
A transparent dressing is placed over the
tube and around the neck to keeps the siteclean. The oesophagostomy tube is capped
and wrapped over the shell (chelonians,
Figure 19.3) or body wall (lizards and snakes).

­Oesophageal Foreign
Bodies
Turtles, both marine and freshwater, notuncommonly swallow fishhooks and assorted
marine debris. Diagnosis is made on clinicalsigns, diagnostic imaging and endoscopy.
Surgical or endoscopic removal is usuallyrequired (Figure 19.4). Prognosis depends
upon the chronicity of the problem, whether
a viscus has been penetrated and the ana­
tomical location of the obstruction.
Complications include infection, gas build‐
up leading to floatation issues and gastroin­
testinal perforation.

­Regurgitation
Regurgitation is often reported in captive
pythons and less so in lizards and chelonians.
This condition may be due to a variety of
causes and poor husbandry is often involved.
The swallowing and digestion of a food item
is a complex physiological process that may
take up to several weeks in some snakes.

Diseases of the Gastrointestinal System

Figure 19.3 Oesophagostomy feedingtube in a young turtle.

Figure 19.4 Endoscopic removal of anoesophageal foreign body in aneastern long‐necked turtle (Chelodini
longicollis).

Aetiology
The causes of regurgitation can be grouped
into husbandry issues, dietary issues, patho­
logical processes and other causes. Husbandry
issues include low environmental tempera­
tures, excessive handling after eating and alack of a hide for the reptile to lie quietly
and undisturbed while it digests its meal.
Excessively large (greater than 10–30% of thesnake’s body weight) or cold (thawed frozen
rats and mice not warmed sufficiently) fooditems will frequently cause regurgitation.
Pathological processes include gastrointesti­
nal obstruction (intra‐ or extramural neo­plasms or abscesses) and gastritis, such as

viral infections (inclusion body disease inboids), Cryptosporidia and other protozoa orbacterial infections. Other causes include theadministration of medications (e.g. parenteralenrofloxacin in tortoises), systemic disease,such as renal or hepatic disease, and toxins
such as organophosphates and pyrethrins.
Clinical signs
The presenting complaint is usually finding
fresh, digested or semi‐digested food in thecage hours, days or weeks after food con­sumption. The reptile may or may not appear
to be lethargic and depressed.

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Reptile Medicine and Surgery in Clinical PracticeDiagnosis
Diagnosis of the cause of regurgitation starts
with a thorough history, including a feeding
history and enclosure conditions (size, tem­
perature, handling, hides, hygiene, etc.).
Careful palpation of the body may reveal
swellings or discomfort. Haematology andbiochemistry analysis is often useful to deter­mine if systemic disease is present. Stomach
washes and faecal analysis are useful for
detecting parasitic infections. Radiology,
ultrasound, flexible endoscopy and, if indi­cated, exploratory coeliotomy and biopsy ofinternal organs are other diagnostic toolsthat can be used to evaluate a regurgitating
patient.
Treatment
Treatment of regurgitation begins with theidentification and correction of husbandry
and dietary issues. Warming the reptile’s
enclosure and reducing the size and fre­quency of the feedings may be all that isrequired to correct the problem, especially if
acute in onset. More chronic problems aremost likely associated with disease andthe animal is often systemically unwell.
Rehydration and patient warming are impor­tant supportive measures. Specific therapy
can then be directed towards identified path­ogens or disease processes.

­Diarrhoea
The passage of loose, unformed faeces withincreased water content is relatively common
in reptiles. It should not be confused withpolyuria. The clinician should be aware of
species differences; for example, many colu­
brids have softer faeces than boids.
Aetiology
Diarrhoea can be due to infectious or non‐
infectious aetiologies. Non‐infectious causes
include change in diet, excessive feeding,Figure 19.5 Coccidia oocysts in the faeces of abearded dragon.

stress or foreign bodies. Infectious causes are
more common and include bacterial, viral,fungal or parasitic infections (e.g. coccidiosis
in bearded dragons; Figure 19.5). Although it
is normal to see some flagellated protozoa in
reptile faeces, overgrowth in a damaged ordiseased gastrointestinal tract can perpetu­
ate diarrhoea, even after the primary prob­
lem has been resolved. See Chapter 31 formore detailed information.
Clinical signs
Diarrhoea is a clinical sign, not a disease in
its own right. It may be acute or chronic.
Animals with acute diarrhoea may be mini­
mally affected or may exhibit mild dehydra­tion and lethargy. Chronic dehydration
usually results on more obvious dehydration,weight loss and lethargy. As well as diar­rhoea, there may be haematochezia andexcessive mucus in the faeces.
Diagnosis
After thorough history and physical exami­
nation, faecal analysis – direct examination,
flotation, cytology and culture – should be
performed to help identify the aetiologicalagent involved. In some cases, polymerase

Diseases of the Gastrointestinal Systemchain reaction (PCR) may be needed todetermine whether viral infections arepresent. If the animal is systemically­affected, haematology and biochemistry
profiles, as well as radiology and ultrasound,can be used to identify systemic disease or
involvement.
Treatment
Supportive care (assisted feeding, fluids,
and warmth) is beneficial for the patient, in
addition to specific therapy directed towards
the aetiological agent. Gastrointestinal motil­
ity modifying drugs such as metoclopramide
or cisapride may also play a role in normalis­
ing intestinal function.

Diagnosis
Careful palpation may detect a mass in the
coelom, often tender when touched. In
snakes, the organ involved can be determinedby measuring its distance from the snout (seeChapter 10). Radiographs may demonstrategas‐filled loops of bowel proximal to the
obstruction. Metallic foreign bodies; forexample, fish hooks are readily detectablewith survey radiographs but the detection ofplastic and rubber foreign bodies may require
contrast studies. Because of the slow gastro­
intestinal transit time in reptiles, contrast
radiography may require hours, days or evenweeks. Ultrasound can be an extremely usefuldiagnostic tool for imaging the intestinal tract
and other coelomic organs.

­Intestinal Obstruction

Treatment

Intestinal obstruction is often an acute andcatastrophic event in reptiles.

Intestinal obstruction is typically an emer­
gency condition requiring surgery to confirm
the diagnosis and relieve the obstruction. This
may require an enterotomy or enterectomy.

Aetiology
Many reptiles are nonselective in their feed­
ing habits and may ingest substrate or otheritems in their enclosure. Although the inges­
tion of foreign bodies (e.g. plastic items,
sand, rocks) is the most common cause ofintestinal obstruction, large masses ofworms, neoplasia, abscesses, volvulus andintussusception can also be responsible for
an intestinal obstruction.
Clinical signs
Animals with intestinal obstruction may pre­sent with an acute onset of lethargy, anorexia,
vomiting or regurgitation, straining andoccasionally diarrhoea. Melena and haema­
tochezia may be present. With severe strain­
ing, cloacal prolapse may occur. Bloating of
the coelom may also be seen. Partial orincomplete obstructions may be more insidi­
ous, with a chronic history of weight loss,
reduced appetite and occasional vomiting/regurgitation.

Prognosis
The prognosis for an intestinal foreign bodyis always guarded, as ischaemic necrosis of
the intestinal wall may be well advanced by
the time that clinical signs are noted.

­Colonic Impaction(Constipation)
Impaction of the colon, often accompanied
by loss of appetite, is a common clinicalproblem of captive bearded dragons andoccasionally other reptiles. The colon
becomes impacted with indigestible material
such as sand, rocks and chitin from insects.
Aetiology
There are many proposed causes of colonic
impaction, including:●●pica associated with nutritional secondary
hyperparathyroidism

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Reptile Medicine and Surgery in Clinical Practiceskeletal abnormalities preventing normal
defecation (lizards with a history of meta­
bolic bone disease appear to be more at
risk of impaction, particularly if they have
pelvic or spinal deformities)●● ingestion of loose substrate (e.g. sand or
gravel)●● lack of dietary fibre (i.e. leafy greens)●● overfeeding insects●● low water intake●● stress (recent acquisition or recent changes
in housing, over‐handling, etc.)●● vitellogenesis●● extramural masses (abscesses, enlarged
kidneys, neoplasia) obstructing the colon.
●●

A variant of colonic impaction is the retro­
grade flushing of urates from the cloaca into
the colon (urate impaction). This occurs
most commonly in overweight, sedentary
lizards that become subclinically dehydrated
and are not defecating regularly due to vari­able food intake and suboptimal enclosure
temperatures.
Clinical signs
Clinical signs may vary depending on thechronicity of the condition and include
decreased or absent faecal output, inap­
petance, lethargy, straining, and occasionallycloacal prolapse. Severely affected animals
may regurgitate food. There may be hindlimb weakness. The coelom may become dis­tended and, in chronic cases, there may beweight loss.
Diagnosis
Careful palpation of the coelom may reveal
an enlarged and firm cylindrical structure
consistent with an impacted colon. This
must be distinguished from the coelomic fat
pads, eggs or ovarian follicles. Radiology andultrasound can help to make this distinction,
as well as assessing other structures suchas skeletal structure, reproductive activity
and the presence of free fluid in the coelom.
A warmed saline enema may assist in

diagnosing the aetiology of the impaction, as
well as assisting in the treatment of the
impaction.
A direct faecal examination is recom­
mended to assess the parasite load, looking
for flagellate protozoa, coccidia and nema­
tode eggs. Examination of the cloaca using an
otoscope or endoscope is useful in cases
refractory to standard treatments.
Treatment
Many patients can be managed as outpa­
tients. Daily soaking in warm water (35–40 °C) for 10–15 minutes daily will help withhydration and stimulate defecation. Daily
spray misting to maintain a good state of
hydration is recommended in susceptible
animals. Any diagnosed underlying condi­
tions should be treated, ensuring that ade­quate levels of supplemental calcium, heatand ultraviolet B lighting are provided.
Increasing dietary fibre by assist feeding her­bivore support diets (e.g. Critical Care®,Oxbow) is often effective and beneficial.
More severe cases will require hospitaliza­tion and parenteral fluids. If bathing does notstimulate the excretion, many will respond to
cloacal stimulation using a well‐lubricatedcotton bud. In some cases an enema may berequired, which is administered by insertinga lubricated catheter or crop needle into thecloaca, guiding it carefully into the procto­
deum. Gently flush with 2–5 ml of a 50 : 50
mix of warm water (35–40 °C) and obstetri­
cal lubricant. If the animal fails to respond to
this treatment, an enterotomy to remove
impacted foreign material or an exploratory
coeliotomy or coelioscopy to assess animpinging coelomic mass may be necessary
to resolve the impaction.

­Cloacal Prolapse
Prolapse of the cloaca, bladder, lower
colon or oviduct is a common problem in
reptiles.

Diseases of the Gastrointestinal System

Aetiology
Causes of cloacal prolapse include:
straining associated with intestinal diseasesuch as colonic impaction (see above) or
enteritis (intestinal obstruction, heavy par­asitic burden or bacterial infections)●● dystocia●● urinary calculi or cystitis●● intestinal stasis secondary to hypocalcae­
mia and/or metabolic bone disease●● obesity and muscular weakness●● spinal trauma or deformity.
●●

Diagnosis
Cloacal prolapses are readily identifiable(Figures 19.6 and 19.7). Close examination
may help to evaluate which tissue has pro­lapsed since each has a unique appearance(although oedema and trauma may makeidentification difficult). Intestinal prolapses
are usually identified by the smooth tubular
appearance of the tissue. Sometimes faeces
may be observed inside the prolapsed tissue.

Figure 19.6 Cloacal prolapse in a bearded dragon.

Oviductal tissue appears similar to intestine,
but has longitudinal striations and there areno faeces inside the prolapse. Bladder tissue
is thin walled and often fluid filled.
Treatment
The prolapsed tissue should be gently cleaned
with warmed saline or dilute chlorhexidine.
Oedematous swelling can be reduced by theapplication of hypertonic saline or glucose
and gentle massage. Once the swelling has
resolved, the prolapsed tissue can be reducedwith the use of a lubricated gloved finger or
cotton‐tipped swab. This may require seda­
tion or general anaesthesia to prevent further
straining while reducing the prolapse. The
application of a local anaesthetic cream (e.g.
EMLA® cream mixed with silver sulfadiazine
cream at a ratio of one to nine) can also mini­
mize this straining. Once the prolapse has
been reduced, the tissue should be returned
to its normal position by gentle probing.
Transverse sutures are then placed throughFigure 19.7 Cloacal prolapse in a green python(Morelia viridis).

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Reptile Medicine and Surgery in Clinical Practicethe lateral margins of the vent to temporarily
reduce the size of the vent. The centre of thevent should be wide enough for urine to pass
while preventing recurrence of the prolapse.
These sutures should be left in place for three
to five days. In snakes, a percutaneous cloa­
copexy can be performed by passing a suture
through the ventral skin into the cloaca(using a probe or small syringe case as a loca­
ter for the cloaca) and fixing the cloaca to thebody wall. If this fails, a more aggressive
approach (a coeliotomy and colopexy or
cloacopexy) may be warranted.
Antibiotics and anti‐inflammatories areoften warranted. The application of EMLA
cream mixed with silver sulfadiazine cream
into the cloaca twice daily for several days
can prevent further straining while the pro­lapsed tissues heal. The reptile should be
kept well hydrated but not fed for several
days to prevent defecation.
Prognosis
If the cause of the prolapse is not identified
and resolved it is likely to recur. The short‐term prognosis is determined by the underly­
ing cause, the condition of the patient, theduration of the prolapse before treatment
and the viability of the prolapsed tissue.

­Cloacitis
Inflammation of the cloaca is occasionallyseen in reptiles, especially snakes and lizards.
Aetiology
Cloacitis can be an extension of an enteritis(bacterial, fungal, viral or parasitic) or a sec­
ondary infection following urate impactionof the cloaca associated with dehydration orconstipation. Inflammation may also occur
after mating.
Clinical Signs
Early cases may present with a malo­
dourous and/or bloody cloacal discharge(Figure 19.8), and oedema and ulceration of
the vent lips. As the condition progresses,
the cloaca and surrounding tissues become
swollen (Figure 19.9). The cloacal wall is
initially erythematous but may become­
swollen, haemorrhagic and covered withnecrotic plaques. Inspissated purulentmaterial and urates may be present in the
cloaca (cloacoliths). Possible outcomes
include an ascending infection of intestinal,
urinary or reproductive tracts, leading tosigns of systemic illness.

Figure 19.8 Cloacitis of unknown
aetiology in a python.

Diseases of the Gastrointestinal System

Figure 19.9 A distended colon due toflagellate protozoal enteritis in adiamond python (Morelia spilota
spilota).

Diagnosis
A good history and physical examination willoften reveal both the diagnosis and likely
aetiology. Cloacoscopy using an endoscopeor otoscope can demonstrate the extent of
the lesions and allow biopsy for histopathol­ogy and culture and sensitivity.
Treatment
Treatment should include thorough but­gentle cleansing with dilute chlorhexidine,
topical application of an antibiotic creamand placing the animal on a nonadherent
substrate such as newspaper or cotton­towels. If the condition is severe, parenteralantibiotics and anti‐inflammatory therapy
are recommended.

classification of liver disease. Hepatic lipido­sis, the pathological increase in intrahepatic
fat associated with overfeeding, obesity andlack of exercise, must be differentiated fromphysiologically normal hepatic fat associatedwith brumation or reproduction. Risk factors
for hepatic lipidosis include age (it is uncom­
mon in juveniles), lack of brumation opportu­
nities and the lack of breeding opportunities
for females. Large carnivorous reptiles (e.g.
tegus, monitors and pythons) and bearded
dragons appear to be most commonly affected.
Clinical signs
Most reptiles with liver disease show only
subtle signs of disease:
reduced appetite
decreased activity●● weight gain (due to ascites) or gradualweight loss●● brumation problems, including post‐bru­
mation anorexia●● biliverdinuria●● diarrhoea●● polyuria.
●●●●­Liver Disease
Liver disease is common in reptiles but
often unrecognized until the disease iswell‐advanced.
Aetiology
Liver disease can be classified as acute or
chronic, inflammatory (hepatitis) or degener­
ative (hepatosis). Table 19.1 shows the

These clinical signs may not be present
all the time, only becoming apparent during
episodes of increased physiologic demand(e.g., brumation, breeding or concurrent
disease).

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Reptile Medicine and Surgery in Clinical PracticeTable 19.1 Classification of liver disease.
Class

Acute

Inflammatory

Degenerative

Infectious:●●●●

Toxins:Bacterial (Salmonella, Campylobacter, Chlamydia,
Escherichia coli)
Viral (adenovirus in bearded dragons, ferlavirus andsunshinevirus in snakes)●●

Fungal●●Parasitic (Rhabdias spp.)●●

Coccidiosis (bearded dragons)●●

Ivermectin‐induced hepatic lipidosis
in chelonians●●

Pyrethrin toxicity●●

Organophosphate (pest strips)

Non‐infectious:

Chronic●●

Leukaemia●●

TraumaChronic active hepatitis

Metabolic:Cholecystitis●●

Hepatic lipidosis

Adenovirus in bearded dragons

●●

Gout

Herpesvirus (turtles)●●

Metabolic bone disease

Mycobacteria●●

Renal metabolic bone disease

Nannizziopsis spp. (CANV)

Neoplastic:

Cryptosporidia●●

Primary neoplasia

Caryospora spp. (turtles)●●

Metastatic disease, e.g. lymphoma

Parasitic (Ophidascaris spp.)

Diagnosis
Haematology and biochemistry analysis
form the mainstay of the diagnosis of liverdisease. It is important that blood samples
are collected before fluid therapy and othersupportive measures are initiated.
Anaemia may be present in cases of chronic
hepatopathy.
●● Marked
heterophilia and monocytosis
suggest acute inflammation or necrosis of
the liver.
●● A normal white cell count does not ruleout hepatitis, as chronic bacterial hepatitis
and abscessation may not elevate the total
white blood cell count.
●● Liver enzymes such as aspartate ami­
notransferase, glutamate dehydrogenase
and gamma glutamyl transferase must be●●

interpreted carefully, as their significancein reptiles has not been fully evaluated. In
reptiles, tissue distribution of many of these
enzymes appears more widespread, making
interpretation more difficult. In cases ofchronic hepatopathy with little active dam­age, enzyme levels may remain normal.
●● Bile acids have also not been fully evalu­
ated but it appears likely that values above
60 µmol/l are indicative of hepatic
dysfunction.
Radiology is of limited use in evaluating liver
size but ultrasound is of much greater use,demonstrating liver size and echogenicity.
Endoscopic or surgical liver biopsy can pro­vide much needed information on the aetiol­ogy, extent and severity of suspected liverdisease. Several samples should be collected
for histopathology, culture and PCR.

Diseases of the Gastrointestinal System

Treatment
The objectives for the therapeutic manage­
ment of liver disease are to support thepatient while specific therapies aimed attreating the causative agent of the liver dis­ease and repairing the damage done to theliver. This may take several weeks to many
months.
Patient support includes correction of­husbandry deficits (especially temperature),
fluid therapy to correct dehydration and to
improve perfusion of the liver and nutri­tional support (see Chapter 4). When provid­
ing nutritional support, it is important toconsider:●●the patient’s energy and nutritional
requirements while recovering

the patient’s natural eating habits (herbivo­
rous, omnivorous or carnivorous)●● the use of natural foods that may better meetthe patient’s nutritional requirements.
●●

Specific therapy will be dictated by the resultsof the histopathology, culture and PCR test­
ing. In many cases, an aetiological cause may
not be determined; if this is the case, broad‐
spectrum antibiotic coverage is often indi­cated. Suggested hepatic supportive therapies
include lactulose, carnitine methionine,ursodeoxycholic acid and silibinin.
Patients should be serially evaluated atthree, six and nine months. Weight and foodintake should be evaluated, as should liver
enzymes and fasting bile acids. Ultrasoundand endoscopic liver biopsies can be used tomonitor response to therapy.

­Further Reading
Divers, S.J. (2000) Reptilian liver andgastrointestinal testing, in Laboratory
Medicin: Avian and Exotic Pets (A.M. Fudge,
ed. WB Saunders, Philadelphia, PA, 205–209.
Divers, S.J. and Cooper, J,E. (2000) Reptile
hepatic lipidosis. Seminars in Avian andExotic Pet Medicine, 9 (3), 153–164.
McAllister, C.T., Upton, S.J., Jacobson, E.R. andKopit, W. (1995) A Description of Isospora
amphiboluri (Apicomplexa:Eimeriidae) fromthe inland bearded dragon, Pogona vitticeps(Sauria: Agamidae). Journal of Parasitology,
81 (2), 281–284.
Mitchell, M.A. and Diaz‐Figueroa, O. (2005)
Clinical reptile gastroenterology. Veterinary
Clinics of North America Exotic Animal
Practice, 8 (2), 277–298.
Wright, K. (2008) Two common disorders of
captive bearded dragons (Pogona vitticeps):
Nutritional secondary hyperparathyroidism
and constipation. Journal of Exotic Pet
Medicine, 17 (4,) 267–272.

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20
Diseases of the Cardiovascular System
Tegan Stephens and Alex Rosenwax

Anatomy and Physiology
Chapter 2 provides a more detailed review ofanatomy and physiology of the cardiovascularsystem.
Key Points
Crocodilian heart:
A four‐chambered heart with complete separation of the ventricles and atria. A small
foramen (foramen of Panizza) persists in theinterventricular septum and a left aortic archallows for a right to left shunt during diving
and prolonged submersion.
●● Non‐crocodilian heart (Figure 20.1a,b):
Three‐chambered heart including two atria,
a single ventricle and a dorsal thin walledsinus venosus. The ventricle is functionallyseparated by a series of muscular ridges
allowing separation of oxygenated anddeoxygenated blood during contraction.
The sinus venosus collects blood from thesystemic circulation before entering theright atrium and acts as a cardiac pacemakerand blood pressure mediator.
●●

Renal portal system:
Afferent renal portal veins are formed by thecaudal vein from the tail and iliac veins fromthe hind limbs. The renal portal system perfuses the renal tubule cells and allows forcontinued blood supply to the tubules during periods of reduced glomerular filtration.
Pelvic veins can allow blood to be redirectedaround the kidney via a valve. Postulated
effects on drug distribution have been
explored in a limited number of studies andshown variable results.
●● Clinical implications:●●Pulmonary oedema generally develops
before ascites during cardiovascular disease. Any reptile presenting with dyspnoea should be investigated for cardiac
disease.

●●Apnoea may be associated with vagal
induced bradycardia, leading to anaesthetic
complications and necessitating the use ofintermittent positive pressure ventilation in
all reptile anaesthesia.

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

288

Reptile Medicine and Surgery in Clinical Practice

(a)

(b)

Figure 20.1 Python heart. (a) Ventral aspect. (b) Dorsal aspect.

­ he CardiovascularT
Examination
History and Husbandry
An appreciation of husbandry is essential in
all reptile disease investigations. Temperature,
hydration, feeding history and access toultraviolet light are all important factors in
cardiovascular health in reptiles. Deficiencies
in husbandry are a common initiating causeof disease.
It is useful to take baseline measurementsof heart and respiratory rate at every routine
annual health check. Values can vary greatly,even between individuals of the same species, and can vary with time of year, temperature, reproductive status and time of lastfeed. Where possible, cardiac examinations
should be performed with the animal at its
preferred optimal temperature zone. Take
note of differences in activity levels between
diurnal and nocturnal species. All measurement should be accompanied by notes
regarding time of day, temperature, and pertinent husbandry points.

The most common reason for presentationof snakes with cardiac disease is a swelling in
the cranial portion of the body. Other general causes of presentation are lethargy, inappetence or exercise intolerance. A history of
open‐mouth breathing may be noted.
Physical Examination
For further detailed information, refer to
Chapter 10.
Mucous Membranes

Familiarity with normal mucous membrane
colour is important when dealing with different
species. Many reptiles have very pale or very
dark normal oral mucosae. Cyanosis or ecchymosis can be seen with cardiovascular disease.
Heart Rate

Heart rate varies with body size, species,
metabolic rate, season, time since last feed
and respiratory rate. A predicted baseline
heart rate for a reptile can be determinedusing allometric scaling (Sedgewick 1991):
33.4 ( weight in kg 0.25)

Diseases of the Cardiovascular System

Reptiles with cardiac disease or those thathave suffered blood loss may display tachycardia. Prolonged apnoea or pulmonary disease may be accompanied by bradycardia.
The heart rate can often be determined bydirect visualization of the heart movement
under the ventral scales in snakes. Other
species will require direct auscultation or
Doppler examination to determine heartrate. A mark should be made over the heartwith permanent marker if further monitoring or auscultation is required to allow it tobe located quickly (e.g. during surgery or
collapse).
It should be noted that the heart may beatin reptiles for minutes or hours following
clinical death. This is an important point
when considering monitoring procedures
during anaesthesia and also when determining death following euthanasia.
Auscultation

Standard stethoscopes may not deliveradequate sound quality for assessment ofreptile hearts due to friction on the scales
and low amplitude heart sounds. Soundquality can be improved by placing a damp
cloth between the scales and the bell of thestethoscope. More accurate auscultation
may be achieved with a Doppler ultrasoundprobe.

Figure 20.2 Cardiomegaly in a python.

Pulse

Peripheral pulse rates are difficult to determine
in reptiles and no effective indirect blood pressure measurement method has been described.
Surgically placed intra‐arterial devices havebeen used to monitor pulse. In larger reptiles
the intraoral vessels may be used to assess pulse
quality but sedation of the animal is required.
Respiration

Measuring the respiratory rate, in conjunction
with heart rate, is good practice. Respiratory
rate will vary greatly with environmental
changes and differences in activity levels.
General Signs

Swelling around the level of the heart, pleuralor peripheral oedema, ascites, cyanosis andecchymosis are all potential indicators of cardiac disease (Figure 20.2). Note that the sizeof a snake heart may enlarge up to 40% in the48 hours following feeding. This is because of
an increased gene expression of muscle contractile proteins. The heart returns to normal
size once the meal is digested.
Laboratory Analysis
Fresh faecal and blood samples should betaken at the time of the consultation for examination and identification of haemoparasites,

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Reptile Medicine and Surgery in Clinical Practice

Figure 20.3 Cardiocentesis in a
black‐headed python (Aspiditesmelanocephalus).

endoparasites and haematological abnormalities. Blood samples may be obtained from theventral tail vein in many species, from thejugular vein in many turtles or by jugular cut‐
down in snakes and lizards, and by cardiocentesis in snakes. Cardiocentesis should only be
performed in animals larger than 300 g
because of the risk of myocardial damage andhaemorrhage in smaller animals. Using theventrocaudal approach through the ventricular myocardium allows the needle to enter at apoint where the wall is thicker and there isminimal twisting motion during contraction(Figure 20.3). Complications reported include
atrophy, fibrosis and haemorrhage. See
Chapter 13 for more detail on sample
collection.
Very little information is available regarding cardiac enzymes in reptiles and no analysis has been done on their relationship to
disease.
The use of pulse oximetry in reptiles isoften not possible, owing to the heavily pigmented mucosa of many species and thepresence of thick scales. In species with minimally pigmented mucosa, probes placed in
the proximal oesophagus give the best
results. The absorption wavelength of reptile
haemoglobin and deoxyhaemoglobin havebeen shown to be roughly equivalent tomammalian levels. However, absolute value
readings have not been validated in reptiles.

The oxygen carrying capacity of reptile
erythrocytes varies greatly, most notably by
being reduced during anaerobic glycolysis
and the resulting acidosis experienced during periods of apnoea.
Doppler analysis gives a quantitative
assessment of the intensity of the speed ofblood traveling through the peripheral vessels. It is a sensitive way of monitoringchanges in blood pressure quality during
anaesthesia, despite not providing a quantitative reading. Doppler use in reptiles
requires large amounts of coupling gel toremove the noise interference of air between
the scales (Figure 20.4).
Imaging
We present the key points here. Refer to
Chapter 12 for more detail.
Radiography

Radiography to assess the heart is generally
not useful in reptile species, with the exception of snakes. There is significant overlap of
the cardiac outline with the pectoral girdle inmost lizards and the carapace and plastron inchelonian species. Cardiomegaly in snakes isdetermined by displacement of the trachea
dorsally as well as distension of the body wall.
Cardiac length may be easily compared to rib
spaces. The best comparison of normal andDiseases of the Cardiovascular System

Figure 20.4 Doppler monitoring of avaranid to confirm death.

Figure 20.5 Ultrasound of a turtle
heart.

abnormal hearts can be made between animals of the same species and a similar size.
While less useful for examining the heart
itself, cranial coelomic radiographs can still
be of benefit in assessing changes to the respiratory system.
Ultrasonography

Ultrasonography has many potential uses ininvestigating reptilian cardiac disease.
Positioning is determined based on species
and heart position.
●●

Snakes – directly through the midline
acoustic window. Sedation and a water
bath may facilitate imaging, otherwise
copious amounts of coupling gel are

required. Standard views include a sagittal
plane with the heart in the long axis to
identify chambers, major vessels ridges
and valves and a 90‐degree rotation to theshort axis for a transverse view.
●● Lizards such as agamids, with cranially
positioned hearts at the level of the pectoral region and chelonians – images are
obtained through the cervical window(Figure 20.5). In very small patients where
the transducer cannot be placed directlyon the acoustic window, a latex glove filledwith water may be used as a standoff(Figure 20.6).
●● Lizard species such as varanids, with hearts
located caudally – the axillary window or aventral approach.

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Reptile Medicine and Surgery in Clinical Practice

Figure 20.6 Ultrasound of small turtle
with standoff.

Patient size limits usefulness, with better
images obtained in patients over 1 kg weight.
M‐mode is generally not considered useful,owing to the spongy myocardium, which
prevents accurate measurement.
Advanced Imaging

Advanced imaging, including computed
tomography (CT) and magnetic resonanceimagining (MRI), may have applications ininvestigation of cardiac disease in reptiles.
CT provides much higher resolution imaging
than standard radiography and may allow
better examination of the major vessels. MRI
provides very good contrast images of soft
tissue and may be used to examine the heart
itself and chambers, however the slow heart
rhythm can disturb the image. These techniques are particularly valuable with chelonians, where the shell structure interferes withstandard radiographic views. The disadvantages of CT and MRI include prolonged
anaesthesia time in patients, which may
already be poor anaesthetic candidates, costand lack of availability.
Electrocardiography
Difficulties arise in reptiles due to small
patient size, difficulty of conduction throughthick scales, changes in depolarization withphysiological state changes and the limited

number of published normal values available.
Reptiles lack the specialised Purkinje fibre‐
based conduction (pacemaker) system foundin mammals. Contraction is initiated in thesinus venosus by the cardiac muscle fibres.
Ventricular systole is long, and diastole isshort. The best results may be achieved using
metal crocodile clips with filed teeth in conjunction with coupling gel:
Chelonians – cranial leads are placed on
cervical or axillary skin folds and caudal
leads on the skin folds caudal to the hindlimb.
●● Lizards – cranial leads are placed on theskin of the forelimbs, axilla or neck, caudal
on the crural or popliteal fold.
●● Snakes – a base‐apex reading may beobtained with electrodes placed two heartlengths cranial and caudal to the heart on
the lateral aspect.
●●

Reptile electrocardiograms demonstrate a P
wave, QRS complex and T wave pattern similar to mammals. An additional SV wave has
been described representing the depolarisation of the sinus venosus. Normal findings
include pleomorphism of the P wave, the
QRS appearing as a single R wave and long
repolarization phases (QT intervals).
Abnormal findings include tachycardia,
increased P or QRS amplitudes and heart
blocks (Figure 20.7).

Diseases of the Cardiovascular System

Figure 20.7 Electrocardiogram trace of python under general anaesthesia.

­Cardiovascular Disease
The clinical signs of cardiovascular disease
in reptiles are generally nonspecific andrarely pathognomonic. These signs may
include lethargy, inappetence, weakness,
exercise intolerance, weight loss, swelling in
the region of the heart, change in skin or
mucous membrane colour and sudden death.
Congestive Heart Failure
While congestive heart failure is common in
geriatric mammals; it is not commonly
reported in reptiles. This may be because
reptiles do not reach advanced ages in captivity owing to poor husbandry. Congestive
heart failure has been described in a Burmese
python (Python bivittatus; Jacobson et al.
1991), a mole kingsnake (Lampropeltis calli­
gaster rhombomaculata; Barton 1980), a
Deckert’s rat snake (Elaphe obsoleta ‘deck­
erti’; Jacobson 1979) and a carpet python(Rishniw and Carmel 1999). Despite advancesin diagnostics available for reptiles, mostcases are still identified post mortem.
Changes may be seen in the cardiac muscle,
valves, pericardium or major vessels.
Therapy for congestive heart failure in­reptiles should follow similar protocols as
for mammals, although the prognosis isconsidered poor, based on reports in the literature. There has been minimal evaluation ofcommon drugs for congestive heart failure in
reptilian species. While loop diuretics such as
furosemide would seem to have little clinicalapplication, owing to the absence of the loop of
Henle in the reptilian nephron, numerous
practitioners have anecdotally reported positive outcomes following their use. This may be
due to a perceived action on the proximal
tubules as noted in mammals. Cardiac glycosides, sympatholytics, vasodilators and diuretics may all be used with care. However,allometric scaling is recommended to determine optimal dose rates. Delivering medications, which are in most cases oral preparations,is also difficult in many reptile species and noinformation is available on oral bioavailability.
Congenital and Hereditary Disease
Congenital cardiac disease is uncommon in
reptiles and generally reported on necropsy.
Abnormalities may occur during embryo
development and organ formation. Severe
malformations generally will lead to deathprior to hatching or birth, or soon after.
Minor abnormalities may not be discovered
for a significant time period (if ever) or may
complete development postnatally, before
signs are noticed.

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Reptile Medicine and Surgery in Clinical Practice­Nutritional Disorders
Affecting
the Cardiovascular System
Hypocalcaemia affects all body muscle including cardiac muscle. Delayed cardiac depolarization can be seen on electrocardiogram(ECG) by increased ST and QT intervals.
Secondary nutritional hyperparathyroidism is
one of the more common causes of presentation of reptiles to veterinary clinics. Affectedanimals may display weakness, lethargy,
depression, muscle tremors and seizures.
While the changes to skeletal muscle are obvious, the affected cardiac muscle should not be
forgotten and potential damage should betreated as an emergency. Nutritional hyperparathyroidism should be considered as apotential poor prognostic indicator whenassessing anaesthetic risk. Diagnosis andtreatment of nutritional hyperparathyroidism
are discussed in Chapter 15.
Vitamin E deficiency may result in cardiac
muscle abnormalities (white muscle disease)in reptiles as in mammals. More commonly
affected species such as snakes, aquatic chelonians and crocodilians may have been fed adiet of excessively obese rodents or oily fish.
Treatment with supplementary vitamin E(12.5 mg/kg) and selenium (0.05 mg/kg) is
generally curative, except for severe cases.
Calcification of the tunica media of large
vessels has been reported in reptiles. The
aetiology is unknown. There have been somelinks made between this condition and both
hypo and hypervitaminosis D.
Hypoalbuminaemia is a common finding
in reptiles fed a suboptimal diet, with orwithout primary liver disease. Affected animals may present with oedema, ascites oranasarca as a result of fluid loss from the vascular space. These animals may present withtachycardia, compensating for fluid loss.
Care must be taken with stress and handling
until the hypoalbuminaemia and fluid deficits have been corrected.
Electrolyte imbalances are a potential
cause of cardiac abnormalities. Hypokalaemia

may occur in animals on suboptimal diets,
where the potassium moves from the intracellular to extracellular space in order to preserve basic functions such as transmission ofaction potentials in nerve cells. Once glucose
is provided, the potassium moves rapidly
back into the intracellular space, which may
result in the development of life‐threatening
arrhythmias. Primary hyperkalaemia is associated with renal disease and may cause
arrhythmias. When arrhythmias are diagnosed, blood electrolyte levels should bemeasured. Calcium may be of benefit in conjunction with diuresis (hyperkalaemia) or
supplementation of potassium to countermyocardial excitability.
Obesity is a contributing factor in somecases of cardiac disease in reptiles. Captive
reptiles are more at risk of obesity than wild
counterparts due to free access to prey anda predominance of high fat food items,
together with a significantly decreased levelof activity. A lack of hibernation has been
postulated as a potential cause of obesity. As
reptiles store excess fat in their coelomic cavity, this may lead to infiltration of the vitalorgans and subsequent health risks. Obesity
should receive attention when assessing
potential causes of cardiac issues in reptiles.
Potential cardiovascular damage andincreased cardiac workload should be considered when evaluating the obese patient.

­TraumaAnimals that present following significant
trauma or blood loss may display tachycardia.
In cases of acute blood loss, fluid may shift
from the intracellular to the extracellularspace and so great care must be taken whenselecting fluids to be used to expand thevascular space. A combination of lactated­
Ringer’s solution or saline and dextrose allows
for expansion of both the vascular space andintracellular spaces. Note that internal bleeding may be an insidious finding in cases ofchelonian trauma due to falling from a height.

Diseases of the Cardiovascular System­Neoplasia
Haematopoietic neoplasms are not generally
detected until the later stages of disease.
Diagnosis is based on leucocyte differential,bone marrow examination and cytochemical
staining. Great variation exists in the reported
incidence of these cancers; however, studies
have shown the cardiovascular system to be
the most commonly affected body system(Hernandez‐Divers and Garner 2003).

­Infectious Disorders
Bacterial Infections
Aetiology

Aerobic Gram‐negative bacteria are the mostcommon isolates to damage the cardiovascular system of reptiles. Bacteria found to havedirectly damaged the heart and vasculatureinclude Salmonella spp., Corynebacterium
spp., Pseudomonas and Escherichia coli. A
chlamydial infection has been reported as
the cause of myocarditis, pericarditis, pneumonia and hepatitis in puff adders (Bitis ari­etans; Jacobson et al. 1989). An outbreak of
mycoplasmosis has also been reported in
captive American alligators (Alligator missis­
sippiensis), causing pneumonia, endocarditis
and arthritis (Clippinger et al. 2000).
Mycobacteria can cause granulomatous disease and potentially cause damage to the cardiovascular system.

Clinical Signs

Similar to other causes of cardiovascular disease, the clinical signs of bacterial infections
are generally non‐specific. The reptile may
present as lethargic, weak and/or anorectic
or may suffer from apparent sudden death.
Diagnosis

Routine blood cultures and haematology
should be performed on all cases of suspected sepsis. Imaging may indicate issues
with the cardiovascular system; however, it isunlikely to determine the cause. Necropsy is
the most common definitive diagnostic tool
used in septic cardiac disease cases.
Treatment

Following a positive blood culture or suspicious haematology findings, appropriate
antibiotic therapy may be initiated. Antibiotic
choice should ideally be made following sensitivity testing. These cases are often systemically affected and other therapies may be
indicated depending on clinical signs andother findings.
Prevention and Control

Most cases of septic cardiovascular disease
are secondary to systemic disease; improperhusbandry is a likely underlying cause inmany cases. Where individual animals arelikely to be suffering from immune suppression, the potential for transfer of infectious
agents means appropriate quarantine procedures should be followed.

Pathogenesis

Parasitic Infections

Septic thromboemboli and secondary septic
endocarditis are potential sequelae of systemic
infection by the common Gram‐negative aerobes. These commonly include Aeromonas,
Proteus, Pseudomonas, E. coli, Klebsiellla,
Serratia, Enterobacter and, while Salmonella
is rarely associated with clinical disease in
reptiles, it can develop into severe septicaemia
with associated secondary complications.
Reptiles debilitated from poor husbandry are
more susceptible.

Adult nematodes may live in the vascularsystem and release microfilaria into the circulation. While most infections are considered nonpathogenic, the adult worms may
block major vessels and may lead to thrombosis, oedema and necrosis. Diagnosis is
made by examining peripheral blood smears,
where filarid worms are readily identified inheavily infected individuals. As these parasites require intermediate vectors, interrupting the life cycle is possible in captivity.

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Reptile Medicine and Surgery in Clinical PracticeTreatment involves ivermectin at 0.2 mg/kg(not to be used in chelonians) or surgicalremoval of the adult worms.
Digenetic spirorchid flukes can be foundin wild aquatic turtles or those housed­outdoors. The adult flukes live in the heartand great vessels and, when eggs are
released, terminal vessels may be occluded.
Cardiovascular lesions may include endocarditis, arteritis and thrombosis. They arecommonly associated with aneurysm formation. Enzyme‐linked immunosorbent
assay testing has been used effectively as adiagnostic tool in green turtles (Chelonia
mydas). Praziquantel is recommended but
its efficacy is unknown.
Haemoparasites are common in wildcaught animals and, while most arenonpathogenic, malarial parasites (Plasmo­
dium spp.) may produce haemolytic anaemia.
Treatment involves use of chloroquine at
125 mg/kg orally every 48 hours for threetreatments.
Viral Infections
McCracken et al. (1994) describe an erythrocytic virus causing anaemia in a diamond
python (Morelia spilota spilota) and Jacobson
et al. (2005) describes myocardial degeneration due to West Nile virus in American­alligators. Viruses which can cause cardiovascular pathology in mammals (such as parvovirus) have been described in reptiles andmay become a more recognized issue withfurther investigation.

References
Barton, S. (1980) Cardiomyopathy in akingsnake (Lampropeltis calligasterrhombomaculata). Veterinary Medicine
Small Animal Clinics, 75, 125–129.
Clippinger, T.L., Bennett, R.A., Johnson, C.M.
et al. (2000) Morbidity and mortality
associated with a new mycoplasma species
from captive American alligators (Alligator
mississippiensis). Journal of Zoo and Wildlife
Medicine, 31, 303–314.
Hernandez‐Divers, S.M. and Garner, M.M.
(2003) Neoplasia of reptiles with an emphasis
on lizards. Veterinary Clinics of North America
Exotic Animal Practice, 6 (1), 251–273.
Jacobson, E.R., Gaskin, J.M. and Mansell, J.
(1989) Chlamydial infection in puff adders(Bitis arietans). Journal of Zoo and Wildlife
Medicine, 20, 364–369.
Jacobson, E.R., Ginn, P.E., Troutman, J.M. et al.
(2005) West Nile virus infection in farmed
American alligators (Alligator
mississippiensis) in Florida. Journal of
Wildlife Diseases, 41 (1), 96–106.
Jacobson, E.R., Homer, B. and Adams, E.
(1991) Endocarditis and congestive heart
failure in a Burmese python. Journal of Zoo
and Wildlife Medicine, 22, 245–248.

Jacobson, E.R., Seely, J.C., Novilla, M.N. andDavidson, J.P. (1979) Heart failure associatedwith unusual hepatic inclusions in a
Deckert’s rat snake. Journal of Wildlife
Diseases, 15, 75–81.
McCracken, H., Hyatt, A.D. and Slocombe,
R.F. (1994) Two cases of anemia in reptiles
treated with blood transfusions: (1)hemolytic anemia in a diamond python
caused by an erythrocytic virus; (2)nutritional anemia in a bearded dragon, in
1994 Scientific Proceedings, Annual
Conference of the American Association of
Zoo Veterinarians 1994. American
Association of Zoo Veterinarians,
Pittsburgh, PA, (pp. 47–51).
Rishniw, M. and Carmel, B.P. (1999)
Atrioventricular valvular insufficiency andcongestive heart failure in a carpet python.
Australian Veterinary Journal, 77 (9),580–583.
Sedgewick, C.J. (1991) Allometrically scaling
the data base for vital sign assessment
used in general anaesthesia of zoological
species. Proceedings of the American
Association of Zoo Veterinarians 1991,
pp. 360–369.

Diseases of the Cardiovascular System

Further Reading
Gartner, G.E.A., Hicks, J.W., Manzani, P.R.
et al. (2010) Phylogeny, ecology and heart
position in snakes. Physiological andBiochemical Zoology, 83 (1), 43–54.
Holz, P., Barker, I.K., Burger, J.P. et al. (1997)
The effect of the renal portal system on
pharmacokinetic parameters in the red‐
eared slider (Trachemys scripta elegans).
Journal of Zoo and Wildlife Medicine, 28 (4),386–393.
Jensen, B., Abe, A.S., Andrade, D.V. et al.
(2010) The heart of the South American
rattlesnake, Crotalus durissus. Journal ofMorphology, 271, 1066–1077.
Jensen, B., Nyengaard, J.R., Pedersen, M. andWang, T. (2010) Anatomy of the python
heart. Anatomical Science International, 85,
194–203.
Kik, M.J.L. and Mitchell, M.A. (2005) Reptile
cardiology: a review of anatomy andphysiology, diagnostic approaches, andclinical disease. Seminars in Avian andExotic Pet Medicine, 14 (1), 52–60.
Latney, L.V. and Wellehan, J. (2013) Selected
emerging infectious diseases of squamates.
Veterinary Clinics of North America Exotic
Animal Practice, 16, 319–228.
Mans, C. (2014) Update on common
nutritional disorders of captive reptiles.
Veterinary Clinics of North America Exotic
Animal Practice, 17, 369–395.
Martinez‐Jimenez, D. and Hernandez‐Divers,
S.J. (2007) Emergency care of reptiles.
Veterinary Clinics of North America Exotic
Animal Practice, 10, 557–585.
Mitchell, M.A. (2009) Reptile cardiology.
Veterinary Clinics of North America Exotic
Animal Practice, 12, 65–79.

Rush, E.M., Donnelly, T.M. and Walberg, J.
(1999) Aortic aneurysm and subsequentcardiopulmonary arrest in a Burmese
python (Python molurus bivittatus).
Proceedings of the Association of American
Zoo Veterinarians 1999, pp. 134–138.
Saggese, M. (2009) Clinical approach to theanaemic reptile. Journal of Exotic Pet
Medicine, 18 (2), 98–111.
Schilliger, L., Chetboul, V. and Tessier, D.
(2005) Standardizing two‐dimensional
examination in snakes. Exotic DVM, 7 (3),63–74.
Schmidt, R. and Reavill, D. (2010)
Cardiopulmonary disease in reptiles. 2010
Proceedings of the Association of Reptile
and Amphibian Veterinarians, pp. 90–98.
Secor, S.M. and White, S.E. (2009) Prioritizing
blood flow: cardiovascular performance in
response to the competing demands oflocomotion and digestion for the Burmese
python, Python molurus. Journal of
Experimental Biology, 213, 78–88.
Slay, C.E., Enok, S., Hicks, J.W. and Wang, T.
(2014) Reduction of blood oxygen levels
enhaces postprandial cardiac hypertrophy in
Burmese python (Python bivittatus). Journalof Experimental Biology, 217, 1784–1789.
Taylor, E.W., Leite, C.A.C., Sartori, M.R. et al.
(2014) The phylogeny and ontogeny ofautonomic control of the heart andcardiorespiratory interactions in vertebrates.
Journal of Experimental Biology, 217,690–703.
Wyneken, J. (2009) Normal reptile heartmorphology and function. Veterinary
Clinics of North America Exotic Animal
Practice, 12, 51–63.

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21
Diseases of the Respiratory System
Melinda L. Cowan

Anatomy and Physiology
See Chapter 2 for more information on the
anatomy and physiology of the respiratory
system.
Key Points
The glottis is located rostrally within the oralcavity in snakes and some carnivorous lizards. Chelonians and most lizards have aglottis positioned caudally in the oral cavity,
at the base of a large tongue.
●● The cartilaginous tracheal rings are complete in chelonians and incomplete in snakes
and lizards.
●● Lung anatomy varies and can be divided
into single, transitional and multi‐chambered.
The lungs of most reptiles are sac‐like and●●­Predisposing Factors
to Respiratory Disease
The reptilian immune system shares many
similarities with that of mammals and birds.
Like other vertebrates, reptiles possess theinnate and adaptive (cell‐mediated andhumoral) components and the efficacy of theoverall immune response appears to declinewith age. Compared with mammals, however, reptiles have a weaker and slower

paired, although in most snakes the left lungis vestigial or absent.
●● The cranial lung in snakes participates in gas
exchange and the caudal aspect of the lungforms a non‐respiratory air sac. Some lizards
have a similar lung structure.
●● Gas exchange surfaces are ediculi and faveoli.
●● Reptiles lack a diaphragm. Expiration andinspiration are therefore mostly active processes in most reptiles, although there are
passive components to the respiratory cycle
in snakes.
●● Stimulus to breathe comes from low blood
oxygen levels and increased oxygen demand
is normally met with an increase in tidal volume, rather than respiratory rate.

humoral response. The immune system in
reptiles can also be directly influenced byother factors, such as the season, the animal’s
reproductive state and the environmental
climate.
Being ectothermic, the most unique feature of the reptilian immune system is the
response to variation in environmental temperature. In species that have been studied,peak immune performance occurs within atemperature range. When reptiles are
exposed to environmental temperatures

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

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Reptile Medicine and Surgery in Clinical Practice

Figure 21.1 This spotted python(Antaresia maculosa) is exhibiting
open‐mouth breathing, which is likely
secondary to dysecdysis andobstruction of the nasal passages(courtesy of Bob Doneley).

­ utside this range, impaired immune funcotion is the consequence. While chronically
low environmental temperatures are themost common scenario leading to disease,persistent overheating and acute, severe
alterations in temperature can also impact
the immune system in reptiles.
Reduced immune function secondary to
the provision of inappropriate climatic conditions is the most common predisposing
factor in the development of respiratory
infections in reptiles. Other factors that candirectly contribute to the development of
respiratory disease include poor hygiene,
irritating substrates (e.g. sawdust), substrates
with high microbial concentrations (e.g. peatmoss, mulch, potting soil) and transmissionof disease through inadequate quarantine.

­Aetiologies of Respiratory
DiseaseRespiratory disease in reptiles appears to becommonly caused by infectious organisms.
Bacteria, fungi, viruses and parasites can all
cause disease in susceptible animals. Other,
non‐infectious diseases of the respiratory
tract have been reported in reptiles includingtrauma, foreign bodies, neoplasia and inhaledirritants (smoke, pesticides). Hypovitaminosis
A is a well‐recognized condition affectingsome reptile species. Clinical signs of respiratory disease can occur with occlusion of thenostrils from retention of skin after ecdysis(Figure 21.1).
Non‐infectious Disease
TraumaCaptive reptiles can suffer from significant
damage to the rostral maxillary region from
repetitive collisions with enclosure walls.
Lizards appear particularly prone to this typeof trauma. Stress and small enclosure size areconsidered the main contributing factors.
Although wild reptiles held in captivity are
considered most at risk, this problem also
occurs frequently in captive‐bred lizards. It
appears to be more common in anxious species, such as water dragons, Frill‐neck lizards, monitors and some species of iguanas.
Wild reptiles frequently present to the veternarian with traumatic injuries caused bynatural predators, domestic pets, vehicles andhumans. Penetrating bite wounds can often
involve respiratory tissue and can easily leadto both local infection and sepsis. Lawnmower
blades are a common cause of severe lacerations in wild blue‐tongued lizards in Australia.
Often, these wounds are extensive and pulmonary tissue is exposed or exteriorized.
A common presentation in many captive
reptile are wounds inflicted by other pets.

Diseases of the Respiratory System

Cats and dogs can cause penetrating wounds
to the thoracic region. The nasal cavity andnares are occasionally traumatized in lizards
from fights between enclosure cohabitants.
Snakes can suffer severe wounds when live
rodent prey is offered.
Neoplasia

Various neoplasia affecting the respiratory
tract have been reported in reptiles. These
include cases of tracheal chondroma in ballpythons, a pulmonary melanophoroma in a
Rio Fuerte beaded lizard (Heloderma horridum exasperatum), multicentric lymphoma,
fibroma, fibroadenoma and adenocarcinoma.
Metastases from a range of primary neoplasms have been documented. Retroviruseshave been detected in neoplastic tissue andmay be associated with the development of
neoplasia in snakes. Clinical signs are dependent on the location of the disease within the
respiratory tract.
Nutritional diseases

Hypovitaminosis A is well‐recognized nutritional disease in chelonians, chameleons,bearded dragons and iguanas. Vague clinicalsigns include lethargy, anorexia and weightloss. Periorbital oedema, nasal discharge, ocular discharge, stomatitis and aural abscesses
are reported clinical signs that appear to be
due to squamous metaplasia of epithelium.
Diagnosis can be difficult and is usually reliant
on consistent clinical signs and response totreatment. Cytology and histology may demonstrate hyperkeratosis that support a diagnosis of hypovitaminosis A. Weekly treatment
with parenteral vitamin A (see Appendix I) is
recommended, although care must be taken
to avoid iatrogenic hypervitaminosis A.
Infectious Diseases
Bacteria

Bacteria that have been isolated from the reptilian respiratory tract include Pseudomonas,
Klebsiella, Salmonella, Proteus, Aeromonas
species and Morganella morganii. The upper
respiratory system and oral cavity in reptiles

are normally colonized by some of these bacteria and others are also common environmental organisms. The presence of bacteria
in the upper respiratory and digestive tracts is
not necessarily indicative of infection,although isolation of them from the lower
respiratory tract is more consistent with disease. Culture and sensitivities are recommended for diagnosis of bacterial infection
and appropriate antibiotic therapy. Blood cultures and samples from bronchial lavage are
warranted in cases of suspect pneumonia.
Swabs and samples from nasal cavity flushing
may be taken in cases of upper respiratory
infection.
Mycoplasma

Respiratory disease in tortoises caused by
Mycoplasma agassizii and M. testudineum
can be particularly debilitating and potentially fatal. Wild and captive populations areaffected and outbreaks are often reported.
Environmental changes, especially thoseresulting in immunosuppression have been
implicated in the development of infection
and the conversion from subclinical to clinical disease. Rhinitis is the main feature of disease, although other manifestations, such as
pneumonia, have been reported. Clinicalsigns include nasal and ocular discharge,
lethargy, inappetance, periorbital oedema
and conjunctivitis. Chronic cases can lead toerosion of the nasal cavity. Significant exudates can accumulate in the nasal and oralcavities, which may lead to dyspnoea andopen‐mouth breathing. Samples of this discharge can be used for culture of mycoplasma
or polymerase chain reaction (PCR) testing.
Material collected from swabs or flushing of
the nasal cavity can also be used.
Mycoplasma has also been documented asa cause of respiratory disease in a variety ofother reptile species, including crocodilians.
Tracheitis and pneumonia have been associated with an undetermined species of mycoplasma in isolated cases in snakes.
Mycoplasmas have also been reported in thegreen iguana, although their involvement inclinical disease is currently unknown.

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Reptile Medicine and Surgery in Clinical PracticeComplete eradication of mycoplasma organisms is unlikely and infected animals often
relapse after treatment. Antibiotics that havebeen used include fluoroquinolones, aminoglycosides, macrolides and tetracyclines.
Chlamydia

Chlamydiosis has been reported in captive
and wild reptiles. Chlamydia pneumoniae
appears to be the most widespread species
and has been documented in snakes, crocodiles, chameleons and chelonians. Its detection is considered important since strains of
C. pneumoniae are a common cause of respiratory and other chronic disease in
humans. Unclassified organisms have also
been detected. Infection results in granulomatous inflammation of the lungs, heart,
liver and spleen, although asymptomatic carriers can occur. Treatment with doxycycline
can be considered, although extensive granulomas will limit treatment efficacy.
Mycobacteria

A wide range of mycobacteria species havebeen associated with disease in reptiles,
including Mycobacterium chelonae, M. fortuitum,
M. intracellulare, M. marinum, M. phlei,
M. smegmatis, M. ulcerans, M. confluentis,
M. haemophilum, M. hiberniae, M. neoaurum, M. nonchromogenicum. M. tuberculosis
complex has not been reported in a reptile.
Owing to their ubiquitous presence in theenvironment, the development of infection
often requires chronic immunosuppressionof the host. Captive wild animals appear to
be at greater risk, which may be associatedwith chronic stress. Lesions are typically
granulomatous and because mycobacteria
can colonize many tissues, clinical signs ofdisease are dependent on the system affected.
Weight loss is a common nonspecific featureof disease. Reported clinical signs that reflectdisease of the respiratory system include
tachypnoea, increased respiratory effort andnasal discharge. Diagnosis of mycobacteria isbased on detection of acid‐fast organisms
with Ziehl‐Neelsen stain of affected tissues.

Broad range PCR followed by gene sequencing
is important, as mycobacteria can haveimportant zoonotic consequences. Euthanasia
of affected animals remains the most appropriate course of action, although treatment
protocols have been developed. Mycobacteria
have also been detected in the faeces ofasymptomatic pet reptiles, so strict hygiene
is important when reptiles are kept in
captivity.
Fungi

Mycotic infection of the respiratory tract waspreviously considered to be rare and required
significant immunosuppression for disease
to develop. While this is still considered true
for saprophytic fungus, primary mycotic
pathogens have more recently been identified as a major cause of disease in reptiles. It
is possible that immunocompetent animals
may develop infection if there is overwhelming exposure, particularly to an aggressive
fungal species. This is more likely to occur inthe confines of a captive environment, wherepredisposing factors include high humidity
and poor hygiene. Both facultative and pathological species of fungi have also beenshown to colonize normal reptilian skin.
Mycotic disease appears to more commonly
affect the skin than the respiratory tract,
although there is considerable variation
within reptilian species. Fungal lesions in thelungs have been reported in chelonians,
snakes, crocodilians, chameleons. Mycotic
respiratory infections in reptiles haveincluded Aspergillus and Fusarium spp.,
Cryptococcus neoformans, Trichophyton,
Acremonium (Cephalosporium), Beauveria,
Chamaeleomyces and Chrysosporium species. Fungal infection can be demonstrated
by histopathology of lesions but species identification requires culture or PCR. Common
antifungal agents include azoles (ketoconazole, itraconazole, clotrimazole, and miconazole) and polyene macrolides (amphotericin
B, nystatin). Surgical debridement of granulomas is often required in addition to medical therapy.

Diseases of the Respiratory System

Parasites

The types of parasites affecting reptiles
are covered in Chapter 32. Those parasitesthat cause disease in the respiratory system
include parasitic invertebrates (pentastomids), nematodes (lungworms, ascarids,
oxyurids and filaroid nematodes), trematodes (spirorchids) and more rarely protozoan organisms (coccidia, flagellates).
Viruses

Ferlavirus, formerly known as ophidian paramyxovirus or OPMV, lies within the family
Paramyxoviridae. Neurorespiratory diseaseis the main feature of ferlavirus infection insnakes. Nonspecific clinical signs include
lethargy, food refusal, regurgitation andacute death. Respiratory lesions such as
pneumonia are the primary pathology,
with clinical signs including nasal discharge, increased oropharyngeal mucus,­respiratory noise and open‐mouth breathing(Figure 21.2). Neurological signs may include
opisthotonos, loss of righting reflex, abnormal movements, tremors and flaccid paralysis. Asymptomatic infection and chronic,
subtle infection can occur. Outbreaks of
disease can occur, although these appear­
to be confined to captive populations with
only sporadic reports of the presence of ferlavirus in wild snakes.
Figure 21.2 Typical open mouth
posture of a dyspnoeic snake. This
carpet python hybrid has evidence of
stomatitis that is often a concurrent
disease process (courtesy of Tegan
Stephens).

Sunshinevirus, also a paramyxovirus, hasbeen identified in snakes from Australia.
Similar clinical signs to ferlavirus have beenreported in affected animals, although histopathological lesions are predominately foundin the brain, rather than the respiratory tract.
Dermatitis and stomatitis are other potential
features of sunshinevirus infection. Chronicviral shedding has been documented insnakes with asymptomatic infection and vertical transmission has been documented.
Diagnosis is based on PCR testing of bloodand swabs of the oropharynx and cloaca.
Inclusion body disease has been associatedwith respiratory symptoms in snakes fromthe family Boidae. An arenavirus has been
implicated in the disease and it appears likelythat the immunosuppressive effects allow
secondary infections, such as pneumonia, tooccur. The disease appears to be progressive
and chronic, characterized by weight loss,
regurgitation and anorexia. Neurologicalsymptoms include head tremors, incoordination, opisthotonos and loss of righting reflex.
Other important causes of respiratory
disease in snakes include reovirus and a­nidovirus, which appears to cause severe­respiratory disease in captive ball pythons.
The Iridoviridae family that includes thegenera Ranavirus, has mainly been associated with disease in chelonians. Clinical signs

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Reptile Medicine and Surgery in Clinical Practicethat may be observed include nasal discharge,
conjunctivitis and subcutaneous oedema of
the neck. Pneumonia, stomatitis, hepatitis
and enteritis have been reported with ranavirus infections. Ulceration of the nasal mucosa
has been documented in green tree pythons,in addition to necrosis of the liver andpharyngeal region. Anorexia, lethargy, cloacal prolapse and sudden death have beenreported in juvenile animals.
Herpesviruses have been documented inchelonians, snakes, lizards and crocodilians.
Chelonians appear to be more commonly
affected and the respiratory tract is frequently
involved. Tortoises affected by testudinid
herpesviruses can present with nasal andocular discharge, caseous stomatitis, anorexia, lethargy and dyspnoea. Neurologicalsigns, such as ataxia and paralysis, are occasionally observed. Diagnosis is based on PCRof swab or tissue samples. Acyclovir has
been used with frequency in the treatmentof these cases.
Painted turtles (Chrysemys picta), map turtles (Graptemys spp.) and Pacific pond turtles (Clemmys marmorata) have been
documented with a herpesvirus that resultsin hepatic necrosis and pulmonary oedema.
Lethargy, anorexia and subcutaneous
oedema have been the observed clinical features. A variety of herpesviruses affect anumber of sea turtle species. Lung, eye andtrachea disease in green sea turtles resultsin caseous material in the eyes, oropharynx
and trachea. Other clinical features include
problems with buoyancy and dyspnoea.
Loggerhead sea turtles have been documented with two herpesvirus‐associated diseases known as loggerhead genital–respiratory
herpesvirus (LGRV) and loggerhead orocutaneous herpesvirus (LOCV). Affected animals develop ulcers in the mucosal surfacesof the trachea and cloacal tissue in LGRV,
while LOCV results in ulcers in the oral cavity and integument. Exudate adheres to theulcers in LOCV and pneumonia has also
been associated with infection.
Other viruses, such as flavivirus and adenovirus, have been documented to cause

mild pneumonia, although infections resultin more significant pathology in other organs.

­Diagnosis of Respiratory
Disease
Evaluating the respiratory system of the reptile can be challenging, primarily because of
the thick, horny integument that limits auscultation and accurate localization of disease.
Investigative methods include lung washes,
multiple radiographical views, advanced
imaging (computed tomography, magnetic
resonance imaging), tracheoscopy andpulmonoscopy.
A thorough assessment of the respiratory
system may include haematology, biochemistries and blood cultures. Exudates from theupper respiratory tract should be examined
cytologically. Samples from the lower respiratory tract are best obtained with a tracheal
or lung wash.
Sampling of the trachea or lung is best
performed under sedation or anaesthesia,­
although it is possible to perform a cranialtracheal wash on a conscious animal. Care istaken to avoid touching the oral cavity
mucosa as a sterile, flexible, plastic tube
(such as a nasogastric feeding tube) is passed
into the trachea (Figure 21.3). In small
patients, an intravenous catheter without
stylet can be used. The collecting tube canalso be directed through a previously placedsterile endotracheal tube. The level of thetracheal bifurcation depends on the species.
The catheter should be advanced to the levelof the forelimbs in lizards and just caudal tothe heart in snakes. Further advancement
will facilitate sampling from the lung. A volume of sterile saline (5–10 ml/kg) is recommended for flushing. Cytology, microbial
culture and PCR for viral aetiologies can be
performed on samples.
The lung can also be accessed transcutaneously in snakes via the air sac portion of thelung (Figure 21.4). The entry point in the
coelom is made 35–45% of the snout–ventlength on the right side of the body; afterDiseases of the Respiratory System

Figure 21.3 A sterile feeding tube has
been passed into the glottis andtrachea of this carpet python (Morelia
spilota) for a tracheal wash (courtesy of
Bob Doneley).

Figure 21.4 Endoscopic examination
lower respiratory tract via the air sac ina spotted python (courtesy of Bob
Doneley).

entering the coelom, the air sac of the rightlung can be visualized and entered. Exudates,
mucosal scrapings and biopsy samples can betaken. A coeliotomy can also be performed insnakes and lizards to access the lung. Accessin chelonians is more difficult, with pulmonoscopy best performed via the pre‐femoral
region. It is critical to close the horizontal
septum that is perforated when accessing thelung with this approach. A dorsal osteotomy
over the affected area of lung can also be performed in chelonians for the collection ofsamples, but has limited value in terms ofvisualization of the architecture of the lung.

­Principles of Treatment
Initial treatment and the requirement for hospitalization depends on the presenting clinicalsigns. A thermal gradient should be provided
if a patient is hospitalized; supportive care
may include fluid therapy and tube feeding.
Although severe dyspnoea warrants oxygentherapy, it must be remembered that the stimulus for ventilation in reptiles is hypoxaemia.
Chronic oxygen supplementation, especiallyat high levels, is therefore not recommended.
Nebulization with saline can be employed tohelp reduce congestion in the upper respira-

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Reptile Medicine and Surgery in Clinical Practice

Figure 21.5 Nebulization of a
black‐headed python (Aspiditesmelanocephalus) in an oxygen
chamber (courtesy of Bob Doneley).

tory system and improve the function of therespiratory mucosa. Nebulization can alsodeliver aerosolized antimicrobials to the lower
respiratory tract (Figure 21.5).
Other methods of drug administration
include parenteral, per os and topical routes.
Medication supplied in drinking water is notrecommended, owing to the likelihood ofinconsistent intake. Injectable medications
are preferred in snakes because of their infrequent feeding patterns and the potential for
erratic absorption with oral administration.
This should also be a consideration for all reptile species where digestion may be delayed or
impaired, such as can occur with debility, brumation and hypothermia. Chelonians can bedifficult to medicate orally, so parenteral formulations of medication are usually selected.
Granulomas and abscesses are common
developments in reptile infections. Surgicalexcision of abscesses or debridement of caseous exudates is required to treat these infections effectively. While the upper respiratory
tract is reasonably accessible, surgery of
the lower respiratory tract is more difficult,especially in chelonians. Debridement of
pulmonary lesions and biopsy of masses canalso be performed with endoscopic guidance.
Endoscopy is also useful in the removal of foreign bodies, pentastomids and other parasites.
The air sac component of the lung in manysnakes and lizards can pose a significant
challenge in treating respiratory infections.
Exudates can accumulate in this portion of
the lung and are unable to be cleared effectively. Clearance is impaired by the absenceof a diaphragm and the subsequent inability
to cough. It may be required in some cases todrain mucous or surgically remove caseous
accumulations.

­Further Reading
Jacobson, E.R. (2007) Parasites and parasitic
diseases of reptiles, in Infectious Diseases
and Pathology of Reptiles (E.R. Jacobson,ed.) CRC Press, Boca Raton, FL,
pp. 571–666.
Mehler, S.J. and Bennett, R.A. (2006) Upper
alimentary tract disease, in Reptile Medicine
and Surgery (D.R. Mader, ed.) WB Saunders,Philadelphia, PA, pp. 299–322.

Lock, B.A. and Wellehan, J. (2015) Ophidia:
snakes, in Fowler’s Zoo and Wild Animal
Medicine 8th ed. (R.E. Miller and M.E. Fowler,eds), Saunders, St Louis, MO, pp. 60–74.
Schumacher, J. (1997) Respiratory diseases ofreptiles. Seminars in Avian and Exotic Pet
Medicine, 6, 209–215.
Marschang, R.E. (2011) Viruses infecting
reptiles. Viruses, 3, 2087–2126.

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22
Disorders of the Reproductive System
Timothy J. Portas

Anatomy and Physiology
See Chapter 2 for a more detailed review of the
anatomy and physiology of the reproductive system. See also Chapter 7 for general information
about the management of normal reproduction.
Key Points
Male chelonians and crocodilians have a single copulatory organ referred to as the penis,
which is located on the cranioventral aspectof the cloaca.
●● Male snakes and lizards have paired hemipenes located in the caudal cloaca and inverted
into the ventral tail base.
●●­Dystocia/Post‐Ovulatory
Egg Stasis
Aetiology
Captive reptiles are commonly presented forveterinary evaluation and care as a result ofdystocia. Dystocia occurs most frequently
in oviparous reptiles but can also occur inviviparous reptile species.
Pathogenesis
Predisposing environmental and husbandry
related factors include:

The copulatory organs do not contain aurethra.
●● The paired testes are intracoelomic.
●● Some female reptiles can retain viable
sperm in their uterus for several years after
copulation.
●● All chelonians and crocodilians are oviparous.
●● Some snakes and lizards are viviparous.
●● Allcrocodilians and some chelonians,­lizards and the tuatara (Sphenodon punctatus) exhibit temperature‐dependent sex
determination.
●●

inappropriate humidity, temperature andphotoperiod●● absence of ultraviolet lighting●● inappropriate
or insufficient nesting
substrate●● lack of a nesting site in which the female
feels sufficiently secure.
●●

Host factors that can contribute to dystocia
include:metabolic imbalances such as hypocalcaemia and hypovitaminosis A●● obesity and/or poor muscle tone●● nutritional imbalances●● salpingitis●●

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

308

Reptile Medicine and Surgery in Clinical Practiceoviductal rupture
coelomic cavity masses, including nephromegaly●● cystic and cloacal calculi●● gastrointestinal tract obstruction●● relative oversize or malformation of theegg(s)●● dehydration●● pelvic stenosis caused by nutritional secondary hyperparathyroidism or trauma●● concurrent disease.
●●●●

Clinical Signs
The clinical signs of dystocia may vary from
species to species and individual to individual. Clinical signs may be nonspecific or
absent but may include reduced appetite oranorexia, dehydration, nesting behaviour,
straining and cloacal or oviductal prolapse,
weight loss, posterior paresis, coelomic cavity distension and lethargy. Coelomic cavity
distension and partial or complete anorexia
can occur normally during folliculogenesis
and during advanced gravidity in some lizard
species. The normal oviposition of a partial
clutch with retention of one to two eggs canalso occur and is most common in snakes.
Diagnosis
Dystocia can be challenging to diagnose insome cases. Some clinical signs exhibited
during dystocia can be difficult to differentiate from those exhibited by gravid females
progressing normally to oviposition or parturition, including coelomic cavity distension
and anorexia. Additionally, chelonians canretain eggs for prolonged periods without
apparent ill effect and snakes may retain eggs
without systemic effects for variable periodsof time. Multiple diagnostic techniques areoften required to obtain a definitive diagnosis of dystocia and to develop an appropriate
treatment plan. Eggs may be detected via palpation of the coelomic cavity. In chelonians,
the shell limits coelomic cavity palpation but
eggs may still be palpated or balloted via
the inguinal fossa, although they must be­ ifferentiated from faecoliths and uroliths.
dPalpation of fetuses in viviparous species canbe challenging and ultrasonography or radiography is indicated for definitive diagnosis
of pregnancy.
Ultrasonography and radiography are an
integral component of the diagnostic evaluation of the dystocic reptile. Both imaging
modalities can be used to demonstrate thepresence of eggs, although it should be notedthat the presence of eggs alone does not indicate dystocia. Retained eggs in chelonians
may develop abnormally thickened shells. In
those species producing soft‐shelled eggs
(snakes and many lizard species), poor mineralization of the shell, particularly in theearly post‐ovulatory stage, results in a radiolucent shell which may be difficult to differentiate radiographically from preovulatory
ova. Preovulatory ova are typically roundedin shape and tightly associated while post‐
ovulatory ova tend to be more oval anddevelop a linear association particularly
as oviposition approaches. On ultrasoundexamination eggs have a hyperechoic perimeter equating to the mineralized shell and,in squamates, the albumin tends to be hypoechoic while the yolk is hyperechoic. The
inguinal fossa of chelonians provides anappropriate acoustic window for ultrasonographic examination of the female reproductive tract.
Radiography is superior to ultrasonography in determining the size, shape, positionand number of eggs present. Additionally,
radiography can be used to evaluate thepatient for the presence of underlying metabolic bone diseases, pelvic stenosis, cystic
and cloacal uroliths, faecoliths and coelomic
cavity masses. Radiography can also be used
to detect the embryos of viviparous species
in late stages of development.
Blood should be collected to assess underlying or concurrent disease. A complete
blood count and full biochemical analysis (orat a minimum, serum calcium, phosphorous
and uric acid values) should be determined
as dehydration, hypocalcaemia, infection
and renal insufficiency may all accompany

Disorders of the Reproductive System

dystocia in reptiles. Results should be interpreted in the light of other clinical findings,
as elevations in serum calcium and phosphorous can occur during normal vitellogenesis
in some lizard species as well as in dystocic
patients.
Treatment
General Principles

Underlying physiological abnormalities mustfirst be corrected and the patient stabilized
before correction of the dystocia can takeplace. Dehydration is treated with intracoelomic, intravenous or intraosseous Ringer’s
solution for reptiles (one part lactated Ringer’s
solution, two parts 2.5% dextrose/0.45%
saline solution) at 10–20 ml/kg every 24
hours. Hypocalcaemia is treated with oralcalcium glubionate at 360 mg/kg every 6–24
hours. Parenteral calcium supplementationis generally avoided unless hypocalcaemic
tetany is present, in which case parenteral
calcium gluconate at 100 mg/kg may be
administered until the patient is stabilized. A
thermal gradient appropriate to the species
in question should be supplied. Appropriate
analgesia and antibiotic therapy, where indicated, should be provided. Empirical antibiotic therapy with ceftazidime at 20 mg/kg
every 72 hours or piperacillin at 100 mg/kg
every 48 hours may be used if the results of
microbial culture and sensitivity are notavailable. The reader is referred to the­relevant chapters within this text for managing underlying and concurrent disease
processes.
In the early stages of non‐obstructive dystocia, where the patient is otherwise clinically normal, correction of environmental
and husbandry deficiencies may be sufficient. Providing an appropriate thermal gradient, correcting dehydration through warm
water soaks or parenteral fluid administration and provision of a suitable nesting site
may induce oviposition.
Medical management of non‐obstructive
dystocia may be attempted in reptiles without
significant underlying or concurrent disease.

Following administration of oral calcium
glubionate, intramuscular oxytocin (5–30 iu/kg) is administered. The dose may be repeatedwithin 3–12 hours if there is no response toinitial administration. Oxytocin is most effective in chelonians, less so in lizards, withsnakes being the least responsive. Oxytocin
therapy is most likely to be effective if administered within 48–72 hours of the onset ofoviposition or parturition in squamates.
The intravenous administration of oxytocin
may result in more rapid induction and subsequent completion of oviposition thanintramuscular administration. Oxytocin iscontraindicated in cases of follicular stasis
or obstructive dystocia. Arginine vasotocin is
described in the literature as being potentiallymore effective than oxytocin it but is notavailable for routine clinical use. The use of
prostaglandin F2 alpha has also been reported
but with variable efficacy.
Cases of nonobstructive dystocia unresponsive to medical management and mostcases of obstructive dystocia will requirecoeliotomy (or coelioscopic assisted surgery)and surgical correction. In viviparous species
presenting with dystocia, a caesarean section
is indicated (Figure 22.1). The reader isreferred to Chapter 28 for a detailed
account of surgical approaches to dystocia.
Supportive care includes thermal support,
fluid and nutritional support, antibiotic­therapy and analgesia.
Management in Chelonians

In chelonians, eggs maybe retained for­variable and prolonged periods without ill
effect, so a decision to intervene must be
based on the results of the physical examination and ancillary diagnostic tests (Innis
2002). Dystocia in chelonians is rarely amedical emergency, so correction of underlying environmental and husbandry related
issues is a reasonable first step in otherwise
clinically normal animals. Oxytocin can beadministered every 3–12 hours, althoughtreatment should cease if no eggs are produced in a 48‐hour period. Oxytocin administration and supportive medical therapy

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Reptile Medicine and Surgery in Clinical Practice

Figure 22.1 Caesarean section tocorrect dystocia in a broad‐headed
snake (Hoplocephalus bungaroides).
The snake had given birth to two deadfoetuses over the preceding 48 hours
and was presented for evaluation forpotential dystocia. Ultrasoundexamination revealed the presence ofadditional foetuses and a further threedead foetuses were removed by
performing a coeliotomy and multiple
salpingotomies.

may be continued over several days until all
eggs have been deposited if there is no underlying pathology. Beta‐adrenergic blockers
such as propranolol and atenolol have beenshown to potentiate the effects of oxytocin
and their use prior to oxytocin administration has been advocated in chelonians (Chitty
and Raftery 2013).
In cases of obstructive dystocia, per cloacal
aspiration and collapse of eggs that have progressed to the junction of the oviduct andurodeum is possible, although cloacoscopy
may be necessary to effectively and safely
access the egg. If oversized eggs are notaccessible per cloaca then surgical intervention is indicated.
Management in Lizards

In contrast to chelonians, dystocia in oviparous lizards often progresses rapidly and canbe fatal without prompt and appropriate
intervention. Cases of nonobstructive dystocia that are not responsive to medical therapy
and most cases of obstructive dystocia will
require surgery. Per cloacal aspiration of egg
contents, followed by collapse and removalof the egg, is possible in lizards (Figure 22.2).
Cloacoscopy and ovocentesis can be performed with readily available nonspecialized
equipment, such as a standard domestic
animal otoscope in many lizard species.

Percutaneous aspiration of egg contents
for the correction of dystocia has also been
described in lizards. Potential complications
associated with per cutaneous aspiration of
eggs include yolk coelomitis and penetrationof viscera.
Management in Snakes

In the case of snakes with non‐obstructive
dystocia unresponsive to medical therapy,
eggs may be gently manipulated, with the aidof adequate lubrication, towards the cloaca
and removed under anaesthesia. Oversized
eggs may require per cloacal or per cutaneous aspiration to collapse the egg shell andallow passage through the cloaca. Oviductal
rupture and/or prolapse are potential sequelae to the physical manipulation of retained
eggs and this approach should be used withcaution (Stahl 2002).
Prevention and Control
Dystocia in captive reptiles is best prevented by ensuring appropriate environmental conditions and husbandry practices
for the species in question, maintaining
physically fit animals at appropriate bodyweights, careful breeding management andclose behavioural monitoring and observation of breeding animals.

Disorders of the Reproductive System

Figure 22.2 (a) Per cloacal aspirationof yolk and albumin from an oversized
egg in a gila monster (Heloderma
suspectum). (b) Following aspirationand lubrication of the cloaca, thecollapsed egg is removed using
alligator forceps.

(a)

(b)

­Preovulatory Follicular
StasisAetiology
Preovulatory follicular stasis occurs when afemale undergoes vitellogenesis but then fails
to ovulate or resorb the ova. The condition
occurs most commonly in lizards, in particular iguanids, agamids, chameleons and varanids; it also occurs in chelonians but isuncommon in snakes.

Pathogenesis
The pathogenesis of preovulatory follicularstasis in captive reptiles in poorly understood. However, many of the same environmental and host factors that underlie thedevelopment of post‐ovulatory egg stasis
have been implicated in the development ofpreovulatory follicular stasis. Inappropriate
environmental conditions (temperature,
photoperiod) seem to be particularly important in some tortoise species held outside

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Reptile Medicine and Surgery in Clinical Practice

Figure 22.3 Inflamed, necrotic andruptured follicles in an ovary removed
from a female perentie (Varanus
giganteus) with follicular stasis(reproduced with the permission of
Timothy Portas and Reptile Publishers).

their natural range. The endocrinology offolliculogenesis and ovulation is incompletely understood in many reptile species
and disruption of normal endocrine processes in captivity may underlie some casesof follicular stasis. The presence of a male has
been shown to be necessary for folliculardevelopment and ovulation in some species(Sykes 2010). Static follicles may eventually
become inspissated and necrotic or may rupture, liberating yolk material into the coelomic cavity (Figure 22.3).
Clinical signs
Clinical signs include coelomic cavity
distension, reduced appetite or anorexia,­
dehydration and lethargy. In some cases,
the reptile may be found dead without­premonitory signs.
Diagnosis
While the clinical signs of coelomic cavity
distension, anorexia, dehydration and lethargy are suggestive, follicular stasis must be
differentiated from dystocia. Follicles can bedetected via coelomic cavity palpation insome species, although care should be taken
to avoid rupturing the thin‐walled ovarianfollicles. Follicles may be difficult to see radiographically and a contrast penumocoelogram can be performed using 10 ml of room
air injected into the coelomic cavity toprovide greater contrast (Funk 2002).
Abundant vitellogenic follicles can also bereadily detected via ultrasonography in most
species, although follicles are of variableechogenicity depending upon the stage ofdevelopment and species in question.
Sequential ultrasound examinations can beused to track follicular development anddemonstrate stasis (over a period of several
weeks). With experience, developing andatretic follicles can be differentiated on thebasis of echogenicity or ultrasonographic
appearance (Figure 22.4). Coelioscopy underanaesthesia, while more invasive, provides
for visualization of the ovaries and internalorgans. Haematology and biochemistry
may indicate systemic illness and further
support the diagnosis. Potential abnormalities include heterophilia (with or without
toxic changes), leucopenia, haemoconcentration, hypoproteinaemia, hyperalbuminaemia,
hypercalcaemia, hyperphosphataemia andelevated alkaline phosphatase and creatine
kinase (Sykes 2010, Chitty and Raftery 2013).
Treatment
While it is theoretically possible that female
reptiles exhibiting follicular stasis may subsequently resorb these follicles, in theauthor’s experience this is rarely, if ever, thecase. Medical management of follicular stasis
through attempted induction of ovulation
are usually unsuccessful. Follicle‐stimulating

Disorders of the Reproductive System

Figure 22.4 Ultrasonographic
appearance of a vitellogenic (a) andatretic (b) follicle in an Aldabran
tortoise (Aldabrachelys gigantea).

(a)

(b)

hormone, gonadotropin‐releasing hormone
II and progesterone followed by prostaglandin F2 alpha are ineffective in inducing ovulation in veiled chameleons (Chamaeleo
calyptratus). Proligestone has variable efficacy in inducing follicular resorption in chelonians (Chitty and Raftery 2013). Treatmentof follicular stasis is currently limited to coeliotomy (or a coelioscope‐assisted approachin chelonians) for ovariectomy or ovariosalpingectomy. As with dystocia, the patientmust first be stabilized and any underlying or
concurrent disease processes managed prior

to surgery. The reader is referred to
Chapter 28 for a detailed account of surgicalapproaches to ovariectomy. Supportive careincludes thermal support, fluid and nutritional support, antibiotic therapy and analgesia. Any concurrent disease, such as hepatic
lipidosis, must also be managed.
Prevention and Control
Contraception of females, not required forbreeding, either via surgical sterilization or
the administration of exogenous hormones

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Reptile Medicine and Surgery in Clinical Practice

are currently the only preventative options.
However, variable results have been observedwith the administration of exogenous hormones for contraception. Administration ofleuprolide acetate or medroxyprogesterone
during the previtellogenic phase does notinhibit or delay follicular development inveiled chameleons. However implantation ofthe
gonadotrophin‐releasing
hormone(GnRH) agonist deslorelin acetate appears tobe effective in inhibiting the production of
estrogen and progesterone and preventing
follicular development in green iguanas(Iguana iguana). Further investigation into
the application of deslorelin as a contraceptive implant for females not required forbreeding is warranted. For those female reptiles required for breeding, prevention is limited to ensuring optimal environmental andhusbandry conditions specific to the species
and routine ultrasonography of folliculardevelopment during the breeding season.

­Yolk‐Associated Coelomitis
Aetiology
Yolk‐associated coelomitis occurs as asequel to follicular stasis or dystocia. It has
been reported as a common problem ingreen iguanas, Fijian banded iguanas, variousv­ aranids, bearded dragons and various chelonian species (Jacobson 2003, Sykes 2010).
Pathogenesis
The physiology of vitellogenic follicle atresia
and resorption in reptiles remains incompletely understood. However, it appears thatspontaneous rupture of multiple large,
atretic, vitellogenic follicles can overwhelm
the coelomic resorptive capacity of yolk
material, leading to coelomitis (Stacy et al.
2008). Liberation of yolk material into the
coelomic cavity may also occur subsequent
to trauma, overly rough palpation of follicles
or per cutaneous aspiration of egg contents.
The liberation of vitellin into the coelomic
cavity incites a sterile inflammatory reaction leading to granulomatous coelomitis,
serositis, extensive mesothelial proliferationof serosal surfaces and yolk embolism(Figure 22.5). Secondary bacterial infections
are common.
Clinical Signs
As with dystocia and follicular stasis cases
the clinical presentation can be variable,
often nonspecific, and may include coelomic
cavity distension, dehydration, inappetance,dark discolouration of the skin or death without premonitory signs (Figure 22.6).

Figure 22.5 Intraoperative
photograph of a female perentie(Varanus giganteus) with yolk
coelomitis following ovariectomy andremoval of yolk material from thecoelomic cavity. The mesovarium andthe serosal surfaces of oviducts andgastrointestinal tract are severely
inflamed as a result of yolk material in
the coelomic cavity.

Disorders of the Reproductive System

Figure 22.6 Abundant yolk material
removed from coelomic cavity of afemale green iguana (Iguana iguana)that died of egg yolk coelomitis
without exhibiting premonitory signs(courtesy of Claude Lacasse).

Diagnosis
Establishing a definitive diagnosis of yolk
associated coelomitis can be challenging as
the clinical signs are often nonspecific.
Clinical pathological changes can be variable
but may include hypercalcaemia, hyperphosphataemia, hyperuricaemia (and elevatedblood urea nitrogen in terrestrial chelonians), heterophilia and elevated aspartate
aminotransferase. Coelomic cavity ultrasonography can be used to demonstrate coelomic cavity fluid and guide coelomic cavity
centesis for fluid analysis (Rivera 2008).
Coelioscopy is a more invasive method but
allows for direct visualization of the ovaries
and coelomic cavity and definitive diagnosis.
Treatment
The prognosis is guarded as affected reptiles
are typically profoundly unwell at the time ofdiagnosis and often have concurrent renal
dysfunction. Patients must be stabilized
before anaesthesia and surgical management.
Treatment involves surgical management;
ovariectomy or ovariosalpingectomy, removalof yolk material and copious coelomic cavity
lavage. The reader is referred to Chapter 28
for a detailed account of surgical approaches
to ovariectomy. Supportive care includes

thermal support, fluid and nutritional support, appropriate antibiotic therapy andanalgesia.
Prevention and Control
Prevention in breeding females involves
ensuring optimal environmental and husbandry conditions specific to the species,
close monitoring during the breeding season and routine clinical evaluation andultrasonography of high risk patients.
Females not required for breeding may besurgically sterilized or contracepted (seefollicular stasis section).

­Salpingitis
Aetiology
Salpingitis has been reported from various
chelonian and squamate species but appears
to be an uncommon finding.
Pathogenesis
Salpingitis may be the result of infection
with a wide range of bacteria including
Pseudomonas and Salmonella species.
Infection may occur following oviposition or

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Reptile Medicine and Surgery in Clinical Practice

Figure 22.7 Eggs removed via
salpingotomy to correct a dystocia in afemale western brown snake(Pseudonaja nuchalis) with a
Pseudomonas aeruginosa salpingitis.
Note the thickened and deformed
shells and the variable size of the eggs.

secondary to dystocia or other reproductive
problems. In chelonians, obstruction of thepelvic canal by oversized or malformed eggs
may result in the backflow of urine and faecal
material into the oviducts resulting in salpingitis. Conversely, where salpingitis occurs asa primary disorder it may be a predisposing
factor for dystocia.
Clinical Signs
The clinical signs of salpingitis may include
infertility and dystocia. Affected reptiles
may produce eggs with thickened, unevenshells, deformed eggs or eggs of variable size
(Figure 22.7).
Diagnosis

Prevention and Control
As with other reproductive diseases forwhich the causes are incompletely understood, prevention is limited to ensuring
appropriate species specific environmental
conditions and husbandry practices.

­Oviductal Prolapse
Aetiology
Oviductal prolapse is seen most commonlyin snakes but can also occur in lizards andchelonians.
Pathogenesis

Salpingitis may be diagnosed by demonstrating oviductal enlargement via ultrasonographic examination or coelioscopy.
Haematology and biochemistry may provide
further evidence of an infectious process.

Oviductal prolapse occurs secondary to dystocia or other causes of straining such as constipation or cystic and cloacal calculi.
Oviductal prolapse may also be iatrogenically induced following attempts to manipulate retained eggs in snakes.

Treatment

Clinical Signs

Therapy with appropriate antibiotics andanti‐inflammatories may be effective in earlycases but is unlikely to be successful in casesof advanced infection. Ovariosalpingectomy
is indicated in advanced cases or those cases
failing to respond to medical therapy.

The thin‐walled oviduct, which may or may
not contain eggs, is evident protrudingfrom the cloaca (Figure 22.8). Depending
upon the duration of the prolapse the oviduct may be oedematous, traumatized or
necrotic.

Disorders of the Reproductive System

Figure 22.8 Prolapse of the oviduct ina Steppe tortoise (Testudo horsfieldii)
subsequent to dystocia. Photo credit
Zdenek Knotek.

Diagnosis
The prolapsed oviduct is generally self‐­
evident but may need to be differentiated fromprolapsed cloacal tissue, bladder or colon.
Treatment
Damage to the suspensory ligaments of theoviduct is highly likely following prolapse.
Even with successful inversion and reductionof the prolapsed oviduct per cloaca, suspensory ligament damage will likely limit theability of the oviduct to receive ovulated
follicles in the future. Additionally, theprolapsed oviduct is frequently severely
traumatized and compromised following
prolapse. Surgical removal of the affected
oviduct and its associated ovary is recommended. Retention of the contralateral ovaryand oviduct preserves the breeding potentialof the female if required. The underlying
cause must also be addressed. Appropriate
antibiotic therapy, analgesia and symptomatic support should be initiated in affectedanimals.
Prevention and Control
Ovariosalpingectomy via coeliotomy isrecommended to prevent recurrence.
­
Nonbreeding females may undergo elective
ovariectomy or ovariosalpingectomy orcontraception.

­Phallus Prolapse
Aetiology
The term ‘phallus’ is used to encompass boththe penis of crocodilians and chelonians andthe hemipenis of squamate species in thissection. Phallus prolapse occurs most commonly in chelonians; can also occur insnakes and lizards; but is uncommon in
crocodilians.
Pathogenesis
Predisposing factors include:
excessive breeding and breeding on particulate substrate●● inflammation and infection including frominappropriate probing techniques●● hemipenal abscessation●● nutritional causes such as hypovitaminosis
A (lizards) and nutritional secondary
hyperparathyroidism (young chelonians
and lizards)●● straining
secondary to endoparasitism,
constipation or cystic and cloacal calculi●● trauma including autotomy close to thebase of the tail in lizards●● neurologicaldeficits of the retractor
muscles●● gastrointestinal foreign bodies.
●●

The prolapsed phallus is typically swollen,because of decreased venous and lymphatic

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Reptile Medicine and Surgery in Clinical Practicedrainage, and inflamed, preventing inversion
or retraction into a normal anatomical position. It is likely to sustain physical trauma,including from conspecifics and become desiccated and necrotic with prolonged exposure.

Radiography may be useful to demonstratespinal lesions such as scoliosis, kyphosis,
fractures and other underlying causes which
may be contributory.

Clinical Signs

Under general anaesthesia, the prolapsed
phallus is cleaned and debrided as required,lubricated and replaced into the normal anatomical position. If the prolapsed phallus has
become extensively swollen, the applicationof hypertonic solutions, cold compresses
and the use of topical and systemic anti‐­
inflammatory drugs may be necessary to
reduce swelling sufficiently to replace theprolapsed tissue. Care should be taken
manipulating the phallus as the prolapsed
tissue is frequently fragile and prone to further

The prolapsed phallus is evident protruding
through the vent and may exhibit varying
degrees of oedema, trauma and necrosis
depending upon the cause and the durationof the prolapse (Figure 22.9).
Diagnosis
A prolapsed phallus is generally self‐evident
but may need to be differentiated fromprolapsed cloacal tissue, bladder or colon.
(a)

(b)

Treatment

Figure 22.9 (a) Prolapse of the phallus
in a Krefft’s turtle (Emydura macquarii
krefftii) following conspecific trauma
during the breeding season. (b)Hemipenal prolapse in a Komodo
dragon (Varanus komodensis)
secondary to neurological deficits
associated with a spinal lesion(reproduced with the permission of
Timothy Portas and Reptile Publishers).

Disorders of the Reproductive Systemdamage. Once returned to a normal anatomical position, the cloaca of chelonians may besutured partially closed with a purse‐string
suture. In lizards and snakes, single interrupted sutures are more suited to the linear
opening of the cloaca. Sutures can be left inplace for up to two weeks. If the underlying
cause of the prolapse is not identified andmanaged or resolved recurrent prolapse is adistinct possibility. Where there is extensive
tissue necrosis or swelling, neurological deficit or where the phallus has repeatedly prolapsed surgical amputation may be performed
as the phallus has no function in urination.
The reader is referred to Chapter 28 for a
detailed account of surgical approaches tophallus amputation. Amputation of a hemipenis in snakes and lizards does not preclude
future reproduction. Systemic (and topical)
antibiotic therapy and appropriate analgesia
should be initiated.
Prevention and Control
The breeding activity of males should be
limited to reduce the risk of trauma andprolapse associated with overuse of thephallus or hemipenes. Consideration should
be given to appropriate substrates inbreeding enclosures. Ensuring adequate­
nutrition, particularly for young growing
chelonians and herbivorous or insectivorous lizards, is important to prevent nutritional secondary hyperparathyroidism andhypovitaminosis A, which may be contributory to the condition.

­Hemipenal Plugs

Pathogenesis
Hemipenal plug formation is a normal occurrence and plugs are typically shed when thehemipenes are everted during breeding. In
some lizards, these plugs may fail to shed andbecome enlarged and impacted. Large plugs
preclude the lizard from everting the hemipenes, inhibit defecation and may be associated with dysecdysis around the vent.
Hemipenal abscessation and rupture canoccur in severe cases. Potential causes
include hypovitaminosis A associated squamous metaplasia, inappropriate humidity
and reduced opportunities to breed.
Clinical Signs
Hemipenal plugs are evident as pale waxy
material protruding from the inverted hemipenis into the caudal cloaca (Figure 22.10a,b).
The cranial end of the plug may be covered in
faecal material and/or urates. Large hemipenal plugs may cause pronounced hemipenalbulging and where abscessation has occurred
there may be localised cellulitis.
Diagnosis
Hemipenal plugs are readily diagnosed on
the basis of clinical examination.
Treatment
In mild cases, the plug may be removed fromthe conscious lizard using gentle traction andlubrication. For larger plugs or where there issignificant impaction, general anaesthesia may
be required to facilitate removal. Complete
eversion of the hemipenis may be necessary toensure that all of the plug material is removed.

Aetiology
Hemipenal plugs have a firm waxy consistency, are composed of seminal material,
glandular material and sloughing epithelium
and form within the lumen of the hemipenes
in various lizard (iguanids, agamids and gekkonids) and snake species.

Prevention and Control
Prevention is limited to ensuring appropriate
species specific environmental conditions
and nutrition. The caudal vent should be
regularly inspected and hemipenal plugs
removed before they become a problem.

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Reptile Medicine and Surgery in Clinical Practice­Ectopic Eggs
Aetiology
Ectopic eggs are seen most frequently in chelonians but can also occur in squamates.
Ectopic eggs may be located free in the coelomic cavity in all reptiles or in the urinary
bladder of chelonians.
Pathogenesis
Ectopic eggs in the urinary bladder of chelonians can occur subsequent to oxytocin therapy; oxytocin administration is thought toresult in the retrograde movement of cloacal
eggs through the wide urethral opening into
the bladder. Previous salpingotomy, without
suturing of the thin‐walled oviduct, may be
a risk factor for ectopic eggs in subsequent
breeding events. Nutritional secondary(a)hyperparathyroidism and failure to provide
appropriate nesting sites have also been
postulated as potential causes in terrestrial
chelonians.
Clinical Signs
The clinical signs associated with ectopic
eggs are frequently nonspecific or absent all
together.
Diagnosis
Differentiating ectopic eggs that are either
free in the coelomic cavity or in the urinary
bladder from those in the oviduct using radiography can be challenging. Eggs within theurinary bladder of chelonians may be identified by ultrasonography although if urine is
not present in the bladder differentiationfrom the eggs in the oviduct is challenging.
(b)

Figure 22.10 (a) Fijian crested iguana (Brachylophus vitiensis) with a hemipenal plug. (b) Hemipenal plugfollowing removal.

Disorders of the Reproductive System

Cystoscopy using saline infusion, for eggs
located in the bladder, and coelioscopy, foreggs free in the coelomic cavity, can be used
to obtain a definitive diagnosis.
Treatment
Coeliotomy is indicated for eggs free in the
coelomic cavity. Ectopic eggs in the urinary
bladder may be removed or cystotomy or via
a cystoscopic approach in which the egg issnared or destroyed for removal (Di Girolamo
and Selleri 2015). The reader is referred tochapter 28 for detailed accounts of theseprocedures.

­Infertility
Potential causes of infertility in female reptiles
include inappropriate environmental cues,
malnutrition, underlying systemic disease andsalpingitis. Options for evaluating infertile
females include reviewing husbandry andnutrition, clinical examination to rule out
underlying disease processes, ultrasonographic evaluation of the ovaries to confirm
vitellogenesis, ultrasonographic evaluationof the oviduct for evidence of salpingitis,and endoscopic evaluation of the reproductive tract.
Potential causes of infertility in male reptiles include lack of interest in or inability
to copulate and lack of spermatogenesis.
Options for evaluating infertile males include
analysis of serum testosterone or faecal testosterone metabolites, testicular biopsy via a
coelioscopic approach and semen collection
either postcopulation or via electroejaculation. However, normal values for testosterone
concentration are unknown for many species
and semen analysis has rarely been performedin reptiles, such that reference values for agiven species are unlikely to be known.

­References
Chitty, J. and Raftery, A. (2013) Essentials of
Tortoise Medicine and Surgery. John Wileyand Sons Ltd, Oxford.
Di Girolamo, N. and Selleri, P. (2015). Clinicalapplications of cystoscopy in chelonians.
Veterinary Clinics of North America Exotic
Animal Practice, 18, 506–526.
Funk, R.S. (2002) Lizard reproductive
medicine and surgery. Veterinary Clinics ofNorth America Exotic Animal Practice, 5,
579–613.
Innis, C.J. and Boyer, T.H. (2002) Chelonian
reproductive disorders. Veterinary Clinics ofNorth America Exotic Animal Practice, 5,555–578.
Jacobson, E.R. (2003) Biology, Husbandry andMedicine of the Green Iguana. Krieger
Publishing, Malabar, FL.
Pimm, R.H. (2013) Characterization of
Follicular Stasis in a Colony of Female Veiled

Chameleons (Chamaeleo calyptratus). MSc
Thesis, University of Guelph. https://atrium.
lib.uoguelph.ca/xmlui/bitstream/
handle/10214/6678/Pimm_Robyn_201305_
Msc.pdf?sequence=1 (accessed 12 June 2017).
Rivera, S. (2008) Health assessment of thereptilian reproductive tract. Journal of
Exotic Pet Medicine, 17, 259–266.
Stacy, B.A., Howard, L., Kinkaid, J. et al. (2008)
Yolk coelomitis in Fiji Island banded
iguanas. Journal of Zoo and Wildlife
Medicine, 39, 161–169.
Stahl, S.J. (2002) Veterinary management ofsnake reproduction. Veterinary Clinics ofNorth America Exotic Animal Practice, 5,
615–636.
Sykes, J.M. (2010) Updates and practical
approaches to reproductive disorders in
reptiles. Veterinary Clinics of North America
Exotic Animal Practice, 13, 349–373.

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23
Diseases of the Urinary Tract
Peter Holz

This chapter provides a practical approach to
the diagnosis, treatment and prevention ofurinary system disease in reptiles. It is notintended to be a comprehensive review of thereptilian urinary system, its disorders andtreatments. ­Anatomy and Physiology
Consult Chapter 2 for more detailed information on the anatomy and physiology of the urinary system, Chapter 11 for diagnostic testing
and Chapter 13 for clinical techniques.
Key Points
The fundamental structure and function of
the reptilian urinary system is similar to
mammals with several key variations:●● There is no loop of Henle. Reptiles cannot
therefore produce hypertonic urine.
●● Terrestrial reptiles excrete uric acid insteadof urea.
●● Reptiles have a renal portal system, whichallows reptiles to shunt venous blood from●●

Renal Disease
Diagnosis
Renal disease in reptiles is underdiagnosed,
frequently presenting in conjunction withsystemic illness. It can be difficult to recognize as signs are vague, nonspecific and manyof the diagnostic tests used to detect renal
disease in mammals do not apply.

the caudal part of the body through the kidneys during periods of water deprivation toprevent renal tubular ischaemia.
●● A urinary bladder is present in chelonians,
tuataras and some lizards (some skinks,
geckos, iguanas and chameleons) but islacking in snakes and crocodilians.
●● Ureters connect directly with the cloaca, notthe urinary bladder (where present).
●● In most lizard species, the kidneys arelocated within the pelvis.
●● Many of the standard blood and urine tests
used to diagnose renal disease in mammals
do not apply in reptiles.

As with all reptile disorders, it is important
to obtain as thorough a history as possible.
This should focus not just on the animal but
also on the environment and husbandry. Has
the patient been eating? What is its diet? Are
protein type and levels appropriate for thatspecies? Does it have access to fresh water ina form it will recognize? Chameleons, forexample, only drink dripping water and will

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

324

Reptile Medicine and Surgery in Clinical Practicedehydrate if water is put out in a dish. Is thehumidity level appropriate for the species? Is
the environment warm enough? Is there sufficient ultraviolet light and how often are thelight globes replaced? Is there a history of
exposure to poisonous plants or other possible toxins, including antibiotics? Obtaining athorough background is vital to direct the clinician to a possibility of renal disease. For
more information refer to Chapters 4, 5 and 6.
Often, particularly in acute renal disease,clinical signs are minimal. There may be nonspecific signs such as anorexia, depression
and weakness. If more chronic renal disease ispresent, signs may include chronic weightloss or emaciation, dehydration and general
ill thrift. Polyuria and polydipsia are rare.
Published normal blood values for reptiles
are often based on a small number of individuals and vary widely (Table 23.1).
Consequently, it is best to establish normal
values for the particular animal in question
when it presents for its initial wellness examination. Blood should be drawn and, assumingthat the animal is healthy at the time of examination, these results should be used as acomparison against future disease states. This
will provide a more accurate representationof what is happening inside the patient thanrelying on published data collected on animals held in differing conditions. While diagnosis of renal disease via blood work is
problematic, a few abnormalities may appear
which can lead the clinician in that direction.
Early stages of renal disease may present
with no haematological changes. The haematocrit may be increased because of dehydration. Nonregenerative anaemia has beenreported, as have a mild leucocytosis withmonocytosis or heterophilia.
Biochemistry is of limited use. Blood urea
nitrogen and creatinine are poor indicatorsof renal function as terrestrial reptiles excreteuric acid, while sea turtles and crocodilians
predominantly excrete ammonia. Only freshwater chelonians excrete significant amounts
of urea and blood urea nitrogen may beof more use in these species. However, elevated levels usually indicate dehydration or

increased protein catabolism rather thanrenal disease.
Uric acid is secreted by the renal tubules
and is unaffected by glomerular filtration
rate. Three times as much uric acid is
excreted in a hydrated reptile compared witha dehydrated one. Once secreted into thetubule, uric acid complexes with protein andeither sodium or potassium to form a suspension. A herbivorous diet leads to a greater
amount of potassium complexing with urate,
while a carnivorous diet favours sodium
urate complexes.
Reptiles should be fasted prior to blood
sampling as uric acid increases by 1.5–2
times the day after a meal, particularly in carnivores. Uric acid levels may be normal earlyin renal disease but increase with end stage
renal disease. Hyperuricaemia or uraemia is
generally a terminal event as it indicates that
two‐thirds or more of the functional renal
mass has been lost. A single elevated value is
not diagnostic but chronic elevations in herbivorous reptiles warrant further evaluation.
Uric acid levels should be under 600 µmol/lfor herbivorous reptiles. Hyperuricaemia
greater than 900 µmol/l is usually associatedwith renal disease, with urate deposition
occurring in tissues above 1500 µmol/l. Morethan twofold increases in uric acid generally
signify renal disease or gout.
Total calcium levels may be low, normal or
high. Phosphorus is frequently elevated, especially with advanced renal disease, and animals may have an inverted calcium tophosphorus ratio. The solubility index is calculated as the product of calcium (mmol/l)and phosphate (mmol/l) and is normally lessthan nine. If the solubility index rises above
12 then healthy tissue will start to mineralize,
while if it is between 9 and 12, mineralizationof diseased tissue (kidneys) occurs. Potassium
may be elevated. Haemolysis will artificially
increase both phosphorus and potassium.
Aspartate aminotransferase is present in theproximal tubule cells and levels may be elevated if these are damaged. However, it isusually excreted into the urine rather than the
blood. Total protein and albumin may be low.

Diseases of the Urinary Tract

Table 23.1 Blood parametersa in the red‐eared
slider (Trachemys scripta elegans), boa constrictor(Boa constrictor constrictor) and bearded dragon(Pogona vitticeps) used in the assessment of renal
disease (Carpenter 2013).
Bloodparameter

Diagnostic use

Total whiteblood cells

May be increased as a result of
inflammation or infection

Heterophils

Usually increased with bacterial
infection

Lymphocytes

May be increased with viraldiseaseAzurophils

Elevated during bacterial
infections and necrosis

Monocytes

May be increased with chronic
infections

Packed cellvolumeMay be increased withdehydration or decreased withanaemia

Red blood cells Decreased with anaemia
Haemoglobin

Decreased with anaemia

Urea

Poor indicator of renal function;
may be increased withdehydration and protein
catabolism

Creatinine

Limited and variable production;
not reliable

Uric acid

Raised during dehydration andwith renal disease; affected bynutrition

Calcium

May be low, normal or high;affected by nutrition andalbumin levels, decreased during
chronic renal disease

Phosphorus

Increased during renal disease

Potassium

Often increased, especially inacute renal failureaPlease note that normal values vary with species, sex,
nutrition, environment, season and reproductive status.

Unfortunately, urinalysis is not very helpful
in diagnosing renal disease. Polyuria is rareand difficult to recognize, as the urine isoften mixed with faeces. Urine specific gravity is of limited usefulness, as reptiles cannot
produce a hypertonic urine as they lack loops
of Henle. A low urine specific gravity reflects

normal hydration. Herbivore urine should bealkaline, while carnivore and omnivore urine
is acidic. Herbivorous tortoises will produce
acidic urine during times of drought, at theend of hibernation, if they are anorexic or fed
a high protein diet. After recovery the urine
becomes alkaline again. Ureteral urine normally contains a large amount of protein.
When it enters the urodeum the urine moves
into the rectum by reverse peristalsis, where
the protein is reabsorbed and recycled. Thus,
voided urine should contain little to no protein. Glucose should also be absent. Bladderurine does not reflect renal function because
water, sodium and bicarbonate are absorbed
across the bladder wall while hydrogen is
excreted. Unlike mammals, it is also nonsterile as it has passed through the urodeum.
Urine should be clear or yellow. Green urine
is indicative of starvation or hepatic diseasebecause of the presence of biliverdin.
Radiography is an insensitive tool for the
diagnosis of renal disease but may show soft
tissue mineralization. Ultrasound can beused but it is difficult to visualize the kidneys, as they lie deep in the pelvis in turtles
and most lizards, with the exception of monitors. Endoscopy is probably the most useful
tool to diagnose renal disease, as it can beused to take a renal biopsy, which can be
examined histologically and submitted for
culture. However, if lesions are not uniformly
distributed throughout the kidneys it is possible to miss them with a biopsy.
Aetiology
The causes of renal disease are many and varied. Some are specific to the urinary system
while others cause a multisystem disease
with renal manifestations.
Infection

As reptile kidneys have a relatively highblood flow and can receive additional bloodfrom the caudal part of the body via the renal
portal system, bacteria frequently localize tothe kidneys and can often be cultured fromthe kidney. There are no specific bacterial

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Reptile Medicine and Surgery in Clinical Practice

Figure 23.1 Klossiella sp. (arrow) inrenal tubule; haematoxylin and eosin
stain.

aetiologies of renal disease. Common Gram‐
negative bacteria that may be found in thekidneys as part of a systemic disease processinclude Salmonella and Pseudomonas.
Similarly, systemic mycotic infections can
produce renal granulomas. Evidence of viral
infections, such as inclusion body disease,can be detected by the presence of inclusion
bodies in the kidney.
Microsporidia were considered to be protozoa but have been reclassified as fungi.
They have been found in snakes, turtles, andlizards, including bearded dragons where
they can be associated with systemic disease.
Signs include lethargy, anorexia and weightloss. Infections are probably opportunistic
secondary to immunosuppression. No treatment has been described and diagnosis will
likely be at post mortem.
Spironucleus (synonymous with Hexamita)
appears similar to Giardia. Trophozoites are
pyriform, with two anterior nuclei, four pairsof flagella and no adhesive disc. It is found in
the urinary tract of chelonians and snakes
and has a direct lifecycle. Signs include lethargy, anorexia and weight loss. Diagnosis isby finding the organism in fresh urine or faeces. Treatment is with 50 mg/kg metronidazole, repeated in two weeks. Prevention is via
regular cleaning and disinfection of the environment to stop direct transmission. Cysts
are destroyed by exposure to 70% ethanol orboiling water for one minute but are reasonably resistant to bleach, requiring contact for
at least 24 hours before they are devitalized.
Klossiella is found in the kidney ofboa constrictors. It has a direct life cycle.
Infections are generally asymptomatic.
Diagnosis is by histological demonstration of
sporocysts in the kidney or in fresh urine/
urates (Figure 23.1). Prevention is via cleaning and disinfection. Other protozoa such as
Entamoeba invadens and Eimeria spp. can befound in the kidneys as part of a systemic
disease.
Myxozoa have been found in the renal
tubules of freshwater turtles, potentially associated with nephritis. Trematodes can occur
in the renal tubules and ureters of snakes andcrocodiles and the urinary bladder of sea turtles. Infections are generally asymptomatic.
Diagnosis is by finding the characteristic
yellow, 40 × 18 µm eggs in the urine or faeces.
The lifecycle is unknown but probably
involves an intermediate host. Infections in
captivity should therefore be self‐limiting.
Non‐Infectious Aetiologies

As well as infectious causes of renal disease
there are numerous non‐infectious aetiologies. These include congenital or hereditaryconditions, such as renal cysts and aplasia.
Degenerative conditions, such as glomerulosclerosis, have been described in snakes andDiseases of the Urinary Tract

Figure 23.2 Inland bearded dragon(Pogona vitticeps) with articular gout.
Note swollen forelimb.

alligators. Glomerulosclerosis consists offibrous tissue accumulations in the glomeruli. Amyloid‐like material has been found in
the glomeruli of a range of reptile species.
While similar in appearance to amyloid
microscopically the composition of thismaterial has not be determined.
Various renal neoplasms have been
described including adenocarcinomas insnakes, lizards and chelonians, myxofibromas in chelonians, renal adenomas in snakes
and lizards and transitional cell carcinomas
in snakes. Unfortunately, diagnoses are often
made post mortem.
Inappropriate diet can result in renal disease. Hypervitaminosis D3 through oversupplementation or accidental ingestion ofcholecalciferol rodenticides can cause nephrocalcinosis. Signs include depression, weakness
and anorexia. Prognosis is poor. Treatment
includes fluids and corticosteroids (prednisolone 5–10 mg/kg intramuscularly), which suppress bone resorption and intestinal calcium
absorption and promote calciuresis.
One of the more common manifestationsof renal disease is visceral gout, which occurs
in uricotelic (fully terrestrial) reptiles only. It
does not occur in aquatic or amphibious reptiles that excrete predominantly urea orammonia. In terrestrial reptiles purine ismetabolized to uric acid while, in aquatic
reptiles, it is broken down to allantoin.

Predisposing factors for gout include low
water intake, excessive dietary purine ingestion and nephrotoxic drugs. Renal disease,especially tubular disease (as uric acid is
excreted by the tubules) can lead to decreased
uric acid excretion and hyperuricaemia.
High blood uric acid leads to precipitation in
joints (articular gout; Figure 23.2), on serosal
surfaces (e.g. pericardial sac) and in various
tissues (visceral gout; Figure 23.3; see Case
Report 1), particularly kidney, liver andlung. Urate crystals destroy kidney tubules(urate nephrosis) leading to renal failure(Figure 23.4). The characteristic lesions arewhite nodules called tophi, which consist ofrefractile, radiating, faintly basophilic urate
crystals with fine spicules, in a tubule lumen,surrounded by heterophils and necrotic
tubular epithelial cells during the acutephase, and by giant cells later. Urates dissolve
during routine processing for histology
but the tophi remain visible and are more
obvious with silver stains.
Prognosis is guarded but hyperuricaemia
can be treated with allopurinol, which
decreases uric acid production by halting
purine breakdown. 20–25 mg/kg/day or
50 mg/kg every three days has proven effective. Treatment is long term, over several
months. Prevention focuses on not providing
animal protein to herbivores, as it is highin purines. Minimize the feeding of peas,

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Reptile Medicine and Surgery in Clinical Practice

Figure 23.3 Visceral gout. Note palestreaks through kidneys, representing
urates.

Figure 23.4 Urate tophi in renal
tubules. Silver stain has stained urate
crystals black.

spinach and cauliflower, as they are also highin purines.
Renal toxins include antibiotics and antifungals. High doses of aminoglycosides suchas gentamicin and amikacin can cause renal
tubule damage, particularly in dehydrated
animals. Amphotericin B causes renal vasoconstriction, reduced glomerular filtration
rate and renal tubule damage leading to acutetubular necrosis. Clinical signs are vague andinclude anorexia, lethargy and weight loss.
Treatment involves discontinuation of the
drug and fluid therapy.
Ingestion of oak leaves has been associatedwith renal tubular necrosis and death in

tortoises. This is caused by tannic acid contained within the leaves.
Renal disease, once established, leads to a
gradual deterioration of the patient that can
result in hyperphosphataemia and renal secondary hyperparathyroidism due to decreased
phosphorus filtration. Increased phosphorus
results in hypertrophy and hyperplasia of theparathyroid gland, which secretes parathyroid
hormone to mobilize calcium from the osseous matrix, leading to an osteomalacia called
renal osteodystrophy. The bones and shell
become demineralized and soft with bones
potentially increasing in girth due to the deposition of excessive fibrous tissue.

Diseases of the Urinary Tract

Prognosis and Treatment
Long‐term prognosis for reptiles with renal
disease is poor. As reptiles cannot produce a
hypertonic urine, they conserve water bydecreasing the number of filtering glomeruli,
resulting in tubule collapse. However, uricacid continues to be secreted into the proximal tubules leading to tubule blockage.
Restoring hydration is therefore vital to flushout the accumulated uric acid. Use an isotonic fluid, such as lactated Ringer’s solution,delivered at 20–40 ml/kg/day intravenously
or intraosseously. If this is not possible,
administer a bolus of 5–10 ml/kg intravenously or intracoelomically twice a day.
Aluminium hydroxide given orally at
100 mg/kg once a day can be administered totreat hyperphosphataemia. B vitamins (10 mg/
kg intramuscularly) and anabolic steroids(nandrolone 1 mg/kg intramuscularly), given
every one to four weeks, may also be beneficial.
Aim to correct any husbandry issues. In
cases of prolonged anorexia, lizards can bestomach tubed while chelonians will require
oesophageal tube feeding.

­Lower Urinary Tract Disease
Uroliths
Snakes and crocodilians lack urinary bladders.
Chelonians, rhynchocephalians (tuataras) andsome lizards (skinks, geckos, iguanas, andchameleons) have bladders. Uroliths havebeen found in lizards, turtles and snakes (inthe distal ureter). Causes of urolithiasis
include vitamin A or vitamin D deficiency,
excess dietary protein or oxalates (e.g. spinach), bacterial infection, and dehydration.
Animals are often asymptomatic but clinicalsigns can include straining, constipation, anorexia, paresis/paralysis and cloacal prolapse. If
the animal is not experiencing signs thentreatment may not be required but the urolith
will probably continue to increase in size,
potentially leading to haematuria, bladderwall irritation and thickening, and pressure
necrosis.
Uroliths may be visible or palpable in the
cloaca. They can also be diagnosed via radiography, ultrasonography or endoscopy.
Urate stones are radiolucent but becomeradiodense when complexed with calcium or
potassium. Blood uric acid levels are notelevated.
If the urolith is in the cloaca, it can usually
be removed manually. The urolith will appear
rough, white and crumbly. If a piece of it isplaced on a slide with a drop of water, urate
crystals should be visible. If the urolith is in
the bladder, it may be possible to remove it
endoscopically via the cloaca, otherwise acystotomy will be required. Urolith prevention focuses on the provision of adequate
hydration and excellent husbandry.

Case Report 1
A carpet python was referred with a history of
inappetence. Clinical examination revealed an
obviously swollen mouth. The gingiva
appeared thickened, with petechial haemorrhages evident on the surface. A small amountof caseous material was present around someteeth. The referring veterinarian had diagnosed a case of necrotic stomatitis and treatedthe snake with high doses of gentamicin for
two weeks.
The snake was extremely lethargic withpoor muscle tone. It had not eaten for fourmonths. A blood sample revealed extremely

high uric acid levels. Given the history andblood result, renal disease was strongly suspected. The owner declined a renal biopsy
and, given the snake’s poor condition andprognosis, it was euthanized.
Necropsy revealed swollen and pale kidneys
with white streaks, indicative of visceral gout.
While gentamicin can be an excellent antibiotic for treating bacterial infections in reptiles,
high and/or prolonged doses without the provision of fluid support, especially in an animal
that is not eating, can frequently result in renal
disease.

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Reptile Medicine and Surgery in Clinical PracticeCase Report 2
A panther chameleon was presented with aone‐week history of hind limb lameness. On
examination, the chameleon could move bothhind limbs but the movements were weak andpoorly coordinated. There were no visible
wounds or palpable fractures. Based on theclinical signs, a spinal lesion was suspected.
Dorsoventral and lateral radiographs weretaken. No spinal damage was visible but alarge mass was apparent in the caudal abdo-men. The chameleon was anaesthetized and asmall incision was made in the paralumbar
region, to allow endoscopic access. A large
irregularly shaped mass was visible. Two biopsies of the mass were taken and submitted forhistological evaluation. The diagnosis was
renal adenocarcinoma, necessitating euthanasia of the lizard. This case highlights the factthat renal disease will not always present withsymptoms relating to the urinary system.

­Further Reading
Carpenter, J.W. (2013) Exotic Animal
Formulary, 4th ed. Elsevier, St. Louis, MO.
Girling, S. and Raiti, P. (2004) BSAVA Manualof Reptiles, 2nd ed. British Small Animal
Veterinary Association, Gloucester.
Mader, D.R. (2006) Reptile Medicine andSurgery, 2nd ed. Elsevier, Philadelphia, PA.

Mader, D.R. and Divers, S.J. (2014) Current
Therapy in Reptile Medicine and Surgery.
Elsevier, St. Louis, MO.
McCracken, H.E. (1994) Husbandry anddiseases of captive reptiles. Proceedings of
the Post‐Graduate Committee in Veterinary
Science, University of Sydney, 233, 461–545.

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24
Diseases of the Nervous System
Hamish Baron and David N. Phalen

Anatomy and Physiology
See Chapter 2 for a review of the anatomy andphysiology of the nervous system.
Key Points●●

The reptilian nervous system is organised ina linear fashion. The central nervous system
consists of the brain and the spinal cord,
which extends virtually the entire length ofthe vertebral canal. The peripheral nervous
system includes the cranial nerves and thespinal nerves.

­History and Husbandry
Malnutrition and improper management areleading causes of neurological disease. A
detailed history of the feeding and care practices for the patient and collection will often
reveal inadequacies. For more information
on history and husbandry refer to Chapter 4.
Infectious diseases are common causes ofneurological signs and are more likely tooccur in recently obtained animals orcollections where animals have recently­
been introduced. A history of disease in

There are both subdural (beneath the duramater) and epidural (above the dura mater)
spaces within the brain case.
●● There is no arachnoid mater or subarachnoid space in reptiles. There are two meninges which cover the brain and spinal cord;
the outer dura mater is tough and largely
avascular while the inner pia mater is moredelicate and vascular and lies directly on thesurface of the brain.
●● Nerve function can be modified by temperature (heat and cold), medication, trauma,
viral, bacterial, fungal, parasitic and metabolic disorders.
●●

other reptiles in the collection may also
­provide clues to the aetiology of the current
reptile’s condition.

­The Neurological
Examination
Distant Examination
The first step of the assessment of a reptile
with neurological signs is the distant examination, observing natural and instinctive
behaviours and movement. Snakes, lizards

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

332

Reptile Medicine and Surgery in Clinical Practiceand skinks should take an interest in theirsurroundings while turtles may be actively
swimming or completely withdrawn into
their shell. For additional information refer
to Chapter 10.
Signs of central neurological disease insnakes include reduced frequency of tongue
flicking, slow protrusion and withdrawal of
the tongue and incomplete withdrawal of the
tongue. Affected snakes often hold their head
up at an angle with the mouth open. Thisbehaviour can also occur in snakes having difficulty breathing. Abnormal movements or
the absence of movement in any section of
the snake is often the result of neurologicaldisease. Generalized weakness, inability tosupport the weight of the body and muscle
fasciculations are manifestations of neurological disease in lizards. Inability to use one
or more legs may represent peripheral or spinal cord disease in lizards and turtles. Lizards
and turtles with advanced neurological disease may present with severe weakness andmay be obtunded. Secondary nutritional
hyperparathyroidism can cause scoliosis and/or ventral or dorsal curvatures of the spine.
Spinal fractures sometimes cause deviation of
the vertebral column. Fractures across the
midline of the carapace in a turtle, with the
exception of its most caudal aspects, will generally result in hind limb paresis or paralysis.
Close Examination
The neurological examination is best done withthe animal within its preferred optimum temperature zone. During the winter months, reptiles are likely to be cold on presentation. Thiscan be assessed by touch or, more accurately,using a remote heat‐sensing thermometer.
Cranial Nerves
The cranial nerve structure and function of
reptiles is much the same as in small mammals, although it is more difficult to assess in
reptiles. Table 24.1 outlines the cranial
nerves that are able to be examined in reptile
patients.

Assessment of Muscle Innervation
SnakesSpinal reflexes are part of the reptilian nervous system control. Somatic spinal reflexes
sense and control muscles, tendons and skinto maintain posture. Visceral spinal reflexes
control cardiac muscle, smooth muscles ofthe digestive tract and blood vessels andglands. Generalized atrophy of the epaxial
muscles suggests a disease of many months ormore. A well‐muscled snake is more likely tohave an acute or subacute problem, althoughloss of condition may take many weeks.
Segmental loss of epaxial muscles may also
occur and may indicate a spinal cord lesion at
the junction of the normal and abnormal
musculature. Proliferative lesions of the vertebrae may compress spinal nerves, resulting
in segmental muscle atrophy (Figure 24.1).
Healthy snakes are uniformly strong andresponsive to handling or noxious stimuli.
Weakness may be determined by holding
the snake’s tail off the table and observing
how it uses the rest of the body. The righting
reflex assesses both brain and spinal cord
function. A normal snake will immediately
right itself beginning head first if turned
over (Figure 24.2). In snakes with spinal
cord lesions, the portion of the body caudal
to the lesion will be unable to right itself.
­ eurological dysSnakes with viral induced nfunction may be unable to right themselves
or righting may be delayed (Figure 24.3).
Snakes have sensitive skin over the dorsum. The cutaneous nerves supply tissuecaudal to their nerve root and so if the skinbecomes nonresponsive to a pin prick, thespinal lesion is likely to be cranial to thepoint at which denervation is evident.
Cloacal tone may be absent in some cases ofspinal cord disease.
Lizards

Lizards normally have a strong withdrawal
response and placing reflex. In some lizards,
especially those with long legs, hoppingreflexes and even the ability to wheelbarrowcan be assessed. As with snakes, response toTable 24.1 Nerves suitable for assessing cranial nerve function.
No.

Name

Innervation

Function

Assessment

I

Olfactory

Chemosensory

Olfaction

Place a cotton tip applicator soaked in alcohol beneath the nostrils; a healthy patient willshow an aversive response.

II

Optic

Sensory

VisionReptiles with eyelids will display a menace response.
Snakes and small lizards without eyelids can be placed in a novel environment and theirability to navigate can be assessed.
Pupillary light response is not relevant in reptiles as iris diameter is voluntarily controlled
by skeletal muscle.

V

Trigeminal

Sensory andmotor

Reptiles with normal trigeminal nerve function will clamp their jaw tightly if an attempt toMotor function to themandible; sensory around open their mouth is made.
Stimulating the skin surrounding the eye using a blunted needle will cause animals withthe eyeeyelids to close them and may cause other reptiles to exhibit an aversive behaviour.

VII

FacialMotor

Motor function to
structures of the face

In reptiles with eyelids, the facial nerve can be assessed using the palpebral reflex as withcranial nerve II. Otherwise, this nerve cannot be assessed.

VIII Vestibulocochlear

Sensory

Audition

Most reptiles respond poorly to sound in the hearing range of humans and are moresensitive to low‐frequency sound and vibrations. This makes assessment of thevestibulocochlear nerve very difficult. Diseases of the inner ear, however, can result insigns common in other animals such as head tilt and circling.

IX

Glossopharyngeal

Sensory andmotor

Taste and motor function
to the tongue, jaw andswallowing

The application of a bitter substance, such as lemon juice, to the tongue and thesubsequent behavioural response indicates the ability of the reptile to taste.
Observation of normal swallowing or eating indicates that cranial nerves IX, X and XI (thespinal accessory nerve) are intact.

X

Vagus

Motor

Parasympathetic
innervation

Assessed as per glossopharyngeal nerve.

XII

Hypoglossal

Motor

Movement of the tongue,
jaw and swallowing

The normal position of the tongue and the ability to withdraw the tongue into the mouthallows assessment of the hypoglossal nerve.

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Reptile Medicine and Surgery in Clinical Practice

Figure 24.2 A normal Spotted python (Antaresia
maculosa) performing righting reflex during aneurological examination. Note the normal head
position, with the remainder of the body returning
to ventral recumbency.

Figure 24.1 Segmental aplasia in a 14‐year‐old
coastal carpet python (Morelia spilota) secondary to
a proliferative spinal osteopathy. Note the muscle
atrophy which is the result of nerve impingement
and subsequent denervation (arrows).

Figure 24.3 Spotted python(Antaresia maculosa) with central
nervous system dysfunction. Thissnake was polymerase chain
reaction‐positive for sunshinevirus.

Diseases of the Nervous Systemskin pricking can be assessed in those withloose skin (e.g. dragons) and in all lizards
there should be cloacal tone. Lizards should
rapidly right themselves if turned over.
Denervation is one differential for localizedmuscle atrophy.
Chelonians

Healthy chelonians are strong and active ortightly withdrawn into their shell. The cloaca
should have tone and will contract whenpinched which may also cause the pelvic limbs
to be brought together caudally. Chelonians
placed on their back will right themselvesusing their head and neck. Stranded sea turtles with advanced disease exhibit nonspecificcentral nervous system depression. Localized
brain disease may cause a head tilt, circling or
infrequently nystagmus.
Crocodiles

While crocodiles are subject to a number of
infectious diseases and disease syndromesthat can involve the central nervous system,
specific signs relating to central nervous system lesions are infrequently seen.

­Diagnosis
The diagnostic work‐up for neurological disease is much the same as for any unwell reptile (Table 24.2). Based on the history andclinical findings ancillary testing may be necessary to determine the location or locationsof the neurological lesion and it(s) aetiology.

­Congenital and Hereditary
DisordersCongenital abnormalities seen in other animal species may be encountered in reptiles,
including polycephaly (having more than onehead) in snakes and microphthalmia. The
majority of congenital abnormalities are theresult of poor maternal husbandry andimproper incubation conditions. Many ofthese congenital conditions result in early
embryonic or fetal death.

­Non‐Infectious Disorders
Nutritional Secondary
Hyperparathyroidism
Aetiology and Pathogenesis

See Chapter 15 for the aetiology and pathogenesis of nutritional secondary hyperparathyroidism (NSHP).
Clinical Signs

Bone deformation and scoliosis (Figure 24.4)
are common clinical presentations and areoften presented concurrently with pathological fractures of long bones (Figure 24.5).
NSHP occurs in lizards, especially bearded
dragons and blue‐tongued lizards. The
lesions commonly involve the spine and maylead to cord compression and paresis orparalysis of the pelvic limbs. Cases may present with lameness of one or all limbs andmay have an abnormal gait. When blood­calcium levels cannot be maintained, animals
will exhibit muscle fasciculation.
Diagnosis

Diagnosis is based on a thorough history,
identifying incorrect husbandry and dietary
practices, signs and radiographical and biochemical abnormalities.
Treatment

Initial therapy centres on stabilization of thepatient, including correction of hypocalcaemia resulting in tetany and stabilization ofpathological fractures. Parenteral administration of calcium is only indicated if presented with a reptile in acute hypocalcaemic
crisis with muscle tremors and twitching. See
Chapter 15 for further treatment options.
Prognosis

Once paralysis or paresis is present, the disease process is advanced and the prognosis for
return to function is poor. The patient may

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Reptile Medicine and Surgery in Clinical PracticeTable 24.2 Diagnostic work‐up for neurological disease.
Diagnostic modality

SamplesComplete blood count Blood heparin or
fresh blood smear

Clinical application

Total white cell count and differential allows assessmentof infectious or inflammatory changes in the white cell
population. Refer to Chapter 11 for full haematologicalinterpretation.

Plasma biochemistry(including
electrolytes)

Blood in lithium
heparin or serum clot
tube (confirm withlaboratory)

Assessment of organ systems and electrolyte imbalance.
Refer to Chapter 11 for full biochemical interpretation.

Bacterial culture

Blood or CSF in EDTA

Organism isolation and identification as well as treatment
susceptibility spectrum.

Fungal culture

Blood or CSF in EDTA

Organism isolation and identification as well as treatment
susceptibility spectrum.

Viral PCR

Consult with laboratory Sensitive and specific isolation of pathogen with theregarding best samples opportunity to sequence isolates.
for specific PCR

CSF analysis

Direct smear CSF,
centrifuged CSF andsmear of sediment

CSF collection is challenging in reptiles. Reports exist ofcollection in a green iguana with osteomyelitis andAmerican alligators (Alligator mississippiensis) but
collection from Australian reptiles has not been reported.

Radiography

Full body radiographs

Allows visualization of the vertebral column, axial
skeleton and spondylytic changes as well as fractures ofthe spinal column.

CT

Full body CT or
skull CT

More useful at locating anatomical abnormalities,
especially when assessing the skull.

Magnetic resonanceimaging

Full bodyExamination of microscopic structural changes associatedwith inflammation or vascular injury. Superior when
imaging soft tissue such as the brain.

Ultrasonography

Coelomic cavity

Of limited use in determination of neurologicaldisease in reptiles.

Diagnostic necropsy

Full body

Gross and histopathological examination of thebrain, spinal cord. Facilitates tissue sampling for
PCR, bacterial or fungal culture.

CSF, cerebrospinal fluid; CT, computed tomography; EDTA, ethylenediaminetetraacetic acid; PCR, polymerase chain
reaction;continue to live in a modified environment
with a good quality of life. In cases where spinal fractures result in the inability to produce
droppings, owners should be counselled
regarding their pets quality of life and should
consider euthanasia on humane grounds.
Prevention and Control

See Chapters 4 and 6 for detailed information on prevention and control.

Hypocalcaemia
Aetiology

Neurological signs due to low blood calcium
are the result of an acute increased demandon calcium metabolism, such as during timesof vitellogenesis or bone repair. In such cases,
blood calcium levels become low prior toparathyroid hormone release and the subsequent mobilization of calcium from bone.

Diseases of the Nervous System

Clinical Signs

Muscle tremors and fasciculation are themost common presenting complaint. The
disease is progressive and, if left untreated,a single limb fasciculation may progress
to become generalized tetanic spasms
and result in the patient’s death from heart
failure.
Diagnosis

Diagnosis is based on history, examination,
radiographs and biochemistry, which may
show a mild hypocalcaemia or low normal
calcium and an increased phosphorus
level. See Chapter 15 for more detailed
information.
Treatment

Figure 24.4 Bearded dragon (Pogona barbata)showing characteristic weakness, lethargy andscoliosis as a result of secondary nutritional
hyperparathyroidism.

Treatment includes identifying and correcting the underlying cause and the administration of calcium intramuscularly ororally based on blood biochemical results.
Administration of parenteral calcium
without a biochemical panel may lead to­
hypercalcaemia.
TraumaCarapace Fractures in Turtles

Trauma to the carapace may lead to spinal
injury, as the spinal cord is contained within
the carapace. The reptilian spinal cord contains locomotor control centres and the spinal cord has the capacity to regenerate tosome degree. This gives reptiles with spinal
cord or brain injuries a better prognosis
than those same injuries in mammals.
Fracture repair techniques for chelonians are
discussed extensively in Chapter 29.
Spinal and Head Trauma
Figure 24.5 Bearded dragon (Pogona barbata)displaying clinical signs consistent with nutritional
secondary hyperparathyroidism. Note the healed
pathological fracture of the left forelimb and theundershot jaw.

Head trauma may present as opisthotonus,
seizures, paresis, profound depression orparalysis. Many blue‐tongued lizards that
present with head trauma will have their eyes
closed and will be reluctant to open them.
These animals will often have other signs of

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Reptile Medicine and Surgery in Clinical Practice

Figure 24.6 A lace monitor lizard (Varanus varius) mentally obtunded following a motor vehicle accident. With
supportive care, this patient made progress but constantly circled to the left and was euthanized.

brain trauma, including lethargy and reduced
response to stimuli (Figure 24.6). Although
they appear to have a poor prognosis, withsupportive care many will return to normal
function.
Diagnosis and Treatment ofTrauma‐Induced Neuropathies

Diagnosis of neurological disease is based on
history, signs and radiography. The treatmentof these trauma‐induced neuropathies involves
stabilization of fractures, supportive care, analgesia, fluid therapy and antibiotics. Surgicalintervention may be necessary for spinal cord
injuries. Spinal fractures may be immobilisedusing external fixation such as casting.
Egg Binding
Egg binding may cause hind‐limb paresis orparalysis in chelonians and in some lizard
species. The hind‐limb paresis is secondary
to pressure from the internal organs or eggs
engaged in the pelvic canal eliciting pressure
on the sciatic nerves.
Neoplasia
In Australia, the majority of neoplastic diseases impacting the spinal cord are associatedwith the vertebral column of snakes. Bothosteochondrosarcoma and osteosarcoma
have been reported in snakes, often causing a
flaccid paresis caudal to the lesion. There are

few reports of primary central nervous system neoplasia in reptiles but these should be
included as differentials in cases of neurological disease. Other reports of neoplasia causing neurological signs in reptiles are rare andthere are very few cases of successful treatment of neurological neoplasia.
Toxicities
Drugs

The most common toxicities appear to
be species specific such as ivermectin in­chelonians, leading to general neuromuscular weakness, or metronidazole in various­species of snake, resulting in vestibular disease with head tilt, circling and ataxia.
Itraconazole, when used to treat fungal dermatitis in reptiles, is reported to cause hepatotoxicity, with neurological signs including
lethargy and depression. Intoxication froma drug should be considered in any reptile
exhibiting incoordination, circling, head tilt,
opisthotonos or seizures.
Insecticides

Organophosphates are the most commonly
reported toxicity in reptiles, although their use
is declining. Overdose results in paresis, headtilt, circling, opisthotonos and convulsions.
A history of treatment for mite infestation
should cause the practitioner to consider
insecticide toxicity as a differential. Treatment
is aimed at removing the toxic substance andDiseases of the Nervous Systemthen providing supportive care, including fluid
therapy and anticonvulsants if required.
Metal Toxicosis

Lead toxicity from ingestion of lead based
paints is reported in chelonians. Animals
exhibit ataxia, a head tilt and weakness.
Treatment includes removing the lead fromthe gastrointestinal tract using gastric lavage and cathartics, alongside chelation therapy using calcium disodium edetate. Zinc
toxicoses can result in weakness, anorexia
and anaemia. Animals prone to ingesting
foreign material while free ranging aresusceptible.

­Infectious Disorders
Bacterial Infections
Aetiology

Bacterial infection of the nervous system
may be primary or secondary following septicaemia. Septicaemia may result in central
nervous system infection or cause secondary skeletal abnormalities such as spinal
osteopathy.
Pathogenesis

Commonly isolated organisms include
Salmonella, Staphylococcus, Mycoplasma
and Mycobacterium. Infection in the central
nervous system is commonly the result of
septicaemia following respiratory disease orother severe infection. Micro abscesses may
form in the brain and the subsequent inflammatory response results in nonspecific clinical signs that vary in severity from alteredmentation to terminal convulsions. Signs are
dependent on the region of the brain where
the bacteria localize.
Septicaemia, as well as penetrating wounds
such as animal bites, may result in bacterial
infection of the vertebrae and a subsequentosteomyelitis. The proliferative nature of theentheses or periosteal new bone results incompression of the spinal cord.

Localized bacterial infections in the earof chelonians and lizards are relatively
common.
Clinical Signs

Signs vary depending on the location of
the underlying disease process. For example, an ear abscess results in head tilt,­circling and swelling associated with the
tympanic membrane, whereas spinal osteopathy secondary to bacteraemia causes
damage to the spinal cord and leads toeither acute onset or insidious and progressive flaccid paralysis, or paresis caudal to
the lesion. Micro abscessation in the brain
results in signs that are dependent on­location of the lesion.
Fungal Infections
Fungal disease causing neurological clinicalsigns is uncommon in reptiles. Diagnosis of afungal central nervous system infection
would be challenging, possibly requiring cerebrospinal fluid analysis or advanced imaging. Treatment is likely to consist of systemic
antifungals able to cross the blood–brain
barrier and based on culture and sensitivity.
Voriconazole appears safe and efficacious
against a number of fungal infections.

­Viral Diseases of Snakes
Sunshinevirus and two or more bornaviruses cause neurological disease in snakes
in Australia. The ferlavirus and one or morearenaviruses can also cause neurologicalsigns in snakes. Neurological signs causedby all of these virus infections are similar
and reflect significant disease of the brain
and, in many instances, spinal cord. They
include a progressive paresis and paralysis
that may be segmental or generalized, inability to right themselves, opisthotonos,
head tremors and decreased or slow tongue
flicking (Figure 24.7). Polymerase chain

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Reptile Medicine and Surgery in Clinical Practice

Figure 24.7 Spotted python (Antaresia
maculosa) displaying classic signs
associated with neurological viruses.
Note the tight knots and inability toright itself.

reaction (PCR) diagnostics are available for
all four of these viruses.
None of these viruses can be treated.
Prevention and control is through prolonged
quarantine of new snakes and the use ofavailable testing. For more detail on infection
control see Chapter 5 and Chapter 16 for
information on reptile viruses and quarantine recommendations.
Arenavirus
Aetiology

Arenaviruses are enveloped RNA viruses
with a segmented genome. They have been
detected in snakes with neurological signs
and inclusion body disease in the USA andthe Netherlands.
Pathogenesis

Lesions in pythons are generally restricted tothe brain and spinal cord. In other species ofsnakes, lesions can be more generalized andinclusions can be found in the oral mucosa,
oral tonsils, pancreas and kidney. A correlation
between arenavirus infection and cancer has
been suggested, so testing tumours found on
snakes for arenaviruses merits consideration.
Clinical Signs

Neurological signs occur mostly in pythons,
where the disease has an acute onset and is
rapidly progressive, resulting in death. In

more chronic infections, animals may belethargic, stop eating and lose condition.
Diagnosis

Arenavirus infection is a differential for any
snake showing neurological signs. Definitive
diagnosis is based on histopathological findings of eosinophilic intracytoplasmic inclusion bodies in the brain in pythons and liver,pancreas, kidney, oral epithelium or oral tonsils in other species. The PCR assay can be
run on whole blood or serum.
Bornavirus
Aetiology

Bornaviruses are enveloped single stranded
RNA viruses. Three genetically distinct bornaviruses have been identified in an African
garter snake (Elapsoidea loveridgei) andpythons in Australia.
Pathogenesis

Bornavirus‐positive Australian snakes thathave been euthanized have had a nonsuppurative encephalitis.
Diagnosis

Diagnosis is made by finding the characteristic inclusion bodies in the brain and­confirming infection by PCR of fresh brain
tissue. Early results suggest that this virus will

Diseases of the Nervous System

not be consistently detected in oral and cloacal swabs, or in organs other than the brain.
Ferlavirus

possibility of vertical transmission after thevirus was isolated from the allantois, amnionand embryonic tissues of a clutch laid by aninfected dam.

Aetiology

Clinical Signs

Ferlavirus was previously known as ophidianparamyxovirus or OPMV.

Sunshinevirus infection should be suspected
when neurological signs combine with respiratory signs including a clear discharge
from the mouth and dyspnoea. Apparently
healthy snakes have tested positive for sunshinevirus. The majority of these snakes havegone on to develop clinical signs over theensuing years.

Pathogenesis

Ferlavirus infection results in a nonsuppurative encephalitis and myelitis and a chronic
active exudative pneumonia.
Diagnosis

Ferlavirus infection should be a differential
in pythons that are unexpectedly found dead.
Regurgitation is another nonspecific sign.
Respiratory disease can be severe, so ferlavirus infection should be a differential forsnakes that exhibit respiratory disease combined with neurological disease. Unlike insunshinevirus, the material coming from theglottis is typically an exudate. A complete setof tissues from such snakes should be submitted to an experienced reptile pathologist,keeping back fresh frozen tissues for PCR
diagnostics if necessary. Tissues most likely
to be positive on PCR assay for ferlavirus arebrain, kidney, lung and liver.

Diagnosis

Diagnosis of sunshinevirus is via PCR ofswabs of the oral cavity and cloaca and byhistological examination of intact brain for asagittal section if the animal dies.
Adenovirus Infection
in Bearded Dragons
Aetiology

Adenovirus infection is an Agamid atadenovirus, which spreads easily through directcontact and via contaminated hands andequipment.
Pathogenesis

Sunshinevirus (Reptile sunshinevirus 1) is aparamyxovirus.

Adenovirus is now considered to be endemicin Australia, Europe and the United States.
Infected animals have extensive lesions in theliver and clinical signs may be the result of ahepatic encephalopathy.

Pathogenesis

Clinical Signs

Sunshinevirus causes neurorespiratory disease complex, resulting in spongiosis of thehind brain and, in some instances, an interstitial pneumonia. The virus has been isolated
from oral and cloacal swabs and transmission
is likely to occur via aerosol as well as cloacal
secretions and faecal contamination. It has
been isolated from blood. It is, therefore,possible that blood‐sucking ectoparasites
may act as a vector of transmission between
snakes. Research is continuing into theBearded dragons infected with adenovirus
are characterized by poor growth rates,
torticollis and opisthotonos (Figure 24.8).
­
Affected animals range from 4 weeks up to
12 weeks of age and the onset of clinical signs
is rapid.

Sunshinevirus
Aetiology

Diagnosis

Diagnosis is via PCR from fresh liver or oralswabs and by characteristic histopathologicalfindings that include intranuclear inclusion

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Reptile Medicine and Surgery in Clinical Practice

Figure 24.8 Bearded dragon (Pogona
vitticeps) hatchling with adenovirus,
showing classic torticollis and star
gazing behaviour (courtesy of Bob
Doneley).

Figure 24.9 Bearded dragon (Pogona
vitticeps) adenovirus inclusion bodies(40× haematoxylin and eosin staining.
Arrows indicate adenovirus inclusion
bodies.

bodies in the liver (Figure 24.9), oesophagus
and gastric mucosa.

cheloniae. It has yet to be characterized
genetically.

Treatment

Pathogenesis

There is no treatment available for adenovirus infections. Supportive care and nutritional support may help to prolong life.

­Parasitic Infections
Systemic Coccidiosis in Green
Turtles (Chelonia mydas)
Aetiology

Systemic coccidiosis is caused by a coccidianthat morphologically resembles Caryospora

This parasite causes a mild to severe necrotizing enteritis and organisms can be found inother tissues including the brain and meninges. In the brain, it causes a lymphoplasmacytic and histiocytic encephalitis andmeningitis with necrosis and malacia.
Clinical Signs

The majority of affected turtles are subadults.
Outbreaks occur sporadically on the east
coast of Australia. Outbreaks occur between
September and February, with most turtles

Diseases of the Nervous Systempresenting in October, although outbreaks
do not occur annually. Diseased animals areoften found dead, dying or severely depressed.
Some have a head tilt, swim in circles or,rarely, have nystagmus.

Diagnosis

Diagnosis

Treatment in subclinically infected animals is
not indicated.

Oocysts can be found in the faeces of live
animals. Preliminary data suggest that somelive animals may have schizonts in circulating blood cells. At necropsy, oocysts can bedetected in scrapings of the diseased mucosa
and diagnosis can be made by finding thecharacteristic microscopic lesions in haematoxylin and eosin stained tissues.
Treatment

Despite aggressive anticoccidial treatment
and supportive care, most infected animals
die or are euthanized.
Prevention

This appears to be an emerging infectious
disease. Changing environmental conditions
are postulated as being linked to outbreaks.
At this time, there are no known preventative
measures.
Spirorchid Flukes in Green Turtles
Aetiology

Multiple species of flukes in the Spirorchidae
family can infect green turtles.
Pathogenesis

Adult flukes are found in the heart, large arteries and veins. Their eggs cause disease bylodging in capillaries and inducing microfocal
granulomas. These parasites are also associated with formation of arterial thrombi. Septic
aortic thrombosis may also occur with septicaemia. Lesions in the brain can be caused byegg emboli, the presence of trematodes in themeningeal vessels and bacterial meningitis
secondary to septic aortic thrombosis.
Clinical Signs

Most infected animals do not exhibit clinicalsigns. Animals where disease is severe are
generally found dead.

Diagnosis is made at necropsy by finding
the characteristic gross and microscopic
lesions.
Treatment

Prevention and Control

No preventive or control measures are
known.
Diseases of Unknown Aetiology
Systemic Lymphoid Proliferation
and Non‐Suppurative Encephalitis
in Estuarine Crocodiles (Crocodylus
porosus)

A disease syndrome, systemic lymphoidproliferation and non‐suppurative encephalitis (SLPE), has been recognized in farmed
estuarine crocodiles in the Northern
Territory, Australia. Most animals are young
growing animals. Disease occurs in outbreaks, with many animals in an enclosure
affected. The only sign observed is a reduced
growth rate. Microscopically, these animals
have a lymphohistiocytic infiltration ofmultiple tissues. Gliosis and perivascular
cuffing with lymphocytes and histiocytes isseen. The role of newly recognized herpesviruses of crocodiles in this syndrome isunder investigation.
Bellinger River Turtle Mortality

In the autumn of 2015, large numbers of
Bellinger river turtles (Myuchelys georgesi)
were found dead or dying along a short section of the Bellinger River in northern New
South Wales, on Australia’s east coast, thatcomprised their entire range. The mostprominent lesion was a severe conjunctivitis,
keratitis and periocular cellulitis. Some animals also exhibited a posterior paresis.
Microscopically, many animals were found tohave severe necrotizing subacute encephalitis. Hydrocephalus was present in a small
number of animals. This disease is suspected
to have a viral aetiology.

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Reptile Medicine and Surgery in Clinical Practice­Other Infections
Hypothermia resulting in central nervous
system damage occurs commonly in chelonians following hibernation. It can result inblindness, circling or head tilt. It is thoughtthat vasoconstriction leads to ischaemic
brain injury and degenerative changes ofthe peripheral nerves. Hyperthermia may
also result in neurological impairment as aresult of a demyelinating peripheral neuropathy or central nervous system dysfunction, resulting in stupor, ataxia or coma.
Treatment includes long‐term supportive
care, with ­initial slow correction of thepatient’s temperature and managementof intracranial pressure. Antibiotics areindicated for secondary infections and­tracheal intubation and ventilation as­
required.

­Further Reading
Mans, C. and Braun, J. (2014) Update oncommon nutritional disorders of captive
reptiles. Veterinary Clinics of North America
Exotic Animal Practice, 17 (3), 369–395.
Wyneken, J. (2007) Reptilian neurology:
anatomy and function. Veterinary Clinics ofNorth America Exotic Animal Practice, 10(3), 837–853.
Mariani, C.L. (2007) The neurologic
examination and neurodiagnostic
techniques for reptiles. Veterinary Clinics ofNorth America Exotic Animal Practice, 10(3), 855–891.

Hyndman, T.H. and Shilton, C. M. (2015)
An update on Australian reptile viruses,
in Unusual Pet and Avian Veterinarians
Annual Conference 2015 (H.R. Baron, ed.)
AAVAC, Sydney, Australia.
Hyndman, T. and Shilton, C.M. (2011)
Molecular detection of two adenoviruses
associated with disease in Australian lizards.
Australian Veterinary Journal, 89, 232–235.
Hyndman, T.H., Shilton, C.M., Doneley, R.J.T.
and Nicholls, P.K. (2012) Sunshine virus inAustralian pythons. Veterinary
Microbiology, 161, 77–87.

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25
Disorders of the Musculoskeletal System
Adolf K. Maas

Anatomy And Physiology
Reptilian skeletal anatomy has many similarities to other clades, although there are key differences that are important for a clinician tounderstand. See Chapter 2 for a more detailed
review of the anatomy and physiology of themusculoskeletal system.
Key Points
The basic terraform tetrapod body plan isfollowed with key exceptions seen in snakes(loss of limbs) and turtles/tortoises (development of the shell).
●● Uniquely, turtles and tortoises have theirribs external to their thoracic girdle, withmost of them developing bone in the intercostal space to form the carapace and de●●­Congenital and Hereditary
Disorders
Reptiles do not commonly have congenital
disorders of the skeletal system, although
there are a number of specific conditions
reported. Axial deviation is likely the mostcommonly seen (scoliosis, kyphosis, lordo­sis) but has only rarely been reported. Skullnovo formation of bone in their ventral bodywall to form the plastron.
●● Snakes have lost their thoracic and pelvic
girdles and limbs through evolution (except
in rare species) and extended their thoracic
vertebrae to make a long, fusiform body
shape.
●● Reptile bones do not have growth plates
and although they will continually growtheir entire lives, the growth occurs fromendosteal ossification, whereby the bones
progressively and gradually enlarge.
●● Each clinician should undertake research
appropriate to the species at hand so thatthey might be familiar with the unique variations of that reptile.

deformities are not commonly identified but
are well publicized and include bicephalism(Figure 25.1) and axial duplication, brachy­
cephaly and cleft palate. The scientific litera­ture has listed a number of axial skeletal
conditions that are also seen in mammals,
including hemivertebra, rib and vertebral
duplication and intercalated half‐vertebrae.
Hind‐limb paresis secondary to congenital
spinal stenosis has been reported in a turtle.

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

346

Reptile Medicine and Surgery in Clinical Practice

Figure 25.1 A two‐headed red‐eared
slider turtle (Trachemys scripta elegans).

Variations in limb morphology are also
reported including ectromelia and supernu­
merary limbs or digits.
The aetiology of these deformities has notbeen well assessed and they are assumed tooriginate similarly as in other clades. Genetic
mutations, toxins and developmental infec­
tions all should be considered, but issues
such as maternal health and nutrition (bothdeficiencies and excesses), incubation condi­
tions and radiation exposure have been dis­cussed as potential causes of congenital
defects. As there can be significant connec­
tion to other disorders, genetic diseases
should be considered as some of the mostdifficult to diagnose. Although seen primar­
ily in young animals, they should still be con­sidered a diagnosis of exclusion.

­Non‐Infectious Disorders
Metabolic and Nutritional
Conditions

Figure 25.2 Veiled chameleon (Chameleo calyptratus)with advanced nutritional secondary
hyperparathyroidism and multiple pathologicalfractures (courtesy of Todd Driggers DVM, Gilbert, AZ).

There are many causes of reptilian skeletal
disorders that are neither primary congenitalto the skeleton nor are infectious in aetiology.
These primarily include nutritional, trau­
matic, degenerative and neoplastic disorders.
Nutritional skeletal disorders among rep­tiles in captivity are well documented(Figures 25.2, 25.3 and 25.4). Maternal nutri­tion has been shown to be critical for fertility

and very early development; it can be easily
deduced to cause issues in neonate reptiles
whose health depends on their maternallyderived stores. Testing of the mother’s­general metabolic health and eggs for com­position, as well as early testing of affectedanimals, may be necessary to diagnose these
conditions.

Disorders of the Musculoskeletal System

Figure 25.4 Russian tortoise (Agrionemys horsfieldii)
with multiple trauma‐induced shell fractures. This
animal also was found to have moderately advanced
nutritional secondary hyperparathyroidism,
facilitating the fractures (A.K. Maas).

Figure 25.3 Radiograph of a veiled chameleon(Chameleo calyptratus) with nutritional secondary
hyperparathyroidism and multiple pathologicalfractures (A.K. Maas).

Once a reptile is no longer dependent upon
its yolk supply, it becomes more susceptible tonutritional dyscrasias that cause skeletal disor­ders. Most commonly referenced are calcium
deficiencies causing osteopenia, osteomalacia
and hypomineralization. However, a singularcalcium deficiency is not commonly responsi­
ble for many cases of nutritionally caused
osteological disorders.
Metabolic bone disease is commonly
named as an aetiology but, in all accuracy,

this term is not a diagnosis. Rather, it is a col­lection of conditions that, although having asimilar clinical presentation, have different
causes, with often very different treatments
and outcomes. A calcium deficiency is one
form of metabolic bone disease but inappro­
priate levels of magnesium, phosphorus,
vitamin D and vitamin A all fit under thisumbrella description in reptiles. Renal dis­ease, parathyroid disease and neoplasia,
hypothermia and lack of appropriate ultravi­
olet B (UV‐B) light all can produce condi­
tions that can be categorized as metabolicbone disease.
Nutritional secondary hyperparathy­
roidism (NSHP) is one of the more common
non‐infectious skeletal conditions, often cat­egorized as a metabolic bone disease. This is,again, a singular title for a condition with

347

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Reptile Medicine and Surgery in Clinical Practicemultiple aetiologies, including a low calcium
and/or high phosphorus diet and/or hypovi­
taminosis D. Since many species of reptiles
require UV‐B exposure to convert 7‐dehy­
drocholesterol to cholecalciferol, inappro­
priate (low) exposure levels of UV‐B light
can also be a cause. Additionally, as theisomerization of cholecholesterol to vitamin
D3 requires heat, chronic hypothermia(inappropriate husbandry) will also cause
hypovitaminosis.
Since kidney function is critical for the reg­ulation of calcium (formation of calcitriol,
retention of calcium, excretion of phospho­rus), renal secondary hyperparathyroidism(RSHP) is also a common aetiology of reptile
skeletal disease. Nephritis, nephosclerosis,
hypovitaminosis A, toxins (including many
commonly used medications) and chronic
dehydration all need to be considered differen­
tials for the aetiology of RSHP. Furthermore,
NSHP and RSHP can occur concomitantly,
exemplifying that plasma biochemistry anal­
ysis is critical for correct identification of theseand similar conditions. It is easy to see that adiagnosis of any of these conditions without
appropriate diagnostics is inappropriate andcan easily lead to treatment failure (seeChapters 6 and 15 for further information).
TraumaTraumatic skeletal disorders are commonly
seen in practice. Fractures are seen in all rep­
tile bones and can be both primary as well as
secondary (pathological; Figures 25.3 and25.4). As with any other patient, radiographs
are essential to assess bone density and con­dition and, if an underlying infectious aetiol­
ogy is suspected, aerobic and anaerobic
culture should be performed with samples
obtained by surgical biopsy or, if this is not
feasible, a blood culture. Fractures secondary
to osteopenia are exceptionally common in
NSHP and related conditions due to lowbone strength.
Luxations have been reported in multiple
reptile cases but are not considered com­mon. These injuries are believed to occur forthe same reasons as in other quadrupeds andsimilar treatment options should be
pursued.
To obtain an accurate diagnosis for a disor­der, a complete review of the husbandry, fol­
lowed with a further evaluation of the patient
to determine whether additional or underly­
ing conditions in other systems are contrib­
uting to the malaise of the patient. Standard
diagnostic techniques should be employed,
including plasma biochemistries, hormone
and vitamin assays, radiographs, cytology
and histopathology. Once aetiology is deter­
mined, treatment options are similar to inother quadrupeds. Dietary and husbandry
issues must be corrected or successful reso­
lution may not be possible. Bones of normal
density can be reassembled and realigned
using common surgical techniques or, if
appropriate for the species, specific bone andfracture, external coaptation may be applied.
It must be noted that reptilian healing occurs
at slower rates than mammals and avian rep­tiles so treatment is likely to be much more
protracted. As callus formation is not as pro­nounced, owing to endosteal regeneration,
repeat radiographs should be taken to assess
healing. In cases of pathological fracture, theunderlying condition must be addressed at
the same time or healing may be hampered
or inhibited. Many defects (scoliosis, longbone valgus) will not be treatable, so the goalof treatment is to prevent further damage
and improve the general health and welfareof the patient.
Neoplasia
Although once believed to relatively rare in
reptiles, neoplasia occurs at similar frequen­cies to avian and mammal species. In general,bony tumours have been found to be non­metastatic in cases examined, while being
locally invasive. In many cases, complete sur­gical excision is curative, although with thefrequency that osteological neoplasias arefound to be metastases from other primary
tumours, appropriate diagnostic work‐ups
are warranted (Figure 25.5).

Disorders of the Musculoskeletal System

Figure 25.5 Oral mass in a green tree python(Morelia viridis) determined to be osteosarcoma(with permission from Bradley Waffa, DVM,
Portsmouth, VA).

­Infectious Disorders
Bacterial and Mycotic Infections
Infectious diseases, and particularly bacterial
infections, are an exceptionally common
cause of skeletal disorders in reptiles(Figure 25.6). The dissemination and locali­zation of these infections into the bone is afrequent sequela and has been identified
even in the fossil record. Based on clinicalobservations, osteomyelitis may occur at amuch higher frequency than it does in higher
vertebrate forms; this may be because pre­liminary studies have identified septicaemias
in up to 5% of apparently healthy animals
tested at random.
Osteomyelitis can result from any infec­
tion in the body, such as pneumonia, a bitewound, hepatitis, enteritis, bacterial translo­
cation, nephritis and gingivitis. The infec­
tions themselves have been identified in longbones, joints, the spinal column and ribs. In
most cases of both superficial and deep cara­
pacial and plastronal disease of chelonians,
the aetiology is infectious osteomyelitis. No
single bacterial agent is responsible for a sig­
nificant percentage of osteomyelitis cases.

Salmonella has been implicated to occur atgreater frequency in Crotalid snakes and has
been isolated in bony lesions in other species
but by no means is it the only agent.
Mycotic osteomyelitis is reported in rep­tiles and pathogens include Nannizziopsis,
Aspergillus, Mucor and other genera. The
source of these bone infections is similar tothat of bacterial infections – disseminatedinfections. These often originate as mycotic
pneumonia but since fungal infections havebeen reported in all tissues, it can develop
anywhere.
Both bacterial and fungal osteomyelitis areoften insidious in nature. Clinical signs seen
can range from none to swellings of the bone
involved (most common on distal extremities
and the maxilla and mandible) to the devel­
opment of fractures, spinal deviations andeven paralysis and death. Often, the firstpresentation involves a symptom unrelated tothe bony lesions as anorexia may be present
and the animal may be lethargic. Any symp­
tom that may be associated with septicaemia
should have osteomyelitis as a differential.
Diagnosing these conditions first requires
a complete blood count and radiographs ofsuspected or affected areas. Radiographs canbe variable in appearance but commonly
have a mixed lytic/clastic appearance andoften some degree of periosteal proliferation.
A complete blood count may produce a gran­ulocytosis and/or a monocytosis or a gener­
alized leucocytosis. Alongside confirmationof disease, blood cultures (both aerobic andanaerobic) must be taken prior to initiat­
ing antimicrobial therapy, although a bonebiopsy and culture and/or polymerase chain
reaction (PCR) and/or histopathology may
be necessary to identify mycotic and myco­bacterial osteomyelitis. Collecting samples
from the surface of chelonian shell lesions isa poor source, as it will always be contami­
nated with environmental agents while theprimary pathogen may no longer be present.
Repeat blood counts, radiographs and­follow‐up blood cultures are necessary tofollow efficacy of treatment and the patient’s
immune system response.

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Reptile Medicine and Surgery in Clinical Practice

Figure 25.6 Bearded dragon (Pogona
vitticeps) with a jaw mass and aradiographic lesions (circle). This wasfound to be a mycobacterial abscess(A.K. Maas).

Treatment should always be based on the
results of diagnostic testing. In most cases,
pure cultures from blood samples are a good
indicator of the infectious agent, while multi­
ple pathogens identified usually indicate acontaminated sample. Unfortunately, fungal,
mycobacterial and some bacterial agentscannot be identified via blood cultures so, if
the culture does not produce results, treat­ment should be based on the evidence pro­
duced by the blood count, radiographs andbone biopsy. Additional diagnostic tools suchas enzyme‐linked immunosorbent assay and
PCR analysis of samples should be employed
to obtain a diagnosis. Appropriate antimicro­bial agents should be prescribed, dependingon the type identified, response to therapy andthe species of animal treated. Nonsteroidal
anti‐inflammatories are often indicated to
improve general condition as most of theselesions are found to be painful in mammals
and are likely so in reptiles.
Concurrent conditions can be diagnosedin the same animals. With weakened healthfrom substandard husbandry, it is common
to find secondary infections and there havebeen cases of animals that were diagnosed
with both NSHP and osteomyelitis concur­
rently, causing severe skeletal deformities.
Thus, despite common thinking to limit a

condition to a single diagnosis, it is critical tocollect and interpret all data sufficiently toallow for concurrent diagnoses.
As is the case in most reptile diseases, thebest prevention is to provide the best possi­
ble husbandry, emulating the natural history
conditions of the species in hand. In addi­tion, since virtually any bacterial or fungal
disease can develop into osteomyelitis, early
identification, accurate and thorough diag­nosis and aggressive, appropriate treatmentof other infective processes will provide an
excellent means of preventing infectious
osteomyelitis in reptiles.
Parasites
Parasitic bone diseases are not as commonly
seen as bacterial and fungal aetiologies but,as there are specific conditions seen, theyshould be considered in appropriate cases.
Digenaean trematodes of the family
Spirorchiidae inhabit the vascular system ofmany species of semi‐aquatic and sea turtles,
and release their ova within the vessels of thehost. These ova can obstruct terminal arter­
ies throughout the animal, with granulomas
and abscesses developing in the carapace andplastron followed by the sloughing of super­
ficial tissue. Oral infections of trichomonads

Disorders of the Musculoskeletal System

are associated with abscess formation in
the maxilla and mandible following deep
gingivitis, both in extinct species as well as
anecdotally in extant species of reptiles.
Microsporidia is more commonly associatedwith myositis and disseminated infections
in reptiles, but has been identified as theaetiology of skeletal defects in amphibians,
so clinicians should consider it as a differen­tial for skeletal pathologies in reptiles.
Diagnosing parasitic osteomyelitis andassociated osteological disorders generally
requires biopsies of affected bony tissues toobtain an accurate diagnosis. Trematodeeggs can be identified on histopathology but
diagnosis via blood samples or faecal analysis
are generally unrewarding. Oral and faecal
direct mount cytologies can be performed to
identify Parabasalia‐type protists but, again,
these organisms only indicate association
rather than infection, with the determina­tion of infection based on other clinicalinformation.
Effective treatment requires identificationof the aetiological agent and administrationof the appropriate anti‐parasiticide. However,there are anecdotal reports of severe andextensive carapacial disease following treat­ment of pond turtles with praziquantel andfenbendazole. Extensive and acute die‐off ofembedded parasites can induce disseminatedgranuloma formation and tissue necrosis,
Figure 25.7 Radiograph of a snakewith osteitis deformans, showing
irregular bone proliferation along thevertebral margins (with permission
from Robert Schmidt DVM PhDDACVP).

producing a serious health risk, for thepatient. Concurrent with treatment appro­
priate sanitation must be administered toprevent both immediate and long‐term rein­
fection, as there is likely little immunologicalprotection developed.

­Skeletal Disordersof Indeterminate
or Mixed Origin
Spinal Osteopathy
The development of spontaneous spinal
defects (spinal osteopathy) has been reported
in all major orders of reptiles and has been
anecdotally reported by reptile practitioners
many times over (Figures 25.7 and 25.8).
Despite this being not uncommonly seen inclinical practice, the specific aetiology of thiscondition has yet to be elucidated, withtrauma, infectious agents, autoimmune con­ditions, toxins and degenerative metabolic
conditions all believed to play a role. There
are some distinctions within the classifica­tion of spinal osteopathy, such as osteitis
deformans, and while each have histopatho­
logical differences they all have similar pres­entations in the patient. Morphologically,
these lesions display irregular bone prolifera­tion of the spine, often involving articular

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Reptile Medicine and Surgery in Clinical Practice

Figure 25.8 Generalized thickening of
the bony trabeculae at the expense of
the intertrabecular spaces andirregular patches of lamellar bone witha characteristic ‘mosaic’ patternindicate osteitis deformans (courtesyof Robert Schmidt DVM PhD DACVP).

surfaces. There may or may not be active
inflammatory processes and, if bacterial
agents are present, they have been seen in allareas of affected tissue including joint spaces,
superficial bone and new or established skel­
etal bone. A comparison to Paget’s disease(osteitis deformans) has been made in pub­lished reports while, in other cases, the quali­
fications for this definition has not been met.
Just as Paget’s disease has been associatedwith a paramyxoviral infection in humans,
there is some thought that there might be aviral induction of spinal osteopathy in rep­tiles. At this time, though, it is evident that
more research is necessary to fully elucidate
this condition.
Diagnosis of spinal osteopathy requires a
combination of both clinical signs and diag­nostic testing. Affected patients are typicallypresented with reduced mobility and flexi­
bility of the vertebral column. On physicalexamination, portions of the spine are noted
to be rigid and, in more advanced cases,
regions of the spine will palpate as enlarged.
Some cases will have paresis or paralysis cau­dal to the affected areas. Radiographs will
confirm ankylosis of the hyperostotic regionsintermixed with lengths of apparently nor­mal spinal column. Fractures both adjacent
and within area of spinal osteopathy are notuncommon. Bone biopsy, blood and biopsy
cultures, haematological and plasma bio­chemical data, and serum vitamin D levels
should be measured to confirm diagnosis

and identify additional correlating condi­
tions. If it is available, nuclear bone scanningwill provide information that correlates
increased metabolic activity with sites of sus­
pected spinal osteopathy.
At this time, there is no treatment modalitythat reverses the hyperostosis present at thetime of diagnosis. This being said, the resultsof appropriate diagnostics can be applied totreat bacterial and fungal infections, nutri­tional deficiencies, husbandry issues andother pathological processes identified. As
inflammation is often the limiting factor for
quality of life in this condition, this should
also be controlled; the author has had relative
efficacy using long‐term nonsteroidal anti‐
inflammatories, including meloxicam (refer
to Appendix 1 for dosing recommendations).
Shell Deformities of Chelonia
Skeletal deformities are common in cheloni­
ans and are commonly categorized as dis­tortions, pyramiding and ‘flat’ shell. Oftenreferred to as a single condition, these disor­ders have been attributed to multiple aetiolo­
gies. NSHP and RSHP are known to cause
abnormalities of bone formation, causing thecarapace and plastron to form abnormallyand of low density. These conditions often
are associated with thickened bridges andperipheral shell margins. Low environmental
humidity coupled with excessive protein or
caloric intake has been postulated as a

Disorders of the Musculoskeletal System

combinatorial aetiology, in that low humidity
decreases the elasticity of the scutal keratin
while diet increases the growth rate of theunderlying carapacial bone. Increased noctur­
nal heat has been correlated with increased
pyramid formation in leopard tortoises(Stigmochelys pardalis), providing strength
to this argument. Fluoroquinolone adminis­
tration in growing chelonians is also pur­ported to cause shell deformities as a resultof cartilage damage.
As these conditions are probably multifac­
torial, each case must be evaluated indivi­
dually, including radiographs, plasmabiochemistries, hormone and vitamin assays
and, in some cases, shell biopsies may be nec­
essary. Existing shell defects will not be able
to be reversed, so the goal of diagnosis andtreatment is to correct the metabolic abnor­
malities and husbandry shortcomings pre­sent in an effort to reduce (and possibly
eliminate) the advancement of the condition
as well as the development of secondary
conditions.

­Muscular and Soft Tissue
DisordersCongenital and Hereditary
Disorders
There are few reports of congenital musculardisorders in reptiles. The few that are pub­lished appear to be associated with a litany ofother defects, some with putative identifica­tion of a single‐gene defect. It is likely thatcongenital connective tissue disorders could
have the same aetiologies as seen in otherterrestrial vertebrates.
Non‐Infectious Disorders
As husbandry is the greatest underlying
source of pathologies in captive reptiles,
muscular abnormalities from nutrition­aetiologies are the most common reported
non‐infectious disorders. Vitamin E defi­
ciencies have been identified as an aetiology

of steatitis in several species of reptiles ofmuscular degenerative disease in reptiles.
Diets high in either polyunsaturated fatty
acids and in vitamin A are known to increase
vitamin E requirements, so reptiles fed large
amounts of either component (fish oil, grain
or seed‐based diets, or rodents primarily
fed grain or seed diets) should have higher
supplementation of vitamin E.
Identification of these cases is often non­
specific, with anorexia and lethargy being
common identifying signs. In some cases,
elevated aspartate transaminase (AST) was
identified on plasma biochemistries. A diag­nosis can be made with measurement ofplasma alpha‐tocopherol levels. Oral orparenteral vitamin E administration has­
been used for both suspected and confirmed
deficiencies.
Tongue paralysis in old‐world chameleons
has been associated with vitamin A deficien­
cies, with recovery observed with parenteraladministration of preformed vitamin A. No
known clinical studies have been published,
so it is not understood whether this is a mus­culoskeletal or neurological disorder causedby this deficiency.
TraumaAs soft tissue injuries occur in all species,
they are also an issue in reptiles. Bites,
wounds, burns and other muscular injuries
all should be addressed and treated in any
other terrestrial animals. With the uniqueissues encountered in skin anatomy and heal­ing of reptiles, Chapter 18 should be reviewed
for appropriate treatment.
Metabolic Disorders

Metabolic myopathies are specific enzymatic
defects caused by hereditary muscle disorders(defective genes), such as glycogen or lipid
metabolism disorders. No such myopathies
have been reported in reptiles at this time.
Exertional or capture myopathy has been
identified in reptiles and has been postu­
lated in cases of routine handling. Also
known as exertional rhabdomyolysis, thiscondition occurs in cases of exertion where

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Reptile Medicine and Surgery in Clinical Practicethere is additional fear or anxiety, excessive
handling, shock, transport, extremes of age
and other factors. In exertional rhabdomy­
olysis, the muscle tissue breaks down fromdepletion of ATP and increased productionof lactic acid, leaking intracellular contents,
eventually leading to cellular necrosis anddeath. Myoglobin is released into the circu­
lation, causing renal necrosis and acute renal
failure.
Identifying these cases is usually basedon history with subsequent weakness andlethargy. Biochemistry profiles identify
increased creatine kinase and AST, oftenwith free myoglobinaemia and acidosis.
Chelonians have displayed increased mark­ers for exertional rhabdomyolysis in as­little as 10–15 minutes of basic restraint forblood collection.
Treatment involves intravenous fluid
administration and diuresis to increase vas­
cular perfusion to affected tissues and pre­vent myoglobin accumulation in renal tissues.
Nonsteroidal anti‐inflammatories should beconsidered to reduce inflammation and dis­comfort but opiates, with both questionableefficacy in the various clades of reptiles andstudies indicating opiate‐induced exertional
rhabdomyolysis in mammals, should be eval­uated on a case‐by‐case basis.
Neoplasia

Few cases of myological neoplasias have beenreported in reptiles. Rhabdomyosarcoma,
has been reported in a captive Galapagos tor­
toise (Geochelone nigra) but the tumour was
not further evaluated to assess possible aeti­
ologies. A leiomyosarcoma has been reported
in the coelomic cavity of a snake but it was
not stated whether it was associated withthe musculoskeletal system. Other cases ofrhabdomyosarcoma, leiomyosarcoma andfibrosarcoma have been reported in reptile
species.
Induction of a rhabdomyosarcoma by ret­roviral infection has been proposed in a cornsnake (Pantherophis guttatus) and fibrosar­
comas (and other neoplasias) are associatedwith retroviral infection in pythons.

Infectious Disorders
Although there are countless infectious
agents identified in reptilian hosts, none isreported to be specific to the muscular sys­
tem of reptiles.
Viral Infections

Retroviral infection has been associated withthe formation of connective tissue neoplasia
but no other specific muscular pathology has
yet been identified with viral infections in
reptiles. A complete blood count and plasma
electrophoresis can be useful to help identify
viral infections, but histopathology and elec­tron microscopy of the tissue, with subse­
quent nucleotide sequencing for identificationof the specific virus, is necessary to identify
these infectious agents.
Bacterial and Fungal Infections

Any bacterial or fungal agent that can infect a
reptile systemically has the potential to develop
into a myositis. Inflammatory exudates in rep­tiles are typically solid, with granuloma forma­tion expected as part of most inflammatory
reactions. Localized inflammatory reactions
are most common but diffuse inflammatory
reactions are known to occur in Mycoplasmaand Helicobacter infections. Chrysosporium
anamorph of Nannizziopsis vriesii, althoughmost commonly associated with dermatitis(see Chapter 18), has been identified in mosttissues of affected animals and has beenreported in cases of deep myositis.
Clinical signs depend on the disseminationof the disease. Systemic infections can pre­sent as acute or chronic decline, lethargy,
anorexia, failure to thrive, erythema and vas­
culitis, diarrhoea, changes in behaviour ordeath. Localized infections may be seen as
localized swellings, redness, changes inmobility, skin lesions or sloughing, bite orpuncture wounds, with or without the gener­
alized signs seen in disseminated infections.
As in the case of any other bacterial or fungal
disease, appropriate diagnostic tools are nec­
essary to produce an accurate diagnosis (seeSkeletal Disorders section).

Disorders of the Musculoskeletal System

Appropriate antimicrobial therapy should
be started on the identification of disease,with modifications or changes pending blood
and/or wound culture. Haematological anal­
ysis is recommended to assess involvementof other organ systems and to evaluate theimmune system response to the infection. If
abscesses are present, surgery is necessary
for resolution since reptiles lack the enzymes
necessary to liquefy purulent debris andthe installation of drains typically results inadditional tissue necrosis.
Parasitic Infections

Parasitic infections are common in reptiles,
with a remarkable diversity of pathologies
identified. Parasitic muscular disorders areless common but are well reported, involving
a range of host species and both metazoan andprotozoan parasites. Nematodiasis, common
in the gastrointestinal tracts of reptiles, hasalso been identified in the skeletal muscles of
tortoises. Filariasis, with subcutaneous andintramuscular migration and sparganosis, arecommonly reported in wild caught reptiles.
Microsporidia, a class of parasitic intracel­lular fungus, is an emerging disease of con­cern that can involve the musculoskeletal
system of reptiles. A bearded dragon (Pogona
vitticeps) was identified as having a dissemi­
nated microsporidial infection involving thetestes, trachea, right femur and associatedmusculature. Heterosporis anguillarum, amicrosporidian species normally infecting
eels, was associated with myositis having
both extracellular and intracellular locations
in a garter snake.
Identifying muscular parasitic infections
can be challenging. The cases may present as

primary problems, such as limb swelling orlameness, incidental such as focal masses
unrelated to the presenting issue or as a con­clusion to a work‐up of non‐specific signs.
The clinician needs to maintain a perspective
not to focus on a particular condition or
symptom until a complete diagnosis isreached and to be complete in their use ofdiagnostic tools. In most cases, in addition to
the collection of a minimum data base, radio­
graphs, muscle biopsy and speciation of theparasite via PCR sequencing.
Caution must be used when treating dis­seminated metazoan infections. Muscularfilariasis is often associated with coelomic
migration as well as blood‐borne microfi­
larial infections; thrombi formation andanaphylactic shock are associated with­
rapid die‐off. Both these and other meta­zoan infections are best treated surgicallyto remove identified worms prior to sys­
temic treatment, if systemic treatment iseven indicated.
Microsporidial infections have yet to havea consistently effective treatment ascer­
tained in reptile patients. Rabbits (infectedwith Encephalitozoon cuniculi) and fish
infected with microsporidia have had good
response to benzimidazole therapy, whilemost other agents (oxytetracycline/chlo­ramphenicol, fluoroquinolones, monensin,
metronidazole, toltrazuril, etc.) have pro­
duced equivocal or unconfirmed results inthese and amphibian species. At this time,fenbendazole has been used by clinicians in
the treatment of microsporidia in reptiles,
with varying degrees of success, but a spe­cific dose and treatment protocol have yet to
be determined.

­Further Reading
Bellairs, A.D.A. (1965) Cleft palate, microph­thalmia and other malformations in embryosof lizards and snakes. Proceedings of the
Zoological Society of London, 144 (2), 239–252).
Di Girolamo, N., Selleri, P., Nardini, G. et al.
(2014) Computed tomography‐guided bonebiopsies for evaluation of proliferative
vertebral lesions in two boa constrictors(Boa constrictor imperator). Journal of Zoo
and Wildlife Medicine, 45 (4), 973–978.
Dierenfeld, E.S. (1989) Vitamin E deficiency
in zoo reptiles, birds, and ungulates.

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Reptile Medicine and Surgery in Clinical PracticeJournal of Zoo and Wildlife Medicine,
20 (1), 3–11.
Fransworth, R.J., Brannian, R.E., Fletcher, K.C.
and Klassen, S. (1986) A vitamin E–
selenium responsive condition in a green
iguana. Journal of Zoo Animal Medicine, 17(1), 42–43.
Frye, F.L. and Carney, J. (1974) Osteitis
deformans (Paget’s disease) in a boa
constrictor. Veterinary Medicine, Small
Animal Clinician, 69 (2), 186–188.
Girling, S.J. and Raiti, P. (2017) BSAVA Manualof Reptiles, 3rd ed. John Wiley & Sons, Ltd,
Chichester.
Heinrich, M.L. and Heinrich, K.K. (2015) Effectof supplemental heat in captive African
leopard tortoises (Stigmochelys pardalis) andspurred tortoises (Geochelone sulcata) on
growth rate and carapacial scute pyramiding.
Journal of Exotic Pet Medicine, 25 (1), 18–25.
Irizarry‐Rovira, A.R., Wolf, A., Bolek, M. et al.
(2002) Blood smear from a wild‐caught
panther chameleon (Furcifer pardalis).
Veterinary Clinical Pathology, 31 (3),129–132.
Isaza, R., Garner, M. and Jacobson, E. (2000)
Proliferative osteoarthritis andosteoarthrosis in 15 snakes. Journal of Zoo
and Wildlife Medicine, 31 (1), 20–27.
Jacobson, E., ed. (2007) Infectious Diseases andPathology of Reptiles: Color Atlas and Text.
CRC Press, Chichester.
Klaphake, E. (2010) A fresh look at metabolicbone diseases in reptiles and amphibians.
Veterinary Clinics of North America Exotic
Animal Practice, 13 (3), 375–392.
Raftery, A. (2011) Reptile orthopedic medicine
and surgery. Journal of Exotic Pet Medicine,
20 (2), 107–116.
Richter, B., Csokai, J., Graner, I. et al. (2013)
Encephalitozoonosis in two inland bearded
dragons (Pogona vitticeps). Journal ofComparative Pathology, 148 (2), 278–282.
Rothschild, B.M., Schultze, H.P. and Pellegrini,
R. (2012) Summary of osseous pathology inamphibians and reptiles, in Herpetological
Osteopathology: Annotated Bibliography ofAmphibians and Reptiles, Springer ,New
York, NY, pp. 11–53.
Souza, S.O.D., Casagrande, R.A., Guerra, P.R.
et al. (2014) Osteomyelitis caused by
Salmonella enterica serovar derby in boa
constrictor. Journal of Zoo and Wildlife
Medicine, 45 (3), 642–644.

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26
Diseases of the Organs of Special Senses
Alex Rosenwax and Tegan Stephens

Anatomy and Physiology
See Chapter 2 for further information on the
anatomy and physiology of the organs of special senses.
Key Points●●

The eyelids of all snakes and some geckos
and lizards are fused and translucent, forming the spectacle. They are dermal in origin.

­The Eye
Physical Examination
There are many variations in the placementof reptilian eyes, making it difficult to determine whether the eye position is abnormal.
The ophthalmic examination should begin
with an assessment of the symmetry of theeyes to determine whether there is exophthalmos, enophthalmos or any swelling ofeither the eyes or the eyelids.
Ancillary Tests
The Schirmer tear test can be used to­measure tear production in reptiles that do
not have spectacles. Normal values are notknown for many species. Samples may need

Poor development of the rectus muscles
means the movement of the eye in all reptiles, except chameleons, is limited.
●● Chelonia do not have nasolacrimal ducts●● Reptiles are relatively resistant to the effectsof mydriatics.
●● Reptiles have an avascular retina.
●●

to be taken from similar healthy species
as an indication of normal tear productionlevels.
Fluorescein staining is useful for assessing
corneal ulcers and nasolacrimal duct patency.
In species with spectacles, the fluoresceinmust be injected through the spectacle, into
the subspectacular space with a 27‐gauge
needle, while taking care to avoid damaging
the cornea. In turtles, the absence of nasolacrimal duct leads to the fluorescein dye simply
trickling down the side of the face.
Conventional mydriatics such as atropine
and tropicamide are ineffective in reptiles, as
the ciliary body muscles are mainly smoothmuscle, preventing the parasympatholytic
effect on pupillary dilation. Local anaesthetic
drops can be used to assist in opening eyelids
closed due to a response to pain.

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

358

Reptile Medicine and Surgery in Clinical PracticeSpecial Ophthalmic Instrument
Examination
Many of the ophthalmic instruments used in
mammals can be used in reptiles, with somemodifications. A brief examination with a
focal light source will establish if there is any
cloudiness of the cornea or any adnexal problems. Pupillary light response is however notconsidered reliable, as the presence of striated muscle in the reptilian eye interfereswith the autonomic control and can affectthe pupillary light reflex. Reptiles also do nothave consensual light reflex.
Magnification, and especially the use of aslit lamp (Figure 26.1), is essential to avoid
missing subtle changes when examining
the small reptilian eye. The slit lamp is also
necessary to define subspectacular space,corneal depth and the anterior chamber.
Magnification for fundoscopy is best performed in the nondilated eye with a panophthalmoscope or, if this is not available, with a90‐dioptre lens.
Tonometry can be performed on the eyes
without anaesthesia. In animals without
spectacles, both applanation and reboundtonometry have been used. Rebound tonometry is considered to be more precise in larger
reptiles (Table 26.1) with neither method
appearing to be precise in reptiles weighing
less than 100 grams.

Table 26.1 Mean values for intraocular pressure
in reptiles, using rebound tonometry.
Pressure(mmHg)

Species

Red‐eared sliders (Trachemys scripta
elegans)

6.1

Yellow‐footed tortoise (Chelonoidis
denticulata)

14.2

Bearded dragon (Pogona vitticeps)

6.16

Hermann’s tortoises (Testudo
hermanni)

15.74

Andros island iguana (Cyclura
cychlura cychlura)

4.77–5.12

Ultrasound is used to determine theboundaries and constituents of periocularmasses and to define fluid‐filled areas in thesubspectacular space.

­Diseases of the Eye
Spectacle Disorders
The spectacle covers the eye and is formed
from the fusion of transparent cells of theeyelids. Spectacles are found in all snakes,
many geckos, Pygopodidae (legless lizards)
and Xantusiidae (night lizard). Being of
Figure 26.1 Murray river short‐necked
turtle (Emydura macquarii macquarii)
eye examination with a slit lamp.

Diseases of the Organs of Special Senses

Figure 26.2 Python with retained
spectacle.

­ ermal origin, the spectacle is shed as part ofdthe skin during ecdysis. It is not attached tothe cornea and is separated from the cornea
by the subspectacular space. Spectacles willusually become opaque prior to shedding;this is not a cause for concern and the spectacle will be shed with the skin. The spectacle
may also appear slightly indented in snakes;
this is normal and will generally resolve with
the next shed.
Retained Spectacles

Retained spectacles are related to dysecdysis
in snakes (see Chapter 18). The problem ismost commonly related to dehydration, poor
environmental conditions, poor nutritionand systemic disease. Scarring or traumaof the spectacle as well as any primary or
secondary disease affecting the skin, such­as mites, may lead to retained spectacles.
Retained spectacles, especially in recurrent
cases, may temporarily affect vision as theopaque skin debris builds up over the spectacle. This build‐up of debris may also lead tosecondary infection of the spectacle.
Diagnosis is relatively simple if examination of the snake’s sloughed skin fails to findthat the spectacle has been shed. It is notuncommon for clients to fail to realise there
has been an incomplete shed and, as ac­onsequence, they have not kept thesloughed skin for later examination. Thesesnakes may present with a partial shed of
the head, with the eyes appearing opaque.
When multiple unshed layers are present, theopaque dried non‐translucent spectacle isobvious (Figure 26.2). However, when only
one extra layer of spectacle skin is present,
after the rest of the cranial skin has sloughed,a slit lamp may be required to identify thisthin extra layer.
To remove retained spectacles, soak thearea with a moist cotton swab and then gently rub from the medial to lateral canthi witha moist cotton tip. If this fails to remove theretained tissue, add artificial tears five times
daily to soften the spectacle and increase theenclosure’s humidity before attempting
removal of the retained spectacle with a cotton swab one to seven days later. Avoid using
forceps to forcibly remove the retained spectacle as this can damage (Figure 26.3) orremove the healthy new underlying spectacle, leading to exposure keratitis.
Subspectacular Abscess

Infection may occur in the subspectacularspace from penetrating spectacular wounds
or bacteraemia, or via the nasolacrimal ducts.
Subspectacular infections are usually bacterial

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Reptile Medicine and Surgery in Clinical Practice

Figure 26.3 Indented spectacle,
diamond python (Morelia spilota
spilota).

oroccasionally
fungalinorigin.
Subspectacular nematodiasis has also been
seen in ball pythons (Python regius).
Clinically, the spectacle will appear cloudy
and discoloured, and may be distorted or distended and may appear similar to a blocked
nasolacrimal duct. The two conditions canbe differentiated by injecting fluoresceinthrough the spectacle. The dye will drain into
the choana and nares if the nasolacrimal duct
is not blocked.
Treatment involves surgically removing avery small wedge section from the spectacle
under general anaesthesia and flushing out
the area with saline. Antibiotic eye drops(without corticosteroids) can then be applied
into the eye via the resected wedge of thespectacle. A culture and sensitivity test canbe used to determine appropriate antibiotics.
Systemic antibiotics are often warranted
unless unilateral localized trauma can be
confirmed. Management as per traumatic
spectacle loss is also necessary to avoid
development of exposure keratitis.
Loss of Spectacle

The loss of a spectacle is most commonly
related to iatrogenic trauma during attempts
to remove retained spectacles. Infection,
trauma, abrasion and bites by prey species(from the feeding of live rodents or cricket
bites) can also cause spectacle trauma. The
loss of a spectacle leads to the evaporation of

the tear film and desiccation of the cornea.
This may give the appearance of enophthalmos. Partial loss will lead to signs equivalent
to epiphora, as the tears overflow throughthe traumatized area.
Treatment for complete spectacle loss
includes topical antibiotics and commercial‘artificial tears’ solutions applied regularly.
Cut‐down soft contact lenses, collagen grafts
and oral mucosal flaps have been suggested
as protective treatments for partial and total
spectacle loss. As long‐term resolution is difficult, enucleation may be necessary.
Eyelids
Tumours

Melanomas have been diagnosed on the eyelids of bearded dragons (Pogona spp.), related
to artificial ultraviolet lights being in too
close proximity (less than 30 cm) to the enclosure’s basking area. These tumours may beamelanotic melanomas. Many other tumours
have been seen on the eyelids of lizards anddragons, including squamous cell carcinomas
and myxosarcomas. Viral fibropapillomatous
tumours have also been reported in green
sea turtles (Chelonia mydas).
TraumaEyelid trauma is often related to fighting inshort neck turtles (Emydura spp.), red‐eared
sliders (Trachemys scripta elegans) andDiseases of the Organs of Special Senses

occasionally bearded dragons (Pogona­vitticeps). Simple wounds will need cleaning
with povidone‐iodine. Only substantial
wounds will require surgical intervention.
Occasional more serious untreated cases will
require systemic and/or topical ophthalmic
antibiotics.
Swollen Eyelids and AssociatedBlepharospasm

Blepharoedema may be related to primary
infectious agents, environmental irritants
and Vitamin A deficiency. In reptiles withhypovitaminosis A, squamous metaplasiaof the orbital glands and ducts develops,
leading to xerophthalmia followed by asecondary blepharitis and conjunctivitis.
­
Opportunistic bacteria can then invade.
Diagnosis is made on clinical signs of swollen
eyelids combined with dietary history of low
vitamin A intake. Treatment for vitamin A
deficiency may involve dietary or injectablesupplementation, taking care to avoid iatrogenic hypervitaminosis A. Any primary or
secondary infections will require systemic
and topical antibiotics.
Periocular Area
Masses in the periocular region are usuallyfound to be abscesses, although neoplastic
lesions are also commonly encountered.
Associated tissue swelling and exophthalmos
Figure 26.4 Shingleback lizard (Tiliqua
rugosa) with conjunctivitis.

can easily be mistaken for periocular neoplasia. Melanomas, squamous cell carcinomas
and adenocarcinomas have been seen in
many reptile species, especially bearded dragons (Pogona spp.), often related to the basking
area being too close (less than 30 cm) to theultraviolet lights. A lacrimal cystadenoma in a
Chinese box turtle (Cuora flavomarginata)
and a myxosarcoma in a bearded dragon havealso been reported to have caused periocularneoplasia and swelling.
Aspiration of the lesion for diagnosis
may be unrewarding, as the caseous pus­cannot easily be withdrawn through a needle. Ultrasound can be used to differentiate
larger abscesses from neoplastic lesions.
Surgery is then generally indicated to remove
the caseous pus and determine whether
neoplasia is involved. There are no bacterial
infections specific to this area. Antibiotic
coverage should be broad spectrum, including
activity against anaerobes and Pseudomonas
species until culture and sensitivity results
are received.
Conjunctiva
Bacterial conjunctivitis is usually secondary
to poor husbandry conditions. The eyelids
are often semi‐closed with dried caseous
plaques (Figure 26.4) forming under or on
the eyelids and within the conjunctival
fornix. Infections may spread to cause
­

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Reptile Medicine and Surgery in Clinical Practice­ anophthalmitis and eventually septicaemia.
pTreatment involves removing plaques, flushing the eyes with sterile saline and the use of
topical or systemic antibiotics against Gram‐
negative bacteria including Pseudomonas or
Aeromonas species, as well as improving thepredisposing husbandry issues.
Viral conjunctivitis (notably herpesvirus
fibropapillomas in green sea turtles) has
been recorded and is most likely to bediagnosed on biopsy samples. Parasites,­
including Neophystoma in a chelonian andChlamydia in a case of conjunctivitis ina tortoise, have also been seen. In casesof unresolved conjunctivitis, a biopsy isrequired for diagnosis.
Foreign‐body conjunctivitis may be related
to the use of substrates such as corn husks,
hay or sand. Treatment involves removalof the foreign body either under generalanaesthesia or with the assistance of local
anaesthetic ophthalmic drops. Antibiotics
may be needed if secondary bacterial infection is present.
In all cases of conjunctivitis it is best toplace non‐aquatic species on plain sheets ofpaper or similar substrates to avoid foreign
body conjunctivitis forming from small
particles of the substrate adhering to thedried pus.

Nasolacrimal Duct
Nasolacrimal Duct Blockage

The nasolacrimal duct performs a similarfunction in reptiles as it does in all species,
with the duct being absent in Chelonia species. In all reptiles without spectacles, blockage of or absence of the duct leads toepiphora. Nasolacrimal duct blockage iscaused by ulcerative stomatitis, oral or nasal
neoplasia, cranial granulomas, oral burns
and scarring, cysts, as well as congenital
blockage. The duct in any reptile may beclosed by dacryocystitis. Abscessation andocclusion of the duct be may result fromascending oral bacteria or fungal infections,systemic infections as well as penetrating
injuries to the spectacle in snakes. In reptiles
without spectacles (most non‐snakes), thiswill often be seen as a purulent discharge
from the eyes.
Bullous Spectaculopathy(Pseudobuphthalmos)

In snakes with blocked nasolacrimal ducts,
the spectacle does not allow excess tears tobe shed externally. The excess clear fluid
instead accumulates in the subspectacularspace, resulting in a bulging of the spectacle(Figure 26.5). For diagnosis, a slit lamp can be

Figure 26.5 Nasolacrimal duct atresia
in a juvenile eastern brown snake(Pseudonaja textilis).

Diseases of the Organs of Special Senses

used to demonstrate the increased distance
between cornea and spectacle. Fluoresceinstaining can be used to investigate the lack ofpatency of the nasolacrimal duct. In snakes,
this involves injecting fluorescein throughthe lateral canthus of the spectacle into thesubspectacular space and observing whether
the coloured dye drains out of the subspectacular space.
Temporary relief in chronic blockage cases
can be achieved by cutting a small wedge section from the spectacle to allow drainage
from the inferior quadrant of the eye.
Another temporary treatment involves retrograde flushing of the duct with a 27‐gauge
cannula. However, blockage will often recurwith these temporary methods. The continued blockage will lead to infection of the eyeand pressure related pain. For a more permanent solution, surgical reconstruction of theduct has been advocated. However the longterm prognosis post‐surgery is unknown.
CorneaKeratoconjunctivitis Sicca

Keratoconjunctivitis sicca has a similar presentation and aetiology as per all taxa and isrelated to poor tear production. Vitamin A
deficiency may also be a predisposing cause.
The dry eyes lead to metaplasia of the conjunctiva and corneal epithelium. Diagnosis isperformed with a Schirmer tear test andtreatment involves the regular and frequent
use of ‘artificial tears’. While taking care to
avoid iatrogenic hypervitaminosis A, weekly
vitamin A injections have also been advocated for four to six weeks.
Keratitis

White corneal masses from bacterial andfungal keratitis have been seen in tortoises
and viral herpes papillomatous proliferative
corneal lesions have been seen in green sea
turtles. Fungal infections involving aspergillus have reported in tortoises. Bacterial
infections are mostly caused by Pseudomonasand Aeromonas species. The raised corneal
lesions should be removed under generalanaesthesia, combined with concurrent useof local anaesthetic eye drops. Use a 25‐ or
27‐gauge needle to elevate and pry the raised
lesion off the cornea. Microscopic examination for fungi and bacteria should be performed immediately and the sample thensent for bacterial culture and sensitivity.
Enrofloxacin eye drops can be used forGram‐negative bacterial infections andmiconazole used topically for fungal infections prior to receiving the culture and sensitivity results.
Corneal Ulcers

Ulceration of the cornea is commonly causedby foreign body trauma, often related to theuse of inappropriate substrate. It may also be
related to intraspecies fighting or be secondary to keratoconjunctivitis sicca. Healed
ulcers in reptiles may present with whitescarring or slightly elevated areas of the cornea. In snakes, trauma to the spectacle should
not be confused with corneal ulceration, as
the spectacle is part of the dermis and is notpart of the cornea. Diagnosis is made on positive fluorescein dye uptake. Full‐thickness
lacerations can be repaired with 8/0 or 10/0
sutures, preferably using an operating microscope. For minor ulcers, apply enrofloxacin
eye drops. In addition, systemic antibiotics
and nonsteroidal anti‐inflammatory drugs
should be prescribed for deep ulcers and lacerations. In cases of ulceration, remove any
small particulate matter and, where possible,
use plain paper or an equivalent non‐irritant
substrate until the lesion has healed.
Glaucoma

Glaucoma has rarely been reported in reptiles. Secondary glaucoma in reptiles has
been seem with traumatic panophthalmitis(Figure 26.6). However, as normal intraocular pressure values for many species of reptiles are now becoming available, diagnosis ofglaucoma is likely to become more common.
When normal values are not available for a
reptilian species, assess for glaucoma bymeasuring contralateral eye pressure or asimilar species cage mates’ intraocular pressure

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Reptile Medicine and Surgery in Clinical Practice

Figure 26.6 Eastern long‐necked
turtle (Chelodina longicollis) withunilateral panophthalmitis
buphthalmos following trauma. The
lens and anterior chamber are opaque.

values. The accuracy of intraocular pressure
values in smaller reptiles have been affectedby the inability to collect repeatable pressure
results.
Lens
Cataract development is seen in aged reptiles and is assumed to have a similar aetiology to other taxa. Freezing during brumation
has been associated with cataract formationin turtles and may be related to the softer
fluid‐like lenses of reptiles. Exposure toultraviolet light has also been suggested to
be a cause of cataracts. However, no direct
links have yet been found between close
proximity to ultraviolet lights and cataracts.
The relatively soft lens has allowed successful treatment of cataracts in larger reptiles
with phacoemulsification. In snakes, any
cataract surgery also requires an incision
through the spectacle.
RetinaWhen examining the reptilian retina, it isimportant to keep in mind that it is avascular.
Blood supply is via the choriocapillaries.
Reptiles are assumed to suffer similar retinal
issues as per all veterinary patients, althoughthese have rarely been reported in theliterature.

Uvea
Uveitis in reptiles may be fungal, bacterial or
viral. The infection can be local (often following trauma) or systemic in origin. When
hypopyon is present, it is generally considered to be systemic in origin and a resultof septicaemia. Freezing at brumation has
also been associated with hyphaema andhypopyon in Chelonia. Blood tests for biochemistry, haematology and blood cultures
should therefore be considered in cases ofhypopyon. The treatment of uveitis requires
the combined use of systemic nonsteroidal
anti‐inflammatories and antibiotics thatcover for at minimum Klebsiella andPseudomonas species.

­Eye Shape and Position
Exophthalmos
Exophthalmos is caused by retrobulbar swellings or masses. The most common cause of
exophthalmos is abscessation. Owing to the
granulomatous nature of reptile abscesses,
paracentesis may not always easily distinguish abscess from neoplasia. An aneurism
in the retrobulbar vein following trauma has
been reported as a cause of exophthalmos
and a bearded dragon was reported tohave exophthalmos and blepharoedema

Diseases of the Organs of Special Senses

associated with congestive heart failure.
Ultrasound can be used to determine thenature of the lesion but surgery is requiredfor diagnosis and treatment. In snakes,
exophthalmos needs to be distinguishedfrom pseudobuphthalmos using either a slit
lamp or ultrasound.
Enophthalmos
Enophthalmos is more commonly caused byemaciation and severe dehydration. Trauma
may also give the appearance of enophthalmos and microphthalmia. Initial treatment
involves an assessment for signs of dehydration and then, if necessary, rehydrationof the reptile to see if the enophthalmos
resolves.
Microphthalmia
Congenital microphthalmia has beenreported in clutches of snakes. Suspectedcauses include genetics, incubation temperature and humidity with possible nutritional
factors. It has been reported in red rattlesnakes (Crotalus ruber) as well as Burmese(Python bivittatus) and ball pythons (Python
regius). Presumptive anophthalmia has beenused to determine whether a true anophthalmia is present or simply microphthalmia
with scales covering the eye.

­The Ear
Aural Abscesses
Aural abscesses are found in chelonians andoccasionally lizards. Chelonians do not havean external ear. Instead, they have a superficial tympanic membrane and, medial to this,a relatively large tympanic cavity with a
medial blind‐ended sac. Abscesses in chelonians are generally formed from exogenous
bacteria invading and colonizing the tympanic cavity of the middle ear. Abscesses arerare in snakes and lizards because, unlike
turtles, they do not have a tympanic cavity.

The predisposition to aural infection
appears to be related to poor husbandry andthe subsequent invasion of opportunistic
infections. The problem usually involves
below preferred optimal temperature zone
conditions for extended periods combinedwith poor nutrition and unsanitary conditions. When water is not changed regularly,
there will be a build‐up of faeces, with subsequent increased nitrates in the water, resulting in bacterial overgrowth in the pond or
aquarium. This issue, combined with poor
nutrition from inappropriate diets including
poorly formulated commercial turtle dinnerand pellets, will affect the immune system of
the turtles. Dietary issues are especially common when commercial diets formulated
for vegetarian turtles are fed to omnivorousturtles (such as Australian short‐necked turtles, Emydura spp.) or carnivorous turtles(Australian long‐necked turtles, Chelodina
longicollis). Vitamin A deficiency has long
been suspected of being the theoreticalunderlying cause of aural abscesses in vegetarian chelonians. Vitamin A deficiency willlead to squamous metaplasia within the middle ear and Eustachian tube. This results inswelling of cells in the tympanic cavity andthe blockage of the cavity with dried exudate
and exfoliated cells. The high bacterial loadin water with high nitrate levels will overwhelm the already deficient immune system,
allowing colonization of bacteria in theblind‐ended tympanic cavity.
The poor blood supply to the centre of thislesion means antibiotics are unlikely to beeffective. Bacterial infections in reptiles leadto a granulomatous reaction forming a semi‐
dried caseous pus that cannot easily drainout of the very short medial ear canal. This
forms a hard dried often yellow‐covered plugunder the skin in the area of the ear and may
have the initial appearance of a neoplastic
lesion (Figure 26.7).
Diagnosis is made on the appearance andlocation of the lesion. Owing to the granulomatous nature of the lesions, paracentesisof the lesion is not likely to be rewarding andmay simply lead to haemorrhage from the

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Reptile Medicine and Surgery in Clinical Practice

Figure 26.7 Swelling associated with
an aural abscess in a turtle (courtesy of
Bob Doneley).

needle insertion point. Water quality shouldbe tested, using a sample collected from theturtle’s normal enclosure, for pH, ammonia,
nitrite and especially nitrate. A complete history of the diet, water changes, and water andair temperature should also be collected.
Treatment involves surgical incision. Before
surgery, it is important to warm the patient tothe correct optimal temperature and allow
time for the antibiotic therapy to be effective.
As it is assumed that aural abscesses are secondary to multiple husbandry issues, otherorgan or systems failure should be investigated before anaesthesia. Fluid therapy is also
advised. Antibiotics, prior to culture and sensitivity of samples taken at surgery, should
cover for both the water‐borne bacteria
Aeromonas spp. and for the anaerobes likely
to be present within an abscess. Vitamin A
injections may also be considered in susceptible species, while, taking care to avoid iatrogenic hypervitaminosis A.
Surgery involves the incision, shellingout and debridement of the lesion. Samples
should be collected for culture and sensitivity. The area should be lavaged with dilute
chlorhexidine and then packed with silver
sulfadiazine, antibiotic‐impregnated poloxamer‐407 gel or at minimum with an steroid‐
free antibiotic ophthalmic ointment.
Depending on the depth size and ability toeffectively debride the wound, the area willneed to be cleaned and repacked every one tothree days. If it is possible to form an effective plug with poloxamer‐407 gel, the area ismore likely to require changing only every
three days. Systemic antibiotics may not beeffective in these localized lesions prior tosurgery. However, once the wound has beendebrided and inflamed, antibiotic therapy
based on culture and sensitivity should be
more effective.
The type of recovery enclosure will dependon the species. For turtle species that often
spend long periods basking out of water, dry
docking or dry docking with daily swims
prior to wound cleaning are appropriate. For
semi‐aquatic or aquatic species dry docking
for one to three hours once to twice daily
may be more appropriate. Prevention
includes regular water‐quality testing andwater changes, temperature regulation anddietary modification. Vitamin A injections
may also be required until dietary changes
are fully instituted. Initial success rate oftreatment is high but abscess recurrence may
also be seen.

­Jacobson’s Organ(Vomeronasal Organ)
The vomeronasal organ is an olfactory structure found on the roof of the mouth or choana of some reptiles. It detects pheromonesand environmental cues. The organ is best

Diseases of the Organs of Special Senses

developed in snakes and varanid lizards. In
snakes and varanids, the flicking of the
tongue brings air particles into direct contact
with the organ. Any damage to the vomeronasal system through trauma or oral infection may affect both mating behaviour andprey recognition, leading to possible anorexia. Studies on garter snakes with partial
and full removal of the organ showed they
could not follow prey trails and failed to display courtship behaviour.

­ eat‐Sensitive Receptors or
H
Pit Organs
The heat pit sensors are found on some
Boidae, Pythonidae (except womas and black‐headed pythons, Aspidites spp.) and the
Crotalinae (pit vipers). These heat sensors
allow the snakes to make a visual pictureusing the infrared spectrum. This improves
vision, as the snake can add infrared heatvision to their standard vision from their eyes.
These ‘infrared eyes’ are termed ‘pit organs’or simply ‘pits’ because they take the form ofdeep depressions in the skin of the head. The
pit organs of Boidae (boas) and Pythonidae(pythons) are located in the rostral and labial
scales. There may be 3–20 pits on each side,
depending on the species. In some species of
Boidae, the pits are not apparent but the sensors are still present. On clinical examination,
the pits should be examined for mites, ticks,
retained skin and fungus.
The ability to ‘see’ heat has been suggested as
one of the causes of clients being bitten when
feeding cold mice or rats to a snake, as thesnake mistakes the client’s heat for the prey.

Vestibular disease
The typical signs of vestibular disease in
reptiles, including head tilt, rolling andtwisting of the neck, may be caused byeither central nervous system lesions or
inner ear problems. Generalized systemic
conditions often imitate the signs of vestibular disease (e.g. hypocalcaemia tetany
and organophosphate toxicity). Viral infections affecting the nervous system (adenovirus in Pogona spp., inclusion body virus inpythons and paramyxovirus in snakes) as
well as weakness from metabolic and musculoskeletal disease, will also mimic thesigns of vestibular disease. If discrete cranial lesions are present, the head tilt or rollis usually to the side of the cranial lesion.
Strabismus has been reported in reptiles
with vestibular disease but nystagmus has
rarely been seen.
If vestibular disease is suspected, it is best
to initially rule out problems that may imitate vestibular disease. A detailed history isimportant including dietary calcium supplementation, enclosure temperature, appropriate exposure to ultraviolet light and any
use of insecticides. If other generalized signs
are present, including weight loss, anorexia
and respiratory signs, it is also less likely to
be a discrete cranial lesion. While flaccid
paralysis or dyspnoea may suggest a generalized systemic condition rather than cranial
vestibular disease. Samples should then be­collected for PCR for viral infections, biochemistry for underlying systemic illness
and bacterial blood cultures. Prognosis is
more favourable in cases of nonviral systemic diseases that are imitating the signs ofvestibular disease.

­Further Reading
Brown, J.D., Richards, J.M., Robertson, J. et al.
(2004). Pathology of aural abscesses infree‐living eastern box turtles (Terrapene
carolina carolina). Journal of Wildlife
Diseases, 40 (4), 704–712.

Da Silva, M.A., Bertelsen, M.F., Wang, T. et al.
(2015) Unilateral microphthalmia or
anophthalmia in eight pythons (Pythonidae).
Veterinary Ophthalmology, 18 (Suppl 1),
23–29.

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Reptile Medicine and Surgery in Clinical Practice

Goris, R.C. (2011) Infrared organs of snakes:
an integral part of vision. Journal of
Herpetology, 45 (1), 2–14.
Hausmann, J.C., Hollingsworth, S.R., Hawkins,
M.G. et al. (2013) Distribution and outcomeof ocular lesions in snakes examined at aveterinary teaching hospital: 67 cases (1985–2010). Journal of the American Veterinary
Medical Association, 243 (2), 252–260.
Labelle, A.L., Steele, K.A., Breaux, C.B. et al.
(2012).Tonometry and corneal aesthesiometry
in the red‐eared slider turtle (Trachemys
scripta elegans). Journal of Herpetological
Medicine and Surgery, 22, 30–35.

Lawton, M. (2005) Reptilian ophthalmology, in
Reptile Medicine and Surgery (S.J. Divers
and D.R. Mader, eds). Elsevier Health
Sciences, St Louis, MO, pp. 323–342.
Myers, G., Webb, T., Corbett, C.R. et al. (2011)
Phacoemulsification for removal of bilateral
cataracts in a black water monitor (Varanus
salvator macromaculatus). Journal of
Herpetological Medicine and Surgery, 21 (4),
96–100.
William, D.L. (2012) The reptilian eye, inOphthalmology of Exotic Pets (David L.
Williams, ed.). John Wiley & Sons, Ltd,
Chichester, pp. 159–196.

369

27
Analgesia and Anaesthesia
Annabelle Olsson and Mark Simpson­Introduction
The general principles and analgesic andanaesthetic agents available to the generalpractitioner for more traditional patients are
generally applicable to reptiles. Reptiles
constitute an entire class of animals, formany of which there is scant quality evidence
to guide analgesic or anaesthetic protocols.
Practitioners should be aware of the signifi­
cant differences in physiology and anatomy
that may influence analgesia and anaesthesia
in reptiles. Chief among these is ectothermy
and its close relationship with metabolic rate.
Reptiles should be maintained at the upper
end of their preferred body temperature
range throughout anaesthesia to properly
metabolize anaesthetic agents.

­Physiology
Various factors affect metabolic rate, themost influential being temperature. As
temperature decreases, oxygen demand andmetabolic requirements of tissues decrease,leading to increases in both the latency of
onset and duration of effect of anaesthetic
agent and time to recovery. Many reptiles
can convert to anaerobic metabolism whenplaced in an oxygen deficient environment.
This adaptive mechanism can make it impos­
sible to induce anaesthesia with inhalation

agents in some species, as they perceive
the unfamiliar gaseous agent and become
apnoeic, converting to anaerobic metabo­lism. Artificial ventilation, which mimics
the frequency and depth of respiration in a
conscious reptile, is essential to effectively
manage an anaesthetized patient and help tocombat hypoxia and hypercapnia.
The control of respiration in reptiles ismore complex than in mammals. Both carbon
dioxide and pH changes appear importantfor stimulating normal ventilation but thereis evidence that, even under normoxic condi­
tions, oxygen tension may play a role in nor­mal ventilation. Generally, reptile respiration
is an episodic pattern, with cycles of two or
three rapid breaths followed by a longer
pause. The respiration rate depends on thesize of the animal, decreasing with increasing
body mass. Ambient temperature has varia­
ble effects on the frequency, tidal volume andminute ventilation and due consideration
should be given to maintaining the optimal
temperature for a particular species.
The response of reptiles to inspired carbon
dioxide is quite variable, as is the response
to 100% oxygen. During anaesthesia, most
reptiles are maintained with an inhalantanaesthetic delivered in 100% oxygen. Highinspired oxygen may be responsible forsome of the respiratory depression seen
during gaseous anaesthesia. Reptiles appear
to recover faster from isoflurane anaesthesia

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

370

Reptile Medicine and Surgery in Clinical Practice

if the animal is ventilated with room air
rather than 100% oxygen.
While injectable anaesthetics generally
have a long duration of action, with anaes­
thetic depth not changing rapidly or unex­
pectedly, depth and duration of gaseous
anaesthesia are dependent on the rate ofintermittent positive pressure ventilation(IPPV) and the concentration of gasdelivered.
During anaesthesia, cardiac shunting canaffect systemic arterial oxygen content andthe uptake and elimination of inhaledanaesthetics. The size and direction of theshunts are ultimately controlled by pressure
differences between the pulmonary andsystemic circuits and washout of bloodremaining in the vena cava. Changes in thelevel and direction of the shunts may
account for the unexpected awakening seen
in some reptiles anaesthetized with inhal­
ant anaesthetics, emphasising the impor­tance of careful monitoring of anaesthesia.
Intracardiac shunts also have implications
for patient monitoring, in particular airway
gas monitoring and pulse oximetry. Post‐anaesthetic monitoring is also critical in all
reptiles since ‘regression’ apnoea can occur
if animals are left unstimulated following
administration of central nervous systemdepressants.
Although there is debate in the literature
over the importance of the renal portal sys­
tem on uptake, distribution and metabolism
of drugs in reptiles, the system exists and it istherefore recommended that anaesthetic or
sedative drugs be injected into the cranial
half of the body.
As well as physiological features, there areanatomic idiosyncrasies among reptiles that
especially influence the management of cer­tain aspects of anaesthesia in those reptiles.
Muscle relaxants, including most immobili­
zation agents, interfere with the reflex clo­
sure of both the glottal and palatal valves incrocodilians. It is therefore important to beprepared to maintain the patency of the glot­
tis by early placement of an endotracheal
tube in crocodilians.

­Intravenous Access
Intravenous administration of anaesthetic
agents is the preferred choice. A soundknowledge of vascular anatomy is critical toeffective venepuncture because it is fre­quently a blind technique (see Chapter 13).
Added to this, many patients are very small
and their veins can be extremely fragile anddifficult to access. Aseptic preparation of thesite is recommended to minimize the risk ofinfection or other complications.
Venepuncture in Snakes
Two commonly accessed sites in snakes are
the ventral tail or coccygeal vein and the heart.
The tail vein is accessed caudal to the cloaca,
taking care to avoid hemipenal or hemiclitoral
pockets. The needle is inserted 25–50% of theway down the tail on the midline. The needle
is inserted between the scales, at an angle of
45–60%, and is advanced craniodorsally until
it is inserted between the vertebrae.
Cardiac puncture requires excellent restraint,
preferably with sedation or anaesthesia, tominimize the risk of significant cardiac trauma.
The heart is located approximately 25–33% of
the distance from snout to vent and is stabi­
lized with one hand for ease of entry. The
needle is introduced at 45% in a craniodorsal
direction into the apex of the beating ventri­
cle. Digital pressure for up to one minutefollowing venepuncture is advised. It is report­
edly safe for snakes from hatchlings to 150 kg
and lymphatic contamination is less likely
than with venepuncture.
Venepuncture in Lizards
The caudal tail vein is the venepuncture siteof choice in most lizard species (Figure 27.1)
and can be approached in a similar manner tosnakes. An alternative approach is from thelateral aspect, inserting the needle at 45–90%
in a craniomedial direction, just ventral tothe coccygeal vertebrae. Lymphatic contam­
ination is more likely with this approach.
Other sites, such as the ventral abdominal,

Analgesia and Anaesthesia

Figure 27.1 The ventral coccygeal
vein is an ideal route of administration
for injectable induction agents forsquamates such as this eastern blue‐
tongued lizard (Tiliqua scincoides).

Figure 27.2 The jugular vein is reliably
accessed immediately dorsal to theline of colour change on the neck inAustralian long‐necked turtles(Chelodina spp.).

jugular vein and heart, are potentially useful
but more difficult for the inexperienced clini­cian to access.
Venepuncture in Turtles
A variety of veins are accessible in mostchelonian species. The most common site is
the dorsal tail vein, accessed along the­dorsal midline as cranially as possible. The
technique is similar to that used in otherreptiles. In long‐necked turtle species, thejugular is accessible even in the conscious
animal (Figure 27.2). The dorsal occipitalsinus is relatively easily accessed in turtles
but lymphoid contamination may occur.

In freshwater turtles, the sinus is accessed withthe head flexed and the needle inserted justlateral to the dorsal midline. In marine turtles
a more lateral approach is recommended.
Venepuncture in Crocodiles
In small crocodilians, the ventral and­lateral tail veins can be accessed, as for­lizards and chelonians. The dorsal occipi­
tal sinus is the venepuncture site of choicein larger crocodilians (Figure 27.3). Whilea midline approach is most commonly
used, a paravertebral approach is also pos­sible. Lymphatic contamination is possibleat all sites.

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It is very important to note that an absenceof clinical signs attributable to pain is notevidence of an absence of pain. Clinicians
can reasonably assume that interventions
likely to cause pain will do so in reptiles andcan be treated accordingly.

Figure 27.3 The dorsal occipital sinus is thevenepuncture site of choice in larger crocodilians.

­Analgesia
Reptiles possess an endogenous opioid­system. They are observed to display avoid­ance behaviour in response to noxious
stimuli that is obtunded by administrationof opioids. It is highly likely that pain
­p erception in reptiles is analogous to thatof mammals. There is, however, scant­published evidence on pain and pain man­agement in reptiles and many current prac­
tices may be altered as more evidence isestablished.
To manage pain effectively, it is firstimportant to understand normal behav­
iour, to enable correct interpretation ofchanges associated with pain. Signs of pain
can include resting in an abnormal or
hunched position, restlessness, abnormal
gait, increased respiratory rate and effort,
aggression and anorexia.

The stress associated with pain responses
can affect immune function, haematologi­
cal and serum biochemical parameters andmetabolic processes. Acute pain (surgery,trauma, acute infections) should be dif­ferentiated from chronic pain (arthritis,
neoplasia). Acute pain is best managed
pre‐emptively, typically with potent anal­
gesics such as mu‐opioid agonists withdemonstrated effect in the target species.
There is currently very little evidence, fromthe few species studied so far, to support
the use of the mixed agonist and antagonist
opioids butorphanol or buprenorphine as
analgesics in reptiles.
Most recent studies have indicated thatmuch higher doses of mu‐receptor opiateagonists are required to provide effective
analgesia for acute pain (see Appendix 1).
High doses can also lead to respiratory
depression which can be critical in debili­tated patients so caution should be exer­
cised. Morphine is an effective analgesic
in crocodilians, lizards and turtles, but insnakes the evidence is currently equivo­
cal. Some initial research suggests fenta­
nyl patches may be a useful analgesic
modality in snakes. Methadone is metabo­
lized to the same active opiate molecule asmorphine, and anecdotal reports support
extrapolation of its use for analgesia inlizards and turtles. Tramadol has recently
been discussed as a suitable analgesic for
reptiles. It is a weak mu‐agonist with theadvantage of minimal respiratory depres­sion, at least in chelonians. There is some
controversy about how effective tramadol
is as an analgesic, and more study isrequired to confirm its role in analgesia
for reptiles.

Analgesia and Anaesthesia

Any discussion of the use of opiates as
analgesic agents in reptiles must conclude
with the caveat that there is very little
published evidence to guide our clinicaldecisions, and as that becomes available,some of the recommendations madeherein may be reviewed.
Local anaesthesia is indicated for minor
surgical procedures, such as skin laceration
repair or abscess removal or as an adjunct togeneral anaesthesia for larger procedures.
Lignocaine has a fast onset of action for
topical or short‐term analgesia, whereas
bupivacaine has a longer duration of action
for postoperative pain management.
Nonsteroidal Anti‐Inflammatory
Analgesia for Chronic PainManagement
There is limited information regarding
the effectiveness of analgesia for chronic
pain management in reptiles. Nonsteroidal
anti‐inflammatory drugs (NSAIDs) suchas meloxicam appear to provide somedegree of prolonged analgesia in all spe­
cies of reptiles. Ketoprofen and carprofen(see Appendix 1) have also been used withsome success. NSAIDs should be usedwith caution in animals suffering fromdehydration, renal insufficiency or gastro­
intestinal disease.
Given the lack of published data for
analgesic dose rates in reptiles, difficulty inassessing pain, and the likely high incidence
of debilitation in painful patients, multi­
modal analgesia (where pain is treated withdifferent modalities working at different
levels of the sensory pathways) is likely tobe the most successful strategy available toclinicians. Opioids given in conjunction with
NSAIDs may be effective. Consideration
should also be given to nonpharmacologicalinterventions, such as splinting trauma­
tized limbs or even the provision of suitablehides or refuges within enclosures to limit
movement, which can considerably alter
the development of pain.

­ atient Assessment andP
Preparation for Anaesthesia
A detailed history, comprising medical
aspects, as well as general husbandry andnutrition, is critical, since many healthissues that impact on anaesthesia are theconsequence of inappropriate husbandry or
nutrition. A thorough physical examination,
including a current body weight, is essential
prior to anaesthesia. Physical examination
should focus on the cardiopulmonary sys­tem (most effectively using a Doppler torecord heart rate) and any signs of pathol­ogy. In particular, assessment of the rate anddepth of ventilation can be crucial to antici­
pating and then identifying and correcting
respiratory problems during anaesthesia.
Pathological conditions such as a coelomic
mass or ovarian follicular stasis can com­
promise ventilation and can therefore com­plicate anaesthesia. Since clinical signs ofdisease may not be readily apparent, a pre‐anaesthesia complete blood count andplasma biochemistry profile is recom­
mended. At a minimum, a blood sample
should be collected to provide haematocrit,
blood glucose and total protein. Assessmentof hydration status and correction of any
fluid imbalances is critical to managementof a safe anaesthetic procedure.
Reptiles, as a rule, benefit from fasting
before anaesthesia where possible. For mostlizards and turtles, 24 hours is usually ade­quate. Snake anaesthesia should ideally bedelayed for at least two to three days after thelast meal, as the potential for regurgitation
during or immediately after anaesthesia ishigh. Additionally, a large food mass in atubular patient may interfere with normal
cardiovascular or respiratory function.
Since they are ectotherms, it is essentialthat reptiles be maintained within their pre­ferred body temperature range during anaes­
thesia where possible. This is important not
only for proper immune and cardiovascularfunction but also provides a more predicta­
ble and repeatable response to anaesthetic

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Reptile Medicine and Surgery in Clinical Practiceagents. Monitoring of body temperatureusing an oesophageal or cloacal probe isstrongly advised to prevent excessively highor low body temperatures.

­Premedication
Premedication should serve the following
purposes in an anaesthesia protocol:
to render a candidate for anaesthesia more
tractable for safer and easier handling●● to lower the anaesthetic induction andmaintenance agent doses●● to provide additional or complementary
analgesia.

now. They provide profound muscle relaxa­
tion but no analgesia or sensory deprivation.
Their major advantage is the lack of sudden
or unexpected recovery. Neuromuscular
blocking agents can be antagonized with
neostigmine methylsulfate.
Anticholinergics are not routinely usedduring reptile anaesthesia, except for proce­dures involving the oral or pharyngeal region
where excessive salivation should be avoided.

●●

Premedication protocol varies depending on
the species and procedure being undertaken.
Pre‐anaesthesia analgesia is appropriate
where painful or invasive procedures areplanned. Opioids are the analgesics of choice(see previous section). These medications
are often given in conjunction with a muscle
relaxant, particularly in larger or more dan­gerous species. Extreme care must be taken
when using local anaesthesia as part of theanaesthetic regimen, since overdosing can
be fatal.
Hypothermia induces immobilization bylowering the metabolic rate. It does notprovide muscle relaxation or analgesia andis not considered acceptable as a means ofimmobilization.

Benzodiazepines are useful premedicantsfor reptiles (see Appendix 1 for doses).
Midazolam is advocated for all reptile species.
It is useful in combination with dissociativeand neuromuscular blocking agents. Anta­
gonism of benzodiazepines with flumazenil
is possible but usually unnecessary.
Neuromuscular blocking agents havehistorically been used for immobilization oflarge crocodilians, although they are inhumane
when given alone and are largely outdated­Induction of Anaesthesia
The choice of an induction agent depends
on the reptile species and the procedure
being undertaken. Under hospital condi­
tions, inhalational anaesthetics and advanced
monitoring are usually available. Field immo­
bilization requires a safe protocol using
short‐term or reversible, and usually inject­
able, immobilization agents. It is importantto allometrically scale drug dosage rates forlarger reptiles.
Commonly used medications and dose
rates (listed in Appendix 1) vary, dependingon the various species, and much of theinformation is anecdotal. Many agents resultin prolonged recovery if used alone or at highdoses. Barbiturates result in a long andunpredictable induction time and recovery
period, and their use in reptiles is generally
not recommended. Ketamine hydrochloride
is a short‐acting dissociative agent with
analgesic properties used for immobilizationin all reptilian orders. Ketamine given intra­
muscularly alone results in very effective
chemical restraint, producing minimal res­piratory depression and, except at high doses,
minimal cardiac stimulation. However, it
results in inadequate muscle relaxation char­acterized by the presence of uncoordinatedvoluntary muscle movement in response toexternal stimuli. This is not considered to bea surgical plane of anaesthesia. Bradycardia,
respiratory arrest and even death have beenreported at high doses. There is no antago­
nist agent and recovery can be very slow. It is
common and highly preferable to use ketamine

Analgesia and Anaesthesia

in combination with alpha‐2 adrenergic
agonists or benzodiazepines.
Zolazepam‐tiletamine is a long acting
benzodiazepine dissociative combined agent.
Lower doses produce sedation without immo­
bilization but higher doses (up to 100 mg/kg)
provide prolonged surgical anaesthesia of up
to 16 hours. Recovery from anaesthesia is up
to 24 hours and deaths have been reported ina number of species.
Alpha‐2 adrenergic agonists are sedatives
and analgesics and have widespread effects
on vertebrate physiology. The net clinicalresult of these effects varies with species,
route of administration and time elapsed
since administration. A major advantage ofthese agents is their ability to be antago­
nized. However, this also antagonizes theiranalgesic effects, so alternative analgesics
may be required.
Medetomidine can be given intramuscu­
larly in combination with local anaesthesia
to perform minor surgery. It provides very
effective sedation for mature reptiles,
regardless of environmental temperature,and is readily antagonized by atipamezole.
Dose rates vary depending on body size.
Atipamezole is administered at an equalvolume of medetomidine 1 mg/ml for rep­tiles less than 10–15 kg. For larger reptiles,
the dose rate (5000 μg/m2) is based on bodysurface area. Bradycardia and bradypnoea
occurs following medetomidine administra­tion but resolve within 15 minutes of admin­
istration of atipamezole. If not antagonized,
immobilization is variable and can be pro­longed. It is an extremely effective sedative
for crocodilians.
Propofol is a commonly used induction
agent in reptiles and can also be used as acontinuous infusion for longer anaesthetic
procedures (refer to Appendix 1). Its disad­vantage is that it must be administeredintravenously. Apnoea has been observed insome reptile species.
Alfaxalone is an injectable neuroactive
steroid anaesthetic with a wide safety margin.
It can be used intravenously, intramuscularly
or intracoelomically. Its onset and durationof action are more variable by the intramus­
cular or intracoelomic route and higher dose
rates are required. Alfaxalone is rapidly
cleared and its metabolism is independent oforgan function. Its safety and availability
have led to frequent use among clinicians
dealing with squamates and chelonians (refer
to Appendix 1). It produces rapid induction
but transient apnoea is common so prompt
intubation is recommended. There may
also be muscle fasciculations or tremors on
induction but, generally, appropriate premedi­
cation controls these responses. Although it
has reportedly produced surgical anaesthesia
in crocodiles, severe muscle twitching andhyperexcitation experienced during recovery
can be dangerous for inexperienced clini­
cians and staff.

­Maintenance of Anaesthesia
Isoflurane is currently the inhalational anaes­
thetic of choice for reptiles. Inhalant anaes­
thetics undergo minimal metabolism before
elimination by the lungs. Any underlying
kidney or liver dysfunction therefore does
not affect the clearance of inhalant anaes­
thetics. However, because of right‐to‐left
cardiac shunting in reptiles, reduced lungperfusion can occur. Thus concentrations of
inhalant anaesthetic gases in the lungs do notnecessarily reflect concentrations in the
blood and brain. Sudden changes in shunting
direction of blood can lead to sudden changes
in serum concentration of inhalant anaes­
thetic, which can prolong induction times,
induce sudden changes in anaesthetic depth
and increase or markedly decrease recovery
times. Endotracheal intubation and assisted
respiration are therefore recommended forinhalant anaesthesia in reptiles.
Most reptiles can sustain long periods ofapnoea and are not suited to a mask induction.
Anaesthesia is best induced using an injectableagent to allow for safe intubation, particularly
in elapids (Figure 27.4). Once induced, theanimal can be intubated (Figures 27.5a,b). In
crocodilians, the top jaw is opened and a solid

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Figure 27.4 Use of a mouth gag
facilitates visualization of the glottis ina tiger snake (Notechis scutatus).
Elapids should be handled byexperienced operators.

(a)Figure 27.5 (a) The large, rostral glottis
provides easy airways access insquamates such as this Shingleback
lizard (Tiliqua rugosa). (b) Endotracheal
tube in situ in an eastern water dragon(Intellagama lesueurii).

(b)mouth gag is inserted between the jaws andtaped in place. Before passing the tube, thepalatal flap must be displaced rostroventrally
to allow visualization of the glottis (Figure 27.6).

Unlike most reptiles, the trachea of croc­
odilians and chelonians is composed ofcomplete cartilaginous rings, so intubation
with an uncuffed tube is recommended.

Analgesia and Anaesthesia

Figure 27.6 The passive valve actionof the palatal and, visible here, glottal
folds means early airway access andcontrol is important in crocodilians.

Inhalational anaesthesia is maintained using
positive pressure ventilation. A non‐rebreathing system is indicated for animals
under 5 kg and a circle system for animals
over 5 kg. Since oxygen consumption in rep­tiles is less than that of mammals an oxygen
flow of 1–2 litres/minute for larger animals is
usually adequate.

­Anaesthetic Support
Mechanical/Assisted Ventilation
Reptiles, which lack a diaphragm, are depen­
dent on skeletal muscle activity for venti­
lation to permit adequate gas exchange andoxygenation. Recumbency may cause viscera
to place pressure on the simple lungs. As aconsequence, reptiles are best artificiallyventilated in all but the shortest of anaes­
thetic procedures. IPPV must be performed
very gently owing to the fragile nature of thepulmonary tissue. Careful observation of theextent of ventilatory excursions of the tho­racic wall in the conscious reptile before
induction is valuable in indicating theamount of pressure required during IPPV.
IPPV can be performed manually at 4–12
breaths/minute to effect induction and thenmost reptiles can be maintained at 2–6 breaths/
minute. IPPV is generally reduced to once aminute during recovery until spontaneous

ventilation resumes. Room air is preferably
used during recovery. A number of mechani­
cal ventilators suitable for reptile anaesthesia,
such as the Vetronics Small Animal Ventilator
VT‐9093 (BASi Vetronics) are available. These
are typically set with pressures of 6–10 cm ofwater, adjusted to cause identical chest excur­
sions to those noted in the conscious patient.
Monitoring of reptiles being maintained
under anaesthesia by IPPV is critical as an
overdose of anaesthetic is possible due to theforced delivery of gas to the patient.
Thermal Support
Appropriate thermal support is important
for reptile patients undergoing anaesthesia
to maintain body temperature within thepreferred optimal temperature zone. Hypo­
thermia significantly affects some drug per­formances. Body temperature is measured
with a cloacal thermometer or thermistor(Figure 27.7). Ensuring that the reptile patientis at the preferred optimal temperature
before induction makes it much easier tomaintain the body temperature rather thantrying to raise it once the animal is hypother­mic. Electrical heating mats and hot waterbottles or ‘wheat bags’ have largely given way
to forced‐air warming devices, conductive
fabric (resistive polymer), electric warming(HotDogR Patient Warming SystemR) andradiant heat lamps as safer and more effective

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Reptile Medicine and Surgery in Clinical Practice

Figure 27.7 A small estuarine
crocodile (Crocodylus porosus) withelectrocardiogram leads attached tothe thorax and thermal probe inserted
cloacally.

Figure 27.8 An anaesthetized lacemonitor (Varanus varius) being
monitored by electrocardiogram,oesophageal thermal probe, pulse
oximetry and capnography, and being
thermally supported by a forced air
warmer as well as being mechanicallyventilated.

methods of protecting anaesthetized patientsfrom hypothermia (Figure 27.5).
Fluid Support
Hydration status is difficult to assess in most
reptile patients. Where indicated by history or
clinical presentation, appropriate fluid ther­
apy with normal saline or Ringer’s solution
should be administered by the subcutaneous,
intracoelomic, intravenous or intraosseousroute, depending on the size and species of thereptile patient and the ease of venous access.
In most cases, fluids are administered subcu­
taneously or intracoelomically. Intravenous or
intraosseous fluids are usually given at a rateof 2 ml/kg/hour.

­Monitoring of Anaesthesia
Monitoring Parameters
Physiological monitoring equipment includes
stethoscope (may be of limited value), pulse
oximeter, Doppler blood flow transducer,
electrocardiography, ultrasound and blood
gas analysis (Figure 27.8). It is of the utmost
importance to develop good observational
skills for assessing depth of immobilizationand to correctly interpret changes in physi­
ological parameters. A monitoring protocol
should be developed for each species com­monly encountered and should be suffi­
ciently flexible depending on the individual
situation (Figure 27.9).

Analgesia and Anaesthesia

Figure 27.9 A wooden tongue
depressor can be used to stabilize
endotracheal tubes and Doppler
ultrasound probe against the patient
during anaesthesia, as in this eastern
bearded dragon (Pogona barbata).

Anaesthetic depth is evaluated using signs
including the limb withdrawal reflex, cardiac
rate, righting response and bite and corneal
reflexes. Other useful signs include tail ‘flick’or withdrawal reflex, respiratory rate and depth
and palpebral reflex. Mucous membrane col­our is not particularly helpful but a degree of
cyanosis is frequently observed due to changes
in peripheral blood flow. Intermittent positive
pressure ventilation is advised to reduce shunt­
ing mechanisms from being triggered and tomaintain aerobic respiration.
Blood Gases
Blood gas measurements in reptiles are diffi­
cult to interpret because variables such astemperature, feeding and sample site (arte­rial, venous or a combination of both) influ­
ence the results. Blood gas measurements inreptiles are difficult to interpret because var­iables such as temperature, feeding and sam­ple site (arterial, venous or a combination ofboth) influence the results.
Capnography
Capnography is the measurement of end‐tidal
carbon dioxide in expired air and provides
useful information on quality of ventilationand pulmonary perfusion. While it has notbeen validated for reptiles, and there areconcerns about how the intracardiac shunt­ing (especially of aquatic reptiles) will affectcapnography, there is a growing bank of data
to suggest that it will indeed become a usefuladditional monitoring modality for anaes­
thetized reptiles.
Pulse Oximetry
There is conflicting information as to theusefulness of pulse oximetry as a monitoring
technique in reptiles. Reptile haemoglobin
differs from mammalian haemoglobin. Pulse
oximeters are calibrated to measure relativearterial saturation in humans so absolutevalues will not relate to the values in thereptile. However, pulse oximetry can be used
on a comparative basis. In most reptiles, anoesophageal probe level with the carotid
artery or a rectal probe can be used, althoughprobes may not be validated for reptiles andfor these locations.
Doppler
Doppler blood flow detection is a very reliable
method of obtaining heart rate and rhythm.
The probe is placed over the heart or a large
blood vessel, such as the ventral coccygeal,
brachial or femoral artery. Blood flow in the

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Reptile Medicine and Surgery in Clinical Practice

optic arteries may be detected by placing theprobe against the globe with the eyelid or
third eyelid closed. Alternatively, a dorsally
directed probe placed in the cloaca may
detect arterial blood flow.
Electrocardiogram
The electrocardiogram (ECG) and reference
values have been described for the American
alligator (Alligator mississippiensis). The three
ECG leads are attached by 2.5‐cm needles
passed through the skin, alligator clamps oradhesive ECG pads on the skin of the ventral
body (Figures 27.7 and 27.8). Depressed reptil­
ian heart rates under anaesthesia may trigger
bradycardia alarms in machines manufactured
for use in mammals.

­Recovery and Post‐Operative
Management
Any animal which has been anesthetized
requires monitoring during recovery. It isimperative that regular voluntary respira­tion, in conjunction with movement of thelimbs, is established since re‐sedation may
occur if the animal is not continually stimu­
lated and apnoea can occur. Apnoea increases
intrapulmonary pressure, diverting oxygen­
ated blood away from the brain and heart,and reduces metabolic rate. Intermittent
ventilation with room air simulates voluntary
respiration and allows oxygenated blood tobe directed to the brain and heart, increasing
metabolic rate and assisting in recovery. The
gular fold relaxes in crocodilians underimmobilization. Post‐anaesthetic monitor­
ing of crocodilians is required until normal
gular fold function occurs. Temperatures
outside preferred optimal temperatures will
potentially affect the rate of clearance of any
drugs from the system. Under field condi­
tions, it is extremely important to know how
an adverse environmental temperature will
impact on the anaesthesia and recovery.
Semi‐aquatic and aquatic reptiles which haveundergone immobilization should be denied
access to water until they can protect theirairway, surface to breathe and protect them­selves from danger.

­Further Reading
Bradley, T. (2001) Pain management
considerations and pain‐associatedbehaviors in reptiles and amphibians, inProceedings of the Association of Reptilianand Amphibian Veterinarians and American
Association of Zoo Veterinarians, Orlando,
FL. pp. 45–49.
Carpenter, J.W., Klaphake, E. and Gibbons,
P.M. (2014) Appendix 3: Reptile
formulary and laboratory normal, in
Current Therapy in Reptile Medicine andSurgery (D.R. Mader and S.J. Divers, eds).
Elsevier Saunders, St Louis, MO,
pp. 382–410.
Heard, D.J. (2007) Monitoring, in Zoo
Animal and Wildlife Immobilization andAnesthesia (G. West, D. Heard and

N. Caulkett, eds). Blackwell Publishing,Ames, IA, pp. 83–91.
Hernandez‐Divers, S.M., Schumacher, J.,
Stahl, S. et al. (2004) Reptile clinicalanesthesia: advances in research. Exotic
DVM, 6, 64–69.
Mosley, C.A. (2005) Anesthesia and analgesia
in reptiles. Seminars in Avian and Exotic Pet
Medicine, 14, 243–262.
Olsson, A.R. and Phalen, D.N. (2012)
Preliminary studies of chemical
immobilization of captive juvenile estuarine(Crocodylus porosus) and Australian
freshwater (C. johnstoni) crocodiles withmedetomidine and reversal withatipamezole. Veterinary Anaesthesia andAnalgesia, 39, 345–356.

Analgesia and Anaesthesia

Ramsey, I. (2008) Small Animal Formulary,
BSAVA Press, Gloucester.
Schumacher, J. and Yelen, T. (2006)
Anesthesia and Analgesia, in
Reptile Medicine and Surgery (D.R.
Mader, ed.). Elsevier, St Louis, MO,
pp. 442–452.

Sladky, K.K. (2014) Analgesia, in Current
Therapy in Reptile Medicine and Surgery(D.R. Mader and S.J. Divers, eds). Elsevier,
St Louis, MO, pp. 217–228.
Sladky, K.K. and Mans, C. (2012) Clinicalanesthesia in reptiles. Journal of Exotic Pet
Medicine, 21, 17–31.

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28
SurgeryZdeněk Knotek and Stacey Leonatti Wilkinson­Introduction
In reptiles, standard surgical methods apply,
although the unique anatomy of reptiles andthe huge variety in patient size are importantfactors to consider.

­Patient Assessment
and Preparation for Surgery
Preoperative physical examination is vital.
Pre‐anaesthesia blood work, such as a complete blood count and chemistry panel, areideal. Diagnostic radiography, ultrasound,computed tomography (CT) and magnetic
resonance imaging (MRI) are useful in bothpresurgical patient assessment and surgicalplanning. Reptile patients generally do not
require fasting for surgery, as they are notprone to regurgitation under anaesthesia,
nonetheless, fasting (lizards 1–2 days, snakes
2–3 days, tortoises 3–5 days) is recommended for elective surgery on the gastrointestinal tract.

­Pre‐ and Perioperative Care
Many surgical procedures are not true
emergencies and the patient may need to behospitalized for supportive care measuresprior to surgery. Thermal support is provided

to the reptile patient before, during and after
surgery. Before surgery, the patient is given
analgesia (e.g. a combination of opioids
and nonsteroidal anti‐inflammatory drugs,
NSAIDs) and fluids (see Chapter 27 andAppendix 1). After 30–45 minutes, anaesthetic drugs are given and the patient isprepared for intubation. After successful
intubation, the patient is placed under inhalation anaesthesia using isoflurane or sevoflurane and oxygen.

­Positioning
Most lizards and crocodilians are positioned
similarly to mammals (e.g. ventral, lateral or
dorsal recumbency). Chameleons are best
positioned in lateral recumbency. For surgery involving the coelomic cavity, snakes are
best positioned in right lateral recumbency(left lateral approach) to avoid the incision of
the right air sac. Turtles and tortoises, whenplaced in dorsal recumbency, can be placedin the middle of a towel rolled into a ring.

­Patient Preparation
Plastic adhesive drapes are recommended toaid visibility of the surgical field. Alternatively,
spray adhesives may be used on standard

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

384

Reptile Medicine and Surgery in Clinical Practicedrapes. Standard patient surgical preparationis undertaken. When shell repair is necessary
for chelonian patients, the surface of the shell
must be prepared by cleansing and degreasing the surface, to enable restorative material
to adhere to the shell.

­Instruments
Small reptile patients necessitate the use offine ophthalmological surgical instruments(e.g. micro haemostats, iris scissors), whilelarge chelonians or crocodilians may require
special equipment; for example for orthopaedic surgery. Haemostatic clips are useful
where application of ligatures is difficult.
Absorbable gelatin sponges should be used
for controlling haemorrhage in reptiles(Figure 28.1). Eyelid retractors work well as
wound retractors. Lone Star Veterinary
Retractor Rings (type 4407G or 4405G, withretractor hooks, Cooper Surgical) are ideal
for middle‐sized and large reptile patients.

­Sutures, Radiosurgery
and Surgical Laser
Most reptiles do not traumatize surgicalincisions. This makes closure with a continuous pattern safe and efficient (Mader et al.
2006). In the reptile, synthetic absorbablesuture materials are absorbed very slowly.
Recommended suture materials for thereptile patient are monofilament thread­(e.g. Caprolon®, a copolymer of lactic acidand caprolactone), nylon or polypropylene(Mader et al. 2006). Wound healing is slow
in reptiles and suture removal is generally
scheduled four to six weeks after surgery.
Skin closure is best accomplished with an
everting suture pattern such as horizontal
or vertical mattress. Radiosurgery is usefulin reptile patients for skin incision, bodywall incision, organ biopsies and a variety ofother procedures. Bipolar forceps allow
fine coagulation of vessels. Surgical lasers
are used for precise cutting through reptile
skin to minimize blood loss (Hodshon et al.
2013).

­Soft‐Tissue Surgery
Skin Wounds and Burns
Many wounds will heal by second intention
with appropriate topical wound care andantibiotic use. However, some are large
enough that repair is needed. Large wounds
will eventually granulate and heal but may
take months of care for full healing. Wounds
on the chelonian shell can take up to one year
or more to fully heal (Mader et al. 2006,
Alworth et al. 2011).
Figure 28.1 Absorbable gelatin
sponges are useful for controllinghaemorrhage in reptiles.

Surgery

Subcutaneous Abscess Removal

Subspectacular Abscess

There are different options for surgical management of abscesses in reptiles (Figure 28.2).
One option is to lance the abscess, remove thecaseous material inside and leave the woundopen to heal by second intention (Mader et al.
2006, Alworth et al. 2011, Huchzermeyer andCooper 2000). The cavity is then flushed
daily with dilute chlorhexidine or povidone
iodine and antibacterial creams or ointments
are used to pack the capsule. Poloxamer gel
infused with antibiotics may also be used.
Another option is to remove both the innercaseous material and the entire fibrous capsule
as well (Mader et al. 2006, Alworth et al. 2011).
The resulting wound can be left open (to healby second intention and should be cleaned
daily and topical antibacterial creams applied
if needed) or sutured closed.

Subspectacular abscess typically develops
from bacteria that ascend the nasolacrimal
duct from the mouth and colonize the subspectacular space but it can also arise froma penetrating wound to the eye or haematogenous spread (Alworth et al. 2011). An
incision is made in the ventral half of thespectacle and a 30–90‐degree wedge of thespectacle is removed (Alworth et al. 2011,
Lawton 2006). A sterile swab in inserted toremove material for cytology and culture,then a small catheter (such as an intravenous catheter) is inserted and the area
flushed with saline. Antibiotics can be
flushed inside the spectacle and systemic
antibiotics are often indicated, ideally chosen based on culture and sensitivity results(Lawton 2006). Within 24 hours, a hyaline
proteinaceous plug and inflammatory
debris fills the defect, sealing the subspectacular space and providing a barrier whilehealing progresses. This plug may need tobe gently disrupted daily to apply topicalantibiotics to the subspectacular space. By
21 days, healing has typically progressedsuch that the snake will have a multilayered regenerating spectacle and will havere‐established subspectacular space. Bythree months, the spectacle is usually fully
healed.

Aural Abscesses
Aural abscesses are common in chelonians,
specifically aquatic turtles and box turtles.
The swelling over the ear is lanced and thecaseous material removed. The skin over theventral half of the ear is removed to keep
the cavity open and allow it to heal (Murray2006). The cavity is flushed with saline,
appropriate antibiotic therapy is prescribedand any husbandry deficiencies corrected.

Figure 28.2 Surgical curettage of amandibular abscess in a green iguana(Iguana iguana).

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Reptile Medicine and Surgery in Clinical Practice

Nasolacrimal Duct Obstruction
and Pseudobuphthalmos
Blockage of the nasolacrimal duct is mostcommonly encountered in snakes and geckoes (Alworth et al. 2011, Lawton 2006).
As with an abscess, a wedge in the ventral
aspect of the spectacle can be removed toallow the fluid to drain. Fluid should be­collected from the subspectacular space andcytology performed to rule out other causesof fluid accumulation, as flagellates havebeen reported (Lawton 2006). If the problem
recurs, a conjunctivoralostomy can be performed by inserting an 18‐guage needle atthe medial aspect of the inferior fornix ofthe subspectacular space and emerging on
the roof of the mouth between the palatine
and maxillary teeth. A fine silicon tube isthreaded through the needle, the needle
removed and the tube sutured in place on
the periorbital scales and left in place for atleast six weeks (Alworth et al. 2011, Lawton
2006, Millichamp et al. 1986).
Enucleation
In species with eyelids, the globe and all ocular tissue are removed and the eyelid margins
are removed and sutured together (Alworth
et al. 2011). In snakes or lizards with a spectacle, a circular incision is made around theentire circumference of the spectacle and all
ocular tissue is removed. Vessels can be ligatedwith small suture, vascular clips or radiosurgery, or a gelatin sponge or direct pressure
can be applied for haemostasis. The wound isleft open to heal by second intention (Alworth
et al. 2011, Lawton 2006).
Eyelid Surgery
There are many species in which one eyelid ismore moveable than the others (the lower lid
in lizards and chelonians and the upper lid incrocodilians). This needs to be accounted forwhen performing surgery and considering
the function of the eyelids postoperatively(Lawton 2006). Snakes do not have eyelids.

Tracheal Resection and Anastomosis
Chondromas arising from the tracheal cartilage have been reported in snakes and cangrow large enough to obstruct the airway andcause significant dyspnoea. Resection andanastomosis of the trachea is the treatmentof choice. The anaesthetized patient is intubated with a long polypropylene or rubber
catheter to the level of the mass. Stay suturesusing a fine monofilament suture are placed
and the affected area of the trachea removed.
The catheter is advanced into the distal partof the trachea, both to help to realign the trachea for closure and to maintain anaesthesia.
The absorbable sutures should encompass atleast one or two tracheal rings on each side of
the incision. All sutures are preplaced andthen tightened. Care should be taken not todamage the dorsal tracheal membrane during the procedure. The trachea is tested forleaks by dribbling saline on the incision andwatching for bubbles (Mader et al. 2006).

­Surgery of the Tongue
In chameleons, small wounds of the tongue
can be managed by putting the tongue backin its sheath and suturing. Serious or prolonged tongue injuries may involve completeor partial amputation of the tongue. The
veins and tongue are carefully ligated rostrally, just before the attachment to hyoid
apparatus, and the damaged part is snipped
off. The cartilaginous apex of the hyoid boneshould be adequately shortened to reduce
the risk of perforation of the tongue stump.
The patient may require hand feeding longterm, although snakes have managed to eat
normally after tongue amputation (Brendan
Carmel, personal communication).

­Oesophagostomy Tube Placement
Placement of an oesophagostomy tube ismost commonly indicated in chelonians
and can be placed in a similar manner inSurgerylizards. A tube should be premeasured andmarked so that it can be inserted the distance from the cranial rim of the plastron to
the junction of the pectoral and abdominal
scutes. A curved pair of hemostats isinserted into the oral cavity. The hemostats
are pushed laterally in order to ‘tent’ theskin on either side of the neck and allow thevessels on the neck to ‘roll’ out of the way so
as not to be damaged. An incision is madeon the lateral aspect of the neck where it
meets the shoulder, just large enough topass the tips of the hemostats out of theincision. The distal end of the feeding tube
is grasped and pulled through the incisionand back out of the mouth; it is then redirected and passed down the oesophagus
into the distal oesophagus or proximal
stomach. The tube is secured in place at theskin with a purse‐string suture and, ideally,a Chinese finger‐trap suture is placed aroundthe tube with nonabsorbable material.
Finally, the tube is taped or sutured in place
along the animal’s dorsum. Radiographs or
endoscopy can be used to confirm proper
placement. When removal is necessary, thesutures and tube can be removed and thesurgical site left to heal by second intention(Alworth et al. 2011).

Figure 28.3 Coeliotomy in a green
iguana (Iguana iguana).

­Coeliotomy
Coeliotomy has a wide range of applications(Mader et al. 2006, Alworth et al. 2011;
Figure 28.3). Indications include reproductive disorders, gastrointestinal disease, urinary system dysfunction and exploration for
obtaining organ biopsies. In all species, anonabsorbable suture material is used forclosing the skin in a continuous everting
pattern. Sealing the incision site with tissue
glue may help prevent postoperative infection. Plastron or carapace fixation should
remain for approximately six months before
removal. For at least 10–14 days postoperatively, the patient should remain in a warmand dry environment. Antibiotics and fluid
therapy may be required. If the patient isanorectic, forced feeding may be required.
Coeliotomy in Lizards
Most lizards are positioned in dorsal recumbency, except chameleons, which are placedin the lateral recumbency, with the head andhind legs fixed to the drape. The skin is
incised along the curvature of the ribs (chameleons) or in paramedial line of the abdominal
wall (other lizards). Lone Star Veterinary

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Reptile Medicine and Surgery in Clinical PracticeRetractor System may be used for improved
access to the surgical field and better visibility of organs. The skin is separated from themuscle layer. The muscle layer and pleuroperitoneum are incised along the curvature of
the ribs (in chameleons) or in the paramedial
line (other lizards). In chameleons, the surgeon must be careful not to damage small
veins located around the ribs. In chameleons,pause IPPV before entering the body cavity;
if this is not done, air sacs may sharply protrude into the surgical incision. In otherlizards, entering the body cavity is much easier. Take care to avoid the ventral abdominal
vein by performing a paramedial incision or
by starting caudally and incising the skin cranially on the midline. The muscle layer andpleuroperitoneum are closed (together insmall patients and as two separate layers inlarge lizards) with 3‐0 4‐0 guage absorbablesutures in a simple interrupted pattern.
Thereafter, 3‐0 or 4‐0 absorbable materialor 3‐0 non‐absorbable material is used forclosing the skin, as previously described.
Coeliotomy in Snakes
The snake is positioned in right lateralrecumbency and fixed to a sterile drape. The
incision is made between the first and second
row of lateral skin scales. The muscle layer
and the pleuroperitoneum are gently perforated. At the end of the surgical procedure,
the pleuroperitoneum and the muscle layer
are closed (together in small patients and as
two separate layers in large snakes) with asingle simple continuous pattern of absorbable material.
Coeliotomy in Chelonians
In chelonians, a plastronotomy is needed
to reach the organs in the coelom (Figure
28.4a,b,c), except in sea turtles, where theoesophagus and stomach can often beaccessed through an axillary incision.
Oscillating saws or small circular saws are
ideally suited for cutting through shell. The
blades must not be overused, as a dull blade

does not cut well and prevents proper healing. With careful handling, the same blade
can be used for two to three patients before
requiring disposal.

­Ovariectomy
Ovariectomy is a common surgical procedure in lizards and chelonians. Once thecoelom is entered, the fat body and the ipsilateral ovarium with follicles are exteriorized.
In chelonians, this can be done through a
pre‐femoral incision or plastronotomy. An
avascular area of ovarian interfollicular connective tissue is selected for placement of finger or grasping forceps, taking care to avoid
rupture of ovarian follicles. Gentle traction isapplied and the ovary is cautiously retracted
toward the coelom incision. The ovarian vasculature is ligated with suture or haemostatic
clips and the mesovarium is transected. Caremust be taken not to accidentally remove theadrenal gland. The ligation sites are examined to verify haemostasis and to confirm
complete excision of all ovarian tissue. The
second ovary is exteriorized and resected in
the same way as the first. The surgeon should
ensure that all follicles are removed. If verysmall follicles (smaller than a pinhead) areoverlooked, they can dramatically enlarge
within few weeks or months and the surgery
needs to be repeated. If the ovaries are being
removed for prophylactic reasons and theoviducts are healthy, the latter can be left inplace.

­Salpingectomy
Salpingectomy is usually indicated in cases of
postovulatory egg stasis in lizards and chelonians, removing the entire oviduct, eggs
included. The distal part of the oviduct andveins in the mesosalpinx are ligated withsutures (Figure 28.5) or haemostatic clips
and the mesosalpinx is transected close to
the cloaca and removed.

SurgeryFigure 28.4 (a) Tortoise positioned in
dorsal recumbency for plastronotomy.
(b) A square segment of plastron isgently elevated to provide excellent
exposure for a cystotomy. (c) A soundseal over the surgical wound isessential for good healing after aplastronotomy.

(a)

(b)

(c)

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Reptile Medicine and Surgery in Clinical Practice

Figure 28.5 Ligation of the ovarianvasculature in a chameleon.

­Salpingotomy
Salpingotomy is the same regardless of species. Surgical intervention is usually requiredfor causes of dystocia in snakes (Alworth
et al. 2011). The oviduct is gently elevatedout of the coelom and assessed. Two absorbable fixation sutures are made in the wallof the oviduct and the central part of theoviduct wall is incised. An incision is madeover the eggs. To decrease the distance
between the eggs, they are gently massaged
closer to the incision from the proximal anddistal parts of the oviduct. Eggs are gently
withdrawn from the lumen of the oviductand the mucosa washed with warm sterile
saline. The wall of the oviduct is sutured witha single simple continuous pattern of absorbable material and the pleuroperitoneal cavity
is then evaluated and examined for any local
complications (Mader et al. 2006, Alworth
et al. 2011).

­Orchidectomy in Lizards
The surgical technique is similar to that
described for ovariectomy. The gonads aretightly adhered to adjacent structures, so
excellent exposure is vital for successful
removal. The right testicle is attached to thevena cava by very short vessels while the left
adrenal gland sits between the testicle and its
blood supply. Avoid removing or damaging

this gland during surgery, although a patient
can survive if it is inadvertently removed.
The testes are gently elevated to expose thevasculature; a fine suture can be placed in thecapsule to aid this if needed. The vessels
ligated with haemostatic clips and the testicle
removed. It is vital that all areas are ligatedproperly before cutting, as marked haemorrhage can occur. It is also important to ensure
all testicular tissue is removed, as it canregrow if cells are left behind (Mader et al.
2006, Alworth et al. 2011).

­Gastrotomy
and Gastrectomy
In lizards and chelonians, the stomach isanchored tightly, making it difficult to fully
exteriorize; however, it is much more mobile
in snakes. In chelonians, a plastronotomy isneeded to reach the stomach, except in sea
turtles, where the oesophagus and stomach
can often be accessed through an axillary
incision. The stomach is isolated on saline‐
soaked laparotomy pads. Stay sutures areplaced and an incision made in an avasculararea. In the case of a mass removal or gastrectomy, the affected part of the stomachwall is removed. Closure is routine with adouble layer inverting pattern (Mader et al.
2006, Alworth et al. 2011). Removal of foreign bodies from the stomach is also possibleusing endoscopy.

Surgery­Enterotomy
Once the coelom is entered, the intestine isexteriorized. The colon (which is black insome lizards) can be used as a guide forrecognizing the organs of the body cavity.
The affected part of intestine is gently elevatedand placed on saline soaked laparotomy pads
to assess the extent of any pathologicalchanges. Two absorbable fixation sutures areplaced (Figure 28.6a) and the central part ofthe intestine wall is incised. Foreign body andfaeces are gently withdrawn (Figure 28.6b)from the lumen and the mucosa is flushedwith warm sterile saline. The wall of theintestine is closed with absorbable suturematerial in two layers. The first layer is a
Figure 28.6 (a) Stay sutures placed in
the intestine to assist surgical access.
(b) Faeces are gently massaged out of
the intestine through an enterotomy
wound.

(a)(b)

simple interrupted pattern and the second acontinuous inverting pattern. The coelomic
cavity is then carefully examined for any
abnormalities. The coelom is then cleaned byrepetitive irrigations with sterile saline solution and antibiotics.
Surgery of any of intestinal segment inlarger lizards and snakes is usually uncomplicated; however, in chelonians it can be difficult. Complications arise particularly inthe transverse colon and the functionalityof the intestine after enterotomy cannot be
always ensured. Enterotomy and colostomy(especially in the transverse colon) throughthe pre‐femoral fossa is rather difficult,although in some aquatic chelonians it may
be more accessible.

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Reptile Medicine and Surgery in Clinical Practice­ omplete or Partial LiverC
Lobectomy, Liver Biopsy
In snakes, the affected part of the liver is gently elevated out of the coelom cavity to assess
any pathological changes. Temporary vascular clamps are placed cranially and caudally
to the affected part of the organ. Ligatures
are then placed allowing complete excision of
the affected part of liver. Finally, the vascularclamps are released and occlusive ligatures
tightened and examined. The cut surfaces of
the remaining parts of the liver are rinsed
with a sterile 0.9% sodium chloride solution
to locate any bleeding.
In lizards and chelonians, an entire lobe
can be removed if needed; the lobe is isolated
and the blood vessels and bile duct double
ligated and removed. The use of haemostatic
clips can facilitate removal. Liver biopsy is
performed as in other species via surgery(a)(laparoscopy), minimal invasive surgery(endoscopy) or under ultrasound guidance.

­Cystotomy
In most lizards, the bladder is readily elevated out of the coelom (Figure 28.7a,b,c).
In chelonians, it can be accessed via a­p lastronotomy or though the pre‐femoral
fossa. The bladder wall is usually thickened if cystitis present. For small stone
removal, retrieve with a lens loop or small
forceps. Larger stones can be grasped andbroken in situ if needed and the pieces
removed. After the stone has been removed,
the exteriorized bladder should be copiously flushed with sterile saline. A standard
two‐Iayer closure is generally recommended,then the coelom cavity irrigated with warm,
sterile saline.
(b)

(c)

Figure 28.7 (a) Prior to cystotomy, urine is aspirated from the bladder. (b) The urolith is visible through thebladder wall. (c) Urolith surgically removed from the bladder of a tortoise.

Surgery­Nephrectomy and Renal
BiopsyNephrectomy is mostly straightforward insnakes and is usually indicated in cases ofneoplasia. The kidney or mass is bluntly
dissected out and the vessels supplying it
and the ureter ligated and the kidney
removed. In males, the seminiferous tubule
may need to be bluntly dissected off andpreserved (Vasaruchapong and Chanhome2012). In lizards, the kidney is locatedwithin the pelvis, so complete nephrectomy
is extremely difficult without transection of
the pelvis and is not commonly performed.
Endoscopy is the preferred method for
obtaining biopsies but can also be obtainedwith a Tru‐Cut device through a coeliotomy
or an incision between the tail base and therear leg in lizards.

­Prolapsed Hemipeneor Phallus
A prolapsed hemipene or phallus should be
attended to as soon as possible, keeping thetissue moist, otherwise necrosis will occur.
The prolapsed organ should be cleaned andany lacerations repaired. Tissue swelling canbe reduced using sugar or other hypertonic
solutions. The organ is then replaced and ahorizontal mattress suture placed on eitherside of the cloaca. It is important to makethe suture tight enough to prevent further
prolapse but still allow the passage of faeces
and urates. This suture can be removed
after seven days. The underlying cause must
be addressed and systemic antibiotics areindicated if infection is present. If necrosis
is present or the hemipene or phallus has
re‐prolapsed multiple times, amputation
may be necessary (Mader et al. 2006). For
snakes and lizards with hemipenes, as longas one hemipene remains, the animal is still
able to breed. To perform amputation, one
or two transfixing sutures are placed at thebase of the organ for haemostasis, the tissuetransected and removed. The stump can beoversewn with a simple continuous suture if
necessary. The tissue stump will usually
retract easily into the cloaca. Postoperative
antibiotics are recommended if there is evidence of infection.

­Orthopaedic Surgery
Principles of Fracture Repair
and Bone Healing
External coaptation, internal fixation andexternal fixation methods have all been usedin reptiles. The method of repair is chosen
based on the location of the fracture, the sizeof the patient, the ease of application andtolerance by the patient, the owner’s ability
to manage the patient postoperatively, financial concerns and the surgeon’s comfort level.
Complete healing from a traumatic fracture
can take 6–18 months (although fixation
is usually only needed for 6–12 weeks),although fractures due to nutritional secondary hyperparathyroidism (NSHP) seem toheal much faster, as long as the underlying
problem is corrected. If significant damage tothe soft tissues and vascular supply has
occurred, amputation may be necessary.
External Coaptation
External coaptation involves the use of splints,
slings or bandages to immobilize a fracture.
Fractures with minimal displacement that are
not compound tend to heal well with thistechnique. For patients with NSHP, this is thetreatment of choice, as the bones are notstrong enough to support additional hardware. The limb should be splinted in a normal
walking position so that the patient can still
ambulate and to avoid the potential for disuse
atrophy or decreased range of motion in the
joints after the bandage is removed. In lizards, a modified spica splint crossing overthe pelvic or pectoral girdle to the limb on
the opposite side can be used, particularly for
fractures of the humerus and femur. Thismethod keeps the limb in a normal position.

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Reptile Medicine and Surgery in Clinical Practice

Alternatively, the pectoral limb can be pulledcaudally and taped to the body or the pelvic
limb taped to the tail. The disadvantage tothis method is that the limb being held inextension but the results are usually acceptable. In small chelonians with a humeral or
femoral fracture, the limb can be flexed up
inside the shell and taped in place.
External and Internal Fixation
Intramedullary pins and cerclage wire arecommonly used for internal fixation in smaller
reptiles. Pins can also be tied in to an external
skeletal fixator to provide additional stability.
For external fixation, common injection needles or K‐wires can be used, which arethreaded transversely through the affectedbone under and above the fracture and fixatedfrom outside on both sides by an infusion tube
filled with quick‐setting cement or a lightweight casting material (Figure 28.8). In large
chelonians, bone plates can be used to stabilize fractures of the long bones (Mitchell2002). The same principles apply when using
these techniques in reptiles as in other animals. Complications can occur such as premature pin loosening, infection, damage tojoints, and so on. In the case of non‐union
fractures, bone grafts can be harvested andplaced at the fracture site to stimulate healing.

Grafts can be collected from the humerus,
femur, a rib or the wing of the ilium.

­Amputation
Tail
Tail necrosis is common in lizards and partial
amputation of the tail is often required.
A ring block with lidocaine or bupivacaine is
performed or the procedure performed
under sedation or general anaesthesia. The
tail is cut straight through with a scalpel
blade. Pressure is applied for haemostasis
and the end of the tail is left open to granulate in, so that the tail can regenerate; the skincan be closed in patients without natural tailautonomy (for instance chameleons, bearded
dragons, green iguanas). The end of the tailshould be kept clean and dry and the patient
kept on nonparticulate substrate until thewound heals. When the diameter of the tail islarge, primary closure should be used.
Limb or Digit
Determining when to amputate a limb or
digit is based on how the species will use
the limb postoperatively; sometimes leaving a stump for ambulation is preferable.

Figure 28.8 Repair of a forelimb
fracture in a chameleon using
segments of infusion tube filled withquick‐setting cement and fine pins.

Surgery

Regardless of the site, enough soft tissue
should be left to pad the end of the bone.
A skin flap should be created ventrally sothat, when the incision is closed, it will lie on
the dorsal aspect of the limb and not on thewalking surface; healing is not delayed andthe possibility of contamination of the incision is greatly reduced (Mader et al. 2006,
Alworth et al. 2011). In chelonians, the prosthesis can be placed on the ventral aspect ofthe plastron postoperatively so that thepatient does not fall to one side when walking. It usually needs to be replaced over time.
The amputation of digits can be performedat an interphalangeal joint leaving healthy
tissue and the skin closed routinely.
(a)­ kull and Facial BoneS
Fractures
Common principles of fracture repair areused for fractures of the maxilla or mandible
in reptiles (Mader et al. 2006, Alworth et al.
2011, Tuxbury et al. 2010). If enough normalbone structure remains, hypodermic needles can be used to drill holes. Cerclage wireis passed through the needle, the needle isremoved and the wire tightened to stabilize
the fracture (Figure 28.9a,b,c). The use of
external fixators has also been described.
A ‘bridge’ over a fracture site should be created using a fibreglass and epoxy patch as
one would use to repair shell fractures.

(b)

(c)

Figure 28.9 (a) Wiring of a mandibular symphysis fracture in a chameleon. (b) Gentle tension band wiring
incorporating the transverse fixator. (c) Resin is applied to the sharp ends of the wires.

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Reptile Medicine and Surgery in Clinical Practice­Venomoid Surgery
Owners of venomous species may request
this surgery to make their venomous reptile
less dangerous, but this reason must be
actively discouraged. To provide such surgery
is against the law, against the principles ofanimal welfare and unethical. Venomoid
animals must still be treated as venomous
for the safety of all involved and, in many
Australian states these animals are legally still
considered venomous (Johnson 2011). Theremay be limited situations where venomoid
surgery is deemed appropriate. Once thesnake is fully anaesthetized, the snake isplaced in dorsal recumbency and the jaws are
opened wide. An incision is made in the oral
mucosa between the teeth and lip margin andthe gland and duct are dissected out and carefully discarded. Sterile silicone prosthesis isplaced in the surgical site and the mucosa
closed with absorbable suture (Mader et al.
2006). After surgery, the snake is fasted forseveral weeks and must only be fed dead prey.

­References
Alworth, L.C., Hernandez, S.M. and Divers,
S.J. (2011) Laboratory reptile surgery:principles and techniques. Journal of theAmerican Association of Laboratory Animal
Sciences, 50, 11–26.
Hodshon, R.T., Sura, P.A. and Schumacher, J.P.
et al. (2013) Comparison of first‐intention
healing of carbon dioxide laser, 4.0‐MHz
radiosurgery, and scalpel incisions in ballpythons (Python regius). American Journalof Veterinary Research, 74, 499–508.
Huchzermeyer, F.W. and Cooper, J.E. (2000)
Fibricess, not abscess, resulting from a
localised inflammatory response to infection
in reptiles and birds. Veterinary Record, 147,
515–517.
Johnson, R. (2011) Clinical technique:handling and treating venomous snakes.
Journal of Exotic Pet Medicine, 20, 124–130.
Lawton, M.P.C. (2006) Reptilian
ophthalmology, in Reptile Medicine andSurgery, 2nd ed. (D.R. Mader, ed.). Elsevier,St. Louis, MO, pp. 323–342.
Mader, D.R., Bennett, R.A., Funk, R.S. et al.
(2006) Surgery, in Reptile Medicine andSurgery (D.R. Mader ed.). Saunders,
St. Louis, MO, pp. 581–630.
Millichamp, N.J., Jacobson, E.R. and Dziezyc, J.
(1986) Conjunctivoralostomy for treatmentof an occluded lacrimal duct in a blood
python. Journal of the American Veterinary
Medicine Association, 11, 1136–1138.
Mitchell, M.A. (2002) Diagnosis andmanagement of reptile orthopedic injuries.
Veterinary Clinics of North America Exotic
Animal Practice, 5, 97–114.
Murray, M.J. (2006) Aural abscesses, in Reptile
Medicine and Surgery, 2nd ed. (D.R. Mader,ed.). Elsevier, St. Louis, MO, pp. 742–746.
Tuxbury, K.A., Clayton, L.A., Snakard, E.P. andFishman, E.K. (2010) Multiple skull fracturesin a captive Fly river turtle (Carretochelys
insculpta): diagnosis, surgical repair, andmedical management. Journal of
Herpetological Medicine and Surgery, 20,
11–19.
Vasaruchapong, T. and Chanhome, L. (2012)
Surgical treatment of renal gout inmonocellate cobra, Naja kaouthia. Thai
Journal of Veterinary Medicine, 42, 383–386.

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29
Turtle Shell Repair
Jane Roffey and Sasha Miles­Introduction
There are approximately 250 species of­turtles and tortoises in the world (Boyer andBoyer 2006). Shell injuries are common inwild chelonians but are also seen in captive
animals. Causes of shell trauma include roadtrauma, predator attacks, falling, being trod­
den on, lawn mower injuries, boat propeller
strikes and hailstone strikes (Figure 29.1).
Shells may also require repair due to diseasesuch as infection and abscess. Managementof shell repair may be a prolonged process.

et al. 2015). The trunk vertebrae and sacrum
form part of the shell structure, as they areattached to the ribs, which in turn are fused tothe dermal bone plates. The pectoral and pelvic
girdles are situated internal to the ribs whichmean they act to give additional strength to theshell in a vertical plane. Both these girdles attach
to the plastron and carapace by pectoral andpelvic musculature (O’Malley 2005). Because ofthis structure, limb movement can be affectedby some shell fractures and contraction of thesemuscles can sometimes cause movement of
fractured shell segments (Vella 2009a).

­Anatomy­Triage

The turtle shell consists of two main sections:the dorsal carapace and ventral plastron, con­nected laterally by the bridges. The shell con­sists of about 60 dermal bone plates and these
are covered externally by keratinized scales
called scutes (Horowitz et al. 2015, O’Malley2005). The scutes form from the epidermis andare the equivalent to scales in other reptiles.
The position of the scutes does not correspondto the underlying bone plates of the shell, whichacts to strengthen the shell (Barten 2006). Boththe dermal bone plates and scutes are inner­vated and vascular (O’Malley 2005).
As well as the shell, the bone plates also form
the modified pectoral and pelvic limb girdles,
trunk vertebrae, sacrum and ribs (Horowitz

Turtles presenting with shell damage shouldbe triaged promptly. Evaluation of the patient’s
condition over the first few hours will deter­mine which individuals should receive treat­ment and which require euthanasia. Wild
turtles that will not be able to be returned to
the wild in a fully functional state will need
to be euthanized immediately. The time andresources required for rehabilitation areimportant factors to consider, particularly
for wild turtles. Some turtles may require
many months of treatment.
If a transverse fracture of the carapace ispresent then further work‐up is required toassess for damage to the spine; for example,
radiographs and/or computed tomography

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

398

Reptile Medicine and Surgery in Clinical Practice(Abou‐Madi et al. 2004, Fleming 2014).
Further work‐up is also required if turtles
demonstrate neurological disorders. An initialassessment of all patients should include aneurological examination including assessmentof gait, proprioception, sensation, withdrawal
reflexes, deep pain, bladder and rectal func­tion (Innis 2008). Evaluation of sensation anddeep pain may assist in determining theextent of the injury (Fleming 2008). Fiveprognostic categories have been developed toassess shell injuries and these are detailed inTable 29.1 (Fleming 2008, 2014).

­Supportive Care and Stabilization
Turtles with treatable shell injuries will requirestabilization and supportive care as soon as
the triage has been performed. The following
steps should be taken:
Figure 29.1 Multiple, depressed fractures of thecarapace caused by hailstone trauma.

●●●●

provide analgesia
control haemorrhage

Table 29.1 A guide to the five prognostic categories for turtles with shell injuries.
Prognostic
category

Excellent

Good

Fair

GuardedCharacteristics

Single fracture
Hairline fracture●● Fracture that does not involve the spine●● Minor road rashSupportive care
Often do not require surgicalstabilization●● Short term hospitalization (may only
be a few days)

●●

●●

●●

●●

Multiple fractures
Unstable fractures●● Open fractures (i.e. coelom visible) ± minor
pieces of shell missing●● Shell punctures (e.g. dog bite)

Supportive care
Surgical stabilization of the fractures●● Several months of treatment

●●

●●

●●

●●

Multiple fractures involving pectoral and/or
pelvic areas (can lead to ambulation difficulties)●● Coelomic penetration●● Fractures involving the bridge/s●● Open fractures with large pieces of shell missing
●●

●●
●●

Grave

Expectations of treatment

Open fractures with damage to viscera
Gross contamination of the coelom

Multiple comminuted fractures
Unable to stabilize shell●● Internal injuries●● Head injuries (including eye and jaw injuries)●● Fractured spine●● Paralysed limbs●●●●

Supportive care
Surgical stabilization of the fractures●● At least several months of treatment●●●●

Further diagnostics warranted (e.g.
computed tomography and endoscopy)●● Difficult to treat successfully●●

Euthanasia advisedTurtle Shell Repair

provide warmth
give antibiotics and fluid therapy●● stabilize fractures and protect wounds●● radiography and computed tomography (CT).
●●●●

Analgesia
The turtle should be weighed and appro­
priate analgesia provided, depending on theseverity of the injuries. Local anaesthetic
splash blocks or infiltration can be admin­
istered. Opioid analgesia should also be
administered in all but the mildest of cases.
Butorphanol has been shown to be ineffec­
tive in one species of chelonian, whereas
methadone, morphine and tramadol haveshown more promising study results in termsof efficacy in reptiles including chelonians(Baker et al. 2011, Sladky et al. 2007).
Morphine has been associated with signifi­
cant respiratory depression so should be usedwith caution (Sladky et al. 2007). Nonsteroidal
anti‐inflammatory drugs can also be used inhydrated patients who are not experiencing
shock. Meloxicam is widely used in reptiles
based on anecdotal evidence (Fleming 2014).
Refer to Chapter 27 for further information
on analgesia.
Control Haemorrhage
If active bleeding is occurring from fracturesites, haemostasis can be achieved with avariety of methods including digital pressure,a pressure bandage, vessel ligation, absorba­
ble gelatin sponges (e.g. Gelfoam®, Pfizer)
and electrocautery.
WarmthTurtles should be provided with an appropri­
ate temperature gradient by maintaining
them at 24–26 °C on a moist towel. Thisshould be continued for the time that they
are unable to be immersed in water. Fluid
therapy and support feeding may be required
during this time as many turtles will not eat
while dry docked. The time the turtle willneed to be kept out of the water will dependon the severity and location of the shellwounds and whether or not the coelom ispenetrated.
Antibiotics
Almost all turtles with shell lesions will require
antibiotics. Initially, an antibiotic with a broad
Gram‐negative spectrum is preferred, as mostinfectious bacteria in reptiles are gram nega­tive (Fleming 2008). The third‐generation
cephalosporin, ceftazidime, is commonly used
and it is given at 20 mg/kg intramuscularly
every three days (Raftery 2011). It has a wide
spectrum of activity against Gram‐negative
bacteria, including Pseudomonas aeruginosa(Gregory 2008). Alternatively, fluoroquinolo­
nes have a wide activity against both Gram‐
positive and ‐negative bacteria but limited
spectrum against anaerobes (Gregory 2008).
Enrofloxacin can be given at 10 mg/kg intra­
muscularly or orally every second day. This
medication is associated with pain and tissue
necrosis at the injection site and should bediluted with sterile water to reduce this effect(Fleming 2008). The choice of antibiotic forlong‐term use, with chronic wounds or
abscesses, should be guided by culture andsensitivity (Fleming 2014).
Fluid Therapy
Turtles with shell injuries have often lost flu­
ids and are not maintaining normal fluid
uptake so can be considered mildly (less than5%) to moderately (7%) dehydrated in mostcases (Chitty et al. 2013, Fleming 2014).
Dehydration can be indicated by sunken eyes,skin tenting, a dry mouth, thick oral mucus, aslow or faint heartbeat, minimal or no urina­
tion, a poor demeanour and increasing serial
packed cell volume and total protein meas­
urements (Norton 2005). Fluids should be
warmed and can be given intravenously,
intraosseously, subcutaneously, epicoelomi­
cally or intracoelomically in the initial phase,depending on the patient’s requirements(Vella 2009a). Fluid maintenance rates are
15–25 ml/kg/day in most species (Norton

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Reptile Medicine and Surgery in Clinical Practice2005). Fluid therapy should be calculated
based on this and the estimated deficit. After
three or four days of parenteral fluids, mostpatients can often be switched to oral fluid
therapy (Fleming 2008).
Initial Fracture Stabilizationand Wound Protection
Displaced fractures may be temporarily sta­bilized to prevent further contamination andto assist with analgesia. An adhesive dressing
tape can be used for this purpose, until theanimal is stabilized and can be anaesthetizedfor repair (Figure 29.2). Any coelomic pene­
tration or other wounds should also be band­aged to prevent any further contamination,
until cleaning and irrigation can occur.
Radiographs
All turtles should be radiographed within
the first 24 hours for a detailed assessmentof injuries and to determine whether the
turtle is gravid. The limbs, spine, pectoraland pelvic girdles should be assessed fordamage. Occasionally, fractures to the boneplates of the carapace or plastron are notapparent as the overlying scutes are stillintact (Fleming 2014). Three radiographic
projections are required: dorsoventral, lateraland craniocaudal (Figure 29.3). Bridge frac­tures can be superimposed on dorsoventral
views (Fleming 2008).
Computed Tomography
Some fractures may not be apparent on plainradiographs and computed tomography has
been used as a more sensitive diagnostic tool
(Abou‐Madi et al. 2004). It may also be usefulfor assessing internal injuries.

­Wound Care
Wound care should commence within a few
hours of presentation and may need to becontinued in the long term. Flushing of shelllesions should be performed with a 2%
solution of chlorhexidine initially, and thenfollowed by copious volumes of warm, sterile
saline. Ensure the foreign material is flushedout, instead of into the wound, by holding thewounds ventrally. Depending on the severityof contamination, flushing may have to berepeated daily for the first few days andthen reduced to every other day or weekly if
required (Fleming 2008, Mitchell and Diaz‐
Figueroa 2004, Vella 2009b). If there is
coelomic penetration, saline should be used
for wound flushing, not chlorhexidine.
Depending on the degree of coelomic pene­
tration, endoscopy or a coeliotomy may be
Figure 29.2 A clear adhesive dressing
adhered to the shell with adhesive tape.

Turtle Shell Repair

Figure 29.3 Performing a dorsoventral radiograph on an anaesthetised eastern long‐necked turtle (Chelodina
expansa).
Figure 29.4 Severe, multiple bridgeand carapace fractures with shell
deficits. The wound is grossly
contaminated and has necrotic tissuepresent.

required to assess for potential internal
bleeding and organ trauma. Coelomic lavage
may be required if there is contamination;
however, gross contamination of the coelom
is associated with a poor prognosis. Fractured
shell sites may need to be cleaned with brushes,
cloths or sponges. Topical anaesthesia can beprovided during this time with splash blocksof lignocaine and/or bupivacaine.

Some cases will require debridement andexcision of necrotic tissue (Figure 29.4).
Depending on the severity, this can be per­formed under local or general anaesthesia.
If required, various tools can be used todebride the shell and these include needles,
scalpels, rongeurs and electric high‐speed
burrs. The shell should be debrided until light
bleeding occurs (Vella 2009b).

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Reptile Medicine and Surgery in Clinical Practice

Wet‐to‐dry bandages are commonly placed
after irrigation to facilitate the removal ofdebris and prevent further contamination(Mitchell and Diaz‐Figueroa 2004). Thesebandages can be attached to the shell with anadhesive tape. Wet‐to‐dry bandages usuallyare used until wound exudate is controlled
and from there non‐adhesive dressings canbe used. In cases of severe infection, silver‐
impregnated dressings can be used as theprimary layer (Fleming 2014, Norton 2005).
Closed fractures can be treated with band­
aging alone to prevent contamination andencourage granulation tissue formation(Fleming 2014). For shell fractures that
require surgical fixation, bandages areapplied until the turtle is stabilized and thewound is clean enough to undergo surgery(Chitty and Raftery 2013).
In the case of shell deficits, which cannot
be closed surgically, bandaging will need tobe continued for many months. Generally
two weeks of wet‐to‐dry bandaging is per­formed and then nonadherent bandages
are used until a thick granulation tissue bed
is present. This process takes at least six toeight weeks. Once a thick granulation tissue
bed has formed, the area can be left unband­aged but monitored closely and kept clean(Fleming 2014).

anticoagulant therapy and the use over
exposed vessels, nerves, tendons, ligaments
or unprotected organs (Howe 2015).

­Fracture Fixation
Fractures can be permanently fixated once
the turtle has been stabilized and wounds
have been treated appropriately. All repairs
are performed under sedation or generalanaesthesia (Figure 29.5). See Chapter 27
for further information on analgesia, sedationand general anaesthesia. There are currently
many different techniques and materials
used in the repair of shell fractures. Methodsof repair discussed are sometimes used inconjunction with each other.

Vacuum‐Assisted Wound Closure
An alternative to wet‐to‐dry bandaging,­vacuum‐assisted wound closure or negative
pressure wound therapy, is becoming increas­
ingly common in human and veterinary
medicine (Atay et al. 2013; Howe 2015). It
has been shown to promote and expedite
wound healing by increasing blood flow to
the wound bed, increasing the rate of granu­
lation tissue formation, reducing bacterial
tissue counts and by removing exudates
and reducing oedema (Marin et al. 2014,
Morykwas et al. 1997). Contraindications
for negative pressure wound therapy include
the presence of local malignancy, undebrided
osteomyelitis, active bleeding, concurrent

Figure 29.5 A turtle under general anaesthesia forshell repair. Note the placement of an intravenous
catheter delivering intravenous fluids, anendotracheal tube (which is attached to a ventilator)
and a rectal temperature probe.

Turtle Shell Repair

Adhesives
The use of epoxies and fibreglass to com­pletely cover shell fractures has fallen out
of favour for the repair of traumatic andinfected wounds, because of the risk of seal­
ing in infection and the inability to manage
wounds once this has been placed. Thismethod of repair may also interfere withwound healing and growth (Bogard andInnis 2008, Fleming 2008, 2014, Vella 2009b).
Epoxy products can generate a high degreeof heat during placement and can damage
soft tissue and live bone (Mitchell 2002);
however, epoxy and other adhesives, such as
resins, glues, cements and acrylics can still
Figure 29.6 Ultraviolet light curing ofa methyl‐methacrylate repair (courtesyof Robert Johnson).

Figure 29.7 Filling small fissures in theshell with a dental acrylic.

be used as suitable materials for repairing
nondisplaced fractures and for elective plas­
tronotomy closure (Figure 29.6). When nolonger required, these materials should be
removed from young chelonians to prevent
growth impediment and deformity (Fleming2014). Adhesives can also be used to secure
devices to the shell, as discussed in thesection on bridging methods.
Glass ionomers have been used to seal
fissures in the shell, cover small open wounds
and seal areas that have not been completely
closed by orthopaedic fixation (Figure 29.7).
This material is used in human dentistry forpermanent tooth fillings. The silicate cement

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Reptile Medicine and Surgery in Clinical Practicein the product releases fluorine which pro­vides a local antibacterial effect and increases
precipitation of calcium in the surrounding
tissue (Fowler and Magelakis 2004). This
material should only be used at sterile orsterilized wound sites. Glass ionomers areusually shed with the scutes (Wilson andBurns 2000).
Bridging Methods
A bridging method involves securing various
devices to the shell, on either side of the frac­ture to achieve compression and appositionof the fracture segments. A major advantageof this method is that the fracture site itself
remains uncovered which allows for accessto the wound and monitoring of the healing
process. This method is also cost effective,
minimally invasive and easy to perform.
Disadvantages of this method include thepossibility of the device detaching from theshell due to poor placement and that it gen­erally does not provide the same degree ofstabilisation as orthopaedic repair (Fleming2014).
Many fixation devices can be purchasedfrom hardware and haberdashery shops,
including saddle clamps, wall hanging hooks,
clothing hooks (Figure 29.8), curtain hooks
and cable ties (Chitty and Raftery 2013, Divers

2011, Fleming 2014, Forrester and Satta 2005,
Lloyd 2007, Vella 2009b). These devices may
be placed once or many times along thefracture line, depending on the length of
the fracture. Hook‐like devices will need tobe linked and tightened to reduced andstabilize the fracture. Suitable materials forthis purpose include stainless steel wire andsuture material (Bogard and Innis 2008,
Fleming 2014, Vella 2009b). Saddle clamps
are U‐shaped clamps used to attach pipes toflat surfaces. These can be bent and cut tothe contour of the shell and then attachedwith an adhesive (Vella 2009b). When using
cable ties, a cable tie mount is adhered tothe shell on either side of the fracture. A cabletie is then placed through both mounts andsecured in place at one end with another cabletie. Once adequate tension is achieved, theends are trimmed short (Divers 2001, Forrester
and Satta 2005). A method using a humandevice designed for stretching skin called the
TopClosure® Tension Relief System has also
been described (Horowitz et al. 2015).
Metal plates have also been used to bridge
fracture sites. Orthopaedic bone plates ormetal plates from hardware shops can beused. These are particularly useful for plas­tron fractures as their low profile can allow
for ambulation (Fleming 2014, Richards
2001). The plate should be cut and moulded

Figure 29.8 A bridging method ofplastron fracture repair using clothinghooks and Knead‐IT® (Selleys Australia& New Zealand).

Turtle Shell Repair

to the shaped of the shell and if possible, acentral arch will allow for increased wound
management and visualization (Chitty andRaftery 2013).
Suitable adhesives for attaching thesefixation devices to the shell include epoxies,
polymethyl methacrylates, including dental
acrylics and strong glues or adhesives includ­ing cyanoacrylates from hardware shops(Bogard and Innis 2008, Chitty and Raftery
2013, Horowitz et al. 2015, Vella 2009b). The
keratin at the site of attachment can beroughened with a high speed burr or hand
tool to improve adhesion (Bogard and Innis
2008, Horowitz et al. 2015). If wiring or
suturing is required to attach the devices,then in most cases it is best to allow theadhesive to set for 12 hours prior to tighten­
ing. During this time, the fracture can be
temporarily stabilized with adhesive tape
(Bogard and Innis 2008). Care should betaken that adhesives do not come into con­tact with soft tissue or live bone during
placement (Fleming 2014).
Once the fracture has healed, the devices
can generally be removed with gentle rota­
tional force applied by a grasping tool or byusing a periosteal elevator or chisel to pry
them from the shell (Divers 2011, Bogard andInnis 2008). There is generally little trauma
to the underlying scutes using this method(Bogard and Innis 2008).

Figure 29.9 Peripheral carapace
fractures have been repaired here
using metal sutures (courtesy of RobertJohnson).

Orthopaedic Fixation
All orthopaedic repairs are performed undergeneral anaesthesia using strict aseptic
techniques (Mitchell 2002, Vella 2009b).
The shell and surrounding soft tissue is asep­
tically prepared prior to fixation (Fleming2014). Implants must be constructed fromstainless steel as galvanized metals canrelease zinc systemically. Stainless steelscrews can be purchased in a variety of sizes
from hardware shops and then sterilized(Fleming 2014). Orthopaedic repairs may be
used in combination with bridging andadhesive methods.
Advantages associated with this repair
method include the ability to reduce complex
fracture and increased fracture stability, par­ticularly in larger chelonians. Disadvantages
include increased costs, potential introduc­tion of infection, requirement for generalanaesthesia and the potential for implantfailure (Vella 2009b).
One of the simplest methods of orthopae­
dic fixation involves drilling a hole on eitherside of the fracture and tightening Kirschner
wires or cerclage wires through the holes(Figure 29.9). This method is repeated along
the length of the fracture (Heatley 2011,
Mitchell 2002, Barten 2006). Holes can be
drilled using a Kirschner wire, power tool orelectric drill. Care should be taken as damage

405

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Reptile Medicine and Surgery in Clinical Practice

Figure 29.10 Stainless steel screws
have been placed in the shell andorthopaedic wire has been applied in a
figure of eight pattern to stabilize thisbridge fracture. Note that the wire on
the left side of the photo has been
covered in an adhesive to protect soft
tissue from trauma during ambulation.

to the internal organs and surrounding soft
tissue can occur during drilling, wire place­ment and tightening. Depending on thelocation, placement of wires can be difficult.
Wires should be covered to prevent tracking
of infection into the bone and/or coelom(Heatley 2011, Kishimori et al. 2001).
A variation of this method involves placing
orthopaedic or stainless steel screws on eitherside of the fracture line and connecting themwith orthopaedic wire in a figure of eightpattern (Figure 29.10). This is repeated along
the fracture line as required. The wire willneed to be tightened to provide close apposi­tion of the fracture segments (Chitty andRaftery 2013, Kishimori et al. 2001). Pilot
holes are made with a drill bit slightly smaller
than the size of the screw, prior to screw
placement. Screws should be placed approxi­
mately 0.5 cm from the edge of the fracture,
if possible (Fleming 2014). Screws should beorientated at 45–60 degrees to the healthy
shell surface (Kishimori et al. 2001). The knotof the cerclage wire should be located between
the two screw heads and this can be bent
parallel with the shell or covered with epoxy
putty or bandaging material (Fleming 2014).
Damage to the internal organs and surround­ing soft tissue is also a risk associated withthis technique (Heatley 2011).
Metal bridges or bone plates attached tothe shell with screws across a fracture site

can also be used as a repair method (Chitty
and Raftery 2013). This method is helpful forplastron fractures as it can allow for normal
ambulation. Care should be taken as a large
portion of the fracture site is likely to be cov­
ered by the plate which means wound moni­
toring and care is inhibited (Fleming 2014).
To remove any external fixation, the shellshould again be aseptically prepared. Thiscan generally be performed under sedation
but in some cases general anaesthesia may
be required. Screws are removed using anappropriate screw driver (Fleming 2014).
The remaining holes will need to be kept
clean and protected until they heal. Healing
can take from four to eight weeks (Chitty andRaftery 2013). The holes can be bandaged,
filled with a water proofing ointment orpacked with a silver sulfadiazine‐containing
cream twice a week (Chitty and Raftery 2013,
Fleming 2014). A course of antibiotics is indi­cated if there are a large number of screw
holes (Fleming 2014).

­Post‐Surgical Care
Turtles should be kept warm and dry docked
on moist towels after surgery. As turtles
usually require immersion in water to eat
and drink, dry docking is only continued for
as long as it is necessary. It will need to beTurtle Shell Repair

continued until there is sufficient epitheliali­
zation of the fracture and any wounds that
may also be present. This time period canvary between two weeks for simple fracturesand one to two years for a severe fracturewith shell deficits (Fleming 2008, Vella 2009a).
In some cases the fracture site may be able tobe covered with a waterproof dressing to allow
a 30–60‐minute swim each day (Figure 29.3).
This will assist in maintaining hydration andallow for food intake, urination and defeca­tion. Turtles without plastron damage can beplaced into a container of shallow water toallow water absorption though the cloaca.
If a turtle is unable to be placed into water
for many weeks or months, then nutritional

support will be required. Tube feeding withan orogastric tube or placement of anoesophagostomy tube are possible options.
Fluid therapy is also likely to be required forthese turtles.
All fixation devices should be checked
regularly to ensure that they remain intact
and stable. Healing generally occurs bet­
ween 4–8 weeks but in some cases can be
up to 30 months (Fleming 2014, Mitchell2002). Staged removal of the fixation devices
is recommended for complex fractures.
Callus formation is not often visible on radi­
ographs so palpation for stability is often
the best guide in assessing fracture healing(Fleming 2014).

References
Abou‐Madi, N., Scrivani, P. V., Kollias, G. V.
and Hernandez‐Divers, S. M. (2004)
Diagnosis of skeletal injuries in Chelonians
using computed tomography. Journal of
Zoo and Wildlife Medicine, 35 (2),
226–231.
Atay, T., Burc, H., Baykal, Y.B. and Kirdemir, V.
(2013) Results of vacuum assisted woundclosure application. Indian Journal ofSurgery, 75 (4), 302–305.
Baker, B., Sladky, K. and Johnston, S. (2011)
Evaluations of the analgesic effects of oral
and subcutaneous tramadol administrationin red‐eared slider turtles. Journal of theAmerican Veterinary Medical Association,
238, 220–227.
Barten, S. (2006) Shell damage, in Reptile
Medicine and Surgery, 2nd ed. (D.R. Mader,ed.), Elsevier Saunders, St Louis, MO, pp.
893–899.
Bogard, C. and Innis, C. (2008) A simple andinexpensive method of shell repair in
Chelonia. Journal of Herpetological Medicine
and Surgery, 18 (1), 12–13.
Boyer, T. and Boyer, D. (2006) Turtles,
tortoises, and terrapins, in Reptile Medicine
and Surgery, 2nd ed. (D. Mader, ed.).
Elsevier Saunders, St Louis, MO,
pp. 696–704.

Chitty, J. and Raftery, A. Fractures of the shell,in Essentials of Tortoise Medicine andSurgery. John Wiley & Sons, Ltd, Chichester,
pp. 216–221.
Divers, S. (2011) Zip‐tie closure for turtle
shell fractures: quick, simple and cheap!
in NAVC Conference Proceedings,
Orlando, FL.
Fleming, G.J. (2008) Clinical technique:
Chelonian shell repair. Journal of Exotic Pet
Medicine, 17 (4), 246–258.
Fleming, G.J. (2014) New techniques in
Chelonian shell repair, in Current Therapy
in Reptile Medicine and Surgery (D. Mader
and S. Divers, eds). Elsevier Saunders,
St Louis, MO, pp. 205–212.
Forrester, H. and Satta, J. (2005) Easy shell
repair. Exotic DVM, 6 (6), 13.
Fowler, A. and Magelakis, N. (2004) Shellfracture repair using glass ionomer cementin the long neck turtle, in Proceedings of theAustralian Veterinary Association
Conference, Canberra, pp. 137–139.
Gregory, J. (2008) Clinical technique:chelonian shell repair. Journal of Exotic Pet
Medicine, 17, 246–258.
Heatley, J. (2011) Chelonian shell repair, in
American Board of Veterinary Practitioners
Conference Proceedings, St Louis, MO.

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Horowitz, I.H., Yanco, E. and Topaz, M. (2015)
TopClosure System adapted to Chelonianshell repair. Journal of Exotic Pet Medicine,24 (1), 65–70.
Howe, L. (2015) Current concepts in negative
pressure wound therapy. Veterinary Clinics
of North America Small Animal Practice, 45(3), 565–584.
Innes, C. (2008) Restraint and physicalexamination of chelonians, in NAVC
Conference, pp. 1780–1782.
Kishimori, J., Lewbart, G., Marcellin‐Little, D.
et al. (2001) Chelonian shell fracture repair
techniques. Exotic DVM, 3, 35–41.
Lloyd, C. (2007) Alternative method for cabletie shell repair in chelonian. Exotic DVM, 9,
9–10.
Marin, M.L., Norton, T.M. and Mettee, N.S.
(2014) Vacuum‐assisted wound closure inchelonians, in Current Therapy in Reptile
Medicine and Surgery (D.R. Mader and S.J.
Divers, eds). Elsevier Saunders, St Louis,
MO, pp. 197–204.
Mitchell, M.A. (2002) Diagnosis andmanagement of reptile orthopedic injuries.
Veterinary Clinics of North America Exotic
Animal Practice, 5 (1), 97–114.
Mitchell, M.A. and Diaz‐Figueroa, O. (2004)
Wound management in reptiles. Veterinary
Clinics of North America Exotic Animal
Practice, 7, 123–140.
Morykwas, M.J., Argenta, L.C., Shelton‐
Brown, E.I. and McGuirt, W. (1997)

Vacuum‐assisted closure: a new method forwound control and treatment: animalstudies and basic foundation. Annals of
Plastic Surgery, 38 (6), 553–562.
Norton, T.M. (2005) Chelonian emergency andcritical care. Seminars in Avian and Exotic
Pet Medicine, 14 (2), 106–130.
O’Malley, B. (2005) Tortoises and turtles, inClinical Anatomy and Physiology of Exotic
Species. Elsevier Saunders, St Louis, MO,
pp. 41–56.
Raftery, A. (2011) Reptile orthopaedic
medicine and surgery. Journal of Exotic Pet
Medicine, 20, 107–116.
Richards, J. (2001) Metal bridges: a newtechnique of turtle shell repair. Journal of
Herpetological Medicine and Surgery, 11 (4),31–34.
Sladky, K., Miletic, V., Paul‐Murphy, J. et al.
(2007) Analgesic efficacy and respiratory
effects of butorphanol and morphine inturtles. Journal of the American Veterinary
Medical Association, 230, 1356–1362.
Vella, D. (2009a) Management of aquatic turtle
shell fractures. Lab Animal (NY), 38 (2),52–53.
Vella, D. (2009b) Management of freshwater
turtle shell injuries. Lab Animal (NY), 38 (1),
13–14.
Wilson, G. and Burns, P. (2000) The use of alow exothermic‐curing dental acrylic torepair turtle shell injuries. Australian
Veterinary Practitioner, 30, 63–66.

Further Reading
KCI Animal Health (2012) V.A.C. Therapy for
Veterinary Use User Manual. San Antonio,
TX, KCI Licensing.
Kirchgessner, M. and Mitchell, M., (2009)
Chelonians, in Manual of Exotic Pet Practice(M.A. Mitchell and T.N. Tully, eds).
Saunders Elsevier, St Louis, MO,
pp. 207–249.

409

30
Necropsy
Catherine M. Shilton­Introduction
A diagnostic necropsy is the dissection ofan animal after death to inform the cause ofmorbidity or mortality. The two main compo­
nents are detailed systematic gross examina­tion of organs to look for clues and sampling
for further ancillary testing. A necropsy offers
the opportunity for the clinician to compare
necropsy results to clinical data and to add tothe expanding field of reptile medicine anddisease diagnosis.

­Preliminary Considerations
Maximize Carcase Quality
Poor carcase quality will decrease the amountof information that can be gained fromboth gross examination and histopathology,
and may limit interpretation of other tests(Table 30.1). Many reptiles are kept in proxi­
mity to a heat source, which hastens decom­
position, resulting in significant degradationof carcase quality within a few hours ofdeath. Decomposition can be minimized byrefrigeration of the carcase for up to fourdays, after which it should be frozen. In an
outbreak of disease in a reptile collection,
carcasses for necropsy should be of thebest quality, representative of the disease or

syndrome of interest and performed on
multiple affected individuals, so that a con­sistent pattern in necropsy findings can bediscerned.
Necropsy Safety
Although there is a long list of theoreticallypossible reptilian zoonoses, with the excep­
tions of Salmonella species and pentastomes,
actual transmission under natural circum­
stances is either rare or has never been doc­
umented (Johnson‐Delaney 2006). However,opening the carcase of a diseased reptile
may increase risk of human exposure to avariety of opportunistic or pathogenic orga­
nisms. This risk can be mitigated by use of
disposable gloves and antiseptic hand wash
for personal protection and hospital‐grade
disinfectant for equipment clean‐up. Any
wounds incurred by the dissector during
necropsy should be immediately disinfected
and bandaged. After necropsy, freezing thecarcase in a designated carcase freezer is agood interim measure prior to disposal bydeep burial or incineration, depending on
disposal services available. When dissect­ing a venomous snake, the head should
never be handled directly with fingers but
always with instruments. The head should
be removed as the first step of the necropsy
and placed in formalin for complete fixa­
tion prior to detailed examination or brain
removal.

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

410

Reptile Medicine and Surgery in Clinical PracticeTable 30.1 Post‐mortem factors that may impact necropsy findings.
ChangeDefinition

Necropsy consequences

Hypostaticcongestion

Fluid accumulation intissues due to gravity

Artefactual appearance of congestion and oedema of tissues
on side of carcase that was lowest at death.

Suffusion ofpigment

Passage of pigment tosurrounding tissues

Reddening of tissues near blood vessels or highly perfused organs
by haemoglobin pigment may mimic haemorrhage (Figure 30.2d).
Green tinge to tissues surrounding gall bladder due to bile
pigment.
Indicative of at least moderate decomposition.

Autolysis

Degradation of tissues
by autogenous enzymes

Red‐tinged watery fluid accumulation in body cavities andleakage from orifices.
Loss of fine cellular detail (renders cytology nondiagnostic andreduces accuracy of histological interpretation of subtle lesions).

Putrefaction

Bacterial degradation oftissues, primarily due toanaerobes from thegastrointestinal tract

Colour change of tissues, generally towards pallor and/or
green/grey tinge.
Eventually results in gas production (artefactual emphysema)in organs.
Progressive loss of histological detail.
May confound meaningful bacterial and fungal culture and/orinterpretation of results.
May inhibit virus isolation and/or molecular testing.

Freeze‐thawcycleFreezing andsubsequent thawing ofcarcaseGeneralized reddening of tissues due to suffusion of
haemoglobin pigment from lysed red cells.
Accumulation of red‐tinged fluid in body cavities at thawing.
Proliferation of putrefactive bacteria during thawing (minimize
by thawing under refrigeration).
Histological interpretation is severely confounded.
Advantage is decomposition is greatly slowed so carcase isrelatively well preserved for some ancillary tests (culture andmolecular testing).

Euthanasia
solution
artefact

Due to caustic effect ontissues of concentrated
pentobarbital

Discoloration, necrosis and mineralization of tissue perfusedwith pentobarbital.
Histologically, tissues exhibit artefactual coagulation necrosis
and loss of cellular detail.
Minimize by using appropriate dose of pentobarbital,
preferably injected intravenously rather than intracoelomically.

Necropsy Equipment
Being well equipped and having tools andsampling materials easily accessible during
the necropsy will greatly facilitate dissection,
thorough examination and optimal sampling(Figures 30.1a,b).

­Necropsy Procedure
A list of differential diagnoses should beformed before the necropsy, based on thehistory and clinical record. The necropsy

should involve a thorough examination of allbody systems, plus detailed targeted exami­
nation and/or sampling of other components
as required based on the list of differential
diagnoses. Grossly appreciable abnormalities
relate to organ size, shape, colour, texture
and presence of exudates. For most organs,
there is a wide range of ‘normal’ in reptiles,
depending on the species, its age and meta­
bolic status, which precludes the use of dog­
matic descriptions for normal reptilian organ
appearance. Images have been provided toexemplify the types of changes to look forNecropsy

(a)

(b)

Figure 30.1 Necropsy equipment. (a) Sharp knife, scalpel, scissors and rongeurs (various sizes), forceps,
hacksaw and ruler displayed on a disposable waterproof mat and underlying plastic cutting board. Disposable
gloves, antiseptic hand wash, bandages, antiseptic and hospital‐grade disinfectant displayed along the top. (b)Sampling supplies, clockwise from upper left: flame for sterilizing instruments before samples are taken, jars of
10% buffered formalin of various sizes for histology samples, sterile jars and vials of various sizes for individual
fresh samples, glass slides for cytology impressions, syringe and needle for injecting formalin into tissues(unopened intestine, eyes) for histology, normal saline to moisten plain swabs or small fresh tissue samples,
permanent marker for labelling, plain swab and swabs with bacterial transport media.

411

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Reptile Medicine and Surgery in Clinical Practiceand the wide variation possible in reptiles,
but each dissector will need to gain familiar­
ity with the normal appearance of organs inthe species they most commonly necropsy.
If in doubt about the gross appearance of anorgan, record it and sample the organ forhistology.
External Examinationof the Carcase
Record size (e.g. snout–vent or carapace
length), weight and body condition (poor,
fair, good, obese). Examine the skin, eyes,
ears, oral cavity, take note of any oral, nasal
or cloacal discharges and any asymmetriesof body parts (abnormal size/shape of joints/
bones, abnormal bulges in skin or body cavity)(Figures 30.2a–d).
Opening the Carcase
For snakes, lizards and crocodilians, a­ventral midline incision is made from thejaw to immediately cranial to the cloaca(Figure 30.3a). Increased exposure of theorgans in the body cavity can be obtained byreflecting back or removing the ventral skinand body wall (Figure 30.3b) using scissors
or rongeurs to cut through the ribs and pec­
toral girdle. In chelonians, the plastron isremoved (Figures 30.3c–e). It is at this stage,
with the organs in the body cavity freshly
exposed, that fresh samples should be taken
aseptically for possible bacterial culture.

­Examination of the Major
Organ Systems
Organs are initially examined in situ but may
then be removed to facilitate a more thor­
ough examination, either by removing indi­vidual organs or, in small or medium‐sized
reptiles, the entire visceral mass in one piece(Figure 30.3b).

Cardiovascular System
Take note of any oedema, ascites, petechialor ecchymotic haemorrhages that could
suggest heart failure, increased vascularpermeability or vasculitis. Examine the peri­
cardium for haemorrhages (Figure 30.4a) andincise the pericardium. There may normally
be a small amount of clear, colourless toslightly yellow pericardial fluid. Reptiles withsepticaemia may develop cloudy pericardial
exudate, which is an excellent sample for bac­terial culture (Figure 30.4b). In visceral gout,urates may accumulate in the pericardial sac.
Examine the surface of the epicardium forhaemorrhages (Figure 30.4c), pale streaking(which could be fibrosis or mineralization)or other abnormalities. Remove the heart,
including the first few millimetres of thelarge vessels at the base of the heart. Using
suitably fine scissors, systematically examine
the inside of the heart, including the endocar­
dial surface, heart valves and intimal surfaceof the large arteries, for abnormalities. Any
blood clots in the heart that formed post
mortem will be easily removable with forceps
and not tightly adherent to the endocardium
or valves, which suggests an organized (antemortem) thrombus (Figure 30.4d). For his­
tology, in small reptiles, the entire heart canbe submitted in formalin; otherwise, sample a
1‐cm transverse section across the ventricles,
plus any lesions.
Respiratory System
Incise the lung(s) along their length andinspect the lumen and mucosal surface.
Normal reptile lungs at necropsy are pink topale red (depending on how congested withblood they are) and spongy with a central
lumen free of any exudate. In reptiles thathave been euthanized with pentobarbitone,
died an agonal death, are septicaemic or haveheart failure, the lungs may be dark red (mark­edly congested) and contain watery to foamy,
possibly blood‐tinged fluid (oedematous).

Necropsy

Figure 30.2 External examination of the
carcase. (a) Patchy reddening of the skin ina snake with bacterial septicaemia. Notealso caseous oral exudate. (b) Superficiallyintact plastron in which a layer of keratinoverlies severe caseous necrosis (inset).
Note also patchy reddening of the skinsuggesting concurrent bacterial
septicaemia. (c) Flaky, brown keratin in asnake with superficial fungal skin infection.
(d) Unilateral submandibular swelling in a
lizard. Dissection reveals a large, aged,
chronic, inflammatory focus of caseous
exudate with typical laminated appearance(inset). Note also the generalized
reddening of other tissues of the neck due
to suffusion of haemoglobin pigment inthis moderately autolysed carcase.

(a)

(b)

(c)

(d)

413

(a)

(c)

(b)

(d)

(e)

Figure 30.3 Opening the carcase. (a) Venomous or unidentified species of snakes should have the headremoved as the initial step of the necropsy. The scalpel is turned upward during ventral midline incision tominimize the chance of inadvertently cutting into underlying organs. (b) Lizard opened ventrally with bodywall removed. The internal viscera are being removed in one piece by placing traction on the dissected neckstructures and using scissors to cut through dorsal connective tissue attachments. (c) Plastron removal from alarge sea turtle by cutting the skin at the junction with the plastron and using knife to sever connective tissue
attachments of the lateral plastron to the carapace. (d) Sawing through bony lateral plastron attachment of a
freshwater turtle. (e) Once the skin and lateral connective tissue or bone attachments of the plastron aresevered, the underlying tissue attachments are cut close to the plastron as it is elevated.

Necropsy

(a)

(b)

(c)

(d)

Figure 30.4 Cardiovascular system. (a) Ecchymotic haemorrhages in the connective tissue at the base of theheart (arrow) in a snake with acute Gram‐negative septicaemia. (b) Fibrinopurulent pericardial exudate in a
crocodile with subacute Gram‐negative septicaemia. The pleura (arrows) and hepatic serosa are moist, cloudy
and thickened. (c) Cloudy, moist epicardium with petechial haemorrhages in a sea turtle with Gram‐negative
septicaemia. (d) Multiple irregular, fibrinous nodules adherent to the atrioventricular valves (arrows) in a sea
turtle with bacterial septicaemia.

If exudate or nodules are noted on initial
incision of the lung (Figures 30.5a–c), a swabor tissue for bacterial and/or fungal culture
should be taken aseptically from an unopened
portion of lung. Incise the air sacs (if present)

and inspect for thickenings or exudate.
Palpation of the lungs is a good method todetect inconspicuous nodules or fibrousscarring (Figure 30.5c). Use fine scissors to
cut along the length of the trachea to the

415

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Reptile Medicine and Surgery in Clinical Practice

(a)

(b)

(c)

(d)

Figure 30.5 Respiratory system. (a) Multifocal to coalescing caseous foci in pulmonary infundibulae in a
crocodile with fungal pneumonia. (b) Scattered, discrete, small granulomas in a crocodile with pulmonary
mycobacteriosis. (c) Two large, irregular foci of firm white pulmonary fibrosis in a sea turtle with chronic
mycobacterial infection. (d) Transverse section of the nasal cavity revealing copious yellow exudate in left sideof nasal cavity in a sea turtle with fungal rhinitis.

glottis, looking for haemorrhage, exudate
or obstructions. If there is a suspicion ofabnormalities of the nasal sinuses, these canbe exposed using rongeurs or a hacksaw andsampled for culture or molecular testing
using a swab (Figure 30.5d). An intact sectionof the sinuses (large reptile) or the entire
head (small reptile) should be included forhistological evaluation.

Liver and Biliary System
The normal colour of the liver can varyconsiderably depending on the metabolicstatus of the reptile, the degree of hepaticcongestion and the state of decomposition(Figures 30.6a,b). Thin reptiles will often
have a relatively dark red‐brown liver, owing
to hepatocellular atrophy and absence of

(a)

(b)

(c)

(d)

(e)

(f)

Figure 30.6 Liver and biliary system. (a) Liver of a captive sea turtle in good body condition showing
reticulated pattern due to combined effect of diffuse moderate lipidosis (pale pink colour) and mid‐zonal
congestion (darker pink colour). (b) Dark green, atrophic liver of a thin, chronically injured free‐ranging sea
turtle. (c) Markedly enlarged gall bladder and adjacent bile duct due to cholelithiasis in an aged lizard.
Histologically, the adjacent liver exhibited lipidosis and mild fibrosis but appears grossly dark owing tomoderate numbers of parenchymal melanomacrophage clusters. (d) Multiple, small, caseous hepatic foci in a
crocodile with embolic fungal infection. (e) Pale, indistinctly mottled, friable, fibrinonecrotic liver of a snakewith overwhelming acute Gram‐negative septicaemia. (f ) Numerous discrete, raised, pale hepatic nodules insnake with hepatic neoplasia.

418

Reptile Medicine and Surgery in Clinical Practiceglycogen and lipid. A mild to moderate
degree of hepatocellular lipid is usuallyconsidered within physiological normal in
reptiles and imparts a light brown or pinkcolour to the organ, sometimes with azonal pattern (Figure 30.6a). Congested
liver appears redder than it would other­wise. With decomposition, the liver may
take on a pale greyish‐brown or greenish
hue. Melanomacro­phages may accumulate
in the liver, kidneys and spleen, particularly
with age, and impart a grey or black hue orfine speckling to the organs (Figure 30.6c).
The liver should be inspected for evidenceof embolic showering of infectious organ­
isms from the blood, which manifests
as multiple pale or caseous foci scatteredthroughout the parenchyma (Figure 30.6d).
In bacterial septicaemia, the liver may befriable and irregularly mottled brownand pale red (Figure 30.6Ee). As in otherorgans, neoplastic masses in the liver may besingle or multiple and often appear pale andraised, replacing normal tissue (Figure 30.6f ).
The gall bladder may be enlarged if thereptile has been anorexic or if there isblockage due to choleliths (Figure 30.6c).
Urinary System
The kidneys are relatively easy to locate insnakes, being obvious elongate normally red‐brown lobulated organs in the caudal body
cavity. However, in lizards, crocodilians andturtles, kidney location may be more obscure,lying dorsally inside the pelvic girdle andcovered by adipose tissue and the peritoneal
lining of the body cavity (Figure 30.7a). As
with other organs, pallor can be suggestiveof either fibrosis (Figure 30.7b) or cellular
infiltration (Figure 30.7c). Fine pale streaking
following the lines of renal tubules or ducts
may indicate pyelonephritis (Figure 30.7b) orurate tophi (Figures 30.7c,d). In extreme
cases of urate nephrosis, the kidneys may
appear diffusely white (Figure 30.7e). If pre­sent, the bladder should be located andmucosa inspected.

Reproductive System
In reproductive females, check for yolk peri­
tonitis and egg binding and open the oviductto inspect the mucosa for reddening, ulcera­tion or exudate. The activity status of gonads
can be estimated grossly by the size of thetestes and degree of development of the ova.
Haematopoietic and Lymphoid
Tissues
The reptilian spleen varies from round to
ovoid or elongate, depending on species, andis generally located in the vicinity of the gas­
troduodenal junction, near the gallbladder,often closely approximated to the pancreas.
Normal splenic size and colour can vary con­siderably depending on the species (somespecies have primarily white pulp whileothers have white and red pulp), degree ofcongestion (enlarged and darker red whencongested) and activity (may be enlarged,
brown and meaty with lymphoid aggregatesvisible as indistinct pale foci when very
active). Inspect the spleen and liver for evi­
dence of embolic showering of infectiousorganisms. Bone marrow is relatively uncom­
monly examined in reptiles, either grossly or
histologically, therefore there is little known
regarding interpretation. However, if there isa suggestion from the clinical history or othernecropsy findings that there may be abnor­
malities of bone marrow, bone marrow sam­pling for histological examination should beconsidered. Bone marrow in reptiles is typi­cally interspersed with bone trabeculae at themetaphyses of long bones (or a rib in snakes).
To obtain a sample for histology, rongeurs ora saw can be used to expose the marrow andeither the entire end of the bone or a sectionof the metaphysis placed in formalin.
Gastrointestinal System
It is best to leave this relatively heavily con­taminated system until other internal organs
have been examined and sampled. Use scissors

Necropsy

(a)

(b)

(c)

(d)

(e)

Figure 30.7 Urinary system. (a) Juvenile sea turtle showing inconspicuous retroperitoneal location of
normal kidney (arrows) adjacent to the colon, underlying the immature ovary and oviduct. (b) Transverse
section through kidney showing pallor from fibrosis surrounding caseous exudate in collecting ducts(arrows) in a sea turtle with pyelonephritis. (c) Multiple fine, white, pinpoint foci and streaks visible on therenal surface in a crocodile with visceral gout. There was also marked renal interstitial lymphoidproliferation, imparting the diffusely pale pink colour. (d) End‐stage kidneys in an aged snake. There arepinpoint tan foci representing urate tophi surrounded by granulomas in collecting tubules. Histologically,
generalized interstitial fibrosis was also present, although the gross pallor typical of fibrosis is obscured
by marked renal infiltration by macrophages containing brown ceroid/lipofuscin (aging pigment). (e)Chalky, white, serosal and renal urate deposits in a lizard with severe visceral gout. The heart is to theright of the image, the kidneys to the left.

419

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Reptile Medicine and Surgery in Clinical Practiceor rongeurs to cut through the angle of thejaw to expose the oral cavity. Incise theoesophagus down to the stomach, inspecting
for ulcers, haemorrhages or other lesions.
When examining gastrointestinal mucosa,
lightly scrape mucus and sloughed cells
from the surface so that the mucosa can be

carefully scrutinized (Figures 30.8a,b). Intes­
tinal lesions can often be appreciated byrunning the loops through fingers to detect
irregularities, adhesions (Figure 30.8c) or
haemorrhage (Figure 30.8d). Cuts should bemade in several segments along the length of
the intestine and the mucosa examined.

(a)

(b)

(c)

(d)

(e)

Figure 30.8 Gastrointestinal tract. (a) Normal pale, pink, shiny, smooth mucosa of lizard duodenum revealed
by gently wiping the luminal mucus and sloughed cells from the surface. (b) Multiple red gastric ulcers
overlying areas of mucosa that are raised and pale in a crocodile with lymphoproliferative disease. (c) Serosal
reddening, thickening and light fibrous adhesions between intestinal loops in a crocodile with transmuralcoccidiosis. (d) Segmental enlargement and serosal haemorrhage in a sea turtle with severe bacterial enteritis.
(e) Intestine from previous figure opened to reveal mucosal necrosis and copious caseous exudate. Notenormal, partially pigmented intestinal mucosa to the right of the affected segment.

Necropsy

Musculoskeletal Systemshould be opened and examined for exudate
or bone irregularities (Figure 30.9c). Muscle
in reptiles is generally white to pale pink andcan be examined grossly by cutting throughlarge muscle groups and inspecting them forvariations in colour or texture (Figure 30.9d).

Comparison of the shape of bones and jointsof the left and right sides of the body is use­
ful to determine whether abnormal asym­
metries exist. Particularly in young reptiles,
bone density should be assessed by manuallyattempting to bend bones without having
them break, which is suggestive of metabolicbone disease, and may occur in the absenceof visible bone deformity (Figure 30.9a). If
abnormalities of the vertebral column aresuspected, good visualization of the ventral
vertebral column can be achieved by removalof all the viscera and inspection from inside
the body cavity (Figure 30.9b). A few joints

Although gross examination of the brain istypically unrewarding in reptiles, the brain
should be exposed or removed and submit­
ted for histological examination, particu­
larly if the necropsy has been otherwise
completed and a diagnosis has not yet beenreached (Figure 30.10a,b). If neurological

(a)

(c)

(b)

(d)

Nervous System

Figure 30.9 Musculoskeletal system. (a) Juvenile crocodile with metabolic bone disease. The jaws can be easily
bent without breaking. (b) Viscera removed from juvenile crocodile with metabolic bone disease to reveal afibrous callous (arrow) and haemorrhage of ventral vertebral bodies due to pathological fractures. (c)Fibrinocaseous exudate in the shoulder joint of sea turtle with septic arthritis. (d) Transverse section of theproximal tail of a snake with red‐brown discoloration of muscle, connective tissue and the hemipenes due tothe combined effects of heterophil infiltration, coagulation and liquefactive necrosis and bacterial overgrowthin necrotic tissue. The primary pathogenesis was suspected to be septic thrombosis.

421

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Reptile Medicine and Surgery in Clinical Practice(a)of vertebral column (small reptiles) or todissect out segments of spinal cord (large
reptiles) for formalin fixation and histology.

­ ample Collection andS
Submission to the
Laboratory for Ancillary
Testing(b)

Figure 30.10 Brain removal. (a) Use of fine, sharp,
pointed rongeurs for careful dissection of the head
to expose the brain in a small snake. Once thecalvarium is removed, the brain can be fixed in situ
in formalin. (b) Brain of a sea turtle exposed using
three cuts with a hacksaw. The head is then tilted so
the brain gently ‘spills out’ under gravity as theventral attachments are carefully cut.

disease is suspected, a parasagittal sectionof fresh brain should be sampled and stored
frozen for possible other ancillary testing. If
clinical signs specifically referable to thespinal cord were present, use rongeurs or asaw to either remove entire 1–2 cm sections

A definitive diagnosis is not usually reachedfrom gross examination but rather a refined
list of differential diagnoses is obtained,
which then necessitates more definitive
ancillary testing. The appropriateness andquality of samples taken at necropsy will
directly influence the value of laboratory
results obtained. Table 30.2 provides sam­pling details for a variety of tests andBox 30.1 gives a suggested minimal list of
samples to take routinely during a diagnos­
tic necropsy. Particular tests performed at
the laboratory and test results may varysignificantly depending on the amount ofdetailed information about the case pro­vided to the laboratory.
For transport of formalin fixed samples,
depending on the method of transport
being used (ground or air, regular mail orcourier), the formalin may need to bedrained from the jar and tissues wrapped informalin‐soaked gauzes and outer sealed
plastic bag used to prevent leakage duringtransport. If this procedure is used, it isessential that the tissues are thoroughly
fixed prior to transport.
Fresh (refrigerated or frozen) samples need
to be transported to the laboratory in a small
cooler with ice bricks, with transport timeless than 24–48 hours (depending on theambient temperature). In many cases, thespecific ancillary tests indicated on fresh
samples are unknown before histologicalexamination, in which case, the samples canremain frozen at the clinic until a decision on
further testing is made.

Table 30.2 Sampling for various types of ancillary necropsy testing.
Test

General comments

Specific sampling notes

Histology

Primary routine ancillary testing.
Submit a standard broad range of tissues, even
if they appear grossly normal.
Sample any lesions and describe them to thepathologist.
Sample any margins of lesions with normal
tissue.

Preserve tissues in formalin (10% phosphatebuffered) at 1 : 10 tissue to formalin ratio.
Tissues may be mixed in one jar.
Tissues should generally not exceed 1 cm indiameter.
For small reptiles, entire ‘pluck’ of tissues inbody cavity can be removed as one pieceand placed in formalin.
For very small reptiles (< 1 cm body
diameter), after opening body cavity, wholecarcase can be placed in formalin.
Inject formalin into unopened intestine andeyes.
Store formalin‐fixed samples at room
temperature.

Cytology

Not routinely performed when necropsy tissues
for histological evaluation are available.
Organ impressions may be useful in
conjunction with histology to provide cellulardetail or detect organisms.
In some cases, cytology performed by theclinician may provide sufficient diagnostic
information.

Slides are fixed in methanol and usually
stained with Wright’s type rapid stain
Additional diagnostic potential can beobtained by use of Gram’s stain for bacteria
and periodic acid‐Schiff stain for fungi.
Smears are destroyed by formalin fumes(keep separate).

Bacterial and Minimize contamination as it will influence
culture results or confound interpretation.
fungalSome bacteria (e.g. Mycoplasma spp.) require
culturespecialized storage media and culture
conditions (contact laboratory).
Accurate anaerobic culture requires use of
specialized swabs or immediate transport ofsample to laboratory.
For fungal culture, tissue samples are generally
better than swabs.
If you have sampled a heavily contaminated site(mouth, intestine), advise the laboratory of thebacterial species of interest.
If Salmonella spp. is suspected, request specificculture.

Aseptically sample filtering organs as soon
as the body cavity is opened (liver, kidney,lung and spleen).
Sterilize instruments with flame before
taking samples.
Sample 1‐cm or larger pieces of tissue into
individual sterile vials.
Moisten small (< 5 mm) pieces of tissue
with normal saline.
Use swabs in bacterial transport medium
for exudates.
Store refrigerated (a few days) or frozen.

Molecular
testing

Polymerase chain reaction and/or genetic
sequencing.
Commonly used for detecting reptile viruses.
May also be used for fastidious bacteria andfungi.
Tests are specialized and may only be available
at research laboratories.

Generally, fresh tissues or plain swabs canbe used (contact laboratory).
Moisten small (< 5 mm) pieces of tissue andswabs with 0.9% saline solution.
Store refrigerated (a few days) or frozen.
Testing of formalin‐fixed, paraffin embedded
tissues may be possible but is not ideal.

Virus
isolation

Specialized testing, usually requiring reptilian
cell lines.
May take weeks or months.
Isolates require further testing for identification.
Generally pursued only by researchers looking
for novel viruses.

Generally, fresh tissues or plain swabs canbe used.
Moisten small (< 5 mm) pieces of tissue andswabs with 0.9% saline solution (or specialized
viral transport medium if available).
Store refrigerated (a few days) or frozen.

Serology

Testing for antibodies to a specific disease.
Not commonly used due to poor or unreliable
reptilian humoral response.
Limited availability for only a few diseases(contact laboratory).

Useful serum or plasma may be obtained
from carcase blood after death (as long as
there is minimal decomposition).
Store refrigerated (a few days) or frozen.
(Continued)

424

Reptile Medicine and Surgery in Clinical PracticeTable 30.2 (Continued)
Test

General comments

Specific sampling notes

Parasitology

Identification of parasites may be bymorphological or molecular means.
Availability of testing may be poor
(contact laboratory).

Preserve helminths and arthropods in 70%
ethanol.
Gross examination and faecal flotation for eggs
are generally more sensitive for identi­ficationof helminth infections than histology.
Histology is more useful for detecting
protozoal infections.
Make a blood or lung impression smear if
haemoparasitism is suspected.

Toxicology

Specialized testing by referral laboratories.
Laboratory needs to be advised which toxin(s)to test for.
Interpretation of significance of results may bedifficult.

Sample type required depends on toxin
suspected.
Common samples are liver, kidney andstomach contents.
1–5 g of tissue or material may be required.
Store frozen.

Haematology May be useful under some necropsy
circumstances to clarify gross or histologicaland clinicalfindings (e.g. hypocalcaemia, anaemia, hepatic
chemistry
necrosis).

Only samples taken prior to euthanasia or fromcarcase within minutes of death can be used.
Lithium heparin anticoagulated blood
sample can usually be used for bothhaematology and clinical chemistry.
Store whole blood under refrigeration.
Store serum and plasma refrigerated(few days) or frozen.

Box 30.1 Suggested minimal routine diagnostic necropsy samples.
For Histological Examination(fixed in 10% formalin, stored at room
temperature)
Essential:
lung
heart
●● liver●● spleen●● kidney●● brain●● any grossly abnormal tissues or lesions.
●●●●

Plus, if the carcase is fresh:
stomachpancreas●● duodenum●● jejunum●● colon.
●●●●

Plus, depending on suspected disease:
reproductive organs
segments of spinal cord●● bone (metaphysis with marrow and growthzone).
●●●●For other ancillary testing(stored under refrigeration for a few days,
otherwise frozen)
A 1‐cm2 piece (or as large as available) of:●● liver●● kidney●● lung●● spleen●● pieces or swabs of any abnormal tissues orlesions.
●●­Reference
Johnson‐Delaney, C. (2006) Zoonoses andthreats to public health, in Reptile Medicine
and Surgery,.), 2nd ed. (D.R. Mader, ed).

Elsevier Saunders, St. Louis, MO,
pp. 1017–1030.

425

31
Reptile Parasitology in Health and DiseaseJan Šlapeta, David Modrý and Robert Johnson­Introduction to Parasites
Internal and external parasites occur com­monly in captive and free‐living reptiles anda parasitological examination should be partof every clinical examination. Once a parasite
is identified, determine whether the parasite
requires elimination, management or notreatment. Parasites are associated with adiverse range of clinical signs, including
anorexia, pica, prolapse, regurgitation, diar­rhoea, constipation, lethargy, weight loss anddeath. A thorough parasitological examina­tion is paramount to the formulation of adiagnosis and treatment plan.

­Practical In‐Clinic Diagnostics
A routine parasitological examination should
address the three most commonly affected
systems, the gastrointestinal tract, the res­piratory tract and the skin. In the case oflarge collections, inspecting all individuals
may not be possible. Animals with obvious
clinical signs should undergo a thoroughclinical examination. Gastrointestinal para­sites are routinely detected by examination ofa fresh faecal sample. Parasites from therespiratory system may also be observed in
faeces due to migration from the pharynx
into the gastrointestinal tract.

The gastrointestinal system is commonly
inhabited by a variety of parasites (Figures
31.1–31.6). Similar to birds, reptiles have acloaca through which the faecal sample isexpelled together with urates and urine.
Reptile owners should be instructed to collect
only the moist part of the faecal matter. Faeces
should be stored in a disposable container orsmall Ziplock® bags. All containers should belabelled with the reptile’s identification anddate of collection. A sample size of 1–2 g issufficient for most parasitological tests, but
repeated testing is recommended to rule out
false negative result due to shedding intermit­
tency. If multiple reptiles are housed together
and individual identification is not possible, acollection of pooled faecal samples over sev­
eral days should be collected into a single
container. If an individual is to be examined,
it should be separated temporarily and placed
either into a clean enclosure or a linen bag
for defecation. Faeces should be stored
at 10–20 °C and examined within 48 hours.
Refrigeration is usually not required.
For a routine respiratory examination, apharyngeal swab for detecting parasites
should be carried out on any animal that has
been recently introduced to the collection,
quarantined or is showing respiratory signs.
Pharyngeal swabs will aid in differentiating
lungworms (Rhabdias spp.), causing a respira­tory infection, from Strongyloides species,

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

426

Reptile Medicine and Surgery in Clinical Practice

(a)

(b)

(c)

(d)

20 μm

Figure 31.1 Nematode eggs commonly encountered in faecal samples of reptiles I. Ascarid egg from
Heosemys spinosa (a) and from Morelia viridis (b). Heterakid egg from Agama finchi (c) and from Goniurosaurus
huuliensis (d). Note the smooth outer egg wall surface of heterakid eggs compared with the ascarid eggs
(arrowhead). Heterakids are typically in lizards such as geckoes and agamas.

detected in the faeces, that may be causing
intestinal disease.
Blood parasitism is relatively frequent in ani­mals from the wild, but the clinical significanceis low. Blood parasites found in blood smears
are usually considered an incidental finding.
Ectoparasitism is relatively easy to diagnose
if heavy burdens are present; low burdens
are much harder to detect (Figure 31.7). Mites
are photophobic and consequently favour
hiding under scales, in skin folds, heat sens­
ing pits and around the periorbital con­junctivae. Detection is aided by the use of amagnifying glass or otoscope.
Necropsy may reveal previously undiag­
nosed or subclinical parasitic infections, inparticular Cryptosporidium and Entamoeba.

Gross lesions, such as thickening of the gas­
tric rugae, suggest gastric cryptosporidiosis;
similarly, ulceration and necrosis of the liverand intestine suggest amoebiasis. Fresh t­ issue
samples, including liver, stomach and intes­
tine, placed in buffered 10% formalin, should
be submitted for histopathological examina­tion. Fresh tissue from affected organs should
also be collected and immediately frozen incase molecular diagnostic testing is required(i.e. DNA isolation and diagnostic polymer­
ase chain reaction, PCR).
Some parasites are not detected at grossexamination; these include tissue protozoans(Sarcocystis), larval stages of helminths(plerocercoids/spargana, acanthocephalans,
spirurid larvae, pentastomids) and filaria

Reptile Parasitology in Health and Disease

(a)

(b)

(c)

(d)

20 μm
(e)

(f)

Figure 31.2 Nematode eggs commonly encountered in faecal samples of reptiles II. Capillaria eggs fromAcanthosaura nataliae (a) and Python regius (b). Note the typical barrel‐shaped eggs with polar plugs of capillaria
eggs. Strongylid eggs from Goniurosaurus huuliensis (c) and Corallus caninus (d). Note the presence of unsporulated
Caryospora species oocysts (arrow, D). Mucus from the mouth with eggs (e) and larvae (f) of Rhabdias species from
Pantherophis obsoletus. (images E and F courtesy of Dr Frank Mutschmann, Exomed, Berlin, Germany).

that are present on the serosa of pleuroperi­
toneal cavity (Figure 31.8).

­ verview of Faecal Sample
O
Diagnostic Techniques
A direct microscopic examination of a
faecal smear is a simple and efficacious­
diagnostic test for detecting moderate to
heavy parasite burdens: most nematodeeggs (10× objective); coccidia, Strongyloides/
Rhabdias eggs (20×); Cryptosporidium andflagellates (40×). Flota­tion is a concentra­tion technique and in the case of low bur­dens may detect parasites not revealed indirect smears.

Test samples may need to be submitted
for specific parasites, e.g. Entamoeba and
Cryptosporidium. Some commercial laborato­
ries offer reptile parasite specific PCR, although
the use of a domestic animal PCR panel may besuitable for Giardia and Cryptosporidium, as
they are often not species specific and may
amplify reptile specific species. Alternatively,
direct fluorescence antibody testing for
Cryptosporidium of humans, which is based on
monoclonal antibodies, commonly recognizes
antigen on reptile parasites. Veterinary diag­nostic laboratories should be contacted toenquire about the availability of testing, includ­ing Entamoeba (E. invadens) diagnostics, which
are particularly problematic, with specific PCR
being the most reliable option.

427

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Reptile Medicine and Surgery in Clinical Practice

(a)

(d)

(b)

(e)

(c)

(f)

50 μm
Figure 31.3 Nematode eggs commonly encountered in faecal samples of reptiles III. Pinworm/oxyurid eggs
from Iguana iguana (a), Testudo hermanni (b), Goniurosaurus huuliensis (c), Uromastyx acanthinura (d), Agama
finchi (e) and Eublepharis macularius (f ). Pinworms are highly species specific and their eggs possess a smoothwall and one side is more concave than the other. Operculum is often visible (arrows).

Sedimentation may be requested for heavy
eggs but is rarely required in clinical settings.
If the veterinary practice is not confident in
performing sedimentation, it is best to con­tact the local diagnostic service.

­What to do With
Parasitological Results?
Microscopical examination should aim to
identify the principal structure and featuresof parasitic stages. Identification to species
or genus level will be, in most cases, impos­
sible or even unnecessary. The common par­asitic stages and parasites are demonstrated
in Figures 31.1–31.8. For parasites and eggs infaeces, note the size, colour and organizationof the wall to guide identification. It is impor­tant to note the frequency and load of theparasites. For microscopic specimens, noting
less than 10 (+),10 to less than 50 (++) andover 100 (+++) per field of view at 10‐times
magnification would be a suitable approach
to rank parasite load. At least annual moni­
toring and recording of parasite loads isrecommended.
Determine whether the structures observed
are true parasites causing harm to the animalor harmless parasites from a prey item.
Insectivorous and carnivorous reptiles will
excrete intact parasite stages originating fromthe insect or animal fed to the reptile. These
parasites are specific to the prey and are termed
pseudoparasites (Figure 31.9). A negative test
result in a sample collected 24–48 hours

Reptile Parasitology in Health and Disease

(a)

(b)

(c)

(d)

100 μmFigure 31.4 Pentastomid (tongue worms) eggs of reptiles. Pentastomid and spirurid (arrowhead) in Varanus
species (a). Pentastomid eggs from Goniurosaurus huuliensis (b). Pentastomid and oxyurid (arrowhead) eggs in
Goniurosaurus luii (c). Detail of the pentastomid larvae within the eggs with the typical four pair of V‐shaped
claws (arrows; d).

later from the same animal would confirm
transitory status. Pollen and plant material aswell as chitin‐based structures of insects may
also be confused with parasites. Faecal sam­ples should be fresh, since samples in contact

with the enclosure substrate may be quickly
contaminated with free‐living non‐parasitic
nematodes and their larvae, complicating theaccurate identification of strongylid and rhab­
ditid nematode parasites.

Questions to Ask the Client
What is the animal fed?
This question is asked to rule out the possibility of pseudoparasitism and whether the dietis the source of the parasites. Examination of
faeces of the prey (e.g. rodents, insects) may
reveal coccidia that appear in the faeces ofthe snake or lizard, as they are not digested.
Similarly, rodent mites and their eggs may
appear in faeces of snakes.
●● Where does the animal live?
●●

Is the animal housed with other reptiles?
Does the enclosure have any contact withpotential sources of parasites or the outsideenvironment?
Also consider:●● Is the parasite capable of causing the clinicalsigns?
●● Is the parasite capable of completing its
life cycle within its enclosure or captive
environment?
●●
●●

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Reptile Medicine and Surgery in Clinical Practice

(a)

(b)

(c)

(d)

Figure 31.5 Miscellaneous eggs. Capulotaenia species from Morelia viridis (a). Oochoristica species from
Iguana iguana (b). Operculated trematode eggs from Furcifer pardalis (c). Spirurid egg with coiled larva inside(Abbreviata sp.) from Uromastyx species (d).

­Parasites Associated with Disease
Parasites of reptiles are numerous; neverthe­less, only a handful of parasite groups and par­asite species attract veterinary attention
Table 31.1 outlines the biology and the signifi­
cance of the major parasites of reptiles. Other
parasites not listed represent those that are
only rarely associated with disease. Flagellates
and ciliates (Nyctotherus spp.) are commonly
encountered; however, they probably play only
a secondary role to a primary disease process.
Gastric and Intestinal
Cryptosporidium Species
Cryptosporidium species (Apicomplexa) areprotozoan parasites, which in acute cases

cause regurgitation and diarrhoea and inchronic cases regurgitation and anorexia.
In snakes, postprandial regurgitation is afrequent sign of gastric cryptosporidiosis
caused by C. serpentis. Lizards are more
frequently clinically affected by intestinal
cryptosporidiosis caused by C. varanii (syn.
C. saurophilum). Infected reptiles will shedresistant oocysts. Transmission is via thefaecal and oral route, specifically by the inges­
tion of oocysts. Many chronically infected
reptiles will shed oocysts for life.
Gross lesions associated with gastric
cryptosporidiosis typically include marked
thickening of the gastric rugae, while intesti­
nal cryptosporidiosis is less pronounced. Antemortem diagnostics aim to detect oocysts inthe faeces, in gastric contents sampled byReptile Parasitology in Health and Disease

(a)

(b)

(c)

(d)

(e)

10 μm

(f)

(g)

10 μm

(h)

50 μm

Figure 31.6 Protozoa shed in reptile faeces. Sporulated oocysts of Isospora jaracimrmani each with two
sporocysts, from Chamaeleo calyptratus (a). Sporulated oocyst of Choleoeimeria species with four sporocysts,
from Hemidactylus brooki (b). Sporulated oocyst of Eimeria species with four sporocysts, from Heosemys
depressa (c). Isospora species from Nactus species (d). Sporulated oocyst of Caryospora species with a single
sporocyst, from Naja haje (e). Size comparison of sporulating oocysts of I. jaracimrmani and two oxyurid eggs,
from Chamaeleo calyptratus (f ). Oocysts of Cryptosporidium species from Goniurosaurus luii (g). Cyst for of aciliate Nyctotherus species from Uromastyx species (h).

gastric lavage or in a surgical biopsy. Reptile
species are distinct from those affecting
humans, nevertheless they share the same
oocyst epitopes and tests for human crypto­
sporidiosis based on fluorescently labelled
antibodies binding to the oocyst wall aresuitable for detection. Veterinary diagnostic
laboratories frequently offer tests based on
antibody labelling of Cryptosporidium
oocysts. Alternatively, species specific PCR
for reptile cryptosporidia and multiplex PCR
may also be used. As there is no effective
cure, euthanasia of clinically affected reptiles
is recommended. Quarantine and repeatedtesting are recommended for newly acquired

reptiles. No effective household disinfect­
ant is effective against Cryptosporidium,
although oocysts are highly susceptible toheat and drying.
Intestinal and Biliary Coccidiosis
Coccidiosis is caused by multiple different
genera including Isospora, Eimeria,
Choleoeimeria, Caryospora and Sarcocystis(Figure 31.6). Coccidia (Apicomplexa) com­monly develop in the gastrointestinal tract of
reptiles (e.g. Isospora). Some species affect
the gallbladder and associated bile ducts (e.g.
Choleoeimeria). Coccidia are very common

431

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Reptile Medicine and Surgery in Clinical Practice

(a)

(b)

(c)

500 μmFigure 31.7 Mites on reptiles. Snake mite (Ophionyssus natricis) engorged adult (a). Abdomen of
Acanthodactylus lizard with moderate infestation with mites (b). Trombiculid mites (chiggers) on Ptyodactylus
gecko (c).

parasites and oocysts are found on direct
smear or faecal floats of lizards and snakes.
Oocysts of Isospora, Eimeria, Caryospora areenvironmentally resilient and shed unsporu­
lated, requiring several days to sporulate inmoist faeces. They can directly infect thesame host species. Differentiation to genus
level in the unsporulated state is unreliable.
The only oocysts to be shed already sporu­
lated are those belonging to Choleoeimeria
and Sarcocystis, a genus of coccidia which
cycles between predator and prey (indirect
lifecycle) and thus do not complete their life­
cycle in captive environments.
Detection of oocysts does not immediately
indicate the presence of disease. Coccidiosis canbe a serious problem in intensively reared rep­tiles such as bearded dragons and chameleons.

Young animals will often present emaciated.
Separation of the adult reservoirs fromyounger animals is recommended. Treatment
with toltrazuril or sulfa‐drugs can be consid­
ered; however, in chronically infected animals
treatment is less effective because of the highprobability of reinfection.
Intestinal and Liver Amoebiosis
Caused by Entamoeba invadens
The protozoan parasite Entamoeba invadens(Amoebozoa) causes severe vomiting, anorexia
and diarrhoea. Snakes are more susceptible
than other reptiles. In large snakes, amoebia­
sis can quickly reach epidemic proportions if
not diagnosed early. Transmission is faecal andoral, by the ingestion of the environmentallyReptile Parasitology in Health and Disease

(a)

(b)

(d)

(e)

(c)

(f)

Figure 31.8 Skin nodules with parasitic stages. Larval stages of helminths as seen on the skin of snakes.
Extraction of an acanthocephalan (thorny headed worm) (a, b) and microscopic image of theextracted parasite anterior ‘thorny’ part confirming its identity (c). Extraction of a tapeworm larval stage:
plerocercoid (spargana) through snake skin (d, e) and a necropsy image of spargana in the pleuroperitoneal
cavity of a snake (f ).

resistant cyst form. Importantly, turtles andsome herbivorous reptiles often remain
asymptomatic carriers and reservoirs of
E. invadens. The general recommendation isto separate turtles from snakes.
Lesions caused by E. invadens are confinedto the liver and the gastrointestinal tract.
Ulceration, necrosis and haemorrhage may
extend from the stomach to the cloaca.
Chronic cases of amoebiasis may involve mul­
tifocal abscessation of the liver. Ante mortem
diagnosis may be difficult as routine diagnos­
tic tests are not available. Tropho­zoites andE. invadens cysts may be difficult to observe in
direct faecal smears. E. invadens may be
detected using the emerging multiplex PCRtechnology on faecal samples. Diagnosis

should be promptly followed by treatment
with metronidazole. Strict hygiene and quar­antine measures must be observed. Testing
asymptomatic reptiles is recommended.
Anaemia and Emaciation Causedby Hookworms and Roundworms(Strongylid and Ascarid
Nematodes)
Roundworms (Ascarididae) and hookworms(Strongylidae) are significant parasites of thegastrointestinal tract of snakes and lizards.
Heavy burdens may lead to gastrointestinal
inflammation, haemorrhagic ulceration anddeath. Ophidascaris species (Ascarididae)
and Kalicephalus species (Strongylidae) are

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Reptile Medicine and Surgery in Clinical Practice

(a)

(b)

20 μm

(c)

(d)

50 μm

Figure 31.9 Pseudoparasites encountered in reptile faeces. Coccidia of insects can pass through theintestinal tract of reptiles, typical insect coccidian oocysts possess eight round sporocysts, Adelina grylli
frequently parasitizes common cricket (Gryllus sp.) fed to lizards (a). Faeces of reptiles are a rich source ofnutrients for free‐living nematodes that rapidly invade faeces that is left on the enclosure substrate. In
such faeces, the presence of free‐living nematodes needs to be ruled out. A free‐living nematode crumbled
in the flotation solution (b). Rodents from pet stores are often parasitized by mites. Their exoskeletons andeggs will pass in faeces intact and need to be recognized as parasites of the prey, not as parasites of thereptile (c, d).

frequently found in reptiles. Several othergenera are also present such as Angusticaecus
in tortoises (Testudo). In clinical practice,identification to genus level is usually not
required. Most ascarid eggs are elongated,brownish yellow and have a thick wall
(Figure 31.1). Hookworm eggs are moreelongated, often colourless and thin walled,containing either blastomeres or (later) coiled
larva (Figure 31.2). The life cycle of hook­worms is usually direct with the potential tobuild up heavy burdens within the enclosure.

Even though some species of hookworm
do have an indirect lifecycle, because of
the difficulty of identification to a species
level, it is recommended to consider thatmost have a direct lifecycle and low hostspecificity.
Management of roundworm and hook­worm infestation involves frequent and com­plete removal of faeces from the enclosureand treatment of the affected reptiles using
repeated doses of ivermectin or fenbenda­
zole followed by retesting.

Reptile Parasitology in Health and Disease

Table 31.1 Selection of important reptile parasites and parasite groups.
ClinicalsignificanceLife cycle

Pathology

Cryptosporidium spp.

★★★★

DirectFailure to thrive,
gastritis, enteritis

Coccidia (Isospora, Eimeria)★★

Direct (need to sporulate
outside the host)

Failure to thrive,
enteritis

Entamoeba invadens★★★★

DirectGastritis, ulceration

Rhabditida (Rhabdias)★★★★

Direct (established free living
population in soil)

Pneumonia

Rhabditida (Strongyloides)★★

Direct (established free living
population in soil)Enteritis

Oxyurida (different genera, species)★

Direct (need to embryonate
outside the host)

Beneficial in
herbivorous reptiles

Ascaridida (including ascarids andheterakids), Strongylida, Spirurida(different genera, species)★★★

Direct or indirect

Failure to thrive,
gastritis, enteritis

Pterygosoma spp.

★

DirectNone, dermatitis

Ophionyssus natricis★★★★

Direct (development in theenclosure)Anaemia, dermatitis★★

IndirectNone, zoonosis

Parasite

Protozoa:

Nematodes:

Acari:

Pentastomida:‘tongue worms’

Pneumonia Caused by Rhabdias
Species and Differentiationfrom Intestinal Strongyloides
Species
The nematode order Rhabditida is repre­
sented in reptiles by two genera: Strongyloides
and Rhabdias. Rhabdias commonly para­
sitizes the lungs of snakes, causing a vermin­
ous pneumonia. Clinical signs include open
mouth breathing and a frothy discharge
from the nares. Severe cases may be com­plicated by a secondary bacterial pneumo­nia. Strongyloides parasitize the intestine,
occasionally causing enteritis. Eggs ofRhabdias and Strongyloides are indistin­
guishable, so finding their eggs in faeces is
not conclusive. Diagnosing verminous pneu­
monia is in most cases straightforward by
the detection of larvae and eggs in a throatswab (30 × 60 µm, thin walled with embryo­nated larva) of Rhabdias under a microscope(Figure 31.2).
Rhabditida are significant parasites ofsnakes because they complete their lifecyclein the reptile enclosures. Larvae shed into theenvironment and develop into free‐living
adults, which produce new eggs that hatch
into larvae and subsequently penetrate theskin of the snake. Within the reptile host, thelarvae will migrate either to the lung
(Rhabdias) or intestine (Strongyloides) anddevelop into hermaphroditic females thatwill produce the next generation of eggs.
Eggs and larvae of Rhabdias are moved up
the trachea, swallowed and excreted with
­faeces. Rhabditida are highly fecund and canquickly produce a large free‐living population
within an enclosure, potentially spreading

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Reptile Medicine and Surgery in Clinical Practice

to neighbouring enclosures via shared equip­
ment. Management of a rhabditid infection
must include thorough and frequent cleaningof the enclosure. Snakes with verminous
pneumonia require individual treatment(levamisole, ivermectin, fenbendazole) andhousing in clean enclosures. A nonparticulate
substrate, such as newspaper, is recommended
to hamper maturation of the larval stage.
Secondary, often anaerobic, bacterial infec­
tion needs to be managed simultaneously(metronidazole). All reptiles, especially new
arrivals, should be checked for the presenceof rhabditida.
Non‐Pathogenic Pinworms(Oxyurid Nematodes) in
Herbivorous Reptiles
Pinworms (Oxyurida) are frequently present
in the lower gastrointestinal tract of her­bivorous reptiles such as lizards and turtles(Figure 31.3). Their presence is consideredbeneficial to the host, improving the passage
of ingesta through the intestinal tract.
Consequently, their complete removal may
negatively affect digestion. It is recom­
mended that only heavy burdens are treated.
Pinworms have a direct lifecycle and are
host‐species specific. Eggs are typically
ovoid, with a yellowish egg wall that is thickand smooth and, typically, one side is moreconcave than the other. Eggs possess an oper­
culum that may not always be clearly visible.
In insectivorous reptiles, the presence of pin­
worms and effect on the host is poorly
understood.
Anaemia and Emaciation Causedby Snake Mites
Ectoparasites are commonly found on cap­
tive reptiles and are a common reason forpresentation for veterinary examination. The
most significant ectoparasite of reptiles is the
blood‐sucking snake mite Ophionyssus natri­cis (Acari). Mite infestation may result inpoor skin shedding (dysecdysis), failure to
thrive, anaemia or even death. In captivity,

the snake mite is found on snakes more fre­quently than on lizards and rarely on chelo­nians. In suitable conditions, the snake mite
will complete its life cycle in one to two
weeks, quickly overwhelming the enclosureand the household.
The lifecycle of the mite is completed
within the reptile enclosure, with larval andlate nymph stages being free living. Early
nymph and adult stages are parasitic, aggres­sive and highly motile blood feeders. The
snake mites attach and feed underneath thescales, so a low burden can be difficult todiagnose. Careful inspection of the shed skin
aids identification of mite infestation. During
the week‐long engorgement, the mites
remain attached to the host and, after ingest­
ing a blood meal, they turn red in colour.
Engorged adults are approximately 1 mm inlength. The eggs are laid in dark and moist
crevices within the enclosure and require an
ambient temperature above 20 °C and morethan 85% humidity to hatch. Mites can becollected with the aid of a moistened cottonswab or sticky tape and are easily identified
microscopically (Figure 31.7). Mites preferdark and shaded areas, so the best chance ofthe reptile owner observing them is at night,
as mites will quickly retract to dark places if
exposed to light.
Infected reptiles may display unusual
behaviour. Snakes may spend a long time in
the water bowl or moving erratically within
the enclosure. Preferred sites on the reptile
for mite include the lower jaw, the heat‐sens­
ing pits, the periorbital region and the clo­aca. Careful health monitoring of newly
acquired reptiles and quarantine is manda­
tory in preventing infestation. Snake mites
are easily spread within and between collec­
tions. The snake mite lifecycle can be very
short, although the mites are hardy, remain­
ing in the environment for up to threemonths. Temperatures above 50 °C andhumidity less than 50% will kill mite stages;
alternatively, mites can be easily drowned, so
essential equipment and features within theenclosure can be fully immersed in water
overnight.

Reptile Parasitology in Health and Disease

Box 31.1 A mite management plan.
1) Isolate and treat reptiles within a simple
hygienic enclosure where all components
can be easily cleaned until the reptiles are
deemed free of mites.
2) Clean, scrub and wash enclosures with waterhotter than 50 °C and discard all substrates
and non‐essential cage furniture.
3) Thoroughly clean the room(s) where infected
reptiles are housed, including any husbandry
equipment, to minimize the potential presence of free‐living mite stages.
4) Maintain isolation and quarantine for atleast three months.

Drug treatment

Treatment of a mite infestation must
address both mites on the host as well as
all free‐living stages. Free‐living stages
may remain outside the reptile enclosureand may serve as a reservoir for persistentreinfection. A management plan (Box 31.1)
should include elimination of sources ofreinfection both from the outside as wellas inside the enclosures. The mite larvae
can temporarily infest humans and cause
skin irritation.

and blood vessels of tropical reptiles (e.g.
Foleyella in chameleons) and circulating
larvae (microfilariae) can be detected inperipheral blood smears.
Occasionally, eggs of pentastomids(tongue worms, Pentastomida) are detectedin the faeces of snakes, containing larva withdiagnostically typical four pairs of claws(Figure 31.4). Armillifer and Porocephalus
are both confirmed zoonotic pathogens.
Control in reptiles with antiparasiticide(ivermectin) is not fully effective and reptiles
often remain infected with the parasite
residing in lungs for life.
Some snakes will be presented with skinnodules that harbour either acanthocephalans(thorny headed worms, Acanthocephala) or
tapeworm (Cestoda) larval stages known as
spargana (plerocercoid) that may be surgi­
cally removed (Figure 31.8). Snakes usuallyacquire spargana from eating wild prey suchas frogs and rodents. Tapeworms of thegenus Oochoristica are commonly found in
the intestines of wild insectivorous andherbivorous reptiles (Figure 31.5). The life­
cycle of Oochoristica species includes
beetles and grasshoppers as intermediate
hosts. Oochoristica species may, there­
fore, establish within and be transmitted
within farmed reptiles, like green iguanas.
Treatment of adult tapeworms is recom­
mended (praziquantel).

Other Noteworthy Parasites
Heterakid nematodes (Ascaridida: Anisakidae)
occur in reptiles, sometimes in rather unusual
locations (e.g. the ear of African agamids).
Capillaria (Trichurida: Capillaridae) arecommon in reptiles from humid environ­ments and easily identified in faecal smears
from their typical barrel‐shaped eggs withpolar plugs (Figure 31.2). As the eggs aremorphologically almost identical to thosefrom rodents and birds, a determination
should be made as to whether they are trueparasites or pseudoparasites. Insectivorous
reptiles are commonly infected with spirurid
nematodes (Spirurida), localized usually tothe stomach. The eggs have a smooth andrelatively thick wall with coiled larva inside(Figure 31.5). Similarly, various species offilaria (Spirurida) do occur in the body cavity

Drugs used for treatment of mites include
fipronil and ivermectin.
●● Caution should be exercised when attempting to use pyrethrins, pyrethroids, organophosphates and carbamates because of theirhigh toxicity if overdosed.
●● Acaricides can be highly toxic if inappropriately used by reptile owners.
●● Refer to Appendix 1 for more detailed drug
information.
●●

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Reptile Medicine and Surgery in Clinical Practice

Reptiles can be infected by a range ofmites, some of which e.g. Pterygosoma cancomplete its lifecycle within the enclosure
and potentially cause harm. Ticks can be
encountered on reptiles that are exposed tothe outside or that are recently imported
from the wild. Interestingly, a tick,
Amblyomma komodoensis, imported with
Komodo dragons adapted to large terraria
can now be found on captive monitors inzoos throughout the world.

­Management of Parasite
Infections
To manage and eliminate a parasite infection
successfully, a thorough understanding of theparasite biology and environment of thecaptive reptiles is imperative (Figure 31.10).
For each parasite present, developing a plan
to eliminate environmental stages will beessential for successful parasite management.
For example, the enclosure’s soil needs to becompletely removed if Rhabdias/Strong­yloides are present, because they establish
free‐living population as the source of rein­
fective stages in the soil of the enclosure.
Similarly thorough cleaning of the entire
enclosure is imperative for eliminating
Ophionyssus that has a great capacity to sur­
vive and live outside its hosts and hide.
Application of antiparasiticides must be
in conjunction with the management of
the parasitic stages outside the reptile.
Antiparasiticides should be applied strategi­cally and their effect assessed by re‐testing.
Common antiparasiticides and dose rates for
reptiles are listed in the formulary. Ivermectin
is an effective antiparasiticide for lizards andsnakes but must not be used in chelonians
because of its potential neurotoxicity. An
integrated parasite management is the key tosuccess and prevention of reinfection. In
principle, it includes modification of theenvironment, use of antiparasiticides, regu­
lar testing and supportive care. In addition,
regular health screening and quarantine of
the collection is mandatory.

active movement to next enclosure

Free living multiplying
infective population

Direct life-cycle
Ophionyssus
Rhabdias/Strongyloides
Entamoeba
Cryptosporidium
Coccidia
reptile enclosure
householdskinfaecesenclosuresoil

Indirect life-cycle

CestodesTrematodes
Pentastomids
Nematodes (some)

Non-multiplying
infective stages

passive transfer to next enclosure

quarantine

Figure 31.10 Parasite pathways within, in and outside an enclosure. Resident stages serving as reservoir pool
are highlighted in red and arrows pointing out of the enclosure indicate potential for spread outside theenclosure. Locations of parasitic stages for principle parasite are colour coded for each direct lifecycle parasitic
group. For parasites with an indirect lifecycle, the black arrows indicate either faecal contamination withparasitic stages (outwards arrow) or transmission via food serving as an intermediate host or transfer host(inwards arrow).

Reptile Parasitology in Health and Disease

A reptile enclosure may appear to be a closed
system but there remain opportunities forpassive and even active movement of parasite stages from one enclosure to another(Figure 31.10), either through passive (fomites)
movement of infective stages on cleaning
equipment or cage furniture or from parasites
actively moving to an adjacent enclosure(e.g. Ophionyssus).

Parasites with an indirect lifecycle have
limited opportunity to parasitize captive
reptiles. However, these parasites can betransmitted via feeding equipment or in fooditems, such as free‐living rodents and birds,
fish, amphibians and insects. Identificationand elimination of the source is an integral
component of the parasite management.

Prevention is fundamental and should
be based on a knowledge of the diagnos­
tics, differentiation of the clinically sig­
nificant parasites from commensals andappropriate treatment plans and quaran­tine procedures. Veterinarians have theopportunity to play a significant role ineliminating the parasites before they enter
the enclosure. Establishing standard opera­
tions, diagnostic testing and client educa­tion will demystify parasitology for reptile
owners and improve reptile wellbeing.
Routine parasitological examination andgood record keeping will aid in the well­being of animals by either recognisingassociation with disease or more impor­tantly maintaining the balance between
the host and its commensals within thereptile enclosure.

­Further Reading
Mader, D. and Divers, S., eds (2014)
Current Therapy in Reptile Medicine
and Surgery. Elsevier Saunders,
St Louis, MO.

Schneller, P,. and Pantchev, N. (2008)
Parasitology in Snakes, Lizards andChelonians: A Husbandry Guide. Edition
Chimaira, Frankfurt am Main, Germany.

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32
Nursing the Reptile Patient
Gary Fitzgerald and Emma Whitlock­Reception
Making an Appointment
The initial telephone call is the start of any
diagnostic and treatment regimen, so it iswise to get as much information as possible
in a clear and concise format. Questions to
ask include:
What are the patient’s species and breed,
age and sex?
●● How long the client has owned the animal?
●● What is the appointment for?
●● Has the animal being seen by another vet
and, if so, for what condition(s)?
●● Is the animal receiving any medication?
●●

Ask the client to bring detailed information
about husbandry set‐up, particularly the substrate, enclosure temperatures, diet form andfeeding regimen, species interactions and soon. A concise history can take a significant
amount of consult time; this can often be
reduced by directing the client to an online
form for the client to complete and bringwith them to the appointment.
Digital photographs of the animal’s enclosure are useful. If the patient is an aquatic
species (e.g. a turtle), the client should bringa separate water sample (100 ml) from theenclosure. Any current medications should
also be brought to the appointment.

This is also the time to give any pertinent
information to the client about their appointment: timing and duration of appointments,
transport recommendations and fasting
periods if anaesthesia is likely.
Transportation
Reptiles should be kept at the preferred bodytemperature throughout transportation orat least immediately beforehand. Conversely,
dangerous or particularly aggressive or agile
reptiles may be easier to handle if they areslightly cool, but this should only be encouraged where deemed absolutely necessary(e.g. when dealing with highly venomous
snakes).
Appropriate transport containers varydepending upon the animal and condition.
Many reptiles are less stressed if carried insoft bags or pillow cases, especially in a soft
(polystyrene) or cardboard box (Figures 32.1
and 32.2) Venomous snakes should be transported in a double, locked container. Aquatic
turtles can be transported in a plastic bucketwith a wet towel under them.
The Waiting RoomThe reception area can create extreme stressfor reptile patients if they are subjected toprey–predator interaction during the waiting

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

442

Reptile Medicine and Surgery in Clinical Practiceperiod. Prey species should not be able tosee, hear or smell predator species so, ideally,
a separate waiting area should be available.
Alternatively, the client can wait in the consult room if necessary.

­Hospital Care
Reptile husbandry requirements can be very
species specific, however for a temporary
hospital stay most can be accommodated
effectively and relatively cheaply. There are a
few major factors to be considered.
Housing
The aim of housing reptile patients should be
one of reducing stress during the hospital stay.
Although most reptiles are predator species
themselves, they often fall under the prey
category when compared with the common
small animal patients (dogs and cats). For thisreason, it benefits all patients to house these
species separately. Similarly, different speciesof reptiles should be kept separately. For
example, housing a black‐headed python(Aspidites melanocephalus – a reptile eater) in
direct sight of a bearded dragon (Pogona spp.)
would not benefit either party. Other steps
that can be taken to reduce stress include:
keeping the patient in an area with lowhuman and animal traffic●● keeping the patient in a room with relatively stable temperature (but not overly
cold air conditioning)●● encouraging normal behaviour by offering
cage furnishings such as hides and branches.
●●

Figure 32.1 Transporting a reptile in a soft
cloth bag.

Figure 32.2 A polystyrene box fortransporting a snake.

Nursing the Reptile Patient

Hospital Enclosures
The design of the hospital enclosure is discussed
in Chapter 9. Some summary points are:Materials should be nonporous and easy
to clean. They should be able to retain
heat to help with temperature control
but still allow easy visualization of thepatient.
●● Heating can be achieved by many methods but the best method for hospitalheating is the use of heat lamps controlled
by a thermostat. Heating units such asheat rocks or mats produce localized heatin one area; a sick reptile is less able toregulate its own temperature and, unlessclosely monitored, may lie in an unheatedpart of the enclosure. Conversely, localized heating could also lead to burns if
the patient does not move away fromthem.
●● Lighting has a different function fromheating, although some heat lamps canemit bright light. Considerations include:–– Lighting will affect behaviour. Diurnal
species (e.g. bearded dragon) require
a day–night cycle of approximately 12hours to encourage natural behaviourand for visualization of food items. In
contrast, a nocturnal snake would
require an infrared bulb, as constantwhite light would be stressful and prevent normal behaviour.
–– Ultraviolet B lighting should also beoffered to diurnal and crepuscularreptiles.
●● Humidity
should replicate the naturalenvironment of where the reptile is found.
Humidity can be manipulated by:–– Removal of water sources, increased
ventilation and an absorptive substrate
can lower humidity.
–– Increased water bowl size, placing thewater bowl under the heat lamp, using
a soaked sponge (increased surface
area and evaporation), as well as misting from a spray bottle will increase
humidity.
●●

Substrate helps the reptile move around
while performing normal behaviour but itshould be absorptive of waste, easy toclean, unlikely to be consumed and notadhere to a wound. Newspaper is an excellent choice for most hospital cages.
●● Enclosure furniture should offer appropriate sized hides and, depending on thespecies, encourage normal behaviour(e.g. perches for arboreal species).
●● Biosecurity makes it imperative that anexcellent cleaning and disinfection regimen is maintained. A veterinary grade disinfectant should be used to clean theenclosure and all furnishings between
patients. While the patient is in hospital,
the enclosure should be cleaned daily andthe substrate replaced.
●● Diligent care should be taken to preventthe escape of reptile patients. Venomousor dangerous inpatients should be secured
with a lock to prevent escape and appropriate signage to warn staff. The roomshould be secured and only trained staff
should enter.
●●­Daily CareAs with all hospitalized patients, reptiles
must be monitored effectively throughout
their stay. It is imperative that stress be minimized by not over‐handling.
Weighing
Daily weighing should be performed before
treatments are given, particularly where
patients are very small, as it is easy to overdose even if only a very small amount ofweight is lost over 24 hours (Figure 32.3).
Recent feeding of large food items (e.g. rats)
should be taken into account, as this will
increase the animal’s weight significantly but
should not justify a change to dose rate until
the food has been digested. The treating veterinarian should be notified of any changes
to the reptile’s weight.

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Reptile Medicine and Surgery in Clinical Practice

Figure 32.3 A lidded weigh box.

Handling

Observations and Record Keeping

When handling a reptile, the safety of thepatient and the handler is paramount.
Handling techniques are described in
Chapter 13 but the common factor in alltechniques is that everything must be tohand before touching the patient. Not only
does this minimize stress by ensuring any
examinations or procedures are quick but it
also increases handler safety (catch andrelease is the most dangerous time whenhandling a reptile).

Observations and record keeping go hand inhand and treatment charts should be tailormade for reptile patients. Information thatshould be recorded includes:

Feeding
Before feeding reptilian patients, they shouldbe hydrated to prevent the hypothesizedcondition ‘re‐feeding syndrome’, which
occurs where chronically anorexic reptiles
suffer a potentially life‐threatening hypokalaemia following the ingestion of sudden
excessive calories. The patient’s current diet,even if not ideal, should be fed and anychange should be gradual. Many pet reptiles
may also be ‘fussy’ and only eat under certain circumstances (when the mouse is jiggled for example) or may only eat certain
food items. If appropriate food items are notheld in the clinic, ask the owners to provide
it (Figure 32.4).

weightpreferred body temperature for the species
and the patient’s actual temperature (usually measured by infrared thermometers●● enclosure temperature gradient – recommended and actual (daily)●● humidity requirement and readings (daily
or more) and spray frequencies if mistingof enclosure or body required●● feeding behaviour (attempted but did not
swallow; not interested; interested but did
not bite; fed but regurgitated etc.)●● lighting requirements (diurnal cycle andultraviolet B)●● brumation requirements (gradient cooling,change to day length, food reduction, etc.)●● observations
about shedding (opaque,shedding, shed etc.)●● defecation and urination●● any treatment given.
●●●●

Medication
Handling should be kept to a minimum(to minimize patient stress) so where possible

Nursing the Reptile Patient

Figure 32.4 Appropriate food should
be provided.

Figure 32.5 Recording the rotation of
injection sites.

schedule medication administration to occur
only once or twice daily. If injecting medication, ensure injection sites are rotated if multiple or repeated injections need to be given(Figure 32.5). If possible, oral medications canbe offered in food to reduce stress and increase
handler safety. Only offer medication in food
if the whole dose can readily be taken as one
dose and recorded as administered.

­Anaesthesia and Surgical Nursing
The veterinary nurse or technician plays a vitalrole in the preparation for surgery and anaesthesia including preoperative, perioperativeand post‐operative monitoring and care.
In many practices, it is common for the nurse
or technician to monitor anaesthesia under
the supervision of the clinician in charge.
Preoperative Nursing
Ensure that the reptile is in a heated enclosure so the patient is at its preferred bodytemperature (and this may take some timedepending on the patient’s size). As temperature has a dramatic effect on the reptile
metabolism, the patient should be examined
once it is at its preferred body temperatureand before sedation, to record the baseparameters such as the heart rate, respiratory

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Reptile Medicine and Surgery in Clinical Practicerate and respiratory effort. The clinician andnurse should discuss pre‐anaesthetic pathology testing, pain scoring and hydration status.
While the patient is warming up, the operating theatre can be prepared for the surgicalprocedure. The patient will rapidly cool
down once removed from the heated enclosure, so delays should be minimized.
Surgical and Anaesthetic Equipment
The following equipment and supplies will
be needed:
Patient prep solution (warmed):–– Chlorhexidine or iodine scrub solution
are appropriate first prep solutions.
–– Alcohol‐based second and third prep
solutions may cause rapid cooling of thesmall patients. In these cases, aqueous
chlorhexidine solutions are used as the
final skin prep.
●● Sterile surgical kit: choice of surgicalinstruments will come from the clinician
but often ophthalmic instruments are usedon small patients.
●● Sterile patient drapes:–– Clear sterile drapes are often used toallow visual monitoring of the patient
during procedure.
–– Cloth or disposable paper drapes may
be used especially in larger patients, atthe surgeon’s discretion●● Patient positioning equipment: sandbags,
foam blocks and other support may berequired for some patients.
●● Patient heating: can be provided throughthe use of heated air blankets, heat mats,heat lamps and ‘hotties’ (warmed fluidbags). Care should always be taken not toburn the patient, particularly if using aheat mat. A thermostat probe should beplaced in between the mat and patient toensure that it does not overheat. The
heated air and HotDog® patient warming
systems are controlled by an internal
thermostat and are considered the safest
patient warming systems. Monitoringof patient temperature is recommended.
●●

Normal rectal thermometers for small
animals will not read as low as the average
reptile body temperature. Electric probe
thermometers, available from most hardware stores, can be used instead.
●● Endotracheal tubes: a range of non‐cuffed
endotracheal tubes appropriate to thepatient size should be ready at hand.
Tip: for very small patients, intravenous
catheters can be used with the connector
from the 3.5 mm endotracheal tube.
●● Tape and tongue depressor: use tape and a
tongue depressor to secure the endotracheal tube to the patient to prevent thepatient extubating itself if it moves during
anaesthesia.
●● Anaesthetic machine:–– Anaesthetic machines should be set up
and checked for leaks before every
procedure. Access to medical air andoxygen is preferable, as reptiles willoften have to be ventilated on air during recovery to initiate spontaneous
ventilation.
–– The vaporizer should be filled.
Isoflurane or sevoflurane are two common choices of gaseous maintenanceanaesthesia.
●● Breathing system/ventilator:–– A breathing system should be chosen
and attached to the machine andchecked for leaks. Most reptile patients
under 5 kg would use a non‐rebreathing
system (e.g. a T‐piece or Bain breathing
system). Larger species can be maintained on a rebreathing system such asa paediatric Y‐system with a soda lime
absorber to remove expired carbon
dioxide.
–– Expect that all anaesthetized reptiles
will become apnoeic and be prepared tomanually or mechanically ventilate thepatient for the entire procedure until
the patient spontaneously ventilates onrecovery. Ventilation pressure is usually
5 cm H2O for reptiles under 5 kg and
10 cm H2O for patients over 5 kg. The
rate of ventilation is 2–10 breaths per
minute.

Nursing the Reptile Patient

Tip: use the base parameters to replicate
normal resting ventilation for the patient,aiming for the same respiratory rate andrespiratory movement.
●● Anaesthesia record: a legal document andshould begin with your base parametersand end when the patient has recovered.
Record all medications, time, effect androute of administration and five‐minuteinterval records taken.
●● Monitoring equipment:–– The most useful piece of monitoring
equipment for reptile anaesthesia is the
Doppler. It allows the user to listen to theheart rate and rhythm pulse of the patient
in real time, where it would be very difficult to do so with a stethoscope alone.
A Doppler will also accurately pick up aheartbeat from very small patients.
–– Other monitoring equipment can be ofuse: capnography, electrocardiography(ECG), pulse oximetry and blood pressure monitoring can help you to assessyour patient’s status during anaesthesia.

As small endotracheal tubes are often
used, assessing the capnogram can help todetermine whether there are leaks aroundthe tube, or semi‐ or full obstruction of
the tube because of mucous plugs.
●● A Doppler unit can be used to auscultate
the heartbeat of the patient and to monitor
systolic blood pressure in lizards.
●● ECG can be difficult due to the ridged
scales of the skin but alcohol or ultrasoundgel can be used to increase conductivity.
Tip: ECG Alligator clips can be quite traumatic to reptile skin; flattening the teeth
will reduce trauma.
●● Pulse oximetry can be used to monitor
pulse rate and oxygenation. Because reptile
skin is thick, with often highly pigmented
and nucleated blood cells, readings can bedifficult and inaccurate; however, trends
can be followed.
●● Monitoring of the depth of the anaesthesia
can be difficult in reptiles but some reflexes
prove useful (Table 32.1).

Monitoring the Anaesthesia

Patient Support

Anaesthesia monitoring is discussed in detailin Chapter 27 (Anaesthesia and analgesia).
Commonly used monitoring equipment
includes:Patient support during anaesthesia is discussed in Chapter 27. There are a few points
of note for the nurse or technician supporting a patient under anaesthesia.

●●

Capnography will not give an accurate
reading of true endotracheal CO2 but
trends can be evaluated. On average
endotracheal CO2 readings within therange of 10–30 should be expected.

●●

Positive pressure ventilation will be required
at surgical planes of anaesthesia. As reptile
ventilation is controlled by skeletal muscle,
spontaneous respiration is lost at a surgicalplane of anaesthesia.

Table 32.1 Reptile reflexes.
ReflexLight Plane

Surgical Plane

Deep Plane

Righting

Present

AbsentAbsentTail toe pinch

Present

AbsentAbsent

Jaw tone

Increased

Decreased

AbsentPalpebralPresent

AbsentAbsentCornealPresent

Present

AbsentTongue retraction

Present

AbsentAbsent447

448

Reptile Medicine and Surgery in Clinical Practice

Maintaining the patient’s body temperature is paramount.
●● Cardiovascular support can be achieved withperioperative intravenous or intraosseous
fluids at a rate of 1 ml/kg/hour. If this is notachievable, subcutaneous or intracoelomic
fluids can be given at 20–30 ml/kg/24 hours.
Tip: Administering adequate pain relief will
reduce the gaseous anaesthetic requirement
during the procedure, which will in turn
reduce the dose‐dependent effects of vasodilation on the body.
●●

RecoveryRecovery is the most dangerous period of a
reptile anaesthetic procedure. The patent
airway should be closely monitored andmaintained until the patient is spontaneously
ventilating and starting to move. Maintaining

optimal body temperature is important during this time to allow the rapid excretion ofanaesthetic drugs. The recovery period canvary from a few minutes to many hours.
Ventilation with medical (or even room) air
with a reduced inspired oxygen percentage
will stimulate spontaneous ventilation, as
stimulation to breath come from decreasing
oxygen levels rather than increasing carbon
dioxide levels.
Once the patient is spontaneously ventilating and starting to move, it can be extubated.
The patient must be monitored to ensurethat the airway remains patent and thepatient continues to breathe. If not, thepatient should be reintubated and ventilation
continued. Once the patient is stable, it canbe moved back to its heated enclosure andmonitoring reduced to 5–10‐minute intervals until it is behaving normally.

­Further Reading
Ballard, B. and Cheek, R. (2010) Exotic Animal
Medicine for the Veterinary Technician, 2nded. Wiley‐Blackwell, Oxford.
Girling, S. (2003) Veterinary Nursing of Exotic
Pets. Blackwell Publishing, Oxford.
Maclean, B. and Raiti, P. (2004) Emergency
Care, in BSAVA Manual of Reptiles, 2nd ed.
(S. Girling and P. Raiti, eds) BSAVA
Publications, Gloucester, pp. 63–70.
Mader, D. (2005) Reptile Medicine and Surgery,2nd ed. Elsevier Saunders, St. Louis, MO.
Meredith, A. and Johnson‐Delaney, C. (2010)
BSAVA Manual of Exotic Pets, 5th ed.
BSAVA Publications, Gloucester.
Martinez‐Jiminez, D. and Hernandez‐Divers,
S.J. (2007) Emergency Care of Reptiles.
Veterinary Clinics of North America: Exotic
Animal Practice, 11, 551–567.

Mitchell, M.A. (2006) Therapeutics, in Reptile
Medicine and Surgery, 2nd ed. (D.M. Mader,ed.). Elsevier Saunders, St. Louis, MO,
pp. 631–664.
Mitchell, M.A. and Tully, T.N. Jr (2009)
Manual of Exotic Pet Practice. Elsevier
Saunders, St Louis, MO.
Rendle, M. and Cracknell, J. (2012) Reptiles:
biology and husbandry, in BSAVA Manualof Exotic Pet and Wildlife Nursing(M. Varga, R. Lumbis and L. Gott, eds).
BSAVA Publications, Gloucester, pp.
80–108.
Rees Davis R. and Klingengberg, R.J. (2004)
Therapeutics and medicine, in BSAVA
Manual of Reptiles, 2nd ed. (S. Girling and
P. Raiti, eds). BSAVA Publications,Gloucester, pp. 115–130.

449

33
Euthanasia
Tim Hyndman­Introduction
The euthanasia of animals should be smoothand painless; reptiles should not be an exception to this expectation. The clinician should
be aware that it is difficult to achieve humane
euthanasia of reptiles that is both rapid andpalatable to most owners. For this reason, it
is not recommended that reptile euthanasias
are booked during busy consulting hours.
The owner should be made aware that there
are important differences in how a reptile iseuthanized compared with how their dog or
cat would be euthanized. Most notably, thetime to complete the procedure can be very
different.

­Methods of Euthanasia
Instantaneous Brain Destruction
As the name suggests, instantaneous brain
destruction involves the rapid and total
obliteration of the brain, usually by blunt
force trauma. While it can be argued that
this method is rapid and humane, it will
rarely be acceptable to an owner. It will
destroy the brain as a necropsy sample and,if performed incorrectly, the results can becatastrophic.

Decapitation
Decapitation is an equally simple method of
euthanasia but the reptilian brain has aremarkable capacity to function in an anoxic
environment and therefore it is assumed thatthe perception of pain can continue for atleast several minutes after the animal’s headhas been removed.
Freezing
Freezing a reptile (with or without priorrefrigeration) is another simple method of
euthanasia but the progressive freezing andrupture of cells means that this method is
considered by most to be unacceptably painful. Freezing will also destroy the integrity of
necropsy samples intended for histologicalexamination. There is continuing debate as
to whether freezing reptiles (after priorrefrigeration) is ethical and humane. The clinician is therefore encouraged to remain
abreast with advances in research whichattempt to clarify this issue.
Pentobarbitone
Injecting pentobarbitone into the body cavity
or the muscle of an animal (as opposed to
intravenously) has been criticized because

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

450

Reptile Medicine and Surgery in Clinical Practice

preparations of this drug are necessarily alkaline (pH 9–10.5) so the acidic drug does notprecipitate. It is therefore assumed by many
that this injection will cause an unacceptablelevel of pain in the conscious animal. Someveterinarians will address this problem by
diluting pentobarbitone in isotonic saline. In
theory, this may not influence the pH of the
preparation by much, considering that the
pH scale is logarithmic. Anecdotally, however, many practitioners believe that thisdilution significantly reduces the pain associated with this injection.
Using an acidic solution, such as isotonic
saline, as the diluent will decrease the alkaline pH more than solutions which areeither pH neutral or close to it (e.g. water for
injection, Hartmann’s solution or lactated
Ringer’s solution). An alternative practice toattenuate the pain associated with thisinjection is to mix the pentobarbitone withlignocaine. This has been shown to decrease(but not eliminate) the pain associated withintraperitoneal injections of pentobarbitone
in mice.
The administration of undiluted pentobarbitone into the alimentary tract of reptiles isanother method used by some veterinarians.
Barbiturates have high oral bioavailability
and so drug can reach the brain quite quickly.
Moreover, the concern over the alkaline pHof the preparation becomes less importantwhen the drug is instilled into the alimentarytract. This method, if used, is typically reserved
for small lizards and chelonians.
Analgesia
Modern recommendations for the euthanasia of reptiles consist of two stages. The firststage involves anaesthetizing the animal orat least deeply sedating it with analgesia. It
is important to note that an animal thatis deeply sedated without analgesia (i.e.
through the use of benzodiazepines, acepromazine and/or subanaesthetic doses ofbarbiturates or propofol) will still be able toperceive pain, even if they have lost theircapacity to react to it. Once the animal has

been deeply sedated with analgesia or has
been anaesthetized, the perception of pain
should be reduced, if not totally eliminated.
The neurosteroid alfaxalone is a good choice
to anaesthetize a reptile and doses of 5 mg/
kg intravenously or 10 mg/kg intramuscularly are advocated. The dissociative andbenzodiazepine combination of tiletamine–zolazepam can also work well.
Gas
Some clinicians will induce anaesthesia using
gas but this process may not be practical forsnakes and breath‐holding species such as
chelonians.

­Confirming Death
Once the patient is deeply sedated or anaesthetized, as defined by diminished or absent
righting and tail/toe reflexes, intracardiac
pentobarbitone is recommended. A Doppler
probe can be of great help in locating theheart and also in confirming the absence ofa heartbeat (Figure 33.1). Typical doses ofpentobarbitone are 160 mg/kg. Using higher
doses can cause tissue artefacts that may
affect a pathologist’s interpretation of histological lesions (see Chapter 30). Once spontaneous breathing and a heartbeat haveceased and all reflexes have stopped (which
can sometimes take minutes), the animal isconsidered dead.
If a necropsy is then performed on the reptile, the clinician will sometimes be facedwith a beating heart (especially in snakes)
and this can be alarming to see. The leaky
electrolyte channels in the pacemaker cells
allow the heart to beat independently to thenervous system. It can take several minutes
following death, even if the heart is resectedfrom the animal, before the heart has
exhausted all of its energy stores and stops
beating. The presence of a heart beat seen at
necropsy should not be automatically interpreted to mean that the animal was noteuthanized.

Euthanasia

Figure 33.1 A Doppler probe can beused to confirm the absence of aheartbeat.

­Redundancy
Some clinicians choose to add layers of
redundancy into their euthanasia protocols.
For example, once the reptile has been deeply
sedated or anaesthetized and after pentobarbitone has been injected into its heart, someclinicians will choose to decapitate the animal and, even then, pithing of the cranial spinal cord in the decapitated head is sometimes
performed. As before, this is because of a
reptile’s remarkable ability to maintain brain
function in anoxic environments. Pithing is
performed by placing a needle into the cranial spinal cord of the decapitated head andthen advancing it cranially, with agitation,
through the foramen magnum. It goes with-out saying that many owners will be shocked
to see their pet decapitated and pithed and so
this practice is usually reserved for non‐pet
reptiles (e.g. wildlife or zoo animals) or the
animals belonging to highly experienced reptile owners.
If the owner elects to take their reptile
home, it is imperative that the clinician iscertain that the animal has been euthanized.
It is also the duty of the veterinarian toaddress the unpleasant subject of what will
happen to the animal when it is returned
home. If an animal is to be buried, the ownerneeds to be made aware that the drug residues remaining in their reptile could be toxic(and potentially fatal) to other animals thatmay dig up and ingest the deceased reptile.

­Further Reading
American Veterinary Medical Association(2013) AVMA Guidelines for the Euthanasia

of Animals: 2013 Edition. AVMA,
Schaumburg, IL.

451

453

Appendix 1
Formulary
Table A1.3 Anti‐fungal drugs
Table A1.4 Antiviral drugs●● Table A1.5 Anti‐protozoal drugs●● Table A1.6 Internal parasiticides●● Table A1.7 External parasiticides●● Table A1.8 Hormonal therapies●● Table A1.9 Drugs used to treat liver disease●● Table A1.10 Drugs used to treat kidneydisease●● Table A1.11 Drugs used to treat cardiovascular disease●● Table A1.12 Gastrointestinal drugs●● Table A1.13 Anaesthesia and sedatives●● Table A1.14 Analgesia●● Table A1.15 Nutritional support
●●

KEY

●●

The following abbreviations are used in thetables in this formulary:

CSF
CNS
GI
IM
IV
PO
q
SC
spp.

cerebrospinal fluid
central nervous system
gastrointestinal
intramuscularly
intravenously
orallyevery
subcutaneously
species­Tables●●●●

Table A1.1 Emergency drugs
Table A1.2 Antibiotics

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

Table A1.1 Emergency drugs.
Class

Drug

Dose and route

Comments

May thicken respiratory secretions.

Anti‐muscarinic agent:
Used to treat bradycardia

Atropine

0.01–0.2 mg/kg IM or IV●

Glycopyrrolate

0.01 mg/kg IV

Alpha‐ and beta‐adrenergic agonist agent:
Used systemically for treating
anaphylaxis and cardiac resuscitation

Adrenaline(epinephrine)

0.1 mg/kg IV

Care with hypovolaemic patients (not a substitute for adequate
volume replacement).

Opiate antagonist

Naloxone

0.01–0.04 mg/kg
IV q 2–3 minutes to effectAt reversal dosages, naloxone can negate opioid analgesic effects.
The reversal effect may last for a shorter time than opioid effect,
so repeated dosing may be needed.

Benzodiazepine

Diazepam

0.5 mg/kg IM, IV

Seizure control.

Midazolam

1–2 mg/kg IM, IV

Benzodiazepine antagonist

Flumazenil

0.05–0.1 mg/kg IV or IM

Flumazenil is used for the reversal of benzodiazepine after
overdoses or toxicity. The reversal effect may last for a shortertime than benzodiazepine effect, so repeated dosing may beneeded.

Fluids (shock)

Crystalloid fluids(0.9% saline)

10 ml/kg IV bolus

See Chapter 13 for maintenance fluids.

Fluids (shock)

Colloid fluids

5 ml/kg IV bolus

See Chapter 13 for maintenance fluids.

●

Table A1.2 Antibiotics.
Class

Drug

Dose and route

Comments

Amoxicillin

10 mg/kg q 24 hours IM
22 mg/kg q 12–24 hours PO

Ampicillin

3–6 mg/Kg IM, PO,
SC q 12–24 hours

Effective against Gram‐positive bacteria, especially
Staphylococcus; many Gram‐negative bacteria areresistant. Often combined with an aminoglycoside.
Pharmacokinetic studies in reptiles are lacking.

Amoxicillin–
clavulanic acid

15 mg/kg q 24hours IM
30 mg/kg q 12–24 hours PO

Clavulanic acid is added to inhibit beta‐lactamase.

Carbenicillin

400 mg/kg IM q 48 hours

Improved spectrum against Pseudomonas and otherGram‐negative bacteria. Oral form has poorbioavailability.

Piperacillin

100 mg/kg IM q 48 hours

Good activity against most Gram‐negative bacteria
including Pseudomonas, Klebsiella and Enterobacter.
Piperacillin with tazobactam is commonly used toovercome beta‐lactamase‐producing bacteria. Parenteraladministration only. Reconstituted drug should be usedwithin 24 hours or 7 days if refrigerated.

Penicillins:
Bactericidal
Well distributed in extracellular spaces
especially in inflamed tissues● Do not readily penetrate the eye and CNS● Excreted by the kidneys, largely unchanged,
therefore high concentrations can be found in
the urine● Potentially synergistic in combination withaminoglycosides●●

Piperacillin withtazobactam

Penicillin,benzathine

10,000–20,000 units/kg(6.25–12.5 mg/kg)
IM q 48–96 hours

Penicillin G

10,000–20,000 units/kg(6–12 mg/kg) SC, IM,
IV q 8–12 hours

Infrequently used

Ticarcillin

50 mg/kg IM q 24 hours

Similar to carbenicillin; much more active against
Pseudomonas. Also found in combination with clavulanic
acid and used at the same dose. Parenteraladministration only.
(Continued)

Table A1.2 (Continued)
Class

Drug

Dose and route

Comments

Cephalothin

20–40 mg/kg IM q 12hours

Cephalexin

20–40 mg/kg PO q 12hours

First generation cephalosporin:
Effective against most Gram‐positive cocci, many
Gram‐negatives and some anaerobes.

Ceftazidime

20–40 mg/kg IM q 72hours

Third generation. Penetrates CSF. Excreted throughthe kidneys. Dose should be reduced in renally
impaired patients. Following reconstitution, solution
is stable for 18 hours at room temperature, 7 days if
refrigerated or 3 months if frozen at –20 °C. Once
thawed, it should not be refrozen and thawed
solutions are stable for 8 hours if refrigerated and4 hours at room temperature.

Ceftiofur

5–15 mg/kg IM q 12 hours

Third generation with activity against Pasteurella, E. coli,
Streptococcus, Staphylococcus and Salmonella spp.

Cefotaxime

20–40 mg/kg IM q 24 hours

Third generation: expanded Gram‐negative spectrum.
Penetrates CSF.

Chloramphenicol
succinate(injectable)

20–40 mg/kg IM or PO q
12–72hours

Broad spectrum against Chlamydia, Mycoplasma,Gram‐positive and Gram‐negative bacteria and some
protozoa.

Amikacin

2.5–5 mg/kg IM q 48–72
hours

Greater activity against Gram‐negatives, including someresistant to gentamycin and tobramycin.
Achieves higher serum concentrations than gentamycin
but is less toxic so levels are better tolerated.
Fewer toxic adverse effects.

Gentamycin

2.5 mg/kg q 72 hours

Dose > 5 mg/kg may be toxic. Not generally
recommended owing to narrow margin of safety.

Tobramycin

2.5 mg/kg q 24 hours

Pharmacology is similar to gentamycin but has greater
activity against Pseudomonas. Neurotoxicity andnephrotoxicity may develop.

Enrofloxacin

5–10 mg/kg IM q 48 hours

Excellent activity against Mycoplasma, some Gram‐
positive and most Gram‐negative bacteria. However,

Cephalosporins:
Three generations; effective against bothgram Gram‐positive and ‐negative bacteria● Well distributed in extracellular spaces● Do not readily penetrate eye and CNS, except
for cefotaxime and ceftazidime● Synergistic with aminoglycosides●

Chloramphenicol:
Bacteriostatic
Highly lipid soluble, so good tissue
penetration, including CNS and eye; tissue
concentrations often exceed serum levels● Anaemia and CNS depression● Caution needed in handling the drug●●

Aminoglycosides:
Bactericidal
Synergistic with penicillins andcephalosporins● Excellent spectrum against Gram‐positive and‐negative bacteria● Ineffective against anaerobic bacteria and inproteinaceous environments such as abscesses
and exudates● Poor penetration into CNS and eye● Nephrotoxic, especially in snakes, dehydrated
reptiles or those with compromised renal
function (the dose should be reduced or a lesstoxic drug selected)●●

Quinolones:●●

Bactericidal
Most Gram‐negative pathogens, some●

impaired patients. Following reconstitution, solution
is stable for 18 hours at room temperature, 7 days if
refrigerated or 3 months if frozen at –20 °C. Once
thawed, it should not be refrozen and thawed
solutions are stable for 8 hours if refrigerated and4 hours at room temperature.

Synergistic with aminoglycosides

Ceftiofur

5–15 mg/kg IM q 12 hours

Third generation with activity against Pasteurella, E. coli,
Streptococcus, Staphylococcus and Salmonella spp.

Cefotaxime

20–40 mg/kg IM q 24 hours

Third generation: expanded Gram‐negative spectrum.
Penetrates CSF.

Chloramphenicol
succinate(injectable)

20–40 mg/kg IM or PO q
12–72hours

Broad spectrum against Chlamydia, Mycoplasma,Gram‐positive and Gram‐negative bacteria and some
protozoa.

Amikacin

2.5–5 mg/kg IM q 48–72
hours

Greater activity against Gram‐negatives, including someresistant to gentamycin and tobramycin.
Achieves higher serum concentrations than gentamycin
but is less toxic so levels are better tolerated.
Fewer toxic adverse effects.

Gentamycin

2.5 mg/kg q 72 hours

Dose > 5 mg/kg may be toxic. Not generally
recommended owing to narrow margin of safety.

Tobramycin

2.5 mg/kg q 24 hours

Pharmacology is similar to gentamycin but has greater
activity against Pseudomonas. Neurotoxicity andnephrotoxicity may develop.

Enrofloxacin

5–10 mg/kg IM q 48 hours

Excellent activity against Mycoplasma, some Gram‐
positive and most Gram‐negative bacteria. However,Pseudomonas resistance is common. Unsuitable foranaerobic infections. Diluted with saline before injection
as repeated injections cause significant bruising andmuscle necrosis. Alternatively, switch to oral dosing if
gut is motile.

Ciprofloxacin

10 mg/kg PO q 48 hours

Antibacterial spectrum similar to enrofloxacin.

Marbofloxacin

2 mg/kg IM, IV q 24 hours

Chloramphenicol:
Bacteriostatic
Highly lipid soluble, so good tissue
penetration, including CNS and eye; tissue
concentrations often exceed serum levels● Anaemia and CNS depression● Caution needed in handling the drug●●

Aminoglycosides:
Bactericidal
Synergistic with penicillins andcephalosporins● Excellent spectrum against Gram‐positive and‐negative bacteria● Ineffective against anaerobic bacteria and inproteinaceous environments such as abscesses
and exudates● Poor penetration into CNS and eye● Nephrotoxic, especially in snakes, dehydrated
reptiles or those with compromised renal
function (the dose should be reduced or a lesstoxic drug selected)●●

Quinolones:
Bactericidal
Most Gram‐negative pathogens, someGram‐positive pathogens, most Mycoplasmaand possibly Chlamydia are sensitive● Limited efficacy against anaerobes● Achieve high levels, especially in the liver andurinary tract; tissue concentrations may
exceed serum concentrations● Use with caution in juveniles; may cause
permanent articular defects● IM injection causes pain and necrosis at thesite of injections●●

10 mg/kg PO q 48 hours(Continued)

Table A1.2 (Continued)
Class

Drug

Dose and route

Comments

Trimethoprim–sulfadiazine

30 mg/kg PO q 24 hours for
2 days, then q 48 hoursor
20–30 mg/kg IM q
24–48 hours

Oxytetracycline

10–80 mg/kg IM q 4hours

Poorly absorbed when given orally, oral formulations are
not recommended. IM well absorbed and widelydistributed but will cause necrosis at the injection site.

Chlortetracycline

200 mg/kg PO q 24 hours

Better oral absorption than oxytetracycline

Doxycycline

5–10 mg/kg PO q 24 hours
or
50 mg /kg IM once then
25 mg/kg IM q72 hours

More lipophilic than other tetracyclines; absorbed betterand faster through the GI tract and greater
bioavailability.

Clarithromycin

15 mg/kg PO q 3.5 days

Excreted through the kidneys. Effective against a variety
of Gram‐positive and ‐negative bacteria as well as
Mycobacterium avium complex bacteria, Chlamydia andMycoplasma. It may also be effective against someanaerobic bacteria.

Clindamycin

5 mg/kg PO q 12 hours

Used occasionally to treat osteomyelitis caused bysusceptible Gram‐positive pathogens.

Lincomycin

5 mg/kg q 24 hours

It has been used to treat respiratory and GI infections
caused by Gram‐positive bacteria and Mycoplasma.

Azithromycin

10 mg/kg PO q 3–7 days

New generation macrolide; it appears to be active

Trimethoprim–sulfa derivatives:
Bactericidal
Moderate Gram‐positive and ‐negative
spectrum● Pseudomonas and some strains ofEnterobacteriaceae are resistant● May be effective against some coccidia● Wide extracellular distribution● Sulfas are excreted via the same pathway as uricacid; in dehydrated reptiles and those withcompromised renal function sulfas may form
crystals and damage renal glomeruli●●

Tetracyclines:
Bacteriostatic
Spectrum includes many Gram‐positive
organisms; poor efficacy against mostGram‐negative isolates● Used for Chlamydia and Mycoplasma● Wide volume of distribution● Adverse effects:○ Anorexia, vomiting, diarrhoea○ Immunosuppression○ Hepatotoxicity (rare)○ Localized tissue reactions to doxycycline
injections formulations○ Alteration of gut flora, especially yeast
overgrowths and secondary bacterial
infections○ Chelates calcium in gut and bone; dietarycalcium interferes with the oral uptake oftetracyclines; use cautiously if needed forextended periods of time●●

Macrolides and lincosamides:
Bacteriostatic
Indicated for Pasteurella, Bordetella, some
Mycoplasma, Campylobacter spp. andClostridia spp. and obligate anaerobic bacteria● Often used for susceptible upper respiratory
tract infections and osteomyelitis● Active against Gram‐positive organisms andanaerobes but virtually all aerobic
Gram‐negative bacteria are resistant●●Bacteriostatic
Spectrum includes many Gram‐positive
organisms; poor efficacy against mostGram‐negative isolates● Used for Chlamydia and Mycoplasma● Wide volume of distribution● Adverse effects:○ Anorexia, vomiting, diarrhoea○ Immunosuppression○ Hepatotoxicity (rare)○ Localized tissue reactions to doxycycline
injections formulations○ Alteration of gut flora, especially yeast
overgrowths and secondary bacterial
infections○ Chelates calcium in gut and bone; dietarycalcium interferes with the oral uptake oftetracyclines; use cautiously if needed forextended periods of time●

Oxytetracycline

10–80 mg/kg IM q 4hours

Poorly absorbed when given orally, oral formulations are
not recommended. IM well absorbed and widelydistributed but will cause necrosis at the injection site.

Chlortetracycline

200 mg/kg PO q 24 hours

Better oral absorption than oxytetracycline

Doxycycline

5–10 mg/kg PO q 24 hours
or
50 mg /kg IM once then
25 mg/kg IM q72 hours

More lipophilic than other tetracyclines; absorbed betterand faster through the GI tract and greater
bioavailability.

Clarithromycin

15 mg/kg PO q 3.5 days

Excreted through the kidneys. Effective against a variety
of Gram‐positive and ‐negative bacteria as well as
Mycobacterium avium complex bacteria, Chlamydia andMycoplasma. It may also be effective against someanaerobic bacteria.

Clindamycin

5 mg/kg PO q 12 hours

Used occasionally to treat osteomyelitis caused bysusceptible Gram‐positive pathogens.

Lincomycin

5 mg/kg q 24 hours

It has been used to treat respiratory and GI infections
caused by Gram‐positive bacteria and Mycoplasma.

Azithromycin

10 mg/kg PO q 3–7 days

New generation macrolide; it appears to be active
against intracellular infections including Chlamydia,
Toxoplasma, Plasmodium and Cryptosporidium, as well
as a number of Gram‐positive and ‐negative bacteria.
It is excreted through the liver and may be hepatotoxic.
May cause a reversible anaemia in some reptiles.

Tylosin

5 mg/kg IM 24 hours

Used predominantly for suspected Mycoplasma
infections. Intramuscular injections can be very
irritating.

Metronidazole

20 mg/kg PO q 24–48 hours

Frequently used for anaerobic infections, (including
clostridial infections) and motile protozoa.

●

Macrolides and lincosamides:
Bacteriostatic
Indicated for Pasteurella, Bordetella, some
Mycoplasma, Campylobacter spp. andClostridia spp. and obligate anaerobic bacteria● Often used for susceptible upper respiratory
tract infections and osteomyelitis● Active against Gram‐positive organisms andanaerobes but virtually all aerobic
Gram‐negative bacteria are resistant●●

Nitroimidazoles:
Bactericidal
Effective against many Gram‐positive andmost Gram‐negative obligate anaerobes● Ineffective against aerobic bacteria● Highly effective against many motile protozoa● well absorbed from GI tract● highly lipophilic and penetrates bones, CNS
and abscesses●●

Table A1.3 Anti‐fungal drugs.
Class

Drug

Dose and route

Comments

Ketoconazole

15–30 mg/kg PO q 24 hours for 10–30 days
Administer with food.

For Candida infections. Probably not as effective withAspergillus infections as other azoles. Widely distributed
to tissues but is highly protein‐bound and does not
penetrate CNS or eye fluids. Water insoluble unlessdissolved in acid first.

Fluconazole

5 mg/kg PO q 24 hours

Effective against Candida (especially mycelial form),
Aspergillus and Cryptococcus. Penetrates eye, CNS
and CSF. Best safety margin of the azoles.

Itraconazole

5–10 mg/kg PO q 24 hours given withfood for at least one month after signs
have resolved

Some hepatotoxicity noted
Can cause anorexia and weight loss
Has been used for skin infections with Chrysosporium
anamorph of Nannizziopsis vriesii (CANV)

Voriconazole

5–10 mg/kg PO q 24 hours at least
1 month after signs have resolvedHigh oral bioavailability
Can cross into the CNS
Used for CANV infections

Terbinafine

5–10 mg/kg PO q 24 hours
Can also be applied topically.

Aspergillus and dermatophytes
Good oral absorption; distributed well to fat and skin

Amphotericin B

0.5 mg/kg IV q24–72 hours for 14–28days
orIntra‐tracheally 1 mg/kg (diluted in saline)
q 24 hours
or
Nebulize at 0.3–1 mg/ml for 60 minutes
q 24 hours

Fungicidal. Active against both yeast and fungal hyphae.
Not absorbed orally; for aspergillosis, drug must be
administered IV, topically or by nebulization. Widelydistributed when given IV but only minor systemic
absorption with aerosol or topical administration.
Nephrotoxic.

Nystatin

100,000 iu/kg PO q 24 hours

For yeast infections of the gut.

Azoles:Inhibit ergosterol synthesis,
increasing cellular membrane
permeability; also causes secondary
metabolic effects and growth
inhibition● Fungistatic, so months of therapy
are often required● Take several days to reach steady‐state concentrations●

Allylamines:●

Inhibit squalene epoxidase, whichis critical for fungal sterol and cellwall synthesis

Polyenes:●

Act by binding to sterols (primarily
ergosterol) in the cell membrane
and alters the permeability of themembrane, allowing the loss of
intracellular potassium and othercellular constituentsTable A1.4 Antiviral drugs.
Class

Drug

Dose and route

Comments

Aciclovir

80 mg/kg PO q 8 hours for a minimumof 7 days

Poor oral absorption. Efficacy uncertain.

Valaciclovir

40 mg/kg PO q 24 hours

Drug

Dose and route

Comments

Metronidazole

20–50 mg/kg PO q 24–48 hours

Frequently used for motile protozoa (Trichomonas andamoeba).

Sulfadimethoxine

50 mg/kg PO q 24 hours for 3–5 days

Sulfamethazine

25–50 mg/kg PO q 24 hours for 3 days on,
3 days off

Be careful using this in a patient with dehydration, liverdisease, renal disease. Treatment periods greater than
2 weeks may require supplementation with folic acid.
All treatments should be repeated after 5 days to allow
for the prepatent period of coccidia.

Ponazuril

30 mg/kg PO q 48 hours for 2 treatments

Toltrazuril

7–15 mg/kg q 24 hours for 3 daysor
25 mg/kg PO for 1 dose

Quinacrine HCl

19–100 mg/kg PO q 48 hours 14–21 days

Overdosage may cause hepatotoxicity.

Chloroquine

125 mg/kg PO q 48 hours for 3 treatments

Use in conjunction with primaquine.

Purine analogues:
Used for treating outbreaks ofherpesvirus infection in tortoises

Table A1.5 Anti‐protozoal drugs.
Class

Nitroimidazoles:
Used against motile protozoa(Trichomonas, Giardia, Cochlosoma,
Spironucleus, Histomonas)
Sulfonamides:●

Used to treat coccidia

Benzeneacetonitrile derivatives:●●

Used to treat coccidia
All treatments should be repeatedafter 5 days to allow for the
prepatent period of coccidia

Quinacrine HCl●

Used for haemaprotozoa

Chloroquine:●

Used for haemaprotozoa

Table A1.6 Internal parasiticides.
Class

Drug

Dose and route

Comments

Albendazole

50 mg/kg PO for 1 dose

Can be used for treating Microsporidia, as
well as some nematodes.

Fenbendazole

25–100 mg/kg q 14 days for
1–4 treatmentsor
50 mg/kg/day for 3 days

May also be effective against some cestodes,
trematodes and Giardia. Can be toxic to bonemarrow, causing leucopenia.

Oxfendazole

68 mg/kg PO for one dose;
repeat in 14 days

Ivermectin

200–400 µg/kg PO or IM for
one dose

DO NOT use in chelonians, skinks,
crocodilians or indigo snakes.

Moxidectin(2.5%) + imidacloprid(10%)

0.2 ml/kg, applied topically,q 14 days for 3 treatments

Used for nematodes. Only tested in a small
number of agamid lizards. DO NOT use inchelonians, skinks, crocodilians or indigo
snakes.

Emodepside (1.98%) +praziquantel (7.94%)

1.12 ml/kg applied topically

Used for nematodes and cestodes in many
species; aquatic turtles must be kept dry for
48 hours after application.

Praziquantel

5–10 mg/kg PO or IM for
1 dose, repeat in 14 days

Used for treating cestodes and trematodes.
Very unpalatable.

Pyrantel tartrate

5–25 mg/kg PO for 1 dose,
repeat in 14 days

Used for nematodes. Poorly absorbed fromthe GI tract and so only suitable for gut
parasites. Good safety margin.

100 mg/kg PO q 24 hours
for 7 days, then every
2 weeks for 3 months

Used for treating Cryptosporidia. Does not
eliminate the organism.

Fumarate reductase inhibitors:
Benzimidazole derivatives
Used mainly for treating nematodes● Interfere with parasite microtubules and sugar
metabolism● Usually require several days of treatment, although
single high doses can be effective● Can affect haematopoietic cells and intestinal
epithelium● Toxicity varies with species and drug●●

Gamma amino butyric acid‐interfering drugs:
Macrocyclic lactones
Used against Ascarids and other nematodes;
bloodsucking external parasites● Toxicity is low, except in chelonians, but overdosing
and idiosyncratic reactions include severe depression,
inactivity, excessive sleeping and neurological signs●●

Octadepsipeptides:●

Induce paralysis of the parasites

Miscellaneous drugs:

Pyrantel pamoate
Pyrantel embonate
Paromomycin

Table A1.7 External parasiticides.
Class

Drug

Dose and route

Comments

Pyrethrin

Spray or wash

Permethrin

Spray or wash

All are potentially neurotoxic:
Do not leave on the animal – wipe off after
application. Do not use on animals that are
shedding. Caution when applying to juveniles.

Piperonyl butoxide

Usually combinedwith a pyrethrin orpermethrin

Spray or wash

Broad‐spectrum insecticides

Fipronil

Spray or wipe on then wash
off in 5 minutes, Repeat
every 7–10days as required

Potentially neurotoxic
Beware of inhalation or dermal absorptionof the alcohol baseOrganophosphates

CarbarylLightly dust animal andenvironment; rinse after
1 hour; repeat in 7 days

Carbamate flea powder. Use is illegal in many
countries. Narrow therapeutic index. Safer
products are available.

Ivermectin

5–10 mg/l water topical
spray q 3–5 days for up to
28 days for mites.

DO NOT use in chelonians, crocodilians,
skinks and indigo snakes. Spray on skin andin newly cleaned cage, then allow to dry
before replacing water dish.

Pyrethrins and synthetic pyrethroids:

Macrocyclic lactones:●●

Used against reptile mites
Toxicity is low except in chelonians but overdosing
and idiosyncratic reactions include severe depression,
inactivity, excessive sleeping, and neurological signs

Table A1.8 Hormonal therapies.
Class

Drug

Dose and route

Comments

Argininevasotocin

0.01–1 µg/kg IV, SC q 12–24 hours
for 2–3 treatments

No commercial preparations available. Must be purchasedfrom chemical suppliers. Used for dystocia; give 30–60 minutes
after parenteral calcium.

Deslorelin

4.7 mg implant SC

Gonadotrophin‐releasing hormone agonist, shown to suppress
follicular development and steroidogenesis in female iguanas.

Leuprolide
acetate

0.4 mg/kg IM

Gonadotrophin‐releasing hormone agonist. Trialled in iguanas
for aggression without effect.

Oxytocin

1–10 units/kg IM q 4–6 hours for
1–3 treatments

Used to stimulate oviductal contractions but is not naturally
occurring in most reptiles and may not be effective. Works wellin chelonians, less so in snakes and lizards. Use iscontraindicated if uterovaginal sphincter is not dilated. Should
be used in conjunction with calcium gluconate injections: give
1 hour after calcium administration.

Prostaglandin E2

0.02–0.1 mg/kg applied topicallyinto the cloaca

Used to induce egg laying in dystocic reptiles; simultaneously
relaxes uterovaginal sphincter while contracting oviduct.

Prostaglandin
F2α (dinoprost)

50–200 µg/kg SC

Contracts the oviduct but does not relax uterovaginal
sphincter. Use concurrently with prostaglandin E2.

Levothyroxine

0.02 mg/kg PO q 48 hours

Stimulates feeding in debilitated tortoises.

Regular insulin

Lizards and crocodilians:
5–10 iu/kg body weight IM q 24 hours
Snakes and chelonians:
1–5 iu/kg body weight IM every
24–72 hours

These doses are empirical, and should be adjusted based on
response to therapy and continued serial sampling of blood
glucoseCalcitonin

1.5 units/kg SC q 8 hours for
14–21 days as neededor
50 units/kg IM, repeat in 14 days

Administer after calcium; avoid if hypocalcaemic. Inhibits calcium
absorption by the intestines. Inhibits osteoclast activity in bones.
Stimulates osteoblastic activity in bones. Inhibits renal tubular cell
reabsorption of calcium allowing it to be excreted in the urine.

Reproductive hormones:

Thyroxine
Insulin:●●

Used for treating hyperglycaemia
More research is needed

Other hormones:●●

Calcium regulation
Used for treating hypercalcaemia
and hyperparathyroidism

Table A1.9 Drugs used to treat liver disease.
Class
●
●

Anti‐inflammatory
Anti‐fibrotic

Drug

Dose and route

Comments

Colchicine

0.04–0.2 mg/kg PO
q 24 hours

Furosemide(frusemide)

2–5 mg/kg PO, IM,
IV q 12–24 hours

Overdose can lead to dehydration and electrolyte
abnormalities. As reptile kidneys lack a Loop of Henle,
efficacy is uncertain.

Hydrochlorothiazide

1 mg/kg q 24–72 hours

Monitor hydration status.

Lactulose

150–650 mg/kg
PO q 24 hours

Can cause diarrhoea.

Silibinin (active
component ofsilymarin, extractof milk thistle)

4–15 mg/kg
PO q 8–12hours

Use a low‐alcohol or alcohol‐free base.

Ursodeoxycholic acid

10–15 mg/kg
PO q 24 hours

Bile acid. Cytoprotective. Reduces involvement of
hepatocytes and biliary epithelium in inflammatory
process. Changes mix of bile acids to eliminate toxic bile
acids from liver.

Diuretics:●

Reduce ascites

Laxatives:
Reduce intestinal ammonia absorption
Decrease the pH of the intestinal lumen
creating an ‘acidic sink’ that will decreaseammonia levels; also promotes an osmotic
catharsis.
● Best results are seen in carnivorous reptiles,
as vegetable protein lacks many
encephalopathic precursors●●

Antioxidants:
Unproven remedy that offers promise in
reptile medicine as a hepatoprotectant● Enhances protein synthesis andhepatocellular regeneration● Suppresses fibrogenesis● Promotes fibrinolysis●

Hepatoprotective drugs:

Table A1.10 Drugs used to treat kidney disease.
Class

Drug

Dose and route

Comments

Allopurinol

10–20 mg/kg PO q 24 hours

Long‐term therapy; tortoises may respond best.

25 mg/kg PO q 24 hours

Green iguanas.

50 mg/kg PO q 24 hours for
30 days, then q 72 hours

Used in chelonians with hyperuricaemia

Drugs acting on uric acid:
●

●
●

●

Decrease production of uric acid

Increase excretion of uric acid

Probenecid

250 mg/kg PO q 12 hours

Reduce inflammation associated witharticular gout

Colchicine

0.04–0.2 mg/kg PO q 24
hours

Phosphate binders

Aluminium hydroxide

100 mg/kg PO q 12–24 hours

Calcium carbonate andchitosan (Ipakitine®)

1 g diluted in 9 ml water; give
1 ml/500 g PO q 12 hours

Decreases intestinal absorption of phosphorus. Usecautiously in patients with gastric outlet obstruction.

Table A1.11 Drugs used to treat cardiovascular disease.
Class

Drug

Dose and route

Comments

Positive Inotrope

Pimobendan

0.2 mg/kg PO q 24 hours

Similar in effect to digoxin but with lower risk ofadverse effects.

Frusemide

2–5 mg/kg PO, IM, IV q
12–24 hours

Overdose can lead to dehydration and electrolyte
abnormalities. As reptile kidneys lack a loop of Henle,
efficacy is uncertain.

Hydrochlorothiazide

1 mg/kg q 24–72 hours

Monitor hydration status.

Diuretics:●

May reduce ascites associated with liverdisease or congestive heart failureTable A1.12 Gastrointestinal drugs.
Class

Drug

Dose and route

Comments

Metoclopramide

0.06 mg/kg PO q 24 hours for 7 days

Increases force and frequency of gastriccontractions, relaxes pyloric sphincter, andpromotes peristalsis in the duodenum andjejunum. Usually only effective if given with
IV fluids as a constant rate infusion.

Cisapride

0.5–2 mg/kg PO q 8–12 hours

Stimulates GI motility.

Cimetidine

4 mg/kg PO, IM q 8–12 hours

Reduces gastric secretion of HCl and pepsin.
May impair the metabolism of concurrently
administered drugs. Gastric and duodenal
ulceration; oesophagitis; gastroesophageal reflux;
may use in renal failure to increase phosphate loss.

Sucralfate

500–1000 mg/kg PO q 6–8 hours

A complex disaccharide that reacts with stomachacid to form a complex that binds to proteinsassociated with an ulcer and produces a protective
layer that protects the ulcerated mucosa fromgastric acids and microbial pathogens.

Intestinal motility modifiers:●

Used for GI motility disorders

Gastrointestinal protectants:●

Used when gastric ulceration
is present

Laxatives and cathartics:
Dioctyl sodium sulfosuccinate

1–5 mg/kg PO

Use 1 : 20 dilution.

Mineral oil (paraffin oil)

20–30 ml (50 : 50 with electrolyte
solution)/kg PO q 24 hours

Acts unchanged as an emollient laxative. Caremust be taken to prevent aspiration.

Methylcellulose

1–3 ml/100 gAbsorbs water and swells. Care must be taken
not to mix too thickly or give too much, as it canabsorb enough water to block the GI tract.

Lactulose

150–650 mg/kg PO q 24 hours

Has a laxative effect through osmotic catharsis.

Table A1.13 Anaesthesia and sedatives.
Class

Drug

Dose and route

Comments

Can be used as a pre‐medication prior to anaesthesia
if given 10–20 minutes before induction. Onset ofaction 10–20 minutes when given IM. At sedative
doses, there are minimal effects on blood pressureand heart rate.

Benzodiazepines:
Sedation or pre‐medication foranaesthesia
Used in seizures● Often used in conjunction with
an opioid●●

Diazepam

0.2–1 mg/kg IM

Midazolam

1–3 mg/kg IM

Lignocaine

2–4 mg/kg SC

Bupivacaine

1–2 mg/kg SC

Alfaxalone

2–4 mg/kg IM (front leg)

Sedation for chelonians.

5 mg/kg IV

IV induction most species.

10 mg/kg IM

IM induction in most species.

Local anaesthesia:
Techniques for local and regional
anaesthesia, including epiduralanaesthesia, have not been describedin reptiles● Indications for use of local
anaesthetic techniques are similar
to those in domestic animals●

Injectable anaesthesia:
See Chapter 27

2–4 mg/kg IV

IV induction small crocodiles.

Ketamine

20–50 mg/kg IM, IV

Ketamine alone is not recommended for anaesthesia.
Inadequate analgesia and muscle relaxation.
Associated with spontaneous movements andmuscular rigidity. Violent and/or prolonged
recoveries. Lack of coordination.

Xylazine

0.1–1.25 mg/kg IM, IV

Does not usually produce adequate surgicalimmobilization. Reversible with yohimbine
0.11–0.27 mg/kg IM.

Ketamine(K) withbutorphanol (B)(K) 10–30 mg/kg +(B) 0.5–1.5 mg/kg IM

Minor surgical procedures.

Ketamine withdiazepam (D)(K) 60–80 mg/kg +(D) 0.2–1 mg/kg IM

Improved muscle relaxation.

Ketamine withmedetomidine (Me)(K) 10 mg/kg + (Me) 0.1–0.3 mg/kg IM(or half this dose if giving IV)

Medetomidine may no longer be commerciallyavailable in some countries. If not, use
dexmedetomidine at half the dose of medetomidine.
Reverse with atipamezole.

Ketamine withmidazolam (Mi)(K) 20–40 mg/kg + (Mi) 1–2 mg/kg IM

Propofol

5–10 mg/kg IV, IO
orConstant rate infusion at
0.3–0.5 mg/kg/min IV, IO
or
0.5–1 mg/kg IV, IO periodic bolus

Causes pronounced cardiopulmonary depressanteffects in reptiles, so should be titrated to effect.
Apnoea is common following rapid IV induction.
Intubation and IPPV are recommended.

Tiletamine–zolazepam

4–5 mg/kg IM for noninvasive
proceduresor

Variable results – sedation or anaesthesia. Severe
respiratory depression; possible may require IPPV.
Prolonged induction and recovery times. Lower doseand heart rate.

an opioid
Local anaesthesia:
Techniques for local and regional
anaesthesia, including epiduralanaesthesia, have not been describedin reptiles● Indications for use of local
anaesthetic techniques are similar
to those in domestic animals●

Lignocaine

2–4 mg/kg SC

Bupivacaine

1–2 mg/kg SC

Alfaxalone

2–4 mg/kg IM (front leg)

Sedation for chelonians.

5 mg/kg IV

IV induction most species.

10 mg/kg IM

IM induction in most species.

Injectable anaesthesia:
See Chapter 27

2–4 mg/kg IV

IV induction small crocodiles.

Ketamine

20–50 mg/kg IM, IV

Ketamine alone is not recommended for anaesthesia.
Inadequate analgesia and muscle relaxation.
Associated with spontaneous movements andmuscular rigidity. Violent and/or prolonged
recoveries. Lack of coordination.

Xylazine

0.1–1.25 mg/kg IM, IV

Does not usually produce adequate surgicalimmobilization. Reversible with yohimbine
0.11–0.27 mg/kg IM.

Ketamine(K) withbutorphanol (B)(K) 10–30 mg/kg +(B) 0.5–1.5 mg/kg IM

Minor surgical procedures.

Ketamine withdiazepam (D)(K) 60–80 mg/kg +(D) 0.2–1 mg/kg IM

Improved muscle relaxation.

Ketamine withmedetomidine (Me)(K) 10 mg/kg + (Me) 0.1–0.3 mg/kg IM(or half this dose if giving IV)

Medetomidine may no longer be commerciallyavailable in some countries. If not, use
dexmedetomidine at half the dose of medetomidine.
Reverse with atipamezole.

Ketamine withmidazolam (Mi)(K) 20–40 mg/kg + (Mi) 1–2 mg/kg IM

Propofol

5–10 mg/kg IV, IO
orConstant rate infusion at
0.3–0.5 mg/kg/min IV, IO
or
0.5–1 mg/kg IV, IO periodic bolus

Causes pronounced cardiopulmonary depressanteffects in reptiles, so should be titrated to effect.
Apnoea is common following rapid IV induction.
Intubation and IPPV are recommended.

Tiletamine–zolazepam

4–5 mg/kg IM for noninvasive
proceduresor
5–10 mg/kg IM for more invasive
procedures

Variable results – sedation or anaesthesia. Severe
respiratory depression; possible may require IPPV.
Prolonged induction and recovery times. Lower dosein larger patients.

Table A1.14 Analgesia.
Class

Drug

Dose and route

Comments

Opioids

Buprenorphine

0.005–0.02 mg/kg IM q 24–48 hours

Studies have called into question use in providing
analgesia in reptiles, including red‐eared sliders, ballpythons, bearded dragons and green iguanas (for further
information see Chapter 27). Adverse effects include
depression, nausea and vomiting, bradycardia andconstipation.

Butorphanol

0.5–2 mg/kg IM

Morphine

1.0–5.0 mg/kg IM, SC

Evidence of analgesic efficacy in red‐eared sliders andsome lizards.

Methadone

3–5 mg/kg IM, SC

Evidence of analgesic efficacy in red‐eared sliders andanecdotally in some lizards.

Tramadol

5–10 mg/kg IM, PO q 48–72 hours

Evidence of long duration of action in chelonians.

Carprofen

1–4 mg/kg PO, SC, IM, IV q 24 hours,
follow with half the dose q 24–72 hours

Flunixin

0.1–2 mg/kg IM, PO q 12–24 hours

Non‐steroidal anti‐inflammatory drugs:
Indicated when tissue damage andinflammation are the source ofthe pain● Have the potential to cause renal
damage and GI ulceration●

Ketoprofen

2 mg/kg IM q 24–48 hours

Meloxicam

0.2–0.3 mg/kg IM, PO q 24 hours

Choose higher doses for chelonians.

Table A1.15 Nutritional support.
Class

Drug

Dose and route

Calcium borogluconate

10–50 mg/kg IM q 12–24 hours as needed

Comments

Calcium:●

Used to treat
hypocalcaemic
diseases, including
hypocalcaemic tetany,
dystocia, metabolic/nutritional bonediseaseCalcium glubionate

10–100 mg/kg PO q 12–24 hours as needed

Oral supplement.

Calcium gluconate

10–50 mg/kg IM

For hypocalcaemia or dystocia.

100–200 mg/kg IM, SC q 8 hours

For nutritional secondary hyperparathyroidism,
hypocalcaemic muscle tremors and seizures or flaccid paresis
in lizards. When patient is stable, switch to oral calcium.

IodineLugol’s iodine

2–4 mg/kg PO q 24 hours for 2–3 weeks,then weekly

Used in herbivorous species maintained on goitrogenic
diet. Alternatively, can use balanced vitamin–mineral
mixture or iodized salt (0.5% of feed).

Iron

Iron dextran

12 mg/kg IM q 72 hours for 45 days

Used for treating anaemia, although not used as frequently
as it once was.

Vitamin A

1000–5000 iu/kg IM q 7–10 days for
4 treatments

Hypovitaminosis A; may have value in infectious
stomatitis. Overdose may cause epidermal sloughing.

Vitamin B1 (thiamine)

25 mg/kg PO q 24 hours as neededor
30 g/kg feed fish PO

Used in piscivorus species, e.g. crocodilians.

Vitamin B120.05 mg/kg SC, IM

May cause orange/pink urine and urates. Used as anappetite stimulant.

Vitamin C

10–20 mg/kg SC, IM q 24 hours

Supportive therapy for bacterial infections; higher doses(i.e. 100 mg/kg) may be used for severe burns.

100–250 mg/kg PO q 24 hours

Infectious stomatitis.

200 iu/kg IM q 4 weeksor1000 iu/kg IM, repeat in 1 week

See Chapter 6 for details on providing adequate ultraviolet
B lighting. Beware of oversupplementation. Herbivores are
sensitive to excess. Excessive supplementation may resultin soft‐tissue calcification.

Vitamins:●

Vitamin D3:
nutritional secondary
hyperparathyroidism
and hypocalcaemia

Vitamin D3

200 iu/kg PO q 7 days
Vitamin E

25 mg/kg IM weekly

Dietary sources include green plants. Low in whole prey(rodents and fish).

Vitamin K1

0.25–0.50 mg/kg IM

Hypovitaminosis K1; coagulopathies.

473

Appendix 2
Reference Intervals for Commonly Kept Reptile Species
Unless otherwise stated, reference intervals
are adapted from Reptile Medicine andSurgery, 2nd ed. (D.R. Mader, ed., Elsevier,
2006, pp. 1103–1118) and Current Therapy in
Reptile Medicine and Surgery (D.R. Mader and
S.J. Divers, eds, Elsevier, 2014, pp. 382–410).

­Tables
Table A2.1 Lizards
Table A2.2 Snakes●● Table A2.3 Chelonians
●●
●●

KEY
The following abbreviations are used in thetables in this formulary:
AST
BUN
CK
LDH
PCV
WBC

aspartate aminotransferase
blood urea nitrogen
Creatine kinaselactate dehydrogenase
packed cell volume
whole blood countReptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

Table A2.1 Lizards.

Units

Beardeddragon(Pogonavitticeps)

Blue‐tongued
skink(Tiliqua
scincoides)

Tokay
gecko
(Gekkogecko)1

Crestedgecko(Correlophus
ciliatus)

Chinese water
dragon(Physignathus
cocincinus)

Pantherchameleon(Furciferpardalis)Greeniguana(Iguanaiguana)Lacemonitor(Varanusvarius)2

Savannahmonitor(Varanus
exanthematicus)

PCV%(range)30(19–40)31(22–46)30(25–34)26–34

35(32–40)27(16–35)38.5(25–38)35(29–43)

31.2(21–51)WBC× 109/l(range)5.07(1.2–11.3)

7.3(2.2–19.6)

10.3(4.2–20.3)

8–23

19.4
(16–23)0.47–18.6

11.26(7–14)

22.4(0.6–63.8)

5.07(1.2–11.3)

1.95(0.38–4.06)

2.45(0.54–6.24)

2.2(0.8–4.4)–

5.1(3.9–6.9)

1.57(0.09–4.17)

0.35–5.2

6.39(0.33–26.72)

1.95(0.38–4.06)

3–39

26–50

55–72

43–69

12–81

–

5–15

7.2
(5.6–9.5)

2.96(0.21–9.67)

0.5–5.5

11.1(0.13–32.3)

2.12(0.43–5.25)

–

22–65

22–31

31–55

2–68

–

1.1
(0.4–1.9)

–

0–0.1

4.14
(0.07–12)

6–33

0–2

5–18

0–8

7–57

–

0
(0–0.6)1.25(0.08–3.74)

0–1.7

–

0.11

–

–

–

0–2

–

–

–

0.2
(0.1–0.3)

–

0–1

–

–

0–2

0–1

–

0–3

–

–

–

0.5
(0.2–0.8)

0.1(0.07–0.13)

0–0.5

–

0.15
(0.07–0.28)

0–12

0–2

0–2

0–3

–

–

MeasureHaematology

9

Heterophils

× 10 /l(range)
%

17–43

25–32

Lymphocytes

× 109/l(range)2.12(0.43–5.25)

2.75(0.32–10.9)

%

47–69

15–56

Monocytes

× 109/l(range)1.64(0.06–2.72)

0.84(0.35–1.49)

%

0–4

7–16

Azurophils

× 109/l(range)0.54(0.04–1.84)

0.34(0–1.08)

4.8(1.6–10.1)
0.84(0.15–3.0)
0.77(0.2–1.6)

1.64(0.06–6.67)

%

0–9

0–5

× 109/l(range)0.15(0.06–0.27)

1.5(0.03–2.96)

%

<1

1–2

×109/l(range)0.15(0.07–0.28)

0.98(0.11–2.24)

%

<1

1–2

AST

units /l(range)15–447

7–106

9–146

9–127

4–60

0–31

12–84

11–36

22
(1–78)

CK

units/l(range)59–7000

73–35832

117

58–3905

19–6630

331–
>1000

150–450

50–809764(150–3048)

–

35–89

–

–

1–13

–

–

364–1106

189

–

–

–

12–95

–

427
(29–3699)

Eosinophils

Basophils

0.07(0.05–1.0)
2.2(0.3–9.4)

Biochemistry

Bile acidsµmol/l

–LDH

units/l(range)35–628Uric acidµmol/l

95–68041–50680–70048–68478–450

238–958

113–653

123–925

71.4–1070

Calcium

mmol/l

4.3–13.5

2.6–5.15

4.3–4.5

2.9–5

2.4–3.7

2.2–2.9

2.25–
3.99

2.67–3.74

3.0–4.4

1.7–2.5

0.81–2.76

1.0–2.4

Phosphorous

mmol/l

0.9–4.9

0.9–2.5

0.9–2.5

1.3–3.1

1.1–2.7

1.8–3.2

BUN

mmol/l

0.4–2.5

0.0–0.7

–

–

–

0.36

Glucosemmol/l7.7–16.1

3.5–8.9

5.8–9.6

4.1–7.7

3.3–10.1

3.5–8.9

Cholesterol

mmol/l5.9–23.3

1.9–11.1

–

–

–

–

Triglyceride

mmol/l

1–5

–

–

–

–

–

60–66

66–75

47–78

–

0.0–1.8

5–8.33

5–18.35–9

4.2–6.6

–

1.3–6

49–78

–

0.2–5.4

58–96

42–86

WBC

× 10 /l(range)9

5.07(1.2–11.3)

7.3(2.2–19.6)

10.3(4.2–20.3)

8–23

19.4
(16–23)0.47–18.6

11.26(7–14)

22.4(0.6–63.8)

5.07(1.2–11.3)

1.95(0.38–4.06)

2.45(0.54–6.24)

2.2(0.8–4.4)–

5.1(3.9–6.9)

1.57(0.09–4.17)

0.35–5.2

6.39(0.33–26.72)

1.95(0.38–4.06)

3–39

26–50

55–72

43–69

12–81

–

5–15

7.2
(5.6–9.5)

2.96(0.21–9.67)

0.5–5.5

11.1(0.13–32.3)

2.12(0.43–5.25)

–

22–65

22–31

31–55

2–68

–

1.1
(0.4–1.9)

–

0–0.1

4.14
(0.07–12)

6–33

0–2

5–18

0–8

7–57

–

0
(0–0.6)1.25(0.08–3.74)

0–1.7

–

0.11

–

–

–

0–2

–

–

–

0.2
(0.1–0.3)

–

0–1

–

–

0–2

0–1

–

0–3

–

–

–

0.5
(0.2–0.8)

0.1(0.07–0.13)

0–0.5

–

0.15
(0.07–0.28)

0–12

0–2

0–2

0–3

–

–

Heterophils

× 10 /l(range)
%

17–43

25–32

Lymphocytes

× 109/l(range)2.12(0.43–5.25)

2.75(0.32–10.9)

%

47–69

15–56

Monocytes

× 109/l(range)1.64(0.06–2.72)

0.84(0.35–1.49)

%

0–4

7–16

Azurophils

× 109/l(range)0.54(0.04–1.84)

0.34(0–1.08)

4.8(1.6–10.1)
0.84(0.15–3.0)
0.77(0.2–1.6)

1.64(0.06–6.67)

%

0–9

0–5

× 109/l(range)0.15(0.06–0.27)

1.5(0.03–2.96)

%

<1

1–2

×109/l(range)0.15(0.07–0.28)

0.98(0.11–2.24)

%

<1

1–2

AST

units /l(range)15–447

7–106

9–146

9–127

4–60

0–31

12–84

11–36

22
(1–78)

CK

units/l(range)59–7000

73–35832

117

58–3905

19–6630

331–
>1000

150–450

50–809764(150–3048)

–

35–89

–

–

1–13

–

–

364–1106

189

–

–

–

12–95

–

427
(29–3699)

Eosinophils

Basophils

0.07(0.05–1.0)
2.2(0.3–9.4)

Biochemistry1

Bile acidsµmol/l

–LDH

units/l(range)35–628Uric acidµmol/l

95–68041–50680–70048–68478–450

238–958

113–653

123–925

71.4–1070

Calcium

mmol/l

4.3–13.5

2.6–5.15

4.3–4.5

2.9–5

2.4–3.7

2.2–2.9

2.25–
3.99

2.67–3.74

3.0–4.4

1.7–2.5

0.81–2.76

1.0–2.4

Phosphorous

mmol/l

0.9–4.9

0.9–2.5

0.9–2.5

1.3–3.1

1.1–2.7

1.8–3.2

BUN

mmol/l

0.4–2.5

0.0–0.7

–

–

–

0.36

Glucosemmol/l7.7–16.1

3.5–8.9

5.8–9.6

4.1–7.7

3.3–10.1

3.5–8.9

Cholesterol

mmol/l5.9–23.3

1.9–11.1

–

–

–

–

Triglyceride

mmol/l

1–5

–

–

–

–

–

Protein

g/l

36–64

53–76

–

60–66

66–75

47–78

Sodiummmol/l137–190

142–158158

134–150

147–153

Potassium

mmol/l

1–6.5

43–86

–

1.1–6.5

3.8–4.5

Chloride

mmol/l

104–160

111–115

119

–

–

–

0.0–1.8

5–8.33

5–18.35–9

4.2–6.6

–

1.3–6

–

0.2–5.4

49–78

58–96

42–86

145

157–163

143–169

149–165

5.1

3.6–4

3.9–6.7

3.2–5.7

113

119–121–

105–124

Values provided by CTDS Ltd, UK.
2
From: Scheelings, T. and Jessop, T.S. (2011) Influence of capture method, habitat quality and individual traits on blood parameters of free–ranging lace monitors (Varanus varius).
Australian Veterinary Journal, 89 (9), 360–365.

Table A2.2 Snakes.

Units

Carpetpython(Morelia
spp.)

Green
python(Morelia
viridis)Black‐headed
python(Aspiditesmelanocephalus)

Boa(Boa constrictor
constrictor)

Rainbow boa(Epicrates
cenchria)

Ball (royal)
python(Python regius)Corn snake(Pantherophis
guttatus)%(range)Haematology
PCV25(10–46)17(8–27)

24(20–29)29(10–45)28(11–40)22(10–30)32(21–52)9

11.9(2–34)

11.3(3.5–22.1)

11.8(2–24)

4.35(0.4–10.6)

8(1–35.2)

9.74(1–26)

11.3(1.0–31.4)

9

× 10 /l(range)2.8(0.3–11.3

3.89(0.86–6.63)

1.3(0.14–3.1)

1.6(0.2–5.4)

2.85(0.03–10)

2.86(0.37–10.8)

2.7(0.2–8.35)

%

38–68

–

–

20–65

–

56–67

–

× 109/l(range)

6.11(0.9–19.7)

3.44(0.2–11.2)

8.2(1.2–16.2)

2.5(0.14–8.3)

3.9(0.1–32.4)

4.2(0.13–14.1)

5.6(0.4–22.9)

%

35–51

–

–

10–60

–

7–21

–

× 109/l(range)2.2(0.06–8.8)

0.74(0.04–2.35)

0.4(0.1–0.5)

0.45(0.06–2.1)

0.9(0.03–3.1)

1(0.01–3.2)

0.93(0.04–1.8)

%

0–1

–

–

0–6

–

12–22

–

× 109/l(range)3.46(0.1–18)

5.42(0.97–13.9)

2.1(0.05–7.6)

0.7(0.1–1.84)

1.1(0.11–4.4)

3.4(0.3–13.3)

2(0.15–5.3)

%

0–5

–

–

–

–

–

–

× 109/l(range)0.2(0.08–0.34)

0.16(0.1–0.2)

0.2

0.07
(0.06–0.1)

0.1(0.04–0.2)

0.25(0.12–0.37)

0.1(0.08–0.1)

%

0–1

–

–

0–18

–

–

–

× 109/l(range)0.26(0.05–1.76)

0.55(0.07–1.8)

0.5(0.16–0.9)

0.07(0.03–0.14)

0.1(0.02–0.3)

0.55(0.07–1.8)

0.55(0.07–1.4)

%

0–3

–

–

0–20

–

0–2

–

AST

units/l

5–46

11–75

3–184

3–331

9–136

2–118

10–224

CK

units/l

27–1350600

162–336

53–1728

31–745

93–3108

91–2460

LDH

units/l48–547206

57–270

16–877

141–661

77–78748–444

Uric acidµmol/l81–33360–1213

200–1095

0–708

125–1647

190–245

167–1184

Calcium

mmol/l

3.2–4.1

5.8

2.9–3.6

2.3–6.8

2.8–4.8

2.7–5.5

3.4–4.9

Phosphorous

mmol/l

0.9–1.1

0.4–0.9

1.0–2.1

0.8–3.8

1.2–2.5

0.3–2.7

0.9–1.8

BUN

mmol/l

0–1

0.7–1

0.36–1.1

1.8

0.4–1

0–1

0–2

Glucosemmol/l

0.5–3

0.3–12

0.7–2

0.5–4.7

0.1–2.6

0.1–2.4

1.8–4.9

Cholesterol

mmol/l

6–8–10

3–9.3

7.4–15.7

0.9–8.1

3.6–8.1

0.6–7.8

8.1–14.8

Triglyceride

mmol/L––

1.2

0.04–5.2

0.7–1.1–

0.5–1.3

Proteing/L

56–105

39–69

54–87

43–108

37–80

50–56

46–108

Sodiummmol/L

135–158

157–163153

130–171

137–163

138–173

154–174

Potassium

mmol/L

4.2–5.5

3.4–5

4.3

3–10

1.2–5

2.1–9

3.3–16.6

Chloride

mmol/L

109–123

119–130

115

108–139

94–128

109–130

109–137

WBC
Heterophils

Lymphocytes

Monocytes

Azurophils

Eosinophils

Basophils

× 10 /l(range)Biochemistry

Haematology
PCV%(range)25(10–46)17(8–27)

24(20–29)29(10–45)28(11–40)22(10–30)32(21–52)WBC× 109/l(range)11.9(2–34)

11.3(3.5–22.1)

11.8(2–24)

4.35(0.4–10.6)

8(1–35.2)

9.74(1–26)

11.3(1.0–31.4)

Heterophils

× 109/l(range)2.8(0.3–11.3

3.89(0.86–6.63)

1.3(0.14–3.1)

1.6(0.2–5.4)

2.85(0.03–10)

2.86(0.37–10.8)

2.7(0.2–8.35)

%

38–68

–

–

20–65

–

56–67

–

× 109/l(range)

6.11(0.9–19.7)

3.44(0.2–11.2)

8.2(1.2–16.2)

2.5(0.14–8.3)

3.9(0.1–32.4)

4.2(0.13–14.1)

5.6(0.4–22.9)

%

35–51

–

–

10–60

–

7–21

–

× 109/l(range)2.2(0.06–8.8)

0.74(0.04–2.35)

0.4(0.1–0.5)

0.45(0.06–2.1)

0.9(0.03–3.1)

1(0.01–3.2)

0.93(0.04–1.8)

%

0–1

–

–

0–6

–

12–22

–

× 109/l(range)3.46(0.1–18)

5.42(0.97–13.9)

2.1(0.05–7.6)

0.7(0.1–1.84)

1.1(0.11–4.4)

3.4(0.3–13.3)

2(0.15–5.3)

%

0–5

–

–

–

–

–

–

× 109/l(range)0.2(0.08–0.34)

0.16(0.1–0.2)

0.2

0.07
(0.06–0.1)

0.1(0.04–0.2)

0.25(0.12–0.37)

0.1(0.08–0.1)

%

0–1

–

–

0–18

–

–

–

× 109/l(range)0.26(0.05–1.76)

0.55(0.07–1.8)

0.5(0.16–0.9)

0.07(0.03–0.14)

0.1(0.02–0.3)

0.55(0.07–1.8)

0.55(0.07–1.4)

%

0–3

–

–

0–20

–

0–2

–

AST

units/l

5–46

11–75

3–184

3–331

9–136

2–118

10–224

CK

units/l

27–1350600

162–336

53–1728

31–745

93–3108

91–2460

LDH

units/l48–547206

57–270

16–877

141–661

77–78748–444

Uric acidµmol/l81–33360–1213

200–1095

0–708

125–1647

190–245

167–1184

Calcium

mmol/l

3.2–4.1

5.8

2.9–3.6

2.3–6.8

2.8–4.8

2.7–5.5

3.4–4.9

Phosphorous

mmol/l

0.9–1.1

0.4–0.9

1.0–2.1

0.8–3.8

1.2–2.5

0.3–2.7

0.9–1.8

BUN

mmol/l

0–1

0.7–1

0.36–1.1

1.8

0.4–1

0–1

0–2

Glucosemmol/l

0.5–3

0.3–12

0.7–2

0.5–4.7

0.1–2.6

0.1–2.4

1.8–4.9

Cholesterol

mmol/l

6–8–10

3–9.3

7.4–15.7

0.9–8.1

3.6–8.1

0.6–7.8

8.1–14.8

Triglyceride

mmol/L––

1.2

0.04–5.2

0.7–1.1–

0.5–1.3

Proteing/L

56–105

39–69

54–87

43–108

37–80

50–56

46–108

Sodiummmol/L

135–158

157–163153

130–171

137–163

138–173

154–174

Potassium

mmol/L

4.2–5.5

3.4–5

4.3

3–10

1.2–5

2.1–9

3.3–16.6

Chloride

mmol/L

109–123

119–130

115

108–139

94–128

109–130

109–137

Lymphocytes

Monocytes

Azurophils

Eosinophils

Basophils

BiochemistryTable A2.3 Chelonians.

Units

Long‐necked
turtles(Chelodina spp)1

Short‐necked
turtles(Emydura spp)1

Red‐eared slider(Trachemys scripta
elegans)

Painted turtle(Chrysemys
picta)

Mediterranean
tortoises(Testudo spp)

Sulcata(Centrochelys
sulcata)

Box turtles(Terrapene
spp)

Star tortoise(Geochelone
elegans)

PCV%(range)22(16–26)24(18–30)29(16–47)22(24–30)23(22–34)28(9–48)

22(7–35)

21(12–31)WBC× 109/l(range)

14.6(6–35.9)

6.5(2.4–9.5)

13(3.5–25.5)

5.5(0.4–13)

8.5(5–12.5)

8(1.2–25.6)

7(1.7–16)11(0.75–31)

5(0.95–14)

2.2(0.17–4.3)

3.7(1.3–4.6)

3.44(0.32–9.64)

4.8(1.7–9)4.1(0.7–14.9)

Haematology

Heterophils

9

× 10 /l(range)%Lymphocytes

Monocytes

Azurophils

Eosinophils

18–69

–

–

–

–

11

–

3.3
(0.25–7.9)

1.6(0.23–3.46)

4.7(3.6–7.6)

3.68(0.19–13.7)

4.9(2.6–8.2)

5.14(0.16–17.6)

%

29–82

12–63

–

–

–

–

56

–

× 109/l(range)––0.24(0.14–0.38)

0.26

0.01
(0–0.02)

0.64(0.06–2.25)

0.11(0–0.4)0.38(0.02–1.35)

%

2–19

1–18

–

–

–

–

9.4

–

× 109/l(range)––0.58(0.23–1.33)

0.51(0.25–0.8)

0.05(0.03–0.12)

0.25(0.02–0.54)–

0.72(0.08–1.73)

%

–

–

–

–

–

–

–

–

1.53
(0.17–5.9)

0.55(0.1–1.03)

0.05(0.02–0.06)

0.35(0.03–1.41)

0.02(0–0.1)0.96(0.08–2.24)

–

–

0

3.8
(0.31–8)

2.17(0.04–4.86)

0.05(0.02–0.08)

0.3(0.02–0.54)

0.21(0–0.4)0.76(0.04–3)

× 109/l(range)%Basophils

9–58

× 109/l(range)

4–10

× 109/l(range)

1–24

%

0–4

0

–

–

–

–

8

–

AST

units/l

25–91

54–181

0–522

62–380

12–32

34–401

2–620

12–296

CK

units/l

17–390

100–1360

108–4856

35–355

6–344

103–6205

37–898

144–8518

Bile acidsµmol/l

–

–

–

0.1

–

34–401––

LDH

units/l––

371–5763

412–1035

111–313

258–1980–

12–863Uric acidµmol/l390–8904200–790

18–190

12–130

48–232

125–625

29.8–185

60–482

Calcium

mmol/l

3.3–5

2–4

2.5–4.5

1.4–4.8

2.5–4.9

1.6–5

1.6–6.6

2.3–4.4

Phosphorous

mmol/l

0.9–1.8

1.1–2.8

1.2–2.4

0.8–1.3

0.4–1.3

1.2–2.8

0.5–2.7

1.3–1.9

BUN

mmol/l

––1.4–19.3

7–30

1.4–6.1

0–2.1

7–36

0–3.9

Glucosemmol/l

5–10.4

3.5–8.4

1.1–7.7

3.8–9.8

2.2–4.8

4.4–4.5

1.8–8.5

2.2–11Cholesterol

mmol/l

––2.9–5.9–

0.7–5.4

1.5–10.5

1.7–13

2–6.5

Protein

g/l

37–53

25–42

28–66

19–65

25–46

6–20

25–47

30–60

Sodiummmol/l

124–136

128–135

124–144

126–137

131–149

121–155

138–149

122–150

Potassium

mmol/l

2.9–4.3

2.8–4.2

3.5–9.1

2.6–3.2

1.9–7.2

1.6–7

3–9.7

1.5–3.1

Chloride

mmol/l––97–107

88–99

95–100

69–394

101–112

90–112Biochemistry1

Scheelings, T.F. and Rafferty, A.R. (2012) Hematologic and serum biochemical values of gravid freshwater Australian chelonians. Journal of Wildlife Diseases, 48, 314–321.

Haematology
PCV%(range)22(16–26)24(18–30)29(16–47)22(24–30)23(22–34)28(9–48)

22(7–35)

21(12–31)WBC× 109/l(range)

14.6(6–35.9)

6.5(2.4–9.5)

13(3.5–25.5)

5.5(0.4–13)

8.5(5–12.5)

8(1.2–25.6)

7(1.7–16)11(0.75–31)

5(0.95–14)

2.2(0.17–4.3)

3.7(1.3–4.6)

3.44(0.32–9.64)

4.8(1.7–9)4.1(0.7–14.9)

Heterophils

9

× 10 /l(range)%Lymphocytes

Monocytes

Azurophils

Eosinophils

18–69

–

–

–

–

11

–

3.3
(0.25–7.9)

1.6(0.23–3.46)

4.7(3.6–7.6)

3.68(0.19–13.7)

4.9(2.6–8.2)

5.14(0.16–17.6)

%

29–82

12–63

–

–

–

–

56

–

× 109/l(range)––0.24(0.14–0.38)

0.26

0.01
(0–0.02)

0.64(0.06–2.25)

0.11(0–0.4)0.38(0.02–1.35)

%

2–19

1–18

–

–

–

–

9.4

–

× 109/l(range)––0.58(0.23–1.33)

0.51(0.25–0.8)

0.05(0.03–0.12)

0.25(0.02–0.54)–

0.72(0.08–1.73)

%

–

–

–

–

–

–

–

–

1.53
(0.17–5.9)

0.55(0.1–1.03)

0.05(0.02–0.06)

0.35(0.03–1.41)

0.02(0–0.1)0.96(0.08–2.24)

–

–

0

3.8
(0.31–8)

2.17(0.04–4.86)

0.05(0.02–0.08)

0.3(0.02–0.54)

0.21(0–0.4)0.76(0.04–3)

× 109/l(range)%Basophils

9–58

× 109/l(range)

4–10

× 109/l(range)

1–24

%

0–4

0

–

–

–

–

8

–

AST

units/l

25–91

54–181

0–522

62–380

12–32

34–401

2–620

12–296

CK

units/l

17–390

100–1360

108–4856

35–355

6–344

103–6205

37–898

144–8518

Bile acidsµmol/l

–

–

–

0.1

–

34–401––

LDH

units/l––

371–5763

412–1035

111–313

258–1980–

12–863Uric acidµmol/l390–8904200–790

18–190

12–130

48–232

125–625

29.8–185

60–482

Calcium

mmol/l

3.3–5

2–4

2.5–4.5

1.4–4.8

2.5–4.9

1.6–5

1.6–6.6

2.3–4.4

Phosphorous

mmol/l

0.9–1.8

1.1–2.8

1.2–2.4

0.8–1.3

0.4–1.3

1.2–2.8

0.5–2.7

1.3–1.9

BUN

mmol/l

––1.4–19.3

7–30

1.4–6.1

0–2.1

7–36

0–3.9

Glucosemmol/l

5–10.4

3.5–8.4

1.1–7.7

3.8–9.8

2.2–4.8

4.4–4.5

1.8–8.5

2.2–11Cholesterol

mmol/l

––2.9–5.9–

0.7–5.4

1.5–10.5

1.7–13

2–6.5

Protein

g/l

37–53

25–42

28–66

19–65

25–46

6–20

25–47

30–60

Sodiummmol/l

124–136

128–135

124–144

126–137

131–149

121–155

138–149

122–150

Potassium

mmol/l

2.9–4.3

2.8–4.2

3.5–9.1

2.6–3.2

1.9–7.2

1.6–7

3–9.7

1.5–3.1

Chloride

mmol/l––97–107

88–99

95–100

69–394

101–112

90–112Biochemistry1

Scheelings, T.F. and Rafferty, A.R. (2012) Hematologic and serum biochemical values of gravid freshwater Australian chelonians. Journal of Wildlife Diseases, 48, 314–321.

481

Index
Note: Page numbers followed by “b, f and t” refer to “boxes, figures and tables” respectively.

aabscessesaural 385
closed 142f
intra‐oral 141f
mandibular 385f
papular and swollen/
nodular dermatoses
265–266
sublingual 274, 275f
subspectacular 359–360
absorbable gelatin sponges, forhaemorrhage
control 384, 384f
Acanthocephala 437
Acanthosaura nataliae 427f
acoustic sensation 37
acrodonts, teeth 27
adrenal glands 30
Agama finchi
Heterakid egg 426f
pinworm/oxyurid eggs
from 428f
Aldabrachelys gigantea, see
Aldabran tortoise
Aldabran tortoise 312, 313f
Alethinophidia 1
alfaxalone 375, 450
alimentary tract
lower 207–208
upper 207
alligator, American 93f
Alligatoridae 2

Alligator mississipiensis, see
American alligatoralpha‐2 adrenergic agonists
375
aluminium hydroxide,
hyperphosphataemia
treatment 329
Amblyomma komodoensis
438
American alligator 93f
amoebiosis 432–433
amphotericin B 328
amputation
limb/digit 394–395
tail 394
anaemia and emaciation
hookworms androundworms
433–434
snake mites 436–437, 437b
anaerobic metabolism 369
anaesthesia 111
anaesthetic support
fluid support 378
mechanical/assisted
ventilation 377
recovery and post‐
operative
management 380
thermal support
377–378, 378f
and sedatives 468t–469t
cardiac shunting 370

equipment 124
induction of 374–375
intravenous administration
370–372, 371f, 372f
maintenance of 375–377,
376f, 377f
monitoring ofblood gas measurements
379
capnography 379
Doppler blood flow
detection 379–380
electrocardiogram 380
parameters 378–379,
378f, 379f
pulse oximetry 379
patient assessment andpreparation for
373–374
premedication 374
surgical nursing andalcohol/ultrasoundgel 447
capnography 447
Doppler unit 447
equipment and supplies
446–447
patient support
447–448
preoperative nursing
445–446
pulse oximetry 447
recovery 448

Reptile Medicine and Surgery in Clinical Practice, First Edition. Edited by Bob Doneley, Deborah Monks,
Robert Johnson and Brendan Carmel.
© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd.

482

Index

analgesia 372–373, 470t
euthanasia 450
turtle shell repair 399
analgesics 182–183
anapsid skull 19
anoles 47
Anolis spp., see anoles
Antaresia maculosa, seeChildren’s python;spotted python
antibiotic therapy 455t–459t
dosage of 178, 181
duration of 181
reason for 177–178
specific drug choice 181
treatment recommendations
179t–180t
turtle shell repair 399
antifungals 181, 460t
anti‐inflammatories 182–183
antiparasitics 182
antivirals 181–182, 461t
aquatic chelonians
food preferences 57, 58
nutrition 57–59
obesity in 59
septicaemic cutaneous
ulcerative disease 264
aquatic enclosures 46
and water quality 72–73
arboreal species 45–46
arenavirus infection, in
snakes 340
artificial tears 363
artificial ventilation 369
Aspidites melanocephalus, seeblack‐headed python
atipamezole 375
aural abscesses 385
in chelonians 365
in turtle 365, 366f
azurophils 25bbacterial infections
cardiovascular system 295
in reptilian dermatoses 269t
muscular and soft tissue
disorders 354–355

musculoskeletal system
related 349–350
of nervous systems 339
respiratory system
related 301
ball python, ferlavirus
infection 206f
bandaging 170, 171fbarbiturates 374
Basiliscus plumifrons, seedouble‐crested basilisk
beak and claw overgrowth,chelonians 263
bearded dragon
adenovirus infection
341–342, 342f
blood parameters, renal
disease assessment
325t
cloacal prolapse 281f
coccidia oocysts in faecesof 278f
eyelid trauma 361
haemoclips 123f
hyperglycaemia 194–195
melanomas in eyelids 360
metabolic bone disease 186f
Nannizziopsis guarroi
growth 143f
nutritional secondary
hyperparathyroidism
335, 337f
obesity 191f
rubber jaw 188f
sex identification 131
spinal deformity 187f, 189f
behaviour, captive reptiles
body temperatureand disease 36
and ectothermy 35–36
preferred 36
chemoreception andacoustic sensation 37
comfort signs 42, 42t
digestion and nutrition 38
discomfort signs 42, 42t
distance‐reducing
behaviour 39–41
courtship and mating 39

digging 39
gravid state 39
hand waving 39
head bobbing 39
maternal incubation
39–40
mock combat 40, 40f
social/solitary 39
tail whipping 39
and environmental
enrichment 45
fitness and environmental
enhancement 41–42
light and photoreception
36–37
maintenance behaviours
38–39
captive feedingroutines 39
constriction 38
envenomation 39
feeding 38
heat sensing pits 38
hyperactivity andhypoactivity 39
normal needs and
33–34, 34f
pain and stress 38
physiological responses
34–35
respiration andcirculation 38
water exchange andhumidity 37–38
Bellinger river turtles 343
benzodiazepines 374
biosecurity 122
black‐headed python
cardiocentesis in 290, 290f
nebulization of 306f
blepharospasm 361
blood cells 25, 136f
blood disease 213
blood gas measurements,
anaesthesia 379
blood parasitism 426
blood smears
haemogregarines 136f
slide preparation 135

Indexblood transfusion 170
blood volume 25
blue‐tongued lizard 107f
gender assessment 93f
blue‐tongued skink 89f, 91
kyphosis, lordosis 187f
sex identification 131
Boa constrictor 325
blood parameters, renal
disease assessment
325t
inclusion body disease
210f
body temperature, captive
reptilesand disease 36
and ectothermy 35–36
preferred 36
boid snakes kidneys 149
bone marrow 418
bornavirus infection, in
snakes 340–341
Bosc’s monitor 55
Brachylophus vitiensis, see
Fijian crested iguanabrain destruction,
euthanasia 449
breeding
management 95–96
racks
advantages 71
description 70–71
disadvantages 71–72
for juvenile snakes 72
for nocturnal species 72
size of 72
ventilation 72
broad‐headed snake 309, 310f
broad‐shelled turtle
externalized yolk sac 107f
gender assessment 93f
hatching 106f
umbilicus 107f
bullous spectaculopathy
362–363, 362f

ccaecum 28
canker, see stomatitis

capnography, anaesthesia 379
carapace 16
Carboniferous period 1
cardiocentesis, in black‐headed python 290,290f
cardiovascular disease, clinicalsigns of 293
cardiovascular systemanatomy 22–23, 287, 288f
examination ofcomputed tomography
292
electrocardiography
292, 293f
history and husbandry288
laboratory analysis
289–290, 291f
MRI 292
physical examination
288–289
radiography 290–291
ultrasonography
291–292, 291f, 292f
infectious disorders
bacterial infections 295
parasitic infections
295–296
viral infections 296
necropsy examinationof 412, 415f
neoplasia 295
nutritional disorders 294
physiology 287, 288f
trauma 294
carnivores 55
carpet python 7t, 16t, 100t,
293, 303f, 329
centralian 256f
early stomatitis 274f
glottis and trachea, sterile
feeding tube into
304, 305f
jaguar 111
jungle 108f, 128f, 210f
neonatal 102f
segmental aplasia 332, 334f
sublingual abscess 274, 275f

Caryospora species 427f,
431f
cataract development 364
Cestoda 437
chameleon
characteristics 6t
forelimb fracture, repairof 394f
lateral, mid‐sagittal view ofa male 25f
ligation of ovarianvasculature 388, 390f
lungs 26
mandibular symphysis
fracture, wiringof 395f
veiled 12f
cheilitis 143f
Chelodina expansa, seebroad‐shelled turtles
Chelodina longicollis, seeeastern long‐necked
turtlechelonia 2
adrenal glands 30
anapsid skull 19f
anorexia 235–236
ascites 237
aural abscesses 365
beak and claw overgrowth263
blepharoedema 241
blepharospasm 241
characteristics 1
cloacableeding from 244
swelling 244
coelioscopy 157
coeliotomy in 388
coelomic masses
palpable 243–244
conjunctivitis 241
constipation 243
depression 237
diarrhoea 243
digits/tail tip 245
distended coelom (bulging
inguinal fossae)
236–237

483

484

Index

Caryospora species (cont’d )dyspnoea 242–243
dystocia management309–310ecdysis 18
examination 132, 132f
exophthalmia 241
external anatomy 16–17
eyes 240–241
faecal output reduction
243
gait abnormalities 245
gender assessment 92, 93f
glottis 26
heart 22
herpesvirus infection 304
hind‐limb paresis/paralysis
338
inability to submerge
237–238
infectious agents 204t
intracloacal and pericloacal
ulceration 244
ivermectin in 338
joint swelling 245
kidneys 28
lameness 245
lethargy 237
liver lobectomy, complete/partial 392
lungs 26
midsagittal view 23f
muscle innervationassessment 335
nasal/oral discharge 242
neurological signs 246
nutrition 55–59
ocular discharge 241
oral inflammation 241–242
oral mucous membrane
colour 242
oviposition 244–245
oxytocin therapy 309
pancreas 30
paralysis 245–246
parathyroid glands 30
parenteral formulations of
medication 306
paresis 245–246

phalluseversion 133, 133f
prolapse 244, 317
prolapse 244
pyramidal carapace 239
radiography
positioning 145–146,
146f
reference intervals
for 478t–479t
regurgitation 243
reproductive
system 29–30
respiration 26
sex identification 133, 133f
shell
abscessation 240
deformities of 352–353
deformity 239
discolouration 239–240
epidermis erythema 240
epidermis masses 240
epidermis ulceration 240
flaking 239–240
fractures and wounds 239
petechiae 240
soft 239
thickening 239–240
sight 30
skinabrasions/ulcerations
238–239
discolouration 238
swellings 239
stomach 28
subcutaneous oedema 237
sudden death 246
superficial bacterial
infections 264
swollen limbs 245
thyroid glands 30
toenails 240
tracheal discharge 242
tympanic membranebulge 241
ultrasonography 150–151,
151f
uneven floating 238
vascular access 169

ventral view 22vertebrae 20
vision loss 241
vomiting 243
weakness 237
weight loss 236
Chelonia mydas, see green
turtleschemical burns 263
chemoreception 37
Children’s python
with central nervous systemdysfunction 332, 334f
reflex during neurologicalexamination
332, 334f
chlamydia 302
Chlamydosaurus kingii, see
frilled lizard
Choleoeimeria species 431f
chronic pain management,
NSAIDs for 373
circulation 38
cloaca 28
prolapse 280
in bearded dragon 281f
causes of 281
in green python 281f
prognosis 282
treatment 281–282
scent glands 28
cloacitis 282–283
cloacoscopy‐cystoscopy
156–157, 157f
coastal carpet python,segmental aplasia
332, 334f
Coccidia oocysts 278f
coccidiosis 182, 431–432, 431f
coelioscopy 157
coeliotomy
in chelonians 388, 388f
in green iguana 387f
in lizards 387–388
in snakes 388
collared lizard, cheilitis 143f
colonic impaction
causes of 279–280
clinical signs 280

Indexdiagnosis 280
treatment 280
colonoscopy 156–157, 157f
computed tomography(CT) 153–154
cardiovascular system
examination 292
turtle shell repair 400
congenital cardiac
disease 293
congenital musculoskeletal
system disorders
345–346, 346f
congenital nervous systemdisorders 335
congestive heart failure 293
conjunctivitis 361–362
constipation, see also colonic
impaction
chelonia 243
lizard 232
snakes 222
consultation
appointment 125
diagnosis 133
diagnostic pyramid
126, 126f
patient’s history 126, 127b
physical examination
126–133, 128f, 129b,
129f–131f
summary 133
consultation room 117–118
consumables 124
contrast radiology
angiography, excretory
nephrography 148
barium sulphate
147, 147f
iodine‐based contrast
agents 148
Corallus caninus 427f
corneal disorders 363–364
corneal ulcers 363
corn snake 354
Correlophus ciliatus, seecrested geckos
crested geckos 47
crocodileanorexia 247
behaviour changes 247–248
cloacaprolapse from 251
swelling 251
conjunctival swelling 249
diapsid 19
diarrhoea 250–251
digits 251–252
distended coelom 247
dyspnoea 250
external ear 30
exudation 249–250
eyedischarge 249
distension 249
gender assessment 92, 93f
gingival/oral inflammation
249–280
gravid female 251
heart 287
inability to submerge/
floating 248
increased time spentbasking 248
increased time spentsubmerged inwater 248
lungs 26
mouth gaping 249
muscle innervationassessment 335
musculoskeletal
deformities 251
nasal discharge 250
neurological signs 252
pain 251
paralysis 252
petechiation 249–250
radiography positioning
146, 147f
regurgitation 250
reproductive system
29–30
skin
abrasions 249
blisters 248–249
discolouration 248–249
disruption 249

granulomas proliferative
nodules 248–249
hyperkeratosis 248–249
papules 248–249
pustules 248–249
thickening 249
ulceration 248–249
sudden death 252
supportive care 160
swelling 249, 251
swimming motion,
abnormal 248
tachypnoea 250
tail necrosis/loss 251–252
tooth loss/damage 250
ulceration 249–250
ultrasonography 153
venipuncture in 371, 372f
vomiting 250
weight loss 247
Crocodylia 2
Crocodylidae 2
Crocodylus porosus, seeestuarine crocodile
Crotaphytus collaris, seecollared lizard
Cryptodirans 2
Cryptosporidium
species 431f
cutaneous fibropapillomatosis
267
cystotomy 392, 392f
cytological examination
138–139ddecapitation, euthanasia 449
dehydration 111
dentition
front‐fanged snakes 28
rear fanged snakes 27–28
Dermatophilus congolensis
266–267
dermatoses
abnormal/excessive
scaling 258
bacterial infections 262
drug contraindications
270t

485

486

Index

dermatoses (cont’d )dysecdysis 259, 260f
ectoparasitic infections
260, 261f
erosive/ulcer ative
263–265
fungal infections 261–262
hypovitaminosis A
262–263
moist erythematous
263–265
necrotic 263–265
nutritional osteodystrophy
268
papular and swollen/
nodular 265–268
vesicular 263–265
diagnostic imaging
computed tomography
153–154
diagnostic endoscopy
154–157
magnetic resonanceimaging 154
radiography
contrast radiology
147–148, 147f
evaluation of 148–150
exposure 146–147
plain radiographs 147
positioning 145–146
sedation andanaesthesia 145
training 157
ultrasonography 150–153
diagnostic techniques
blood collection 161–162,
162f
blood handling 162–163,
162f
microbiology 163
diagnostic testing
biochemical analyses
136–138
culture 141–143, 143f
cytology 138–139
haematology 135–136,
136f, 137t
serology

enzyme‐linked
immunosorbent
assay 140
haemagglutination
inhibition tests 140
molecular diagnostics
140
polymerase chain
reaction 140, 141t
virus/serum
neutralization
tests 139
diamond python 282, 283f
diapsid 19
diarrhoea 278–279, 278f
chelonia 243
crocodile 250–251
lizards 232
snakes 222
digestion 28, 38
digestive system 27
Diplodactylus galeatus, see
gecko
Diploglossa 1
Doppler analysis 290, 291f
Doppler blood flow detection
379–380
double‐crested basilisk 168f
dragons
bearded 3f
water 6t
drugs
administration 175–177,
176b
compounding 177
for kidney disease
treatment 466t
for liver disease
treatment 465t
DuoDERMR® use, in shell
fracture repair
170, 171f
dysecdysis 18, 259, 260f,
see also ecdysis
dyspnoeic snake 303f
dystocia
aetiology 307
clinical signs 308
diagnosis 308–309

environmental andhusbandry related
factors 307
host factors 307–308
prevention andcontrol 310
radiography 308
treatment 309–310
ultrasonography 308

eear diseases 365–366, 366f
eastern bearded dragonanaesthesia monitoring
378, 379f
gender assessment 94f
eastern blue‐tongued
skink 187f
eastern brown snake 112f
nasolacrimal ductatresia 362f
eastern long‐necked turtle
dorsoventral
radiograph 400, 401f
oesophageal foreign body,endoscopic removalof 276, 277f
septicaemia 132, 132f
shell fracture repair 171f
traumatic panophthalmitis
363, 364f
eastern water dragons
hatching 106f
sex identification
131–132, 131f
ecdysis 18
ectoparasitic infections
260, 261f
ectoparasitism 426
ectopic eggs 320–321
ectothermy 15, 45, see also
thermoregulationegg
anatomy 92
binding 338
clutches, multiple 99
incubation 99–101
laying 98–99
viability determination 101

IndexEimeria species 431f
Elapidae, fangs 28
electrocardiogram (ECG)
anaesthesia, monitoringof 380cardiovascular system
examination
292, 293f
electrolyte imbalances 294
emergency drugs 454t
enclosure 120–122, 120f,
121f, see also indoor
enclosures; outdoor
enclosuresaquatic 46, 72–73
for arboreal species
45–46
heat and humidity 46
indoor/outdoor 61–62
for non‐climbing
species 46
opening of 46
positioning of 46
semi‐aquatic species 46
shape and interior designof 45
size of 46
for terrestrial species 46
endocrine system 30
endoscopy 154–157
enemas 170
enophthalmos 365
Entamoeba invadens
432–433
enucleation 386
environmental enrichment
46–47
behaviour and 45
epidermal colour andtexture variation
255, 256f
equipment
acrylic oral specula 119f
metal oral specula 118f
reptile sexing probes 119f
estuarine crocodile
body temperature
measurement
377, 378f

systemic lymphoidproliferation andnon‐suppurative
encephalitis 343
Eublepharis macularius, seeleopard gecko
euthanasia
confirming death
450, 451f
methods ofanalgesia 450
decapitation 449
freezing 449
gas 450
instantaneous brain
destruction 449
pentobarbitone
449–450
redundancy 451
exertional rhabdomyolysis
353, 354
exophthalmos 364–365
external marketing
115–116
external parasiticides 463teye(s)
ancillary tests 357
diseasesconjunctivitis 361–362
of cornea 363–364
enophthalmos 365
exophthalmos 364–365
eyeliddisorders 360–361
of lens 364
microphthalmia 365
nasolacrimal
duct 362–363
periocular region 361
of retina 364
spectacle disorders
358–360of uvea 364
examination 129f
ophthalmic
instruments 358
physical examinationof 357sight 31eyeliddisorders 360–361
surgery 386

ffacilities 120
feeding frequency 28
fee setting 116
felt 28
female reproductive
system 30
Ferguson zone concept 84,
85b, 85t
ferlavirus infection, in
snakes 303, 341
Fijian crested iguana 319,
320f
financial health measurement
116–117
fitness, captive reptiles
behaviour 41–42
flagellate protozoal enteritis,in diamond
python 282, 283f
flotation 427
fluid therapy 164, 165f,
165t, 166
turtle shell repair
399–400
fluorescein staining 357
formulary 453
anaesthesia 468t–469t
analgesia 470t
antibiotics 455t–459t
anti‐fungal drugs 460t
antiviral drugs 461t
drugs forkidney disease
treatment 466t
liver disease
treatment 465t
emergency drugs 454t
external parasiticides 463t
gastrointestinal
drugs 467t
hormonal therapies 464t
internal parasiticides 462t
nutritional support 471t
sedatives 468t–469t

487

488

Index

fracture fixation, turtle shell
repairadhesives 403–404, 403f
bridging methods
404–405, 404f
under generalanaesthesia 402, 402f
orthopaedic fixation
methods 405–406,
406f
freezing method,
euthanasia 449
freshwater turtles
inability to submerge
237–238
uneven floating 237–238
frilled lizard 128f
obesity 191f
front‐opening enclosures
67–68
fungal infections 261–262
muscular and soft tissue
disorders 354–355
nervous systems 339
papular and swollen/
nodular dermatoses
267
respiratory system
related 302
Furcifer pardalis 430f
furniture 68–69

ggalapagos
in direct sunlight 84f
rhabdomyosarcoma 354
gas in euthanasia 450
gastrointestinal drugs 467t
gastrointestinal systemanatomy and physiology 273
diseases ofcloacal prolapse
280–282, 281f
cloacitis 282–283,
282f, 283f
colonic impaction
279–280
diarrhoea 278–279,
278f

intestinal obstruction
279
liver disease 283–285,
284t
mandibular and maxillaryfractures 276, 277f
oesophageal foreign
bodies 276, 277f
regurgitation 276–278
stomatitis and dental
disease 273–276,
274f, 275f
necropsy examinationof 418, 420, 420f
gastrointestinal tract 28
radiographs evaluation
148–149, 149f
gastropeges 17
gastroscopy 156
gastrotomy and gastrectomy
390
Gavialidae 2
gecko
albino leopard 89f
characteristics 5t
gender assessment 94f
Gekko gecko, see Tokay gecko
Gekkota 1
gender assessment
chelonians 92, 93f
crocodilians 92, 93f
lizards 92–94, 94f
snakes 95, 95f
genetic defects 111
Geochelone denticulata, see
yellow‐footed tortoise
Geochelone nigra, see
Galapagos tortoisegestation, length 98
glass reptile enclosure
64–65, 64f, 65f
glaucoma 363–364
glucose concentrations 137
Goniurosaurus huuliensis
Heterakid egg 426f
pentastomid eggs
from 429f
pinworm/oxyurid eggs
from 428f

strongylid eggs from 427f
Goniurosaurus luii 429f
gravidity determination
96, 97f
green anoles, skinalterations 212f
green iguana 12f, 48, 50
coeliotomy 387f
lungs 26
MRI 154, 155f
Oochoristica species
from 430f
pinworm/oxyurid eggs
from 428f
post‐ovulatory
period 97f
sex identification 131
supportive care 160f
surgical curettage ofmandibular
abscess 385f
green python
cloacal prolapse 281f
gender assessment 95f
green turtle
CT 153, 153f
spirorchid flukes 343
systemic coccidiosis
342–343
gut transit time 28hhaematocrit 25
haematopoietic tissues 418
haemoclips, bearded
dragon 123f
haemogregarines 136f
haemorrhage control 399
handling
aids 122and restraint techniques 48
hatching/birth 101–102
oviparous neonates
105–107
ovoviviparous/viviparous
neonates 107
health care, of captive
reptiles 49
hearing 30–31

Indexheart, radiographs
evaluation 148
heating 123, 163–164
heat sensing 31
heat‐sensitive receptors 367
heat source 69, 69f, 70f, 122
heliothermy 16
Heosemys spinosa 426f
herbivores
chelonians 56, 57t
lizard 53
herbivorous diets,
disadvantage 50
hereditary cardiac
disease 293
hereditary musculoskeletal
system disorders
345–346, 346f
hereditary nervous systemdisorders 335
Hermann’s tortoise 207f
pinworm/oxyurid eggs
from 428f
Herpesvirus infections 262
hiding places 122
hind‐limb paresis 338
hookworm infestation
433–434
Hoplocephalus bungaroides,
see broad‐headed snake
hormonal therapies 464t
hospital enclosure, design
diligent care 443
furniture 443
heating methods 443
humidity 443
lighting considerations 443
nonporous materials 443
substrate 443
veterinary grade
disinfectant 443
hospitalization 120
housing 45–46, see also
enclosure
breeding racks 70–72, 71f
general considerations
construction
materials 64–68,
64f–68f

design 62–64
furniture 68–69
heat source 69, 70
lighting 69
location 62
pest control 70
substrate options
70, 70thumidity 37–38, 122
husbandry
conspecifics 48
environmental
enrichment 45–47
handling and restraint
techniques 48
housing 45–46
hygiene 47
lighting
artificial sunlight
79–84
natural sunlight 78–79
recommendations
88–89
solar spectrum 75–78
ultraviolet requirement
84–88
preventative healthcare 49
sex identification 48
transport requirements 48
water quality 47–48
hygiene 47
hyperglycaemia 194–195
hyperkalaemia 294
hyperkeratosis, see abnormal/
excessive scaling
hyperuricaemia 137
hypervitaminosis A 265
causes 193
clinical signs 193–194
prevention 194
treatment 194
hypoalbuminaemia 294
hypocalcaemia 110–111, 294
nervous system related
336–337
hypoglycaemia 110
hypokalaemia 294
hypothermia 110, 344

hypovitaminosis A 50,
262–263, 300, 301
clinical signs 193
diagnosis 193
pathogenesis 192–193
prevention 193
treatment 193
hypovitaminosis E 265

i
Iguana iguana, see green
iguanaIguania 1
immune system 25, 299
immunology 214–215
inclusion body disease(IBD) 206
incubation behaviour, python
species 45
indoor enclosures
cage cleaning 67–68, 68f
construction
materials 64–66,
64f–66f
design 62–63
feeding access 67–68
furniture
branches 68–69
cage furniture 69f
food and water
dishes 68
privacy shelters 68
heat sources 69, 69f, 70f
lighting 69
location 62
pest control 70
substrate options 70
infectious diseases 111–112
infectious agents
198t–203t
planning 213–214
undiscovered infectious
agents 214
injectable anaesthetics 370
inland bearded dragon 327f
insecticide toxicity 338–339
instantaneous brain
destruction,
euthanasia 449

489

490

Index

instrumentation 123
integument 17–18
anatomy and physiology
of 255, 256f
disordersabnormal/excessive
scaling 258
bacterial infections 262
beak and claw
overgrowth 263
common clinicallesions 258
dermatoses 263–265
dysecdysis 259–260,
259f, 260f
ectoparasitic infections
260, 261f
fungal infections
261–262
hypovitaminosis A
262–263
papular and swollen/
nodular dermatoses
265–268
skin disease management
approach 256–258,
257fviral infections 262
ecdysis 18
intermandibular cellulitis 266
internal marketing 115
internal parasiticides 462t
intestinal obstruction 279
intracardiac bloodshunting 23–25
intracardiac shunts 370
intracoelomic dosing 169
intra‐oral abscesses 141f
invertebrate dietlimitations 50
Iodosorb®, 170, 171f
Isospora jaracimrmani 431f

j
Jacobson’s organ 31,
366–367
jungle carpet python
mouth gaping 210f
with sunshinevirus 128fk
Kalicephalus
species 433–434
keratitis 363
keratoconjunctivitis sicca 363
ketamine hydrochloride 374
key performance indicators(KPIs) 116, 117, 117t
kidney disease 212–213
Krefft’s turtle, phallus
prolapse 318f

llace monitor
anaesthesia monitoring
378, 378f
bone loss 187f
egg size 97f
laser/radiosurgical unit 123
lead toxicity 339
lens 364
leopard gecko 89f
pinworm/oxyurid eggs
from 428f
leucocyte 136, 136f, 137t
counts 136
light/lighting 122, 164
artificial sunlightbasking lamps 79–81
coloured lamps 81
ultraviolet lamps
82–84
visible light 81–82
captive reptiles behaviour
36–37
for enclosures 69
natural sunlight 78–79
reptile keepers,
recommendations
88–89
solar spectrum
infrared 75–76
ultraviolet A 76–77
ultraviolet B 77
visible light 76–77
vitamin D3, 77–78
ultraviolet requirement
excessive exposure
86–88

Ferguson zone concept
84, 85t
gradient 84–86
lignocaine 373
lithophagia 148, 149f
liver
biopsy 392
disease 208–209
classification 283, 284t
clinical signs 283
haematology andbiochemistry
analysis 284
treatment 285
ultrasound 284
lobectomy, complete/partial 392
necropsy examinationof 416, 417f, 418
lizardadductor muscles 19, 20f
adrenal glands 30
anorexia 226–227
backbone 21
blepharoedema 230
blepharospasm 230
blisters 228
calculus 231
characteristics 4t
cloaca/hemipenal regionswelling 233
cloaca prolapse 233
coelioscopy 157
coeliotomy in 387–388
constipation 232
C. varanii infection 430
deformities 232
dental loss 231
depression 227
diapsid 19
diarrhoea 232
digits/tail tip 234
discoloured urates 233
distended coelom 227
dysecdysis 228
dyspnoea 230–231
dystocia management 310,
311f
ecdysis 18

Indexexamination 131–132
excessive salivation
230–231external anatomy 17
exudation 231
eyescolour change 229
opacities 229
spectacle distension
229–230
facial/jaw swellings 232
gait and postureabnormalities 234
gender assessment
92–94, 94f
gingival inflammation 231
granulomas 228
gravid female 233–234
hyperplasia 231
infectious agents 204t
internal swellings 233
kidneys 28
lameness 234
lethargy 227
limb/vertebral swellings 234
liver lobectomy, complete/partial 392
lungs 26
muscle innervationassessment 332, 335
nails, overgrown/
misshapen 229
nasal discharge 230–231
nephrectomy 393
neurological signs 235
nutrition 53–55
ocular discharge 230
opaque/dry spectacle 229
open mouth
breathing 230–231
oral discharge 231
oral mucous membrane
colour 231–232
papules 228
paralysis 235
parathyroid glands 30
paresis 235
periocular swelling 230
plaque 231

proliferative nodules 228
pustules 228
radiography
positioning 146
recession 231
reduced faecal output 232
reference intervals
for 474t–475t
reproductive
system 29–30
respiration 26–27
salivation 231
sex identification
131–132, 131fsight 30
skinabrasions 228
discolouration 227–228
disruption 228
hyperkeratosis 228
thickening 228
spinal and headtrauma 337–338
sudden death 235
superficial bacterial
infections 263–264
supportive care 159–160,160fswellings 228–229
thermoregulation 16
tongue lesions 231
ulceration 228, 231
ultrasonography 151–152
ultraviolet index (UVI)
exposure levels 85t
uroliths in 329
vascular access 169
venipuncture in 370–371
ventral view of female 24f
weakness 227
weight loss 227
lockable enclosures 67, 68f
loggerhead genital–respiratory
herpesvirus(LGRV) 304
loggerhead orocutaneous
herpesvirus(LOCV) 304
lone star retractor 124f

loss of spectacle 360
lower urinary tract
disease 329
lymphoid tissues 418

mmagnetic resonance imaging(MRI) 154, 292
magnification loupes 123
maintenance behaviours, seebehaviour, captive
reptilesmale reproductive system
29–30
mandibular fractures
276, 277f
marine iguana 84f
marine turtles
inability to submerge
237–238
uneven floating 237–238
marketing, in reptile
practice 115–116
mating 96
maxillary fractures 276, 277f
medetomidine 375
medical records 119–120
medications administration
intramuscular dosing 169
intraosseous dosing 169
intravenous dosing 169
oral and parenteral
dosing 168
subcutaneous dosing
168–169
metabolic bone diseaseaetiology 185
causes 185
clinical signs 186–188,
187f, 188f
diagnosis 188–189, 189f
differential diagnosis 188
pathogenesis 186
prognosis 190
treatment 189–190
vitamin D synthesis
185–186
metabolic myopathies 353
metabolic rate 15

491

492

Index

methadone 372
microphthalmia 365
microsporidia 355
midazolam 374
mite management plan 437b
mites, reptile 130
Morelia spilota, see coastal
carpet python
Morelia viridis, see green tree
pythonAscarid egg from 426f
Capulotaenia species
from 430f
cloacal prolapse 281f
morphine 372
mouth rot, see stomatitis
Murray river turtle eye
examination 358f
muscle relaxants 370
muscular and soft tissue
disordersbacterial and fungal
infections 354–355
congenital and hereditarydisorders 353
infectious disorders
bacterial and fungal
infections 354–355
parasitic infections 355
viral infections 354
non‐infectious disorders
exertional
rhabdomyolysis
353, 354
metabolicmyopathies 353
neoplasia 354
trauma 353
vitamin E deficiency 353
muscular filariasis 355
musculoskeletal systemanatomy and physiology 345
necropsy examinationof 421, 421f
musculoskeletal system,
disorders ofcongenital and hereditarydisorders 345–346,
346f

infectious disorders
bacterial and mycotic
infections 349–350
parasitic infections
350–351
muscular and soft tissue
disorders 353–355
non‐infectious disorders
metabolic and nutritional
conditions 346–348,
346f, 347f
neoplasia 348, 349f
trauma 348
skeletal disorders, ofindeterminate/or
mixed origin
351–353, 351f, 352f
mycobacterial infections
papular and swollen/nodular
dermatoses 267
respiratory system
related 302
Mycoplasma agassizii 197
mycoplasma infections
301–302
mycotic infections
musculoskeletal system
related 349–350
respiratory tract 302
Myuchelys georgesi, see
Bellinger river turtlesnNannizziopsis guarroi 143f
nasolacrimal duct
blockage 362
bullous spectaculopathy
362–363
obstruction 386
nebulization 305–306
of black‐headed python 306f
necropsy
ancillary testing, sample
collection andsubmission for 422,
423t–424t, 424b
description 409
differential diagnoses
before 410

equipment 410, 411f
examination ofcardiovascularsystem 412, 415f
gastrointestinal
system 418, 420, 420f
haematopoietic
tissues 418
liver and biliary
system 416, 417f, 418
lymphoid tissues 418
musculoskeletal
system 421, 421f
nervous system
421–422, 422f
reproductive
system 418
respiratory system 412,
415–416, 416f
urinary system 418,
419f
external examination ofcarcase 412, 413f
maximizing carcase
quality 409
minimal routine diagnostic
necropsy
samples 424b
opening carcase 412, 414f
preliminary considerations
409–410, 410t, 411f
safety 409
necrotic dermatoses
environmental factors 263
fungal infections 265
nutritional factors 265
superficial bacterial
infections 263–264
systemic bacterial
infections 264
thermal/chemicalburns 263
traumatic lesions 263
neonatal careconspecific aggression 109
maternal factors 107
post‐hatch/birth
inappetence 107–108
thermoregulation 108–109

Indexneoplasia
cardiovascular system
related 295
muscular and soft tissues
related 354
musculoskeletal
disorders 348, 349f
nervous system related 338
papular and swollen/
nodular dermatoses
268
respiratory system
related 301
nephrectomy and renal
biopsy 393
nervous system 30–31
anatomy and physiology
331
diseases ofcongenital and hereditarydisorders 335
diagnostic work‐up 335,
336t
history and husbandry
331
hypothermia 344
infectious disorders 339
necropsy examinationof 421–422, 422f
neurological examination
close examination 332
cranial nerve
function 332, 333t
distant examination
331–332
muscle innervationassessment 332, 334f,
335
non‐infectious disorders
egg binding 338
hypocalcaemia 336–337
neoplasia 338
nutritional secondary
hyperparathyroidism
335, 336, 337f
toxicities 338–339
trauma 337–338
viral diseases of snakes
339–342, 340f, 342f

neurological disease
209–211neuromuscular blocking
agents 374
nitrogen cycle 72
non‐climbing species 46
non‐crocodilian heart 287
non‐obstructive dystocia
management 309
non‐pathogenic pinworm
infection 436
nonsteroidal anti‐inflammatory
drugs (NSAIDs) 373
nursing, reptile patient
hospital caredaily care 443–445,
444f, 445f
hospital enclosures 443
housing during 442
reception
fixing appointments 441
separate waiting
area 441–442
transportation
process 441, 442f
surgical nursing andanaesthesia
alcohol/ultrasoundgel 447
capnography 447
Doppler unit 447
equipment and supplies
446–447
patient support 447–448
preoperative nursing
445–446
pulse oximetry 447
recovery 448
nutrition
captive reptiles
behaviour 38
carnivory 50
chelonian 55–59, 56t, 57t
herbivory 50
lizard 53–55
omnivory 50
snake 50, 53
nutritional delivery 167–168,
167tnutritional diseases 301
nutritional
osteodystrophy 268
nutritional secondary
hyperparathyroidism(NSHP) 335, 336,
337f
nutritional support 166–167,
167t, 471toobesity 294
aquatic chelonians 59
bearded dragon 191f
frilled lizard 191f
pathogenesis 190–191,
191f
treatment 191–192, 192f
oculoscopy 155
oesophageal foreign
bodies 276, 277f
oesophagoscopy 156
oesophagostomy tube
placement 386–387
olfactory organ 31
omnivores
chelonians 56–57
lizard 54, 55
omnivorous 1
challenges of 50
Oochoristica species 437
Ophidascaris species 433
ophidian paramyxovirus(OPMV), see ferlavirus
Ophionyssus natricis 436, seereptile mite
opiates 373
opioids 373, 374
oral examination 130f
orchidectomy 390
orthopaedic surgery
bone healing 393
external and internal
fixation 394
external coaptation
393–394
fracture repair
principles 393
osteitis deformans 351f

493

494

Index

otoscopy 155
outdoor enclosures
cage cleaning 67–68, 68f
construction materials
66–67, 67f
design 63–64
feeding access 67–68
furniture
branches 68–69
cage furniture 69f
food and water
dishes 68
privacy shelters 68
heat sources 69, 69f, 70f
lighting 69
location 62, 63f
pest control 70
substrate options 70
ovariectomy 388
oviductal prolapse 316–317,
317f
oviparous 1, 105–107
ovoviviparous 1, 107
oxytocin therapy 309
oxyurid nematodes 436

ppaediatrics
anaesthesia 111
examination and diagnostic
testing 109
failure to thrive 112–113
genetic defects 111
hatching/birthoviparous
neonates 105–107
ovoviviparous/viviparous
neonates 107
infectious diseases
111–112neonatal careconspecificaggression 109
maternal factors 107
post‐hatch/birth
inappetence 107–108
thermoregulation
108–109
substrate ingestion 112

treatment
dehydration 111
hypocalcaemia 110–111
hypoglycaemia 110
hypothermia 110
Paget’s disease, see osteitis
deformans
pain, captive reptiles
behaviour 38
pancreas 28, 30
Pantherophis guttatus, seecorn snake
Pantherophis obsoletus 427f
papillomas 267
papular and swollen/nodular
dermatoses
bacterial infections
abscesses 265–266
D. congolensis 266–267
intermandibular
cellulitis 266
fungal infections 267
mycobacterial
infections 267
viral infections
cutaneousfibropapillomatosis
267
papillomas 267
parasites 268
poxviruses 267
Ranaviruses 267–268
parasitic infections
cardiovascularsystem 295–296
muscular and soft tissue
disorders 355
musculoskeletal system
related 350–351
nervous systems 342–343
papular and swollen/
nodular dermatoses
268
respiratory system
related 303
parasitology
Acanthocephala 437
anaemia and emaciation
433–434, 436–437, 437b

Capillaria 437
Cestoda 437
faecal sample diagnostic
techniques 427–428
gastric and intestinal
diseases 430–431
Heterakid nematodes 437
in‐clinic diagnostics
425–427, 426f–433f
intestinal and biliary
coccidiosis 431–432,
431f
intestinal and liveramoebiosis
432–433
non‐pathogenic pinworm
infection 436
parasite infections,management of
438–439, 438f
parasites and parasitegroups, selectionof 435t
parasitologicalresults 428–429
Pentastomida 437
pneumonia 435–436
spirurid nematodes 437
parathyroid glands 30
parthenogenesis 92
Pentastomida 437
pentobarbitone, euthanasia
449–450
perentie 94f
femur fracture 189f
with yolk coelomitis 314f
periocular region
diseases of 361
disorders 361
pest control, enclosures 70
petechiae/ecchymoses 262
phallus prolapse
clinical signs 318, 318f
diagnosis 318
pathogenesis 317–318
predisposing factors 317
prevention andcontrol 319
treatment 318–319

Index

pharmacology
analgesics 182–183
antibiotic therapy
177–181
antifungals 181
anti‐inflammatories
182–183
antiparasitics 182
antivirals 181–182
drug compounding 177
drugs administration
175–177, 176b
Photo‐kerato‐
conjunctivitis 89f
Photo‐microhabitat 79
photoreception 36–37
physical examination, in
cardiovascularsystemauscultation 289
clinical signs 289
heart rate 288–289
mucous membranes 288
pulse rates 289
respiratory rates 289
pinworm infection 436
pithing technique 451
pit organs 367
plastic moulded enclosures
65, 66f
plastron fracture repair,bridging methodof 404f
plastronotomy 388, 389f
Platynota 1
Pleurodirans 2pleurodont teeth 27
pneumonia 435–436
Pogona barbarta, see eastern
bearded dragon
Pogona vitticeps, see bearded
dragon; inland bearded
dragonpost‐ovulatory egg stasis, seedystocia
postprandial cardiac
hypertrophy,
pythons 194
poxvirus 262, 267

practice management see
reptile practice
preferred body temperature(PBT) 16, 16t
premedication protocol 374
preovulatory follicularstasisaetiology 311
clinical signs 312
diagnosis 312, 313f
pathogenesis 311–312,
312f
prevention and control
313–314treatment 312–313
prolapsed hemipene/
phallus 393
propofol 375
protein catabolism 137
pseudobuphthalmos 386,
see also bullous
spectaculopathy
pulmonoscopy 155–156,
156f
pulse oximetry 447
anaesthesia, monitoringof 379pythonball 8t
capillaria eggs from 427f
cardiomegaly 289f
carpet 7tcloacitis 282f
green 7t, 13f
heart, ventral and dorsal
aspect 287, 288f
jungle carpet 12f
postprandial cardiac
hypertrophy 194
regurgitation 276–278
with retained
spectacle 359f
Python regius 427f
Python reticulatus, seereticulated pythonqquarantine protocol, in healthcare 49rradiography
cardiovascular system
examination 290–291
contrast radiology
147–148, 147f
evaluation of 148–150
exposure 146–147
plain radiographs 147
positioning 145–146
sedation andanaesthesia 145
ranaviruses 267–268
rattlesnakes 91
hemipenes 149
rebound tonometry
358, 358f
record keeping 49
rectum 28
red‐eared slider turtle 346f
blood parameters, renal
disease assessment
325t
eyelid trauma 360
reference intervals 473
for chelonians 478t–479t
for lizards 474t–475t
for snakes 476t–477t
reflexes monitoring 447t
regurgitation
aetiology 277
causes of 277
clinical signs 277
diagnosis 278
in pythons 276
treatment 278
renal diseasediagnosis 323–325, 325t
infectious causes of
325–326, 326f
non‐infectious aetiologies
renal cysts andaplasia 326
urate tophi in renal
tubules 327, 328f
visceral gout 327, 328f
prognosis andtreatment 329
renal osteodystrophy 328

495

496

Index

renal secondary
hyperparathyroidism(RSHP) 190
reproduction 91
breeding management
95–96
clutches, multiple 99
egg
anatomy 92
incubation 99–101
laying 98–99
viability determination
101
embryonic mortality 102
gender assessment
chelonians 92, 93f
crocodilians 92, 93f
lizards 92–94, 94f
snakes 95, 95f
gravid females
management 98
gravidity determination
96, 97f
hatching 101–102
length of gestation
determination 98
mating 96
parthenogenesis 92
physiology 91–92
reproductive system 29–30
anatomy andphysiology 307
disorders ofdystocia/post‐ovulatory
egg stasis 307–310,
311f
ectopic eggs 320–321
hemipenal plugs 319,320f
infertility 321
oviductal prolapse
316–317, 317f
phallus prolapse
317–319, 318f
preovulatory follicularstasis 311–314, 312f,
313f
salpingitis 315–316,
316f

yolk‐associatedcoelomitis 314–315,
314f, 315f
necropsy examinationof 418reptile keepers
recommendations
88–89
reptile practiceanaesthetic
equipment 124
biosecurity 122
consultation room
117–118
consumables 124
enclosures 120–122, 120f,
121f
equipment
acrylic oral specula 119f
metal oral specula 118f
reptile sexing
probes 119f
external marketing
115–116
facilities 120
fee setting for 116
financial healthmeasurement
116–117
handling aids 122
heating 123
heat source 122
hiding places 122
hospitalization 120
humidity 122
instrumentation 123
internal marketing 115
laser/radiosurgicalunit 123
light 122
magnification loupes 123
medical records 119–120
reuseable retractor
rings 123
surgical suite 122–123
vascular clips 123
Reptilia
characteristics 1
families 1, 2t

genera and species 1, 2t
orders 1, 2t
reptilian needs,
hierarchy 33b
respiration
captive reptiles
behaviour 38
control 26
respiratory diseasediagnosis of 304–305, 305f
infectious diseases
bacteria 301
chlamydia 302
fungal 302
mycobacteria 302
mycoplasma 301–302
parasites 303
viral infections 303
non‐infectious disease
neoplasia 301
nutritional diseases 301
trauma 300–301
predisposing
factors 299–300
treatment principles
305–306, 306f
respiratory support 168
respiratory system 25
anatomy andphysiology 299
lower tract 26
necropsy examinationof 412, 415–416, 416f
upper tract 26
respiratory tract
lower 205–206
radiographs evaluation 148
upper 197–205
retained spectacles 359, 359f
reticulated python
clinical examination 129f
egg, ultrasonographic
appearance 97f
retinal diseases 364
reuseable retractor rings 123
Rhabdias 435
rhabdomyosarcoma
in corn snake 354
in Galapagos tortoise 354

IndexRhynchocephalia 2
roundworm
infestation 433–434sSalmonella sp., 142, 159, 178,
247, 250, 252, 263, 265,
269t, 274, 295, 301,
315, 326, 339, 349, 409
salpingectomy 388, 390f
salpingitis 315–316, 316f
salpingotomy 390
savannah monitor 55
scaling, abnormal/
excessive 258
Schirmer tear test 357
Scincomorpha 1
Scolecophidia 1
semi‐aquatic chelonians
feeding
recommendations
57, 58semi‐aquatic species 46
senses 30–31
ear 365–366, 366f
eye 357–365
heat‐sensitive receptors/pit
organs 367
Jacobson’s organ 366–367
septicaemia 339
serology
enzyme‐linked
immunosorbent
assay 140
haemagglutination
inhibition tests 140
molecular diagnostics 140
polymerase chain
reaction 140, 141t
virus/serum neutralization
tests 139
sex identification 48
shell, see also turtle shell repair
abscessation 240
deformities 239, 352–353
discolouration 239–240
diseases 211–212
epidermis erythema 240
epidermis masses 240

epidermis ulceration 240
flaking 239–240
fractures and wounds 239
petechiae 240
soft 239
thickening 239–240
trauma, causes of 397, 398f
shingleback lizards 91
with conjunctivitis 361f
short neck turtles, eyelid
trauma 360
sixth sense 31
skeletal systemdisorders, of indeterminate/or mixed origin
351–353, 351f, 352f
radiographs
evaluation 150
skull 18–20
vertebrae 20–22
skin diseases 211–212
skinks, blue tongued 3f
skin wounds and burns 384
smudgeocytes 135
snake
abnormal body
position 226
adrenal glands 30
anorexia 217–218
blisters 219
characteristics 7t–8t
choanal discharge 221
cloacaprolapse 224
scent glands 28
swelling 224
coelioscopy 157
coeliotomy in 388
constipation 222
corn 13f
C. serpentis infection 430
cutaneous swellings 220
diarrhoea 222
diffuse distension 224
digestion 28
discoloured urates 224
distended coelom 218
Duvernoy’s gland 27f
dysecdysis 219

dyspnoea 221
dystocia management 310
ecdysis 18
examination 132
excessive salivation 221
external anatomy 17
exudation 221
eyescolour change 220
dry spectacle 220
opaque 220
periocular swelling 220
spectacle distension 220
facial/cephalic swelling 221
ferlavirus infection 303
firmness 224
gender assessment 95, 95f
gingival inflammation 221
glottis 27
granulomas 219
hemipenal regionswelling 224
hyperkeratosis 219
increased activity
218–219
infectious agents 204t
injectable medications 306
internal anatomy 18f, 21f
kidneys 28
liver lobectomy, complete/partial 392
mid‐body swelling 222
missing tail tip 225
mouth gaping 221
muscle innervationassessment 332, 334f
muscle tone 218
nasal discharge 221
nephrectomy 393
neurological signs 225
nutrition 50, 53
oral discharge 221
oral mucous membrane
colour 221
osmoregulation 29
with osteitis deformans 351f
papules 219
paralysis 225
parathyroid glands 30

497

498

Index

snake (cont’d)parturition 224–225
petechiation 221
proliferative nodules 219
puffiness 224
pustules 219
radiography positioning 146
reduced faecal output 222
reference intervals
for 476t–477t
regurgitation 221–222
reproductive system
29–30
respiration 27
respiratory disease, causesof 303salpingitis 225
sex identification 132
skinabrasions 220
discolouration 219
disruption 220
thickening 220
skull 20f
spondylosis 225
stridor 221
subcutaneous
swellings 220
sudden death 226
superficial bacterial
infections 263–264
supportive care 159, 160f
tail necrosis 225
teeth 27
thermoregulation 16
thyroid glands 30
time spent basking 219
time spent soaking in waterbowl 219
tongue lesions 221
tooth loss 221
ulceration 219, 221
ultrasonography 152–153
ultraviolet index (UVI)
exposure levels 85t
uroliths in 329
vascular access 169–170
venipuncture in 370
venom gland location 27f

vertebral swellings 225
viral diseases of 339–342,
340f, 342f
visible internal swellings
222–224, 223f
vomiting 221–222
wheezing 221
soft‐tissue surgery
aural abscesses 385
enucleation 386
eyelid surgery 386
nasolacrimal ductobstruction 386
pseudobuphthalmos 386
skin wounds andburns 384
subcutaneous abscessremoval 385
subspectacularabscess 385
tracheal resection andanastomosis 386
spargana (plerocercoid) 426,
433f, 437
spectacle disorders
358–360
Sphenodon punctatus, seetuataraspinal osteopathy 351–352,
351f, 352f
spine 20
spirorchid flukes, in green
turtles 343
Spirurida 437
spotted python
lower respiratory tract,
endoscopic
examination of304, 305f
open‐mouth
breathing 300f
spur‐thighed tortoise,rhinitis 205f
Squamata
Amphisbaenia 1
characteristics 1
Lacertilia 1
order 1
Serpentes 1

steppe tortoise 316, 317f
stomatitis
aetiology 273–274
clinical signs and physicalexamination 274
description 273
diagnosis and categorization
274–275
treatment 275–276
stratum germinatum 17
streptostyly 19
stress, captive reptiles
behaviour 38
Strongyloides 435
subcutaneous abscessremoval 385
subspectacular abscess
359–360, 385
substrate ingestion 112
substrate options,
enclosures 70
sunbeam method 86
Sunshinevirus infection 262,
303, 341
superficial bacterial
infections 262–264
surgery
amputation 394–395
coeliotomy 387–388, 387f,
388f
cystotomy 392, 392f
enterotomy 391, 391f
gastrotomy andgastrectomy 390
lasers 384
liver biopsy 392
liver lobectomy, complete/partial 392
nephrectomy and renal
biopsy 393
oesophagostomy tube
placement
386–387
ophthalmological surgicalinstruments 384
orchidectomy inlizards 390
orthopaedic 393–394
ovariectomy 388

Indexpatient assessment andpreparation 383
patient preparation
383–384
positioning 383
pre‐and perioperative
care 383
prolapsed hemipene/
phallus 393
radiosurgery 384
salpingectomy 388, 390f
salpingotomy 390
skull and facial bone
fractures 395
soft‐tissueaural abscesses 385
enucleation 386
eyelid surgery 386
nasolacrimal ductobstruction 386
pseudobuphthalmos 386
skin wounds andburns 384
subcutaneous abscessremoval 385
subspectacularabscess 385
tracheal resection andanastomosis 386
surgical equipments 384
suture materials 384
of tongue 386
venomoid 396
surgical nursing andanaesthesia
alcohol/ultrasound gel 447
capnography 447
Doppler unit 447
equipment andsupplies 446–447
patient support 447–448
preoperative nursing
445–446
pulse oximetry 447
recovery 448
surgical suite 122–123
swollen eyelids 361
systemic bacterial
infections 264

systemic coccidiosis, in green
turtles 342–343
systemic lymphoidproliferation andnon‐suppurative
encephalitis 343

ttaste buds 31
teeth 27, see also dentition
terrapin 2
terrestrial species
chelonians, nutrition
56–57
enclosure for 46
testudines, see chelonia
Testudo hermanni, see
Hermann’s tortoise
Testudo horsfieldii, see Steppe
tortoisethecodonts, teeth 27
thermal burns 263
thermoregulation 15–16
captive reptiles
behaviour 35–36
mechanism 16
preferred optimum
temperature zone
16, 16tthiamine deficiency 194
thigmothermy 16
thyroid glands 30
ticks 38
Tiliqua rugosa, see
Shingleback lizard
Tiliqua scincoides, seeblue‐tongued
lizards; blue‐tongue
skink
timber enclosure
66–67, 66f
Tokay gecko 55
tonometry 358
TopClosure® Tension Relief
System 404
tortoises 2
osmoregulation 29
spur thighed/Greek 14f
star 14f

stones and pebbles,
stomach 148, 149f
testudinid herpesviral
infection 304
touch, sense 31
tracheal resection andanastomosis 386
tracheal washes 206f
Trachemys scripta elegans, seered‐eared slider turtle
tracheoscopy 155–156, 156f
tramadol 372transport requirements 48
traumacardiovascular system
related 294
eyelids 360–361
induced neuropathies 338
muscular and soft tissues
related 353
musculoskeletal
disorders 348
nervous system
related 337–338
respiratory system
related 300–301
traumatic lesions 263
tuatara 2
characteristics 2
diapsid 19
egg anatomy 92
turtleaural abscesses 365, 366f
Bellinger river 343
broad‐shelled 93f
carapace fractures 337
characteristics 9t–10t
eastern long‐necked turtle
dorsoventral
radiograph 400, 401f
oesophageal foreign body,endoscopic removalof 276, 277f
traumatic panophthalmitis
363, 364f
green turtles
spirorchid flukes 343
systemic coccidiosis
342–343

499

500

Index

turtle (cont’d )Krefft’s turtle, phallus
prolapse 318f
Murray river turtle, eyeexamination of 358f
oesophagostomy feedingtube 276, 277f
short necked 13f, 360
side necked/long necked 2
supportive care 160
uroliths in 329
venipuncture in 371, 371f
turtle shell repair
anatomy 397
appropriate temperature
gradient 399
fracture fixation
adhesives 403–404, 403f
bridging methods
404–405, 404f
under generalanaesthesia 402, 402f
orthopaedic fixation
methods 405–406,
406f
initial fracture stabilization
and wound protection
400, 400f
post‐surgical care 406–407
prognostic categories, forshell injury assessment
398, 398t
radiographs 400, 401f
supportive care andstabilization
analgesia 399
antibiotics 399
appropriate temperature
gradient 399
computed
tomography 400
fluid therapy 399–400
haemorrhage control 399
initial fracturestabilization andwound protection
400, 400f
radiographs 400, 401f

triage 397–398
vacuum‐assisted woundclosure 402
wound care 400–402, 401f

uultrasonography
150–153, 291–292,
291f, 292f
ultraviolet index (UVI)
exposurelevels 85t
ultraviolet lighting 69
uric acid concentrations 138
urinary system 28
anatomy andphysiology 323
case reports 329–330
clinical note 29
lower urinary tract
disease 329
necropsy examinationof 418, 419f
osmoregulation 29
renal disease 323–329,
325t, 326f, 327f, 328f
renal portal system 29
urinary tract
disease 212–213
urogenital tract 149
urolithiasis, causes of 329
uroliths 329
Uromastyx acanthinurus
428f
Uromastyx species 430f
uveitis 364

vvacuum‐assisted woundclosure 402
Varanus exanthematicus, seesavannah monitor
Varanus giganteus, see
perentie
Varanus varius, see lacemonitorvascular access 169
vascular clips 123

veiled chameleon supportive
care 160f
venipuncture
in crocodiles 371, 372f
in lizards 370–371
in snakes 370
in turtles 371, 371f
venomoid surgery 396
venomous reptiles handling
protocols 131
ventilation 26
vestibular disease, signsof 367Viperidae, fangs 28
vipers 91
viral infections
cardiovascularsystem 296
muscular and soft tissue
disorders 354
respiratory system
related 303
vitamin B1, see thiamine
deficiency
vitamin E deficiency
294, 353
vomeronasal organ, see
Jacobson’s organwwater exchange 37–38
water quality 47–48
aquatic enclosuresand 72–73
western brown snake 316f
wound care, turtle shell
repair 400–402, 401f
wound management
170, 171fyyellow‐footed tortoise 89f
yellow fungus
disease 261–262

zzinc toxicoses 339
zolazepam‐tiletamine

375