Equine Disease Quarterly Newsletter

5

The dilemma is clear: excess wild horses andburros on western rangelands and in BLM corrals
and holding pastures. The numbers exceed thosethat can be placed into long-term homes, albeit
with restrictions on what new owners can do withthe animals, through adoptions and sales. The
solutions are anything but straight-forward. BLM
continues to explore better, longer lasting, andpermanent methods of contraception to control
population growth rates. They also continue totry to find new ways to encourage adoption andplacement of excess animals into private long-term
homes. Ultimately, the direction forward depends

on the program’s budget and the policy provided
by Congress as they work to address the realitiesof the situation and wishes of the public.
CONTACT:
Albert J Kane, DVM, MPVM, PhD
albert.j.kane@aphis.usda.gov(970) 494-7234
Advisor, APHIS/BLM WH&B Partnership
USDA APHIS Veterinary Services
Fort Collins, CO

Presorted Standard
US Postage Paid
Permit 51
Lexington KY

Department of Veterinary Science
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky 40546-0099
Address Service Requested

F U N D E D B Y U N D E R W R I T E R S AT L LOY D ' S , LO N D O N

The information, ideas, and opinions expressed arethose of the author and do not necessarily represent
those of the United States Departments of Agriculture
or Interior.

OCTOBER 2019
Volume 28, Number 4

C O M M E N TA RY
KENTUCKY

Guttural Pouch Mycosis

A

Images courtesy of
Dr. Nathan Slovis.

irway dysfunction is one of many causes ofpoor performance in equine athletes. Airway
dysfunction can be classified as either acquired ordevelopmental. One acquired dysfunction that is
generally overlooked is a fungal infection of theguttural pouch, known as guttural pouch mycosis (Figure 1). Guttural pouch mycosis (GPM)
is a potentially life-threatening disease that may

Figure 1. Fungal infection ofguttural pouch.

Figure 2. Intravascular coils on X-ray.

initially present as a simple nosebleed (epistaxis)
or even poor performance in an equine athlete.
GPM has been documented in various parts of
the United States, particularly in the southeast,
as well as the United Kingdom. Clinical signs
include unilateral (one-sided) or bilateral (bothsided) epistaxis, unilateral nasal discharge, dorsal
displacement of the soft palate, dysphagia (difficulty swallowing), and laryngeal
hemiplegia (partial or total paralysisof the larynx). Epistaxis occurs due
to erosion of the guttural pouch
mucosa by a fungal plaque, resulting in hemorrhage from the internal
carotid, occipital, or maxillary arteries. Severe hemorrhage may result in
rapid death from exsanguination.
Dysphagia as well as various formsof pharyngeal dysfunction in GPM
result from mucosal penetration anddamage by fungal hyphae to the glossopharyngeal, hypoglossal, and/or
the pharyngeal branches of the vagus
nerves. A variety of fungi have been
isolated from GPM with Aspergillus spp. being common. Aspergillus
spp. and other opportunistic fungi
are found naturally in the environment and can be found in the upper
respiratory tract of normal horses.
Wet environmental conditions,prolonged treatment with antimicrobials, an immunocompromised
host, or use of corticosteroids havebeen proposed as factors conducive for fungal
overgrowth. It is not fully understood why mycosis
occurs in animals that are not immunosuppressedor debilitated. While no age predilection has beenreported, the disease is more common in mature
horses, but has been documented in foals as young
as two months of age.
Dysphagia is the second most common clinical sign associated with GPM, after epistaxis. The
cranial nerves within the guttural pouch thatinnervate the pharynx are the glossopharyngeal,
vagus, and hypoglossal. Neurological dysfunctionof the pharynx results when the nerves within theguttural pouch are inflamed or fibrosed. Generally,
the presence of dysphagia or other neurologicaldeficits at presentation indicates a poor prognosis.
The severity of cranial nerve deficits depends onwhether nerve injury is restricted to a local neuritis or necrosis of the nerve secondary to fungal
infiltration and fibrosis.
Treatments include both medical and surgical options. While there are reports of successful

medical treatment of GPM with systemic andtopical antifungal medications, medical treatment is generally considered to be less efficacious
than surgical treatment. Topical treatments withenilconazole and miconazole have been used withsuccess in some cases. The presence of a diptheritic
membrane (necrotic material over the surface ofthe fungal plaque) may prevent penetration of systemic antifungals. Additionally, there is increased
risk of fatal hemorrhage due to the longer course of
medical treatment. The preferred method to treat
severe guttural pouch mycosis is to surgically insert
a coil or balloon into the affected blood vessel toquickly cut off the blood supply (Figure 2). Typically, once the blood supply has been removed, thefungus regresses.
CONTACT:
Nathan Slovis, DVM, Dipl. ACVIM,
CHT (Certified Hyperbaric Technologist)(859) 253-0002
Hagyard Equine Medical Institute Director
McGee Critical Care and Medical Center
Lexington, KY

T

he term “Unwanted Horse” was first coinedby the American Association of Equine Practitioners (AAEP) in 2005. Unwanted horses include
Commentaryboth unadoptable feral horses and domestic horsesthat are no longer wanted by their owners because
International
they are geriatric, incurably lame, not athletic,
Second Quarter2019  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2 unmanageable, cost too much to maintain, unmarketable, or fail to meet their owner’s expectations.
Preserving Rare
Horse Breeds .  .  .  .  .  .  .  . 3 Most of the American public was unaware that
there was a subset of horses that become unwanted
National
until the bovine spongiform encephalopathy(BSE) outbreak in Europe in 2000 and the footWild Horse andBurro Program .  .  .  .  .  .  . 4 and-mouth disease epidemic that occurred in the
United Kingdom in 2001. Both outbreaks were
Kentucky
responsible for temporarily changing European
Guttural Pouchconsumers’ preference from beef to horse meat due
Mycosis  .  .  .  .  .  .  .  .  .  .  .  .  . 5to concerns with beef safety. This change drew U.S.
media attention to the fact that many unwanted
horses were being processed in the United States
and their meat exported to Europe. The result
was pressure from the American public and animal activists’ groups to pass federal legislation toprohibit the processing of horses in the UnitedStates for human consumption. Because horses
processed for human consumption epitomize theunwanted horse, they continue to be a part of the
discussion, but normal, healthy horses of all breeds
and disciplines can become unwanted.
At the 2005 American Horse Council meeting,leaders from across the industry came together toCollege of Agriculture, discuss options for resolving the unwanted horse
Food and Environment
issue. The result was the formation of the UnDepartment of
wanted Horse Coalition, which was placed under
Veterinary Science
the umbrella of the American Horse Council. The
goal of the organization was to raise awarenessof the unwanted horse and provide a medium
for the exchange of information about adoption,
Lloyd’s—An international
proper care, alternative careers, and responsible
insurance market forownership. In 2018, it was agreed that awarenessbloodstock and otherhad been accomplished, so the Unwanted Horse
specialist insurance.
IN THIS ISSUE

Coalition transitioned to the United Horse Coalition with a goal of “providing information forexisting and prospective owners, breeders, sellers,and horse organizations regarding the long-term
responsibilities of owning and caring for horses,
as well as focusing on the opportunities available
for these horses through industry collaboration.”
Particular attention has been given to education
regarding the cost of care, proper husbandry, training requirements, expectations and life-ending
decisions. In addition, since 2001 virtually every
horse breed and discipline has developed a program to identify unwanted horses and to provide
options for retraining, rehoming and post-careercare. These include the American Quarter Horse’s
Re-ride Adoption program, the U.S. Trotting
Association’s Full Circle Program, The American
Horse Council’s Time to Ride Initiative, andseveral programs in the Thoroughbred industry
including the TB Aftercare Alliance, Take the Lead
Program, and Retirement Check-off Program. A
new unwanted-horse advocacy group, The Right
Horse Initiative, brought years of experience infinding homes for shelter dogs and cats to thehorse industry.
The horse industry will never completely
eliminate unwanted horses. Horses will always age,sustain career-ending injuries, or not meet theirowner’s expectations. However, I’m optimistic thatthe future is brighter for these horses, because thehorse industry has turned its attention to the issue
and continues to develop strategies to both reduce
the number of unwanted horses on the front end
through responsible care and breeding as well as
the rear end through rescue/retirement programs,
retraining for alternative careers, and low-costeuthanasia options.
CONTACT:Tom Lenz DVM, MS, DACT
horsetrl@aol.com
Louisburg, KS

2

I N T E R N AT I O N A L

Second Quarter 2019T

Equine Disease Quarterly
Editors

Peter Timoney
Alan Loynachan
Rebecca Ruby

Staff

Diane Furry
Tawana Brown
Dennis Duross
Anita HatchettCorrespondence should be
addressed to the editors,
Department of Veterinary
Science, Maxwell H. Gluck
Equine Research Center,
University of Kentucky,
Lexington, Kentucky USA,40546-0099
Telephone (859) 257-4757
Fax (859) 257-8542
Internet address:
http://gluck.ca.uky.edu/
equine-disease-quarterly
Material published in the
Quarterly is not subject tocopyright. Permission istherefore granted toreproduce articles, althoughacknowledgment of thesource and author is requested.
The University of Kentucky
is an Equal Opportunity
Organization.

Printed on recycled paper

he International Collating Centre, Newmarket, United Kingdom, and other sources
reported the following equine disease outbreaks.
African horse sickness was reported in Cameroon,
Chad, Eswatini, and the Republic of South Africa(RSA). Significant losses were recorded in Chadwith a case-fatality rate of 85%. An increased incidence was seen in the endemic areas in RSA, withoutbreaks confirmed in eight of the nine provinces.
No cases were documented in the Western Cape
Province, either in the historically affected area orin the AHS controlled zone.
Outbreaks of equine influenza were confirmed
by France (19), Germany (11), Ireland (19),
Italy (three), Senegal (one), the UK (97), and theUSA (three). The majority of outbreaks involved
unvaccinated horses or horses with incomplete
vaccination histories.
Belgium, France, Germany, Ireland, and the
USA recorded outbreaks of strangles. The numberof outbreaks ranged from one (Belgium and Ireland) to 20 (France) with three in Germany and
14 in the USA. Strangles is considered endemic
by many countries.
Equine herpesvirus 1 (EHV-1) related diseases
were reported by Belgium, France, Germany, theUK, and the USA. Respiratory disease was confirmed in Belgium (four outbreaks), France (twooutbreaks), Germany (five outbreaks), the UK(one outbreak), and the USA (one outbreak; thedisease likely occurred in many states). Outbreaksof EHV-1 abortion were recorded by a numberof countries, most involving a single case of thedisease. The number of outbreaks ranged fromone (Australia and the USA), two (Canada andGermany), three (France and Japan), and 11(Belgium). Two reported cases had co-infections
with Leptospira interrogans and one with L. interrogans and S. zooepidemicus. Abortions wereconfirmed in vaccinated and unvaccinated mares.
EHV-1 neurologic disease was recorded in Canada(one case), Germany (two cases), the UK (onecase), and the USA (11 outbreaks, the majority
involving single cases of the disease, six of which
had recently attended an equine event). Equine
herpesvirus 4 (EHV-4) respiratory disease wasreported by France (12 outbreaks), Germany(several outbreaks), Sweden (three horses in one
outbreak), and the UK (eight outbreaks involving
one to multiple horses). France recorded a single
case of EHV-4 abortion.
Rhodococcus equi infection was confirmed by
France (one case), Ireland (two cases), and theUSA (at least 42 cases).
The UK reported asymptomatic equine arteritis
virus infection in three non-Thoroughbred stallions on one premises and an additional case in a
non-Thoroughbred stallion on a separate premises
epidemiologically linked to the first.
Equine infectious anemia was confirmed by
Canada (five cases, of which one was clinicallyaffected), Chile (one case), France (one clinicalcase), the USA (19 cases, the majority representing isolated cases), and Uruguay (18 cases on apremises; all were euthanized).
Equine piroplasmosis was reported as endemic
in the RSA, the disease being recorded in every
province.
Germany reported outbreaks of contagious
equine metritis on several premises involving a
total of 22 horses (19 stallions and three mares).
Single cases of leptospirosis were recorded by
France and the USA, both involving infection of
the placenta.
There were two reports of equine coital exanthema, one from France (single case) and the otherfrom the USA (two cases).
Salmonellosis was recorded by the USA. Thirtycases were associated with infection with Salmonella Group B and two with Salmonella Group C2.
France, Germany, and the USA reported outbreaks of rotaviral enteritis in foals. Number ofcases ranged from two in Germany, 24 in France,
and 65 in five states in the USA, of which 59 wereof the G14P genotype and six of the G3P genotype. The greatest number of cases were recordedin June.
Clostridial enterocolitis due to Clostridium
perfringens was recorded in the USA (27 cases).
An additional 15 cases of C. difficile infection werealso diagnosed.
Vesicular stomatitis was confirmed in the USA
late in the second quarter of 2019. Three outbreaks
caused by the Indiana serotype were identified, twoin Texas and one in New Mexico.

A total of 13 cases of Eastern Equine Encephalomyelitis were reported by the USA, the majority
in Florida. The RSA and the USA reported casesof West Nile Virus infection, one in the RSA and
two in the USA.
Equine encephalosis was reported in six of thenine provinces in the RSA.

A case of Hendra virus infection was confirmed
in New South Wales, Australia.
Three cases of Tyzzer’s disease in foals wererecorded by the USA. The USA also reported twocases of equine coronavirus infection that werediagnosed at necropsy. Germany confirmed single
cases of equine ehrlichiosis on two premises.

Preservation of Rare Horse BreedsG

enetic erosion is a topic of international
debate found in all sectors of the livestockindustry. Selective breeding in food and fiber species is done for specific effect that has an economic
value. Alternatively, the same actions are taken in
the companion animal industry for less quantifiable, but equally significant reasons. The diversityof the horse industry is testament to our uniqueposition straddling these two worlds, where competitive advantage may be as important as color,size, or temperament. While the national horse
population is trending down, the abundance ofoptions available to horse buyers have left somesegments teetering on the edge of catastrophic loss.
In 2017, The Livestock Conservancy (TLC)
identified an interest in discussing the uniqueneeds of “endangered” breeds, or registries withfewer than 2,000 registrations per year. With agrant from the USA Equestrian Trust, and collaboration between Texas A&M University andVirginia Tech, the TLC brought together representatives from approximately 50 associations
and registries to participate in the first national
Endangered Equine Summit. Attendees were asked
to identify what they believe are the leading causesof breed population decreases and decide what actions may be taken to stabilize that decline.
The concerns addressed at this summit are
not unique to the United States. The Rare Breeds
Survival Trust based in England monitors thenumber of rare and native breeds in the UK. Every
year they collect data from breed registries and usethat information to estimate the total number ofbreeding females. From this data they produce
an annual “Watchlist” that they make available
on their website at https://www.rbst.org.uk/. Additionally, the group monitors internal threats tobreed health. These factors include inbreeding andgeographical over-saturation.
In December of 2018, the TLC released a“Manual of Methods for Preservation of Valuable

Equine Genetics in Live Animals and Post-Mortem.” The manual was created as an educational
resource for owners and veterinarians on how
properly to collect vital tissues in ways that minimize loss and preserve significant genetic material
for conservation. The manual is available for free
to download on the TLC’s website at https://livestockconservancy.org/.
In addition to the efforts of the TLC to educate
the horse owning public, biotechnological companies have highlighted advances in cell collection,
storage, embryo flushes, implantation, and evencloning. The future of “resurrecting“ lost breeds
may be possible and even cost effective due tothe technological strides being made. The industry would benefit from the availability of secure“banks” for stallion semen or somatic cell materials
for preserving the future of important bloodlines.
The first step taken includes the recent approvalto have additional material preserved within therepository of the National Animal Germplasm
Program at the USDA’s Agricultural ResearchService. This program already has shown the valueof re-introducing previously “lost” genetics into
livestock species, and those stories can be found on
the USDA’s website at https://www.ars.usda.gov/.
The health of the equine industry is tied directly
to the health of the animals and the diverse uses of
those animals. The genetic health of an animal has
a direct correlation to its usability and the financial
opportunities open to that animal’s owner as well as
all generations to follow. While we may not know
the ultimate value of a specific group of animals
to the overall health and future of the industry,
we do have the technology to protect them andthus ourselves.

3

4

N AT I O N A L

Management Challenges for the
BLM Wild Horse and Burro ProgramM

anagement of wild horses and burros living on the Bureau of Land Management’s(BLM) western rangelands continues to be challenging. As of March 2018, there were approximately 82,000 animals (67,000 wild horses and15,000 wild burros) on 30 million acres of BLM
rangelands in 177 herd management areas. These
populations usually grow by 15-20% a year, often
doubling in 4 to 5 years, and the annual foal crop
alone is expected to be between 16,000-25,000
animals. In addition to the animals on the range,
the BLM also maintains about 12,000 animals in
off-range corrals that serve as adoption and training centers as well as about 37,000 animals in 33
off-range pastures. The pastures, located in the
Midwest and Western US, each house between 200
and 3,000 horses under federal contracts between
the private landowners and the BLM. While no
reproduction occurs on these pastures, the BLM
still pays for the animal’s care and feeding in thesesemi-free-roaming environments.

CONTACT:
Cliff Williamson
cwilliamson@horsecouncil.org
202-296-4031
American Horse Council
Washington, D.C.

Getty Images

When the Wild Free Roaming Horses andBurros Act (the Act) was passed in 1971 andamended in 2005, it instructed BLM to maintainequid populations in balance with other uses of therange such as wildlife management, recreationaluse, livestock grazing, and mineral, oil, and gas extraction. Toward this end, the Bureau determinedthat the appropriate population size on the range
should be about 27,000 animals. The animals thatexceed this target number (currently about 55,000)
can be considered excess along with the 49,000
animals already in BLM corrals and pastures. The
Act as originally written directs the BLM to offer
the excess animals for adoption and sale without
limitation followed by the humane destruction
for the remaining excess animals. However, in theannual budget provided to BLM since the 1980s,
Congress has prohibited the BLM from euthanizing healthy animals or selling animals in a mannerthat may lead them to being processed for commercial use (i.e. slaughter). This leaves the BLM in
the position of having to feed and care for about
50,000 excess animals off-range, which literally“eats up” almost two-thirds of the program’s $80M
budget. Another 55,000 excess animals struggle tosurvive on public rangelands that exceed population targets and are often overgrazed.
To address population growth rates and excess
numbers on the range, the BLM has supported
the development of contraceptives for wild horses
and burros since the 1980s. A couple of contraceptive products (porcine zona pellucida and GnRH
vaccines) work well to prevent mares from conceiving if given annually or boostered following
the initial vaccination. This approach can work
well on smaller herds where animals can be individually identified and approached for darting.
Unfortunately, repeatedly catching the animals fortreatment just isn’t practical. Most wild horses andburros on BLM rangelands can’t be approachedwithin half a mile, let alone the 20-60 yards neededfor darting. Longer lasting contraceptives have notproven reliable in larger field trials. Recent efforts
to spay mares in the context of a field research/feasibility project have been stopped by litigationfrom wild horse advocacy groups.

2

I N T E R N AT I O N A L

Second Quarter 2019T

Equine Disease Quarterly
Editors

Peter Timoney
Alan Loynachan
Rebecca Ruby

Staff

Diane Furry
Tawana Brown
Dennis Duross
Anita HatchettCorrespondence should be
addressed to the editors,
Department of Veterinary
Science, Maxwell H. Gluck
Equine Research Center,
University of Kentucky,
Lexington, Kentucky USA,40546-0099
Telephone (859) 257-4757
Fax (859) 257-8542
Internet address:
http://gluck.ca.uky.edu/
equine-disease-quarterly
Material published in the
Quarterly is not subject tocopyright. Permission istherefore granted toreproduce articles, althoughacknowledgment of thesource and author is requested.
The University of Kentucky
is an Equal Opportunity
Organization.

Printed on recycled paper

he International Collating Centre, Newmarket, United Kingdom, and other sources
reported the following equine disease outbreaks.
African horse sickness was reported in Cameroon,
Chad, Eswatini, and the Republic of South Africa(RSA). Significant losses were recorded in Chadwith a case-fatality rate of 85%. An increased incidence was seen in the endemic areas in RSA, withoutbreaks confirmed in eight of the nine provinces.
No cases were documented in the Western Cape
Province, either in the historically affected area orin the AHS controlled zone.
Outbreaks of equine influenza were confirmed
by France (19), Germany (11), Ireland (19),
Italy (three), Senegal (one), the UK (97), and theUSA (three). The majority of outbreaks involved
unvaccinated horses or horses with incomplete
vaccination histories.
Belgium, France, Germany, Ireland, and the
USA recorded outbreaks of strangles. The numberof outbreaks ranged from one (Belgium and Ireland) to 20 (France) with three in Germany and
14 in the USA. Strangles is considered endemic
by many countries.
Equine herpesvirus 1 (EHV-1) related diseases
were reported by Belgium, France, Germany, theUK, and the USA. Respiratory disease was confirmed in Belgium (four outbreaks), France (twooutbreaks), Germany (five outbreaks), the UK(one outbreak), and the USA (one outbreak; thedisease likely occurred in many states). Outbreaksof EHV-1 abortion were recorded by a numberof countries, most involving a single case of thedisease. The number of outbreaks ranged fromone (Australia and the USA), two (Canada andGermany), three (France and Japan), and 11(Belgium). Two reported cases had co-infections
with Leptospira interrogans and one with L. interrogans and S. zooepidemicus. Abortions wereconfirmed in vaccinated and unvaccinated mares.
EHV-1 neurologic disease was recorded in Canada(one case), Germany (two cases), the UK (onecase), and the USA (11 outbreaks, the majority
involving single cases of the disease, six of which
had recently attended an equine event). Equine
herpesvirus 4 (EHV-4) respiratory disease wasreported by France (12 outbreaks), Germany(several outbreaks), Sweden (three horses in one
outbreak), and the UK (eight outbreaks involving
one to multiple horses). France recorded a single
case of EHV-4 abortion.
Rhodococcus equi infection was confirmed by
France (one case), Ireland (two cases), and theUSA (at least 42 cases).
The UK reported asymptomatic equine arteritis
virus infection in three non-Thoroughbred stallions on one premises and an additional case in a
non-Thoroughbred stallion on a separate premises
epidemiologically linked to the first.
Equine infectious anemia was confirmed by
Canada (five cases, of which one was clinicallyaffected), Chile (one case), France (one clinicalcase), the USA (19 cases, the majority representing isolated cases), and Uruguay (18 cases on apremises; all were euthanized).
Equine piroplasmosis was reported as endemic
in the RSA, the disease being recorded in every
province.
Germany reported outbreaks of contagious
equine metritis on several premises involving a
total of 22 horses (19 stallions and three mares).
Single cases of leptospirosis were recorded by
France and the USA, both involving infection of
the placenta.
There were two reports of equine coital exanthema, one from France (single case) and the otherfrom the USA (two cases).
Salmonellosis was recorded by the USA. Thirtycases were associated with infection with Salmonella Group B and two with Salmonella Group C2.
France, Germany, and the USA reported outbreaks of rotaviral enteritis in foals. Number ofcases ranged from two in Germany, 24 in France,
and 65 in five states in the USA, of which 59 wereof the G14P genotype and six of the G3P genotype. The greatest number of cases were recordedin June.
Clostridial enterocolitis due to Clostridium
perfringens was recorded in the USA (27 cases).
An additional 15 cases of C. difficile infection werealso diagnosed.
Vesicular stomatitis was confirmed in the USA
late in the second quarter of 2019. Three outbreaks
caused by the Indiana serotype were identified, twoin Texas and one in New Mexico.

A total of 13 cases of Eastern Equine Encephalomyelitis were reported by the USA, the majority
in Florida. The RSA and the USA reported casesof West Nile Virus infection, one in the RSA and
two in the USA.
Equine encephalosis was reported in six of thenine provinces in the RSA.

A case of Hendra virus infection was confirmed
in New South Wales, Australia.
Three cases of Tyzzer’s disease in foals wererecorded by the USA. The USA also reported twocases of equine coronavirus infection that werediagnosed at necropsy. Germany confirmed single
cases of equine ehrlichiosis on two premises.

Preservation of Rare Horse BreedsG

enetic erosion is a topic of international
debate found in all sectors of the livestockindustry. Selective breeding in food and fiber species is done for specific effect that has an economic
value. Alternatively, the same actions are taken in
the companion animal industry for less quantifiable, but equally significant reasons. The diversityof the horse industry is testament to our uniqueposition straddling these two worlds, where competitive advantage may be as important as color,size, or temperament. While the national horse
population is trending down, the abundance ofoptions available to horse buyers have left somesegments teetering on the edge of catastrophic loss.
In 2017, The Livestock Conservancy (TLC)
identified an interest in discussing the uniqueneeds of “endangered” breeds, or registries withfewer than 2,000 registrations per year. With agrant from the USA Equestrian Trust, and collaboration between Texas A&M University andVirginia Tech, the TLC brought together representatives from approximately 50 associations
and registries to participate in the first national
Endangered Equine Summit. Attendees were asked
to identify what they believe are the leading causesof breed population decreases and decide what actions may be taken to stabilize that decline.
The concerns addressed at this summit are
not unique to the United States. The Rare Breeds
Survival Trust based in England monitors thenumber of rare and native breeds in the UK. Every
year they collect data from breed registries and usethat information to estimate the total number ofbreeding females. From this data they produce
an annual “Watchlist” that they make available
on their website at https://www.rbst.org.uk/. Additionally, the group monitors internal threats tobreed health. These factors include inbreeding andgeographical over-saturation.
In December of 2018, the TLC released a“Manual of Methods for Preservation of Valuable

Equine Genetics in Live Animals and Post-Mortem.” The manual was created as an educational
resource for owners and veterinarians on how
properly to collect vital tissues in ways that minimize loss and preserve significant genetic material
for conservation. The manual is available for free
to download on the TLC’s website at https://livestockconservancy.org/.
In addition to the efforts of the TLC to educate
the horse owning public, biotechnological companies have highlighted advances in cell collection,
storage, embryo flushes, implantation, and evencloning. The future of “resurrecting“ lost breeds
may be possible and even cost effective due tothe technological strides being made. The industry would benefit from the availability of secure“banks” for stallion semen or somatic cell materials
for preserving the future of important bloodlines.
The first step taken includes the recent approvalto have additional material preserved within therepository of the National Animal Germplasm
Program at the USDA’s Agricultural ResearchService. This program already has shown the valueof re-introducing previously “lost” genetics into
livestock species, and those stories can be found on
the USDA’s website at https://www.ars.usda.gov/.
The health of the equine industry is tied directly
to the health of the animals and the diverse uses of
those animals. The genetic health of an animal has
a direct correlation to its usability and the financial
opportunities open to that animal’s owner as well as
all generations to follow. While we may not know
the ultimate value of a specific group of animals
to the overall health and future of the industry,
we do have the technology to protect them andthus ourselves.

3

4

N AT I O N A L

Management Challenges for the
BLM Wild Horse and Burro ProgramM

anagement of wild horses and burros living on the Bureau of Land Management’s(BLM) western rangelands continues to be challenging. As of March 2018, there were approximately 82,000 animals (67,000 wild horses and15,000 wild burros) on 30 million acres of BLM
rangelands in 177 herd management areas. These
populations usually grow by 15-20% a year, often
doubling in 4 to 5 years, and the annual foal crop
alone is expected to be between 16,000-25,000
animals. In addition to the animals on the range,
the BLM also maintains about 12,000 animals in
off-range corrals that serve as adoption and training centers as well as about 37,000 animals in 33
off-range pastures. The pastures, located in the
Midwest and Western US, each house between 200
and 3,000 horses under federal contracts between
the private landowners and the BLM. While no
reproduction occurs on these pastures, the BLM
still pays for the animal’s care and feeding in thesesemi-free-roaming environments.

CONTACT:
Cliff Williamson
cwilliamson@horsecouncil.org
202-296-4031
American Horse Council
Washington, D.C.

Getty Images

When the Wild Free Roaming Horses andBurros Act (the Act) was passed in 1971 andamended in 2005, it instructed BLM to maintainequid populations in balance with other uses of therange such as wildlife management, recreationaluse, livestock grazing, and mineral, oil, and gas extraction. Toward this end, the Bureau determinedthat the appropriate population size on the range
should be about 27,000 animals. The animals thatexceed this target number (currently about 55,000)
can be considered excess along with the 49,000
animals already in BLM corrals and pastures. The
Act as originally written directs the BLM to offer
the excess animals for adoption and sale without
limitation followed by the humane destruction
for the remaining excess animals. However, in theannual budget provided to BLM since the 1980s,
Congress has prohibited the BLM from euthanizing healthy animals or selling animals in a mannerthat may lead them to being processed for commercial use (i.e. slaughter). This leaves the BLM in
the position of having to feed and care for about
50,000 excess animals off-range, which literally“eats up” almost two-thirds of the program’s $80M
budget. Another 55,000 excess animals struggle tosurvive on public rangelands that exceed population targets and are often overgrazed.
To address population growth rates and excess
numbers on the range, the BLM has supported
the development of contraceptives for wild horses
and burros since the 1980s. A couple of contraceptive products (porcine zona pellucida and GnRH
vaccines) work well to prevent mares from conceiving if given annually or boostered following
the initial vaccination. This approach can work
well on smaller herds where animals can be individually identified and approached for darting.
Unfortunately, repeatedly catching the animals fortreatment just isn’t practical. Most wild horses andburros on BLM rangelands can’t be approachedwithin half a mile, let alone the 20-60 yards neededfor darting. Longer lasting contraceptives have notproven reliable in larger field trials. Recent efforts
to spay mares in the context of a field research/feasibility project have been stopped by litigationfrom wild horse advocacy groups.

2

I N T E R N AT I O N A L

Second Quarter 2019T

Equine Disease Quarterly
Editors

Peter Timoney
Alan Loynachan
Rebecca Ruby

Staff

Diane Furry
Tawana Brown
Dennis Duross
Anita HatchettCorrespondence should be
addressed to the editors,
Department of Veterinary
Science, Maxwell H. Gluck
Equine Research Center,
University of Kentucky,
Lexington, Kentucky USA,40546-0099
Telephone (859) 257-4757
Fax (859) 257-8542
Internet address:
http://gluck.ca.uky.edu/
equine-disease-quarterly
Material published in the
Quarterly is not subject tocopyright. Permission istherefore granted toreproduce articles, althoughacknowledgment of thesource and author is requested.
The University of Kentucky
is an Equal Opportunity
Organization.

Printed on recycled paper

he International Collating Centre, Newmarket, United Kingdom, and other sources
reported the following equine disease outbreaks.
African horse sickness was reported in Cameroon,
Chad, Eswatini, and the Republic of South Africa(RSA). Significant losses were recorded in Chadwith a case-fatality rate of 85%. An increased incidence was seen in the endemic areas in RSA, withoutbreaks confirmed in eight of the nine provinces.
No cases were documented in the Western Cape
Province, either in the historically affected area orin the AHS controlled zone.
Outbreaks of equine influenza were confirmed
by France (19), Germany (11), Ireland (19),
Italy (three), Senegal (one), the UK (97), and theUSA (three). The majority of outbreaks involved
unvaccinated horses or horses with incomplete
vaccination histories.
Belgium, France, Germany, Ireland, and the
USA recorded outbreaks of strangles. The numberof outbreaks ranged from one (Belgium and Ireland) to 20 (France) with three in Germany and
14 in the USA. Strangles is considered endemic
by many countries.
Equine herpesvirus 1 (EHV-1) related diseases
were reported by Belgium, France, Germany, theUK, and the USA. Respiratory disease was confirmed in Belgium (four outbreaks), France (twooutbreaks), Germany (five outbreaks), the UK(one outbreak), and the USA (one outbreak; thedisease likely occurred in many states). Outbreaksof EHV-1 abortion were recorded by a numberof countries, most involving a single case of thedisease. The number of outbreaks ranged fromone (Australia and the USA), two (Canada andGermany), three (France and Japan), and 11(Belgium). Two reported cases had co-infections
with Leptospira interrogans and one with L. interrogans and S. zooepidemicus. Abortions wereconfirmed in vaccinated and unvaccinated mares.
EHV-1 neurologic disease was recorded in Canada(one case), Germany (two cases), the UK (onecase), and the USA (11 outbreaks, the majority
involving single cases of the disease, six of which
had recently attended an equine event). Equine
herpesvirus 4 (EHV-4) respiratory disease wasreported by France (12 outbreaks), Germany(several outbreaks), Sweden (three horses in one
outbreak), and the UK (eight outbreaks involving
one to multiple horses). France recorded a single
case of EHV-4 abortion.
Rhodococcus equi infection was confirmed by
France (one case), Ireland (two cases), and theUSA (at least 42 cases).
The UK reported asymptomatic equine arteritis
virus infection in three non-Thoroughbred stallions on one premises and an additional case in a
non-Thoroughbred stallion on a separate premises
epidemiologically linked to the first.
Equine infectious anemia was confirmed by
Canada (five cases, of which one was clinicallyaffected), Chile (one case), France (one clinicalcase), the USA (19 cases, the majority representing isolated cases), and Uruguay (18 cases on apremises; all were euthanized).
Equine piroplasmosis was reported as endemic
in the RSA, the disease being recorded in every
province.
Germany reported outbreaks of contagious
equine metritis on several premises involving a
total of 22 horses (19 stallions and three mares).
Single cases of leptospirosis were recorded by
France and the USA, both involving infection of
the placenta.
There were two reports of equine coital exanthema, one from France (single case) and the otherfrom the USA (two cases).
Salmonellosis was recorded by the USA. Thirtycases were associated with infection with Salmonella Group B and two with Salmonella Group C2.
France, Germany, and the USA reported outbreaks of rotaviral enteritis in foals. Number ofcases ranged from two in Germany, 24 in France,
and 65 in five states in the USA, of which 59 wereof the G14P genotype and six of the G3P genotype. The greatest number of cases were recordedin June.
Clostridial enterocolitis due to Clostridium
perfringens was recorded in the USA (27 cases).
An additional 15 cases of C. difficile infection werealso diagnosed.
Vesicular stomatitis was confirmed in the USA
late in the second quarter of 2019. Three outbreaks
caused by the Indiana serotype were identified, twoin Texas and one in New Mexico.

A total of 13 cases of Eastern Equine Encephalomyelitis were reported by the USA, the majority
in Florida. The RSA and the USA reported casesof West Nile Virus infection, one in the RSA and
two in the USA.
Equine encephalosis was reported in six of thenine provinces in the RSA.

A case of Hendra virus infection was confirmed
in New South Wales, Australia.
Three cases of Tyzzer’s disease in foals wererecorded by the USA. The USA also reported twocases of equine coronavirus infection that werediagnosed at necropsy. Germany confirmed single
cases of equine ehrlichiosis on two premises.

Preservation of Rare Horse BreedsG

enetic erosion is a topic of international
debate found in all sectors of the livestockindustry. Selective breeding in food and fiber species is done for specific effect that has an economic
value. Alternatively, the same actions are taken in
the companion animal industry for less quantifiable, but equally significant reasons. The diversityof the horse industry is testament to our uniqueposition straddling these two worlds, where competitive advantage may be as important as color,size, or temperament. While the national horse
population is trending down, the abundance ofoptions available to horse buyers have left somesegments teetering on the edge of catastrophic loss.
In 2017, The Livestock Conservancy (TLC)
identified an interest in discussing the uniqueneeds of “endangered” breeds, or registries withfewer than 2,000 registrations per year. With agrant from the USA Equestrian Trust, and collaboration between Texas A&M University andVirginia Tech, the TLC brought together representatives from approximately 50 associations
and registries to participate in the first national
Endangered Equine Summit. Attendees were asked
to identify what they believe are the leading causesof breed population decreases and decide what actions may be taken to stabilize that decline.
The concerns addressed at this summit are
not unique to the United States. The Rare Breeds
Survival Trust based in England monitors thenumber of rare and native breeds in the UK. Every
year they collect data from breed registries and usethat information to estimate the total number ofbreeding females. From this data they produce
an annual “Watchlist” that they make available
on their website at https://www.rbst.org.uk/. Additionally, the group monitors internal threats tobreed health. These factors include inbreeding andgeographical over-saturation.
In December of 2018, the TLC released a“Manual of Methods for Preservation of Valuable

Equine Genetics in Live Animals and Post-Mortem.” The manual was created as an educational
resource for owners and veterinarians on how
properly to collect vital tissues in ways that minimize loss and preserve significant genetic material
for conservation. The manual is available for free
to download on the TLC’s website at https://livestockconservancy.org/.
In addition to the efforts of the TLC to educate
the horse owning public, biotechnological companies have highlighted advances in cell collection,
storage, embryo flushes, implantation, and evencloning. The future of “resurrecting“ lost breeds
may be possible and even cost effective due tothe technological strides being made. The industry would benefit from the availability of secure“banks” for stallion semen or somatic cell materials
for preserving the future of important bloodlines.
The first step taken includes the recent approvalto have additional material preserved within therepository of the National Animal Germplasm
Program at the USDA’s Agricultural ResearchService. This program already has shown the valueof re-introducing previously “lost” genetics into
livestock species, and those stories can be found on
the USDA’s website at https://www.ars.usda.gov/.
The health of the equine industry is tied directly
to the health of the animals and the diverse uses of
those animals. The genetic health of an animal has
a direct correlation to its usability and the financial
opportunities open to that animal’s owner as well as
all generations to follow. While we may not know
the ultimate value of a specific group of animals
to the overall health and future of the industry,
we do have the technology to protect them andthus ourselves.

3

4

N AT I O N A L

Management Challenges for the
BLM Wild Horse and Burro ProgramM

anagement of wild horses and burros living on the Bureau of Land Management’s(BLM) western rangelands continues to be challenging. As of March 2018, there were approximately 82,000 animals (67,000 wild horses and15,000 wild burros) on 30 million acres of BLM
rangelands in 177 herd management areas. These
populations usually grow by 15-20% a year, often
doubling in 4 to 5 years, and the annual foal crop
alone is expected to be between 16,000-25,000
animals. In addition to the animals on the range,
the BLM also maintains about 12,000 animals in
off-range corrals that serve as adoption and training centers as well as about 37,000 animals in 33
off-range pastures. The pastures, located in the
Midwest and Western US, each house between 200
and 3,000 horses under federal contracts between
the private landowners and the BLM. While no
reproduction occurs on these pastures, the BLM
still pays for the animal’s care and feeding in thesesemi-free-roaming environments.

CONTACT:
Cliff Williamson
cwilliamson@horsecouncil.org
202-296-4031
American Horse Council
Washington, D.C.

Getty Images

When the Wild Free Roaming Horses andBurros Act (the Act) was passed in 1971 andamended in 2005, it instructed BLM to maintainequid populations in balance with other uses of therange such as wildlife management, recreationaluse, livestock grazing, and mineral, oil, and gas extraction. Toward this end, the Bureau determinedthat the appropriate population size on the range
should be about 27,000 animals. The animals thatexceed this target number (currently about 55,000)
can be considered excess along with the 49,000
animals already in BLM corrals and pastures. The
Act as originally written directs the BLM to offer
the excess animals for adoption and sale without
limitation followed by the humane destruction
for the remaining excess animals. However, in theannual budget provided to BLM since the 1980s,
Congress has prohibited the BLM from euthanizing healthy animals or selling animals in a mannerthat may lead them to being processed for commercial use (i.e. slaughter). This leaves the BLM in
the position of having to feed and care for about
50,000 excess animals off-range, which literally“eats up” almost two-thirds of the program’s $80M
budget. Another 55,000 excess animals struggle tosurvive on public rangelands that exceed population targets and are often overgrazed.
To address population growth rates and excess
numbers on the range, the BLM has supported
the development of contraceptives for wild horses
and burros since the 1980s. A couple of contraceptive products (porcine zona pellucida and GnRH
vaccines) work well to prevent mares from conceiving if given annually or boostered following
the initial vaccination. This approach can work
well on smaller herds where animals can be individually identified and approached for darting.
Unfortunately, repeatedly catching the animals fortreatment just isn’t practical. Most wild horses andburros on BLM rangelands can’t be approachedwithin half a mile, let alone the 20-60 yards neededfor darting. Longer lasting contraceptives have notproven reliable in larger field trials. Recent efforts
to spay mares in the context of a field research/feasibility project have been stopped by litigationfrom wild horse advocacy groups.

Equine Disease Quarterly Newsletter

5

The dilemma is clear: excess wild horses andburros on western rangelands and in BLM corrals
and holding pastures. The numbers exceed thosethat can be placed into long-term homes, albeit
with restrictions on what new owners can do withthe animals, through adoptions and sales. The
solutions are anything but straight-forward. BLM
continues to explore better, longer lasting, andpermanent methods of contraception to control
population growth rates. They also continue totry to find new ways to encourage adoption andplacement of excess animals into private long-term
homes. Ultimately, the direction forward depends

on the program’s budget and the policy provided
by Congress as they work to address the realitiesof the situation and wishes of the public.
CONTACT:
Albert J Kane, DVM, MPVM, PhD
albert.j.kane@aphis.usda.gov(970) 494-7234
Advisor, APHIS/BLM WH&B Partnership
USDA APHIS Veterinary Services
Fort Collins, CO

Presorted Standard
US Postage Paid
Permit 51
Lexington KY

Department of Veterinary Science
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky 40546-0099
Address Service Requested

F U N D E D B Y U N D E R W R I T E R S AT L LOY D ' S , LO N D O N

The information, ideas, and opinions expressed arethose of the author and do not necessarily represent
those of the United States Departments of Agriculture
or Interior.

OCTOBER 2019
Volume 28, Number 4

C O M M E N TA RY
KENTUCKY

Guttural Pouch Mycosis

A

Images courtesy of
Dr. Nathan Slovis.

irway dysfunction is one of many causes ofpoor performance in equine athletes. Airway
dysfunction can be classified as either acquired ordevelopmental. One acquired dysfunction that is
generally overlooked is a fungal infection of theguttural pouch, known as guttural pouch mycosis (Figure 1). Guttural pouch mycosis (GPM)
is a potentially life-threatening disease that may

Figure 1. Fungal infection ofguttural pouch.

Figure 2. Intravascular coils on X-ray.

initially present as a simple nosebleed (epistaxis)
or even poor performance in an equine athlete.
GPM has been documented in various parts of
the United States, particularly in the southeast,
as well as the United Kingdom. Clinical signs
include unilateral (one-sided) or bilateral (bothsided) epistaxis, unilateral nasal discharge, dorsal
displacement of the soft palate, dysphagia (difficulty swallowing), and laryngeal
hemiplegia (partial or total paralysisof the larynx). Epistaxis occurs due
to erosion of the guttural pouch
mucosa by a fungal plaque, resulting in hemorrhage from the internal
carotid, occipital, or maxillary arteries. Severe hemorrhage may result in
rapid death from exsanguination.
Dysphagia as well as various formsof pharyngeal dysfunction in GPM
result from mucosal penetration anddamage by fungal hyphae to the glossopharyngeal, hypoglossal, and/or
the pharyngeal branches of the vagus
nerves. A variety of fungi have been
isolated from GPM with Aspergillus spp. being common. Aspergillus
spp. and other opportunistic fungi
are found naturally in the environment and can be found in the upper
respiratory tract of normal horses.
Wet environmental conditions,prolonged treatment with antimicrobials, an immunocompromised
host, or use of corticosteroids havebeen proposed as factors conducive for fungal
overgrowth. It is not fully understood why mycosis
occurs in animals that are not immunosuppressedor debilitated. While no age predilection has beenreported, the disease is more common in mature
horses, but has been documented in foals as young
as two months of age.
Dysphagia is the second most common clinical sign associated with GPM, after epistaxis. The
cranial nerves within the guttural pouch thatinnervate the pharynx are the glossopharyngeal,
vagus, and hypoglossal. Neurological dysfunctionof the pharynx results when the nerves within theguttural pouch are inflamed or fibrosed. Generally,
the presence of dysphagia or other neurologicaldeficits at presentation indicates a poor prognosis.
The severity of cranial nerve deficits depends onwhether nerve injury is restricted to a local neuritis or necrosis of the nerve secondary to fungal
infiltration and fibrosis.
Treatments include both medical and surgical options. While there are reports of successful

medical treatment of GPM with systemic andtopical antifungal medications, medical treatment is generally considered to be less efficacious
than surgical treatment. Topical treatments withenilconazole and miconazole have been used withsuccess in some cases. The presence of a diptheritic
membrane (necrotic material over the surface ofthe fungal plaque) may prevent penetration of systemic antifungals. Additionally, there is increased
risk of fatal hemorrhage due to the longer course of
medical treatment. The preferred method to treat
severe guttural pouch mycosis is to surgically insert
a coil or balloon into the affected blood vessel toquickly cut off the blood supply (Figure 2). Typically, once the blood supply has been removed, thefungus regresses.
CONTACT:
Nathan Slovis, DVM, Dipl. ACVIM,
CHT (Certified Hyperbaric Technologist)(859) 253-0002
Hagyard Equine Medical Institute Director
McGee Critical Care and Medical Center
Lexington, KY

T

he term “Unwanted Horse” was first coinedby the American Association of Equine Practitioners (AAEP) in 2005. Unwanted horses include
Commentaryboth unadoptable feral horses and domestic horsesthat are no longer wanted by their owners because
International
they are geriatric, incurably lame, not athletic,
Second Quarter2019  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2 unmanageable, cost too much to maintain, unmarketable, or fail to meet their owner’s expectations.
Preserving Rare
Horse Breeds .  .  .  .  .  .  .  . 3 Most of the American public was unaware that
there was a subset of horses that become unwanted
National
until the bovine spongiform encephalopathy(BSE) outbreak in Europe in 2000 and the footWild Horse andBurro Program .  .  .  .  .  .  . 4 and-mouth disease epidemic that occurred in the
United Kingdom in 2001. Both outbreaks were
Kentucky
responsible for temporarily changing European
Guttural Pouchconsumers’ preference from beef to horse meat due
Mycosis  .  .  .  .  .  .  .  .  .  .  .  .  . 5to concerns with beef safety. This change drew U.S.
media attention to the fact that many unwanted
horses were being processed in the United States
and their meat exported to Europe. The result
was pressure from the American public and animal activists’ groups to pass federal legislation toprohibit the processing of horses in the UnitedStates for human consumption. Because horses
processed for human consumption epitomize theunwanted horse, they continue to be a part of the
discussion, but normal, healthy horses of all breeds
and disciplines can become unwanted.
At the 2005 American Horse Council meeting,leaders from across the industry came together toCollege of Agriculture, discuss options for resolving the unwanted horse
Food and Environment
issue. The result was the formation of the UnDepartment of
wanted Horse Coalition, which was placed under
Veterinary Science
the umbrella of the American Horse Council. The
goal of the organization was to raise awarenessof the unwanted horse and provide a medium
for the exchange of information about adoption,
Lloyd’s—An international
proper care, alternative careers, and responsible
insurance market forownership. In 2018, it was agreed that awarenessbloodstock and otherhad been accomplished, so the Unwanted Horse
specialist insurance.
IN THIS ISSUE

Coalition transitioned to the United Horse Coalition with a goal of “providing information forexisting and prospective owners, breeders, sellers,and horse organizations regarding the long-term
responsibilities of owning and caring for horses,
as well as focusing on the opportunities available
for these horses through industry collaboration.”
Particular attention has been given to education
regarding the cost of care, proper husbandry, training requirements, expectations and life-ending
decisions. In addition, since 2001 virtually every
horse breed and discipline has developed a program to identify unwanted horses and to provide
options for retraining, rehoming and post-careercare. These include the American Quarter Horse’s
Re-ride Adoption program, the U.S. Trotting
Association’s Full Circle Program, The American
Horse Council’s Time to Ride Initiative, andseveral programs in the Thoroughbred industry
including the TB Aftercare Alliance, Take the Lead
Program, and Retirement Check-off Program. A
new unwanted-horse advocacy group, The Right
Horse Initiative, brought years of experience infinding homes for shelter dogs and cats to thehorse industry.
The horse industry will never completely
eliminate unwanted horses. Horses will always age,sustain career-ending injuries, or not meet theirowner’s expectations. However, I’m optimistic thatthe future is brighter for these horses, because thehorse industry has turned its attention to the issue
and continues to develop strategies to both reduce
the number of unwanted horses on the front end
through responsible care and breeding as well as
the rear end through rescue/retirement programs,
retraining for alternative careers, and low-costeuthanasia options.
CONTACT:Tom Lenz DVM, MS, DACT
horsetrl@aol.com
Louisburg, KS

Equine Disease Quarterly Newsletter

5

The dilemma is clear: excess wild horses andburros on western rangelands and in BLM corrals
and holding pastures. The numbers exceed thosethat can be placed into long-term homes, albeit
with restrictions on what new owners can do withthe animals, through adoptions and sales. The
solutions are anything but straight-forward. BLM
continues to explore better, longer lasting, andpermanent methods of contraception to control
population growth rates. They also continue totry to find new ways to encourage adoption andplacement of excess animals into private long-term
homes. Ultimately, the direction forward depends

on the program’s budget and the policy provided
by Congress as they work to address the realitiesof the situation and wishes of the public.
CONTACT:
Albert J Kane, DVM, MPVM, PhD
albert.j.kane@aphis.usda.gov(970) 494-7234
Advisor, APHIS/BLM WH&B Partnership
USDA APHIS Veterinary Services
Fort Collins, CO

Department of Veterinary Science
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky 40546-0099
Address Service Requested

F U N D E D B Y U N D E R W R I T E R S AT L LOY D ' S , LO N D O N

The information, ideas, and opinions expressed arethose of the author and do not necessarily represent
those of the United States Departments of Agriculture
or Interior.

OCTOBER 2019
Volume 28, Number 4

C O M M E N TA RY
KENTUCKY

Guttural Pouch Mycosis

A

Images courtesy of
Dr. Nathan Slovis.

irway dysfunction is one of many causes ofpoor performance in equine athletes. Airway
dysfunction can be classified as either acquired ordevelopmental. One acquired dysfunction that is
generally overlooked is a fungal infection of theguttural pouch, known as guttural pouch mycosis (Figure 1). Guttural pouch mycosis (GPM)
is a potentially life-threatening disease that may

Figure 1. Fungal infection ofguttural pouch.

Figure 2. Intravascular coils on X-ray.

initially present as a simple nosebleed (epistaxis)
or even poor performance in an equine athlete.
GPM has been documented in various parts of
the United States, particularly in the southeast,
as well as the United Kingdom. Clinical signs
include unilateral (one-sided) or bilateral (bothsided) epistaxis, unilateral nasal discharge, dorsal
displacement of the soft palate, dysphagia (difficulty swallowing), and laryngeal
hemiplegia (partial or total paralysisof the larynx). Epistaxis occurs due
to erosion of the guttural pouch
mucosa by a fungal plaque, resulting in hemorrhage from the internal
carotid, occipital, or maxillary arteries. Severe hemorrhage may result in
rapid death from exsanguination.
Dysphagia as well as various formsof pharyngeal dysfunction in GPM
result from mucosal penetration anddamage by fungal hyphae to the glossopharyngeal, hypoglossal, and/or
the pharyngeal branches of the vagus
nerves. A variety of fungi have been
isolated from GPM with Aspergillus spp. being common. Aspergillus
spp. and other opportunistic fungi
are found naturally in the environment and can be found in the upper
respiratory tract of normal horses.
Wet environmental conditions,prolonged treatment with antimicrobials, an immunocompromised
host, or use of corticosteroids havebeen proposed as factors conducive for fungal
overgrowth. It is not fully understood why mycosis
occurs in animals that are not immunosuppressedor debilitated. While no age predilection has beenreported, the disease is more common in mature
horses, but has been documented in foals as young
as two months of age.
Dysphagia is the second most common clinical sign associated with GPM, after epistaxis. The
cranial nerves within the guttural pouch thatinnervate the pharynx are the glossopharyngeal,
vagus, and hypoglossal. Neurological dysfunctionof the pharynx results when the nerves within theguttural pouch are inflamed or fibrosed. Generally,
the presence of dysphagia or other neurologicaldeficits at presentation indicates a poor prognosis.
The severity of cranial nerve deficits depends onwhether nerve injury is restricted to a local neuritis or necrosis of the nerve secondary to fungal
infiltration and fibrosis.
Treatments include both medical and surgical options. While there are reports of successful

medical treatment of GPM with systemic andtopical antifungal medications, medical treatment is generally considered to be less efficacious
than surgical treatment. Topical treatments withenilconazole and miconazole have been used withsuccess in some cases. The presence of a diptheritic
membrane (necrotic material over the surface ofthe fungal plaque) may prevent penetration of systemic antifungals. Additionally, there is increased
risk of fatal hemorrhage due to the longer course of
medical treatment. The preferred method to treat
severe guttural pouch mycosis is to surgically insert
a coil or balloon into the affected blood vessel toquickly cut off the blood supply (Figure 2). Typically, once the blood supply has been removed, thefungus regresses.
CONTACT:
Nathan Slovis, DVM, Dipl. ACVIM,
CHT (Certified Hyperbaric Technologist)(859) 253-0002
Hagyard Equine Medical Institute Director
McGee Critical Care and Medical Center
Lexington, KY

T

he term “Unwanted Horse” was first coinedby the American Association of Equine Practitioners (AAEP) in 2005. Unwanted horses include
Commentaryboth unadoptable feral horses and domestic horsesthat are no longer wanted by their owners because
International
they are geriatric, incurably lame, not athletic,
Second Quarter2019  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2 unmanageable, cost too much to maintain, unmarketable, or fail to meet their owner’s expectations.
Preserving Rare
Horse Breeds .  .  .  .  .  .  .  . 3 Most of the American public was unaware that
there was a subset of horses that become unwanted
National
until the bovine spongiform encephalopathy(BSE) outbreak in Europe in 2000 and the footWild Horse andBurro Program  .  .  .  .  .  . 4 and-mouth disease epidemic that occurred in the
United Kingdom in 2001. Both outbreaks were
Kentucky
responsible for temporarily changing European
Guttural Pouchconsumers’ preference from beef to horse meat due
Mycosis  .  .  .  .  .  .  .  .  .  .  .  .  . 5to concerns with beef safety. This change drew U.S.
media attention to the fact that many unwanted
horses were being processed in the United States
and their meat exported to Europe. The result
was pressure from the American public and animal activists’ groups to pass federal legislation toprohibit the processing of horses in the UnitedStates for human consumption. Because horses
processed for human consumption epitomize theunwanted horse, they continue to be a part of the
discussion, but normal, healthy horses of all breeds
and disciplines can become unwanted.
At the 2005 American Horse Council meeting,leaders from across the industry came together toCollege of Agriculture, discuss options for resolving the unwanted horse
Food and Environment
issue. The result was the formation of the UnDepartment of
wanted Horse Coalition, which was placed under
Veterinary Science
the umbrella of the American Horse Council. The
goal of the organization was to raise awarenessof the unwanted horse and provide a medium
for the exchange of information about adoption,
Lloyd’s—An international
proper care, alternative careers, and responsible
insurance market forownership. In 2018, it was agreed that awarenessbloodstock and otherhad been accomplished, so the Unwanted Horse
specialist insurance.
IN THIS ISSUE

Coalition transitioned to the United Horse Coalition with a goal of “providing information forexisting and prospective owners, breeders, sellers,and horse organizations regarding the long-term
responsibilities of owning and caring for horses,
as well as focusing on the opportunities available
for these horses through industry collaboration.”
Particular attention has been given to education
regarding the cost of care, proper husbandry, training requirements, expectations and life-ending
decisions. In addition, since 2001 virtually every
horse breed and discipline has developed a program to identify unwanted horses and to provide
options for retraining, rehoming and post-careercare. These include the American Quarter Horse’s
Re-ride Adoption program, the U.S. Trotting
Association’s Full Circle Program, The American
Horse Council’s Time to Ride Initiative, andseveral programs in the Thoroughbred industry
including the TB Aftercare Alliance, Take the Lead
Program, and Retirement Check-off Program. A
new unwanted-horse advocacy group, The Right
Horse Initiative, brought years of experience infinding homes for shelter dogs and cats to thehorse industry.
The horse industry will never completely
eliminate unwanted horses. Horses will always age,sustain career-ending injuries, or not meet theirowner’s expectations. However, I’m optimistic thatthe future is brighter for these horses, because thehorse industry has turned its attention to the issue
and continues to develop strategies to both reduce
the number of unwanted horses on the front end
through responsible care and breeding as well as
the rear end through rescue/retirement programs,
retraining for alternative careers, and low-costeuthanasia options.
CONTACT:Tom Lenz DVM, MS, DACT
horsetrl@aol.com
Louisburg, KS