Equine Disease Quarterly Newsletter

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

5

cessfully medicated, it should have limited intense
exercise during the heat of the day and shouldbe accommodated in facilities that minimize an
increase in body temperature by providing shade,
movement of air, misters, or even cold-water hosing. The simplest of treatments is supplementation
with electrolytes based on abnormalities identified
by the blood chemistry combined with environ-mental management. As a last resort for cases that
do not respond to conventional therapies, moving
the horse to a geographically less hot and humid
climate may eventually restore its ability to sweat.

Address Service Requested

CONTACT:
Dr. Joan Gariboldi(859) 333-5303
jcgariboldi@gmail.com
Lexington, Kentucky

OCTOBER 2015
Volume 24, Number 4

C O M M E N TA RY
IN THIS ISSUEKENTUCKY

Commentary

Manifestations of Equine Herpesvirus–1

E

quine herpesvirus-1 (EHV-1) is one of fiveherpesviruses commonly found in horses.
EHV-1 infections manifest in three syndromes:
respiratory, reproductive, and neurologic. Likeother herpesviruses, EHV-1 can establish latent
infections, making it possible for outbreaks of
disease to occur in herds that are considered closed.
While quarantine of new arrivals, segregation ofyoung stock, breeding stock and show stock, andvaccination are important management tools in
the prevention of EHV-1 infections, complete
protection is not possible to achieve. Vaccination
confirms relatively short-term immunity (4-5months) and immunity is not entirely protective,
meaning that even well-vaccinated horses candevelop disease.
The respiratory form of EHV-1 is generally mildand self-limiting. Clinical signs are indistinguishable from other viral causes of respiratory disease,such as equine influenza and EHV-4. Horses
exhibit a fever, cough, serous nasal discharge, andmild lethargy.
Reproductive disease is generally considered tobe the most economically important manifestationof EHV-1. Infection with EHV-1 causes abortionin the last trimester of gestation. Affected foals
are occasionally born alive but are generally very
weak and succumb within days of birth, often withsecondary disease conditions. The virus infects themare through the respiratory tract and then enters
the bloodstream (viremia), traveling to and infecting the fetus. Infection in the mare is generally
inapparent and abortion occurs without any signsof impending parturition. The fetus is aborted
fresh, in contrast to other causes of abortion suchas leptospirosis where the fetus may be significantly
decomposed.
Following any abortion, the mare should be
isolated, fetal tissues should be contained andsubmitted to a diagnostic laboratory, and incontact mares should not be moved nor should
new mares be brought in until a diagnosis has been
rendered. Fetal tissues and uterine fluids should
be considered infectious, and contaminated areas
should be cleaned with detergent and disinfected.
Contaminated bedding should be bagged anddiscarded and not spread on pastures.
In the case of EHV-1 abortions, the fetal tissues
and fluids contain high concentrations of virus;
infected foals and mares also shed virus via therespiratory route. EHV-1 is transmitted via therespiratory route and fomites. However, since it
is an enveloped virus, herpesvirus is readily inactivated by thorough cleaning with detergents followed by disinfectants. Biosecurity and restrictedmovement of horses are important in containing
EHV-1 infections.
Laboratory diagnosis relies on gross and histologic examination in conjunction with laboratory
testing. Gross lesions can include pleural andperitoneal effusion, over-expanded lungs withrib impressions and small white foci scatteredthroughout the liver. However, there are manycases in which lesions are not identified at necropsy.
Histologically, EHV-1 produces necrotizing lesions
in a number of organs, most notably the lung andInternational
Second Quarter2015  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2Getah Virus .  .  .  .  .  .  .  .  .  . 3National
Eastern Equine
Encephalomyelitis .  .  . 4Anhidrosis .  .  .  .  .  .  .  .  .  .  . 4

liver. Characteristic intranuclear inclusion bodies
are frequent. Common ancillary tests for detectionof the virus include fluorescent antibody testing,virus isolation, and polymerase chain reaction
testing.
EHV-1 abortions can occur singly or may
spread rapidly in a susceptible population, leading
to the classic “abortion storm.” With improved
management and readily available vaccines for
EHV-1, the number of cases of EHV-1 abortion
has declined dramatically over the past 30 years,
with the vast majority of cases being single events.
EHV-1 confirmed abortions diagnosed at the
University of Kentucky Veterinary Diagnostic
Laboratory are shown in Figure 3. During thatsame time, EHV-1 neonatal deaths were diagnosed
in 2011 (one), 2012 (two), and 2014 (one).
Respiratory and reproductive manifestations of
EHV-1 are well-documented and have long beenrecognized. While viral latency and the productionof a vaccine that produces long-term immunityand confirms better protection continue to bestudied, these syndromes are well understood.
A manifestation of EHV-1 that is less understood is equine herpesvirus myeloencephalopathy(EHM). EHM is a neurologic disease that mani-

fests with acute onset ataxia or paresis, often accompanied by weakness, urinary incontinence,poor tail and anal tone, and tail elevation, either
singly or in combination. EHM can occur as asporadic case of neurologic disease, but often
manifests as an outbreak within a single populationof horses. Outbreaks are often identified in dense
populations of horses, such as at racetracks, horseshows or show barns, riding stables, etc. Generally,
these horses are well-vaccinated and vaccination
seems to be neither protective nor a risk factor.
While the pathology of EHM is well-understood,
the production and development of disease is not
and is the subject of continued research. Preventionof outbreaks of EHM relies on close observationof the horses, including monitoring of rectal temperatures, swift isolation of affected horses, andoften quarantine of the premises.
A constant presence in the horse world, EHV-1
is well known, but many challenges remain.
CONTACT:
Dr. Laura Kennedy(859) 257-8283
drlaurakennedy@uky.edu
University of Kentucky
Veterinary Diagnostic Laboratory
Lexington, Kentucky

KentuckyEquineHerpesvirus-1  .  .  .  .  .  .  . 5M

ore than 100 land-grant colleges and universities have Extension educators whobring research-based information to agricultural
producers and the public, including horse owners. Over the last decade, the university specialists
and educators involved with both equine scienceand disaster education (preparedness, mitigation,
response and recovery) have made significant collaborative strides in developing and publishing
resource information. These efforts include materials on three different platforms: eXtension (thenational Extension website: http://learn.extension.
org), My Horse University (a collaborative effort
between university equine specialists: www.myhorseuniversity.com), and the Extension Disaster
Education Network (EDEN) (collaboration ofdisaster educators across the United States: www.
eden.lsu.edu).
Webinars on animal disaster preparedness andbiosecurity are available on eXtension and My
Horse University (enter “disaster” in the searchengines), along with a wealth of other equine andlivestock information. The EDEN website is anextensive information hub that has disaster-specificinformation (e.g., drought, hurricanes, tornadoes,
animal disease), as well as resources for communities, families, and children dealing with disasters.
A notable effort has been the EDEN Strengthening Community Agrosecurity Preparedness(S-CAP) program, which is a two-day course thatfacilitates emergency managers and agriculture/
livestock owners to evaluate vulnerabilities withincounties and develop enhanced agrosecurity plansto address local needs. This process almost always
includes establishing response and evacuation
guidelines for equine owners. To date, 48 S-CAP
workshops have been conducted, which represent
24 states, 285 counties, and 23.7 million residents.

Universities and partners are incorporating rural
readiness into disaster readiness curricula, which
includes specific materials focused on equine issues
before, during, and after disasters strike. Beneaththe surface of many of the partnerships you willfind delegates from EDEN developing, publishing,and collaborating on new materials on a regularbasis.
It is imperative that information and resources
for horse managers during disasters is bothresearch-based and refereed by experts and civic
authorities for validity. With the popular natureof horses internationally, valid information that isreadily available is critical when crucial incidents
are impending or ongoing. No equine manager
can afford to be basing response on “popular” or“web-based” practices or materials during a crisis.
In most cases equine managers will have an averageof 30 minutes to 2 hours to prepare for a disaster,although in some cases it can be as little as 15
minutes. During two floods and seven wildfires
in the western United States it took an average of
15 minutes per horse to respond to disaster if the
responders were already equipped and organized.
If not ready, the average was closer to one hour per
horse.
For those reasons equine managers should havea disaster plan, equipment, personnel, evacuationroutes, emergency supplies, first-aid kits, andemergency contact information ready at all times.
The eXtension, My Horse University, and EDEN
resources can help utilize the hard-earned, factual
knowledge developed by professionals to reduce
impacts from disasters. Remember: Having a plancan save human and animal lives.
CONTACT:
Scott Cotton(307) 235-9400
Scotton1@uwyo.edu
University of Wyoming Extension Area Educator
EDEN Agrosecurity Delegate
Casper, Wyoming

2

3

4

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

N AT I O N A LInternet address:
http://www.ca.uky.edu/
gluck/index.htm
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*First Quarter Report from Australia

CONTACT:
Dr. Peter Timoney(859) 218-1094
ptimoney@uky.edu
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky

800
700

Despite the geographic distribution of equine
EEE cases, the rapid interstate and internationaltransportation of horses for show, racing, recreation, sales, breeding, and other activities strongly
supports the use of EEE vaccines. The EEE vaccine is considered by the American Association of
Equine Practitioners to be a “core” vaccine.
Insect control and appropriate use of approved
insecticides are critical to reducing the risks of
EEE as well as West Nile virus infections, vesicularstomatitis, and other insect-borne diseases.
CONTACT:
Dr. Roberta Dwyer(859) 218-1122
rmdwyer@uky.edu
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky

Anhidrosis

600
500
400

A

300
200
100

Year

14
20

13

12

20

20

11
20

10
20

09

08

20

20

07
20

06

05

0

20

Correspondence 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

astern equine encephalomyelitis (EEE) is only
one of several important vector-borne diseases
that is of significant concern to horse owners. Witha mortality rate of 90%, it is a deadly disease. The
U.S. Department of Agriculture Animal and Plant
Health Inspection Service, Veterinary Services
works with the U.S. Centers for Disease Control
and Prevention and public health officials to collect data on EEE and other vector-borne diseases.
Figure 1 shows the geographic location (shaded
states) of equine EEE cases from 2003-2014, although not every state had cases each year. Figure
2 shows reported U.S. equine EEE cases (which
include presumptive positive and confirmed positive cases) from 2003-2014.

Figure 2. Reported U.S. Equine EEE Cases.

20

Diane Furry
Tawana Brown
Dennis Duross

Adapted from www.aphis.usda.gov

04

Staff

E

20

Roberta Dwyer
Alan LoynachanPeter Timoney

virus is abortigenic in the pregnant mare or that
infection can result in congenital abnormalities infoals.
The only other animal species in which Getah
virus has been implicated in causing disease isswine. The virus has been isolated from newborn
piglets that died of peracute disease and also fromdead fetuses removed from a naturally infected sow.
Getah virus is primarily a mosquito-borne
infection that is transmitted by different speciesof Culex and Aedes mosquitoes depending on thegeographic region of the world in which it occurs.
Swine are thought to play a role in amplificationof the virus in endemic areas. The potential fortransmission through direct horse-to-horse contact
cannot be discounted considering some acutely
infected horses shed significant quantities of infectious virus into the respiratory tract.
Diagnosis of Getah virus infection can be readily accomplished by virus detection in nasal swabs,
unclotted blood (buffy coat) samples, and saliva
either by PCR assay or virus isolation. It can also
be confirmed by serological testing of acute andconvalescent serum samples. Because of the close
clinical similarity between Getah virus infectionand equine viral arteritis and African horse sickness, it is important to differentiate it diagnosticallyfrom either of these two diseases.
Prevention and control of Getah virus infection
is based on measures to reduce mosquito contact
with horses and, optimally, vaccination of at-riskequine populations in countries in which the virus
is endemic.
While Getah virus is not considered an important equine pathogen, it can be significantly
disruptive when extensive outbreaks occur.

03

EditorsAn outbreak of illness at a Japanese racing
stable in the latter half of 2014 re-awakened
awareness of Getah virus and its potential as anequine pathogen. The first indication that the virus
could cause illness in horses was the widespreadoccurrence of a disease syndrome among racehorses at two training centers in Japan in 1978.
Subsequently, the virus was implicated in a clinically similar disease outbreak on a Thoroughbred
breeding farm in India during 1990.
Getah virus is a mosquito-borne arbovirusthat is a member of the genus Alphavirus, family
Togaviridae. First isolated from mosquito pools
collected in Sarawak (Malaysia) between 1968
and 1970, Getah or one of its antigenically related
viruses, can be found over a wide geographic range
extending from Eurasia to Australia. Results ofserologic surveys have confirmed infection inhumans and a wide diversity of domestic andwildlife animal species wherever the virus is present. Serologic evidence of Getah virus activity
in horses in Japan can be traced back to 1961.
Subsequent studies have shown that the infection
was widespread in equine populations throughoutthat country. Notwithstanding this fact, however,disease events caused by Getah virus have beenvery infrequent.
Naturally occurring disease caused by Getah
virus has only been reported in horses and in swine.
While the vast majority of primary infections inhorses are asymptomatic, on occasion the virus
can give rise to extensive outbreaks of mild illness
characterized by fever, anorexia, serous nasal discharge, hind limb edema, stiff gait, scrotal edema,
submandibular lymphadenopathy, and urticarial
skin rash. Affected horses may develop some or allof these clinical signs. Regardless of severity, thedisease is non-fatal and complete clinical recovery
occurs within 7 to 14 days. Symptomatic treatment is seldom indicated. Based on the outbreakrecorded in India, there was no evidence that Getah

20

Equine Disease Quarterly

Two cases of equine coital exanthema werediagnosed in the UK.
Germany confirmed equine arteritis virus infection in two stallions on separate premises.
A single case of equine adenoviral respiratory
infection in a foal was reported in the USA.
Outbreaks of equine infectious anemia wererecorded in Canada, France, and the USA. A totalof 16 cases of the disease were diagnosed on ninepremises in four westernmost provinces in Canada.
A single case was identified in France and threecases on different premises in the USA.
France and the UAE reported that equine piroplasmosis was endemic; Switzerland confirmed one
case of the disease.
Contagious equine metritis was diagnosed inthree horses on separate premises in Germany.
The USA reported isolated cases of nocardioform placentitis and abortion in two states and asingle case of mare reproductive loss syndrome in
Kentucky.
Outbreaks of salmonellosis were confirmed in
the USA, some due to Group B Salmonella spp.
and others to Group C1 Salmonella spp. France
reported five outbreaks of rotavirus infection in
foals. Clostridiosis in foals was recorded in theUSA, several associated with C. perfringens Toxin
Type A and others with C. difficile Toxin A/B genestrains.
Nine cases of Eastern equine encephalomyelitis were diagnosed in the USA, the majority in
Florida, four of which had not been vaccinatedagainst the disease. The USA also reported one caseof West Nile encephalitis in a horse in Oklahoma.
Rhodococcal related disease was recorded in
Switzerland (single case) and the USA (numerous
cases in multiple states in which the disease isendemic).
Isolated cases of other diseases were reported:
Tyzzer’s disease (single case in a foal in the USA),
melioidosis (single case in a riding-school horse in
Singapore), cutaneous leishmaniasis (single casein Switzerland), and anaplasmosis (two cases inGermany).

Eastern Equine Encephalomyelitis

Figure 1. States with Equine EEE Cases, 2003-2014.

www.aphis.usda.gov

Figure 3. Abortions submitted to UKVDL, 2011-2015.
Total Abortions

The International Collating Centre, Newmarket, United Kingdom, and other sources
reported the following disease outbreaks.
Vesicular stomatitis reoccurred in the USA inlate April 2015. Infection with the New Jersey
serotype of the virus had spread to 25 premises in
Arizona, Colorado, New Mexico, Texas, and Utah.
A donkey that strayed across the border from
Mexico into Texas, USA was reported as testing
serologically positive for glanders. The animal was
one of a group of five, all of which were clinicallynormal. With the one exception, the remaining
donkeys were seronegative for antibodies to
Burkholderia mallei. The positive donkey, whose
status was downgraded to suspect on re-test, waseuthanized.
Several outbreaks of strangles were reported in
Denmark, France, Germany, Switzerland, United
Arab Emirates (UAE), and the USA.
Equine influenza was reported by Germany(single cases on four premises), the UK (seven outbreaks including some animals recently imported),
and the USA (outbreaks in four states).
Equine herpesvirus-1 and -4 (EHV-1, -4) related diseases were reported in France, Germany,
Ireland, Japan, Switzerland, the UK, and the USA.
Respiratory disease was recorded by France (threeoutbreaks), Germany (two cases), Ireland (threecases), and the USA (several states). Abortiondue to EHV-1 was confirmed by France (threeoutbreaks), Germany (nine cases), Japan (sevencases of abortion and three deaths in neonatal
foals on seven premises), the UK (one case), andthe USA (three cases). EHV-1 neurologic disease
was reported by Germany (two cases) and the USA(outbreaks in seven states, the majority involving
isolated cases of the disease). Respiratory disease
due to EHV-4 was recorded in France (11 outbreaks), Germany (three cases), Switzerland (onecase), and the UK (five outbreaks, one involving
multiple cases). The UK also reported one case of
EHV-4 related abortion.

Getah Virus: Significance as an Equine Pathogen

400

EHV-1 Abortions

Second Quarter 2015*

15

350

*

300
250
Total
EHV-1

10
5
0

2011

2012

2013

2014

2015

Foaling Season* Submissions for 2011 were subsidized, resulting in an inflated
number of cases.

nhidrosis is a common condition that frequently presents during the long, hot days ofsummer and is the inability of the horse to produce
an adequate amount of sweat. The decreased ability to maintain proper body temperature limits
athletic potential, increases risk for heat stroke, andmay compound other disease processes. The causeof anhidrosis is not well defined, but is believedto involve over-stimulation of the horse’s sweat
glands by stress hormones, typically occurring inthe summer months. A horse may only have minor
decreases in sweat production, resulting in subtle
clinical signs, or a total loss of sweat production
and severe signs of hyperthermia. Most commonly
diagnosed in performance horses, it also affects
non-performance horses and seems to be moreprevalent in dark-colored animals. Anhidrosis canbe especially problematic in animals with coexisting medical diseases (e.g. metabolic or respiratory
conditions) by increasing cortisol levels and respiratory demands.
The most common form seen is incompleteor partial anhidrosis and should be considered
if a decline in performance with an increase inambient temperature during summer months
occurs. A complete history and clinical examination following exercise may be adequate to arrive

at a diagnosis. Clinical signs of partial anhidrosis
include an elevated respiratory rate and increased
rectal temperature that requires an extended periodof time (greater than 30 minutes) to return to thenormal range upon cessation of exercise.
Chronic cases of anhidrosis typically present
with a poor, dry-looking hair coat accompanied bya history of lethargy during the hotter times of theyear. It should be noted that any horse may sufferfrom anhidrosis in the summer months, including
brood mares and retired performance horses withmore sedentary lifestyles. Affected horses will havean elevated respiratory rate at rest and will tend toseek shade if available.
A definitive diagnosis of anhidrosis can be madeby injecting a series of dilutions of terbutaline.
This may be useful in determining severity of thecondition and evaluating response to treatment.
Blood work, including an electrolyte analysis, mayalso be helpful in formulating a treatment plan.
Lastly, a skin biopsy may be performed in severecases to evaluate the histologic structure of thesweat glands, however, this is rarely necessary toconfirm a diagnosis.
There are some treatment options for anhidrosis, and what works on one horse might not workon another. Until the horse with anhidrosis is suc-

2

3

4

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

N AT I O N A LInternet address:
http://www.ca.uky.edu/
gluck/index.htm
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*First Quarter Report from Australia

CONTACT:
Dr. Peter Timoney(859) 218-1094
ptimoney@uky.edu
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky

800
700

Despite the geographic distribution of equine
EEE cases, the rapid interstate and internationaltransportation of horses for show, racing, recreation, sales, breeding, and other activities strongly
supports the use of EEE vaccines. The EEE vaccine is considered by the American Association of
Equine Practitioners to be a “core” vaccine.
Insect control and appropriate use of approved
insecticides are critical to reducing the risks of
EEE as well as West Nile virus infections, vesicularstomatitis, and other insect-borne diseases.
CONTACT:
Dr. Roberta Dwyer(859) 218-1122
rmdwyer@uky.edu
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky

Anhidrosis

600
500
400

A

300
200
100

Year

14
20

13

12

20

20

11
20

10
20

09

08

20

20

07
20

06

05

0

20

Correspondence 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

astern equine encephalomyelitis (EEE) is only
one of several important vector-borne diseases
that is of significant concern to horse owners. Witha mortality rate of 90%, it is a deadly disease. The
U.S. Department of Agriculture Animal and Plant
Health Inspection Service, Veterinary Services
works with the U.S. Centers for Disease Control
and Prevention and public health officials to collect data on EEE and other vector-borne diseases.
Figure 1 shows the geographic location (shaded
states) of equine EEE cases from 2003-2014, although not every state had cases each year. Figure
2 shows reported U.S. equine EEE cases (which
include presumptive positive and confirmed positive cases) from 2003-2014.

Figure 2. Reported U.S. Equine EEE Cases.

20

Diane Furry
Tawana Brown
Dennis Duross

Adapted from www.aphis.usda.gov

04

Staff

E

20

Roberta Dwyer
Alan LoynachanPeter Timoney

virus is abortigenic in the pregnant mare or that
infection can result in congenital abnormalities infoals.
The only other animal species in which Getah
virus has been implicated in causing disease isswine. The virus has been isolated from newborn
piglets that died of peracute disease and also fromdead fetuses removed from a naturally infected sow.
Getah virus is primarily a mosquito-borne
infection that is transmitted by different speciesof Culex and Aedes mosquitoes depending on thegeographic region of the world in which it occurs.
Swine are thought to play a role in amplificationof the virus in endemic areas. The potential fortransmission through direct horse-to-horse contact
cannot be discounted considering some acutely
infected horses shed significant quantities of infectious virus into the respiratory tract.
Diagnosis of Getah virus infection can be readily accomplished by virus detection in nasal swabs,
unclotted blood (buffy coat) samples, and saliva
either by PCR assay or virus isolation. It can also
be confirmed by serological testing of acute andconvalescent serum samples. Because of the close
clinical similarity between Getah virus infectionand equine viral arteritis and African horse sickness, it is important to differentiate it diagnosticallyfrom either of these two diseases.
Prevention and control of Getah virus infection
is based on measures to reduce mosquito contact
with horses and, optimally, vaccination of at-riskequine populations in countries in which the virus
is endemic.
While Getah virus is not considered an important equine pathogen, it can be significantly
disruptive when extensive outbreaks occur.

03

EditorsAn outbreak of illness at a Japanese racing
stable in the latter half of 2014 re-awakened
awareness of Getah virus and its potential as anequine pathogen. The first indication that the virus
could cause illness in horses was the widespreadoccurrence of a disease syndrome among racehorses at two training centers in Japan in 1978.
Subsequently, the virus was implicated in a clinically similar disease outbreak on a Thoroughbred
breeding farm in India during 1990.
Getah virus is a mosquito-borne arbovirusthat is a member of the genus Alphavirus, family
Togaviridae. First isolated from mosquito pools
collected in Sarawak (Malaysia) between 1968
and 1970, Getah or one of its antigenically related
viruses, can be found over a wide geographic range
extending from Eurasia to Australia. Results ofserologic surveys have confirmed infection inhumans and a wide diversity of domestic andwildlife animal species wherever the virus is present. Serologic evidence of Getah virus activity
in horses in Japan can be traced back to 1961.
Subsequent studies have shown that the infection
was widespread in equine populations throughoutthat country. Notwithstanding this fact, however,disease events caused by Getah virus have beenvery infrequent.
Naturally occurring disease caused by Getah
virus has only been reported in horses and in swine.
While the vast majority of primary infections inhorses are asymptomatic, on occasion the virus
can give rise to extensive outbreaks of mild illness
characterized by fever, anorexia, serous nasal discharge, hind limb edema, stiff gait, scrotal edema,
submandibular lymphadenopathy, and urticarial
skin rash. Affected horses may develop some or allof these clinical signs. Regardless of severity, thedisease is non-fatal and complete clinical recovery
occurs within 7 to 14 days. Symptomatic treatment is seldom indicated. Based on the outbreakrecorded in India, there was no evidence that Getah

20

Equine Disease Quarterly

Two cases of equine coital exanthema werediagnosed in the UK.
Germany confirmed equine arteritis virus infection in two stallions on separate premises.
A single case of equine adenoviral respiratory
infection in a foal was reported in the USA.
Outbreaks of equine infectious anemia wererecorded in Canada, France, and the USA. A totalof 16 cases of the disease were diagnosed on ninepremises in four westernmost provinces in Canada.
A single case was identified in France and threecases on different premises in the USA.
France and the UAE reported that equine piroplasmosis was endemic; Switzerland confirmed one
case of the disease.
Contagious equine metritis was diagnosed inthree horses on separate premises in Germany.
The USA reported isolated cases of nocardioform placentitis and abortion in two states and asingle case of mare reproductive loss syndrome in
Kentucky.
Outbreaks of salmonellosis were confirmed in
the USA, some due to Group B Salmonella spp.
and others to Group C1 Salmonella spp. France
reported five outbreaks of rotavirus infection in
foals. Clostridiosis in foals was recorded in theUSA, several associated with C. perfringens Toxin
Type A and others with C. difficile Toxin A/B genestrains.
Nine cases of Eastern equine encephalomyelitis were diagnosed in the USA, the majority in
Florida, four of which had not been vaccinatedagainst the disease. The USA also reported one caseof West Nile encephalitis in a horse in Oklahoma.
Rhodococcal related disease was recorded in
Switzerland (single case) and the USA (numerous
cases in multiple states in which the disease isendemic).
Isolated cases of other diseases were reported:
Tyzzer’s disease (single case in a foal in the USA),
melioidosis (single case in a riding-school horse in
Singapore), cutaneous leishmaniasis (single casein Switzerland), and anaplasmosis (two cases inGermany).

Eastern Equine Encephalomyelitis

Figure 1. States with Equine EEE Cases, 2003-2014.

www.aphis.usda.gov

Figure 3. Abortions submitted to UKVDL, 2011-2015.
Total Abortions

The International Collating Centre, Newmarket, United Kingdom, and other sources
reported the following disease outbreaks.
Vesicular stomatitis reoccurred in the USA inlate April 2015. Infection with the New Jersey
serotype of the virus had spread to 25 premises in
Arizona, Colorado, New Mexico, Texas, and Utah.
A donkey that strayed across the border from
Mexico into Texas, USA was reported as testing
serologically positive for glanders. The animal was
one of a group of five, all of which were clinicallynormal. With the one exception, the remaining
donkeys were seronegative for antibodies to
Burkholderia mallei. The positive donkey, whose
status was downgraded to suspect on re-test, waseuthanized.
Several outbreaks of strangles were reported in
Denmark, France, Germany, Switzerland, United
Arab Emirates (UAE), and the USA.
Equine influenza was reported by Germany(single cases on four premises), the UK (seven outbreaks including some animals recently imported),
and the USA (outbreaks in four states).
Equine herpesvirus-1 and -4 (EHV-1, -4) related diseases were reported in France, Germany,
Ireland, Japan, Switzerland, the UK, and the USA.
Respiratory disease was recorded by France (threeoutbreaks), Germany (two cases), Ireland (threecases), and the USA (several states). Abortiondue to EHV-1 was confirmed by France (threeoutbreaks), Germany (nine cases), Japan (sevencases of abortion and three deaths in neonatal
foals on seven premises), the UK (one case), andthe USA (three cases). EHV-1 neurologic disease
was reported by Germany (two cases) and the USA(outbreaks in seven states, the majority involving
isolated cases of the disease). Respiratory disease
due to EHV-4 was recorded in France (11 outbreaks), Germany (three cases), Switzerland (onecase), and the UK (five outbreaks, one involving
multiple cases). The UK also reported one case of
EHV-4 related abortion.

Getah Virus: Significance as an Equine Pathogen

400

EHV-1 Abortions

Second Quarter 2015*

15

350

*

300
250
Total
EHV-1

10
5
0

2011

2012

2013

2014

2015

Foaling Season* Submissions for 2011 were subsidized, resulting in an inflated
number of cases.

nhidrosis is a common condition that frequently presents during the long, hot days ofsummer and is the inability of the horse to produce
an adequate amount of sweat. The decreased ability to maintain proper body temperature limits
athletic potential, increases risk for heat stroke, andmay compound other disease processes. The causeof anhidrosis is not well defined, but is believedto involve over-stimulation of the horse’s sweat
glands by stress hormones, typically occurring inthe summer months. A horse may only have minor
decreases in sweat production, resulting in subtle
clinical signs, or a total loss of sweat production
and severe signs of hyperthermia. Most commonly
diagnosed in performance horses, it also affects
non-performance horses and seems to be moreprevalent in dark-colored animals. Anhidrosis canbe especially problematic in animals with coexisting medical diseases (e.g. metabolic or respiratory
conditions) by increasing cortisol levels and respiratory demands.
The most common form seen is incompleteor partial anhidrosis and should be considered
if a decline in performance with an increase inambient temperature during summer months
occurs. A complete history and clinical examination following exercise may be adequate to arrive

at a diagnosis. Clinical signs of partial anhidrosis
include an elevated respiratory rate and increased
rectal temperature that requires an extended periodof time (greater than 30 minutes) to return to thenormal range upon cessation of exercise.
Chronic cases of anhidrosis typically present
with a poor, dry-looking hair coat accompanied bya history of lethargy during the hotter times of theyear. It should be noted that any horse may sufferfrom anhidrosis in the summer months, including
brood mares and retired performance horses withmore sedentary lifestyles. Affected horses will havean elevated respiratory rate at rest and will tend toseek shade if available.
A definitive diagnosis of anhidrosis can be madeby injecting a series of dilutions of terbutaline.
This may be useful in determining severity of thecondition and evaluating response to treatment.
Blood work, including an electrolyte analysis, mayalso be helpful in formulating a treatment plan.
Lastly, a skin biopsy may be performed in severecases to evaluate the histologic structure of thesweat glands, however, this is rarely necessary toconfirm a diagnosis.
There are some treatment options for anhidrosis, and what works on one horse might not workon another. Until the horse with anhidrosis is suc-

2

3

4

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

N AT I O N A LInternet address:
http://www.ca.uky.edu/
gluck/index.htm
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*First Quarter Report from Australia

CONTACT:
Dr. Peter Timoney(859) 218-1094
ptimoney@uky.edu
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky

800
700

Despite the geographic distribution of equine
EEE cases, the rapid interstate and internationaltransportation of horses for show, racing, recreation, sales, breeding, and other activities strongly
supports the use of EEE vaccines. The EEE vaccine is considered by the American Association of
Equine Practitioners to be a “core” vaccine.
Insect control and appropriate use of approved
insecticides are critical to reducing the risks of
EEE as well as West Nile virus infections, vesicularstomatitis, and other insect-borne diseases.
CONTACT:
Dr. Roberta Dwyer(859) 218-1122
rmdwyer@uky.edu
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky

Anhidrosis

600
500
400

A

300
200
100

Year

14
20

13

12

20

20

11
20

10
20

09

08

20

20

07
20

06

05

0

20

Correspondence 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

astern equine encephalomyelitis (EEE) is only
one of several important vector-borne diseases
that is of significant concern to horse owners. Witha mortality rate of 90%, it is a deadly disease. The
U.S. Department of Agriculture Animal and Plant
Health Inspection Service, Veterinary Services
works with the U.S. Centers for Disease Control
and Prevention and public health officials to collect data on EEE and other vector-borne diseases.
Figure 1 shows the geographic location (shaded
states) of equine EEE cases from 2003-2014, although not every state had cases each year. Figure
2 shows reported U.S. equine EEE cases (which
include presumptive positive and confirmed positive cases) from 2003-2014.

Figure 2. Reported U.S. Equine EEE Cases.

20

Diane Furry
Tawana Brown
Dennis Duross

Adapted from www.aphis.usda.gov

04

Staff

E

20

Roberta Dwyer
Alan LoynachanPeter Timoney

virus is abortigenic in the pregnant mare or that
infection can result in congenital abnormalities infoals.
The only other animal species in which Getah
virus has been implicated in causing disease isswine. The virus has been isolated from newborn
piglets that died of peracute disease and also fromdead fetuses removed from a naturally infected sow.
Getah virus is primarily a mosquito-borne
infection that is transmitted by different speciesof Culex and Aedes mosquitoes depending on thegeographic region of the world in which it occurs.
Swine are thought to play a role in amplificationof the virus in endemic areas. The potential fortransmission through direct horse-to-horse contact
cannot be discounted considering some acutely
infected horses shed significant quantities of infectious virus into the respiratory tract.
Diagnosis of Getah virus infection can be readily accomplished by virus detection in nasal swabs,
unclotted blood (buffy coat) samples, and saliva
either by PCR assay or virus isolation. It can also
be confirmed by serological testing of acute andconvalescent serum samples. Because of the close
clinical similarity between Getah virus infectionand equine viral arteritis and African horse sickness, it is important to differentiate it diagnosticallyfrom either of these two diseases.
Prevention and control of Getah virus infection
is based on measures to reduce mosquito contact
with horses and, optimally, vaccination of at-riskequine populations in countries in which the virus
is endemic.
While Getah virus is not considered an important equine pathogen, it can be significantly
disruptive when extensive outbreaks occur.

03

EditorsAn outbreak of illness at a Japanese racing
stable in the latter half of 2014 re-awakened
awareness of Getah virus and its potential as anequine pathogen. The first indication that the virus
could cause illness in horses was the widespreadoccurrence of a disease syndrome among racehorses at two training centers in Japan in 1978.
Subsequently, the virus was implicated in a clinically similar disease outbreak on a Thoroughbred
breeding farm in India during 1990.
Getah virus is a mosquito-borne arbovirusthat is a member of the genus Alphavirus, family
Togaviridae. First isolated from mosquito pools
collected in Sarawak (Malaysia) between 1968
and 1970, Getah or one of its antigenically related
viruses, can be found over a wide geographic range
extending from Eurasia to Australia. Results ofserologic surveys have confirmed infection inhumans and a wide diversity of domestic andwildlife animal species wherever the virus is present. Serologic evidence of Getah virus activity
in horses in Japan can be traced back to 1961.
Subsequent studies have shown that the infection
was widespread in equine populations throughoutthat country. Notwithstanding this fact, however,disease events caused by Getah virus have beenvery infrequent.
Naturally occurring disease caused by Getah
virus has only been reported in horses and in swine.
While the vast majority of primary infections inhorses are asymptomatic, on occasion the virus
can give rise to extensive outbreaks of mild illness
characterized by fever, anorexia, serous nasal discharge, hind limb edema, stiff gait, scrotal edema,
submandibular lymphadenopathy, and urticarial
skin rash. Affected horses may develop some or allof these clinical signs. Regardless of severity, thedisease is non-fatal and complete clinical recovery
occurs within 7 to 14 days. Symptomatic treatment is seldom indicated. Based on the outbreakrecorded in India, there was no evidence that Getah

20

Equine Disease Quarterly

Two cases of equine coital exanthema werediagnosed in the UK.
Germany confirmed equine arteritis virus infection in two stallions on separate premises.
A single case of equine adenoviral respiratory
infection in a foal was reported in the USA.
Outbreaks of equine infectious anemia wererecorded in Canada, France, and the USA. A totalof 16 cases of the disease were diagnosed on ninepremises in four westernmost provinces in Canada.
A single case was identified in France and threecases on different premises in the USA.
France and the UAE reported that equine piroplasmosis was endemic; Switzerland confirmed one
case of the disease.
Contagious equine metritis was diagnosed inthree horses on separate premises in Germany.
The USA reported isolated cases of nocardioform placentitis and abortion in two states and asingle case of mare reproductive loss syndrome in
Kentucky.
Outbreaks of salmonellosis were confirmed in
the USA, some due to Group B Salmonella spp.
and others to Group C1 Salmonella spp. France
reported five outbreaks of rotavirus infection in
foals. Clostridiosis in foals was recorded in theUSA, several associated with C. perfringens Toxin
Type A and others with C. difficile Toxin A/B genestrains.
Nine cases of Eastern equine encephalomyelitis were diagnosed in the USA, the majority in
Florida, four of which had not been vaccinatedagainst the disease. The USA also reported one caseof West Nile encephalitis in a horse in Oklahoma.
Rhodococcal related disease was recorded in
Switzerland (single case) and the USA (numerous
cases in multiple states in which the disease isendemic).
Isolated cases of other diseases were reported:
Tyzzer’s disease (single case in a foal in the USA),
melioidosis (single case in a riding-school horse in
Singapore), cutaneous leishmaniasis (single casein Switzerland), and anaplasmosis (two cases inGermany).

Eastern Equine Encephalomyelitis

Figure 1. States with Equine EEE Cases, 2003-2014.

www.aphis.usda.gov

Figure 3. Abortions submitted to UKVDL, 2011-2015.
Total Abortions

The International Collating Centre, Newmarket, United Kingdom, and other sources
reported the following disease outbreaks.
Vesicular stomatitis reoccurred in the USA inlate April 2015. Infection with the New Jersey
serotype of the virus had spread to 25 premises in
Arizona, Colorado, New Mexico, Texas, and Utah.
A donkey that strayed across the border from
Mexico into Texas, USA was reported as testing
serologically positive for glanders. The animal was
one of a group of five, all of which were clinicallynormal. With the one exception, the remaining
donkeys were seronegative for antibodies to
Burkholderia mallei. The positive donkey, whose
status was downgraded to suspect on re-test, waseuthanized.
Several outbreaks of strangles were reported in
Denmark, France, Germany, Switzerland, United
Arab Emirates (UAE), and the USA.
Equine influenza was reported by Germany(single cases on four premises), the UK (seven outbreaks including some animals recently imported),
and the USA (outbreaks in four states).
Equine herpesvirus-1 and -4 (EHV-1, -4) related diseases were reported in France, Germany,
Ireland, Japan, Switzerland, the UK, and the USA.
Respiratory disease was recorded by France (threeoutbreaks), Germany (two cases), Ireland (threecases), and the USA (several states). Abortiondue to EHV-1 was confirmed by France (threeoutbreaks), Germany (nine cases), Japan (sevencases of abortion and three deaths in neonatal
foals on seven premises), the UK (one case), andthe USA (three cases). EHV-1 neurologic disease
was reported by Germany (two cases) and the USA(outbreaks in seven states, the majority involving
isolated cases of the disease). Respiratory disease
due to EHV-4 was recorded in France (11 outbreaks), Germany (three cases), Switzerland (onecase), and the UK (five outbreaks, one involving
multiple cases). The UK also reported one case of
EHV-4 related abortion.

Getah Virus: Significance as an Equine Pathogen

400

EHV-1 Abortions

Second Quarter 2015*

15

350

*

300
250
Total
EHV-1

10
5
0

2011

2012

2013

2014

2015

Foaling Season* Submissions for 2011 were subsidized, resulting in an inflated
number of cases.

nhidrosis is a common condition that frequently presents during the long, hot days ofsummer and is the inability of the horse to produce
an adequate amount of sweat. The decreased ability to maintain proper body temperature limits
athletic potential, increases risk for heat stroke, andmay compound other disease processes. The causeof anhidrosis is not well defined, but is believedto involve over-stimulation of the horse’s sweat
glands by stress hormones, typically occurring inthe summer months. A horse may only have minor
decreases in sweat production, resulting in subtle
clinical signs, or a total loss of sweat production
and severe signs of hyperthermia. Most commonly
diagnosed in performance horses, it also affects
non-performance horses and seems to be moreprevalent in dark-colored animals. Anhidrosis canbe especially problematic in animals with coexisting medical diseases (e.g. metabolic or respiratory
conditions) by increasing cortisol levels and respiratory demands.
The most common form seen is incompleteor partial anhidrosis and should be considered
if a decline in performance with an increase inambient temperature during summer months
occurs. A complete history and clinical examination following exercise may be adequate to arrive

at a diagnosis. Clinical signs of partial anhidrosis
include an elevated respiratory rate and increased
rectal temperature that requires an extended periodof time (greater than 30 minutes) to return to thenormal range upon cessation of exercise.
Chronic cases of anhidrosis typically present
with a poor, dry-looking hair coat accompanied bya history of lethargy during the hotter times of theyear. It should be noted that any horse may sufferfrom anhidrosis in the summer months, including
brood mares and retired performance horses withmore sedentary lifestyles. Affected horses will havean elevated respiratory rate at rest and will tend toseek shade if available.
A definitive diagnosis of anhidrosis can be madeby injecting a series of dilutions of terbutaline.
This may be useful in determining severity of thecondition and evaluating response to treatment.
Blood work, including an electrolyte analysis, mayalso be helpful in formulating a treatment plan.
Lastly, a skin biopsy may be performed in severecases to evaluate the histologic structure of thesweat glands, however, this is rarely necessary toconfirm a diagnosis.
There are some treatment options for anhidrosis, and what works on one horse might not workon another. Until the horse with anhidrosis is suc-

2

3

4

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

N AT I O N A LInternet address:
http://www.ca.uky.edu/
gluck/index.htm
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*First Quarter Report from Australia

CONTACT:
Dr. Peter Timoney(859) 218-1094
ptimoney@uky.edu
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky

800
700

Despite the geographic distribution of equine
EEE cases, the rapid interstate and internationaltransportation of horses for show, racing, recreation, sales, breeding, and other activities strongly
supports the use of EEE vaccines. The EEE vaccine is considered by the American Association of
Equine Practitioners to be a “core” vaccine.
Insect control and appropriate use of approved
insecticides are critical to reducing the risks of
EEE as well as West Nile virus infections, vesicularstomatitis, and other insect-borne diseases.
CONTACT:
Dr. Roberta Dwyer(859) 218-1122
rmdwyer@uky.edu
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky

Anhidrosis

600
500
400

A

300
200
100

Year

14
20

13

12

20

20

11
20

10
20

09

08

20

20

07
20

06

05

0

20

Correspondence 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

astern equine encephalomyelitis (EEE) is only
one of several important vector-borne diseases
that is of significant concern to horse owners. Witha mortality rate of 90%, it is a deadly disease. The
U.S. Department of Agriculture Animal and Plant
Health Inspection Service, Veterinary Services
works with the U.S. Centers for Disease Control
and Prevention and public health officials to collect data on EEE and other vector-borne diseases.
Figure 1 shows the geographic location (shaded
states) of equine EEE cases from 2003-2014, although not every state had cases each year. Figure
2 shows reported U.S. equine EEE cases (which
include presumptive positive and confirmed positive cases) from 2003-2014.

Figure 2. Reported U.S. Equine EEE Cases.

20

Diane Furry
Tawana Brown
Dennis Duross

Adapted from www.aphis.usda.gov

04

Staff

E

20

Roberta Dwyer
Alan LoynachanPeter Timoney

virus is abortigenic in the pregnant mare or that
infection can result in congenital abnormalities infoals.
The only other animal species in which Getah
virus has been implicated in causing disease isswine. The virus has been isolated from newborn
piglets that died of peracute disease and also fromdead fetuses removed from a naturally infected sow.
Getah virus is primarily a mosquito-borne
infection that is transmitted by different speciesof Culex and Aedes mosquitoes depending on thegeographic region of the world in which it occurs.
Swine are thought to play a role in amplificationof the virus in endemic areas. The potential fortransmission through direct horse-to-horse contact
cannot be discounted considering some acutely
infected horses shed significant quantities of infectious virus into the respiratory tract.
Diagnosis of Getah virus infection can be readily accomplished by virus detection in nasal swabs,
unclotted blood (buffy coat) samples, and saliva
either by PCR assay or virus isolation. It can also
be confirmed by serological testing of acute andconvalescent serum samples. Because of the close
clinical similarity between Getah virus infectionand equine viral arteritis and African horse sickness, it is important to differentiate it diagnosticallyfrom either of these two diseases.
Prevention and control of Getah virus infection
is based on measures to reduce mosquito contact
with horses and, optimally, vaccination of at-riskequine populations in countries in which the virus
is endemic.
While Getah virus is not considered an important equine pathogen, it can be significantly
disruptive when extensive outbreaks occur.

03

EditorsAn outbreak of illness at a Japanese racing
stable in the latter half of 2014 re-awakened
awareness of Getah virus and its potential as anequine pathogen. The first indication that the virus
could cause illness in horses was the widespreadoccurrence of a disease syndrome among racehorses at two training centers in Japan in 1978.
Subsequently, the virus was implicated in a clinically similar disease outbreak on a Thoroughbred
breeding farm in India during 1990.
Getah virus is a mosquito-borne arbovirusthat is a member of the genus Alphavirus, family
Togaviridae. First isolated from mosquito pools
collected in Sarawak (Malaysia) between 1968
and 1970, Getah or one of its antigenically related
viruses, can be found over a wide geographic range
extending from Eurasia to Australia. Results ofserologic surveys have confirmed infection inhumans and a wide diversity of domestic andwildlife animal species wherever the virus is present. Serologic evidence of Getah virus activity
in horses in Japan can be traced back to 1961.
Subsequent studies have shown that the infection
was widespread in equine populations throughoutthat country. Notwithstanding this fact, however,disease events caused by Getah virus have beenvery infrequent.
Naturally occurring disease caused by Getah
virus has only been reported in horses and in swine.
While the vast majority of primary infections inhorses are asymptomatic, on occasion the virus
can give rise to extensive outbreaks of mild illness
characterized by fever, anorexia, serous nasal discharge, hind limb edema, stiff gait, scrotal edema,
submandibular lymphadenopathy, and urticarial
skin rash. Affected horses may develop some or allof these clinical signs. Regardless of severity, thedisease is non-fatal and complete clinical recovery
occurs within 7 to 14 days. Symptomatic treatment is seldom indicated. Based on the outbreakrecorded in India, there was no evidence that Getah

20

Equine Disease Quarterly

Two cases of equine coital exanthema werediagnosed in the UK.
Germany confirmed equine arteritis virus infection in two stallions on separate premises.
A single case of equine adenoviral respiratory
infection in a foal was reported in the USA.
Outbreaks of equine infectious anemia wererecorded in Canada, France, and the USA. A totalof 16 cases of the disease were diagnosed on ninepremises in four westernmost provinces in Canada.
A single case was identified in France and threecases on different premises in the USA.
France and the UAE reported that equine piroplasmosis was endemic; Switzerland confirmed one
case of the disease.
Contagious equine metritis was diagnosed inthree horses on separate premises in Germany.
The USA reported isolated cases of nocardioform placentitis and abortion in two states and asingle case of mare reproductive loss syndrome in
Kentucky.
Outbreaks of salmonellosis were confirmed in
the USA, some due to Group B Salmonella spp.
and others to Group C1 Salmonella spp. France
reported five outbreaks of rotavirus infection in
foals. Clostridiosis in foals was recorded in theUSA, several associated with C. perfringens Toxin
Type A and others with C. difficile Toxin A/B genestrains.
Nine cases of Eastern equine encephalomyelitis were diagnosed in the USA, the majority in
Florida, four of which had not been vaccinatedagainst the disease. The USA also reported one caseof West Nile encephalitis in a horse in Oklahoma.
Rhodococcal related disease was recorded in
Switzerland (single case) and the USA (numerous
cases in multiple states in which the disease isendemic).
Isolated cases of other diseases were reported:
Tyzzer’s disease (single case in a foal in the USA),
melioidosis (single case in a riding-school horse in
Singapore), cutaneous leishmaniasis (single casein Switzerland), and anaplasmosis (two cases inGermany).

Eastern Equine Encephalomyelitis

Figure 1. States with Equine EEE Cases, 2003-2014.

www.aphis.usda.gov

Figure 3. Abortions submitted to UKVDL, 2011-2015.
Total Abortions

The International Collating Centre, Newmarket, United Kingdom, and other sources
reported the following disease outbreaks.
Vesicular stomatitis reoccurred in the USA inlate April 2015. Infection with the New Jersey
serotype of the virus had spread to 25 premises in
Arizona, Colorado, New Mexico, Texas, and Utah.
A donkey that strayed across the border from
Mexico into Texas, USA was reported as testing
serologically positive for glanders. The animal was
one of a group of five, all of which were clinicallynormal. With the one exception, the remaining
donkeys were seronegative for antibodies to
Burkholderia mallei. The positive donkey, whose
status was downgraded to suspect on re-test, waseuthanized.
Several outbreaks of strangles were reported in
Denmark, France, Germany, Switzerland, United
Arab Emirates (UAE), and the USA.
Equine influenza was reported by Germany(single cases on four premises), the UK (seven outbreaks including some animals recently imported),
and the USA (outbreaks in four states).
Equine herpesvirus-1 and -4 (EHV-1, -4) related diseases were reported in France, Germany,
Ireland, Japan, Switzerland, the UK, and the USA.
Respiratory disease was recorded by France (threeoutbreaks), Germany (two cases), Ireland (threecases), and the USA (several states). Abortiondue to EHV-1 was confirmed by France (threeoutbreaks), Germany (nine cases), Japan (sevencases of abortion and three deaths in neonatal
foals on seven premises), the UK (one case), andthe USA (three cases). EHV-1 neurologic disease
was reported by Germany (two cases) and the USA(outbreaks in seven states, the majority involving
isolated cases of the disease). Respiratory disease
due to EHV-4 was recorded in France (11 outbreaks), Germany (three cases), Switzerland (onecase), and the UK (five outbreaks, one involving
multiple cases). The UK also reported one case of
EHV-4 related abortion.

Getah Virus: Significance as an Equine Pathogen

400

EHV-1 Abortions

Second Quarter 2015*

15

350

*

300
250
Total
EHV-1

10
5
0

2011

2012

2013

2014

2015

Foaling Season* Submissions for 2011 were subsidized, resulting in an inflated
number of cases.

nhidrosis is a common condition that frequently presents during the long, hot days ofsummer and is the inability of the horse to produce
an adequate amount of sweat. The decreased ability to maintain proper body temperature limits
athletic potential, increases risk for heat stroke, andmay compound other disease processes. The causeof anhidrosis is not well defined, but is believedto involve over-stimulation of the horse’s sweat
glands by stress hormones, typically occurring inthe summer months. A horse may only have minor
decreases in sweat production, resulting in subtle
clinical signs, or a total loss of sweat production
and severe signs of hyperthermia. Most commonly
diagnosed in performance horses, it also affects
non-performance horses and seems to be moreprevalent in dark-colored animals. Anhidrosis canbe especially problematic in animals with coexisting medical diseases (e.g. metabolic or respiratory
conditions) by increasing cortisol levels and respiratory demands.
The most common form seen is incompleteor partial anhidrosis and should be considered
if a decline in performance with an increase inambient temperature during summer months
occurs. A complete history and clinical examination following exercise may be adequate to arrive

at a diagnosis. Clinical signs of partial anhidrosis
include an elevated respiratory rate and increased
rectal temperature that requires an extended periodof time (greater than 30 minutes) to return to thenormal range upon cessation of exercise.
Chronic cases of anhidrosis typically present
with a poor, dry-looking hair coat accompanied bya history of lethargy during the hotter times of theyear. It should be noted that any horse may sufferfrom anhidrosis in the summer months, including
brood mares and retired performance horses withmore sedentary lifestyles. Affected horses will havean elevated respiratory rate at rest and will tend toseek shade if available.
A definitive diagnosis of anhidrosis can be madeby injecting a series of dilutions of terbutaline.
This may be useful in determining severity of thecondition and evaluating response to treatment.
Blood work, including an electrolyte analysis, mayalso be helpful in formulating a treatment plan.
Lastly, a skin biopsy may be performed in severecases to evaluate the histologic structure of thesweat glands, however, this is rarely necessary toconfirm a diagnosis.
There are some treatment options for anhidrosis, and what works on one horse might not workon another. Until the horse with anhidrosis is suc-Equine Disease Quarterly Newsletter

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

5

cessfully medicated, it should have limited intense
exercise during the heat of the day and shouldbe accommodated in facilities that minimize an
increase in body temperature by providing shade,
movement of air, misters, or even cold-water hosing. The simplest of treatments is supplementation
with electrolytes based on abnormalities identified
by the blood chemistry combined with environ-mental management. As a last resort for cases that
do not respond to conventional therapies, moving
the horse to a geographically less hot and humid
climate may eventually restore its ability to sweat.

Address Service Requested

CONTACT:
Dr. Joan Gariboldi(859) 333-5303
jcgariboldi@gmail.com
Lexington, Kentucky

OCTOBER 2015
Volume 24, Number 4

C O M M E N TA RY
IN THIS ISSUEKENTUCKY

Commentary

Manifestations of Equine Herpesvirus–1

E

quine herpesvirus-1 (EHV-1) is one of fiveherpesviruses commonly found in horses.
EHV-1 infections manifest in three syndromes:
respiratory, reproductive, and neurologic. Likeother herpesviruses, EHV-1 can establish latent
infections, making it possible for outbreaks of
disease to occur in herds that are considered closed.
While quarantine of new arrivals, segregation ofyoung stock, breeding stock and show stock, andvaccination are important management tools in
the prevention of EHV-1 infections, complete
protection is not possible to achieve. Vaccination
confirms relatively short-term immunity (4-5months) and immunity is not entirely protective,
meaning that even well-vaccinated horses candevelop disease.
The respiratory form of EHV-1 is generally mildand self-limiting. Clinical signs are indistinguishable from other viral causes of respiratory disease,such as equine influenza and EHV-4. Horses
exhibit a fever, cough, serous nasal discharge, andmild lethargy.
Reproductive disease is generally considered tobe the most economically important manifestationof EHV-1. Infection with EHV-1 causes abortionin the last trimester of gestation. Affected foals
are occasionally born alive but are generally very
weak and succumb within days of birth, often withsecondary disease conditions. The virus infects themare through the respiratory tract and then enters
the bloodstream (viremia), traveling to and infecting the fetus. Infection in the mare is generally
inapparent and abortion occurs without any signsof impending parturition. The fetus is aborted
fresh, in contrast to other causes of abortion suchas leptospirosis where the fetus may be significantly
decomposed.
Following any abortion, the mare should be
isolated, fetal tissues should be contained andsubmitted to a diagnostic laboratory, and incontact mares should not be moved nor should
new mares be brought in until a diagnosis has been
rendered. Fetal tissues and uterine fluids should
be considered infectious, and contaminated areas
should be cleaned with detergent and disinfected.
Contaminated bedding should be bagged anddiscarded and not spread on pastures.
In the case of EHV-1 abortions, the fetal tissues
and fluids contain high concentrations of virus;
infected foals and mares also shed virus via therespiratory route. EHV-1 is transmitted via therespiratory route and fomites. However, since it
is an enveloped virus, herpesvirus is readily inactivated by thorough cleaning with detergents followed by disinfectants. Biosecurity and restrictedmovement of horses are important in containing
EHV-1 infections.
Laboratory diagnosis relies on gross and histologic examination in conjunction with laboratory
testing. Gross lesions can include pleural andperitoneal effusion, over-expanded lungs withrib impressions and small white foci scatteredthroughout the liver. However, there are manycases in which lesions are not identified at necropsy.
Histologically, EHV-1 produces necrotizing lesions
in a number of organs, most notably the lung andInternational
Second Quarter2015  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2Getah Virus .  .  .  .  .  .  .  .  .  . 3National
Eastern Equine
Encephalomyelitis .  .  . 4Anhidrosis .  .  .  .  .  .  .  .  .  .  . 4

liver. Characteristic intranuclear inclusion bodies
are frequent. Common ancillary tests for detectionof the virus include fluorescent antibody testing,virus isolation, and polymerase chain reaction
testing.
EHV-1 abortions can occur singly or may
spread rapidly in a susceptible population, leading
to the classic “abortion storm.” With improved
management and readily available vaccines for
EHV-1, the number of cases of EHV-1 abortion
has declined dramatically over the past 30 years,
with the vast majority of cases being single events.
EHV-1 confirmed abortions diagnosed at the
University of Kentucky Veterinary Diagnostic
Laboratory are shown in Figure 3. During thatsame time, EHV-1 neonatal deaths were diagnosed
in 2011 (one), 2012 (two), and 2014 (one).
Respiratory and reproductive manifestations of
EHV-1 are well-documented and have long beenrecognized. While viral latency and the productionof a vaccine that produces long-term immunityand confirms better protection continue to bestudied, these syndromes are well understood.
A manifestation of EHV-1 that is less understood is equine herpesvirus myeloencephalopathy(EHM). EHM is a neurologic disease that mani-

fests with acute onset ataxia or paresis, often accompanied by weakness, urinary incontinence,poor tail and anal tone, and tail elevation, either
singly or in combination. EHM can occur as asporadic case of neurologic disease, but often
manifests as an outbreak within a single populationof horses. Outbreaks are often identified in dense
populations of horses, such as at racetracks, horseshows or show barns, riding stables, etc. Generally,
these horses are well-vaccinated and vaccination
seems to be neither protective nor a risk factor.
While the pathology of EHM is well-understood,
the production and development of disease is not
and is the subject of continued research. Preventionof outbreaks of EHM relies on close observationof the horses, including monitoring of rectal temperatures, swift isolation of affected horses, andoften quarantine of the premises.
A constant presence in the horse world, EHV-1
is well known, but many challenges remain.
CONTACT:
Dr. Laura Kennedy(859) 257-8283
drlaurakennedy@uky.edu
University of Kentucky
Veterinary Diagnostic Laboratory
Lexington, Kentucky

KentuckyEquineHerpesvirus-1  .  .  .  .  .  .  . 5M

ore than 100 land-grant colleges and universities have Extension educators whobring research-based information to agricultural
producers and the public, including horse owners. Over the last decade, the university specialists
and educators involved with both equine scienceand disaster education (preparedness, mitigation,
response and recovery) have made significant collaborative strides in developing and publishing
resource information. These efforts include materials on three different platforms: eXtension (thenational Extension website: http://learn.extension.
org), My Horse University (a collaborative effort
between university equine specialists: www.myhorseuniversity.com), and the Extension Disaster
Education Network (EDEN) (collaboration ofdisaster educators across the United States: www.
eden.lsu.edu).
Webinars on animal disaster preparedness andbiosecurity are available on eXtension and My
Horse University (enter “disaster” in the searchengines), along with a wealth of other equine andlivestock information. The EDEN website is anextensive information hub that has disaster-specificinformation (e.g., drought, hurricanes, tornadoes,
animal disease), as well as resources for communities, families, and children dealing with disasters.
A notable effort has been the EDEN Strengthening Community Agrosecurity Preparedness(S-CAP) program, which is a two-day course thatfacilitates emergency managers and agriculture/
livestock owners to evaluate vulnerabilities withincounties and develop enhanced agrosecurity plansto address local needs. This process almost always
includes establishing response and evacuation
guidelines for equine owners. To date, 48 S-CAP
workshops have been conducted, which represent
24 states, 285 counties, and 23.7 million residents.

Universities and partners are incorporating rural
readiness into disaster readiness curricula, which
includes specific materials focused on equine issues
before, during, and after disasters strike. Beneaththe surface of many of the partnerships you willfind delegates from EDEN developing, publishing,and collaborating on new materials on a regularbasis.
It is imperative that information and resources
for horse managers during disasters is bothresearch-based and refereed by experts and civic
authorities for validity. With the popular natureof horses internationally, valid information that isreadily available is critical when crucial incidents
are impending or ongoing. No equine manager
can afford to be basing response on “popular” or“web-based” practices or materials during a crisis.
In most cases equine managers will have an averageof 30 minutes to 2 hours to prepare for a disaster,although in some cases it can be as little as 15
minutes. During two floods and seven wildfires
in the western United States it took an average of
15 minutes per horse to respond to disaster if the
responders were already equipped and organized.
If not ready, the average was closer to one hour per
horse.
For those reasons equine managers should havea disaster plan, equipment, personnel, evacuationroutes, emergency supplies, first-aid kits, andemergency contact information ready at all times.
The eXtension, My Horse University, and EDEN
resources can help utilize the hard-earned, factual
knowledge developed by professionals to reduce
impacts from disasters. Remember: Having a plancan save human and animal lives.
CONTACT:
Scott Cotton(307) 235-9400
Scotton1@uwyo.edu
University of Wyoming Extension Area Educator
EDEN Agrosecurity Delegate
Casper, WyomingEquine Disease Quarterly Newsletter

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

5

cessfully medicated, it should have limited intense
exercise during the heat of the day and shouldbe accommodated in facilities that minimize an
increase in body temperature by providing shade,
movement of air, misters, or even cold-water hosing. The simplest of treatments is supplementation
with electrolytes based on abnormalities identified
by the blood chemistry combined with environ-mental management. As a last resort for cases that
do not respond to conventional therapies, moving
the horse to a geographically less hot and humid
climate may eventually restore its ability to sweat.

Address Service Requested

CONTACT:
Dr. Joan Gariboldi(859) 333-5303
jcgariboldi@gmail.com
Lexington, Kentucky

OCTOBER 2015
Volume 24, Number 4

C O M M E N TA RY
IN THIS ISSUEKENTUCKY

Commentary

Manifestations of Equine Herpesvirus–1

E

quine herpesvirus-1 (EHV-1) is one of fiveherpesviruses commonly found in horses.
EHV-1 infections manifest in three syndromes:
respiratory, reproductive, and neurologic. Likeother herpesviruses, EHV-1 can establish latent
infections, making it possible for outbreaks of
disease to occur in herds that are considered closed.
While quarantine of new arrivals, segregation ofyoung stock, breeding stock and show stock, andvaccination are important management tools in
the prevention of EHV-1 infections, complete
protection is not possible to achieve. Vaccination
confirms relatively short-term immunity (4-5months) and immunity is not entirely protective,
meaning that even well-vaccinated horses candevelop disease.
The respiratory form of EHV-1 is generally mildand self-limiting. Clinical signs are indistinguishable from other viral causes of respiratory disease,such as equine influenza and EHV-4. Horses
exhibit a fever, cough, serous nasal discharge, andmild lethargy.
Reproductive disease is generally considered tobe the most economically important manifestationof EHV-1. Infection with EHV-1 causes abortionin the last trimester of gestation. Affected foals
are occasionally born alive but are generally very
weak and succumb within days of birth, often withsecondary disease conditions. The virus infects themare through the respiratory tract and then enters
the bloodstream (viremia), traveling to and infecting the fetus. Infection in the mare is generally
inapparent and abortion occurs without any signsof impending parturition. The fetus is aborted
fresh, in contrast to other causes of abortion suchas leptospirosis where the fetus may be significantly
decomposed.
Following any abortion, the mare should be
isolated, fetal tissues should be contained andsubmitted to a diagnostic laboratory, and incontact mares should not be moved nor should
new mares be brought in until a diagnosis has been
rendered. Fetal tissues and uterine fluids should
be considered infectious, and contaminated areas
should be cleaned with detergent and disinfected.
Contaminated bedding should be bagged anddiscarded and not spread on pastures.
In the case of EHV-1 abortions, the fetal tissues
and fluids contain high concentrations of virus;
infected foals and mares also shed virus via therespiratory route. EHV-1 is transmitted via therespiratory route and fomites. However, since it
is an enveloped virus, herpesvirus is readily inactivated by thorough cleaning with detergents followed by disinfectants. Biosecurity and restrictedmovement of horses are important in containing
EHV-1 infections.
Laboratory diagnosis relies on gross and histologic examination in conjunction with laboratory
testing. Gross lesions can include pleural andperitoneal effusion, over-expanded lungs withrib impressions and small white foci scatteredthroughout the liver. However, there are manycases in which lesions are not identified at necropsy.
Histologically, EHV-1 produces necrotizing lesions
in a number of organs, most notably the lung andInternational
Second Quarter2015  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2Getah Virus .  .  .  .  .  .  .  .  .  . 3National
Eastern Equine
Encephalomyelitis .  .  . 4Anhidrosis .  .  .  .  .  .  .  .  .  .  . 4

liver. Characteristic intranuclear inclusion bodies
are frequent. Common ancillary tests for detectionof the virus include fluorescent antibody testing,virus isolation, and polymerase chain reaction
testing.
EHV-1 abortions can occur singly or may
spread rapidly in a susceptible population, leading
to the classic “abortion storm.” With improved
management and readily available vaccines for
EHV-1, the number of cases of EHV-1 abortion
has declined dramatically over the past 30 years,
with the vast majority of cases being single events.
EHV-1 confirmed abortions diagnosed at the
University of Kentucky Veterinary Diagnostic
Laboratory are shown in Figure 3. During thatsame time, EHV-1 neonatal deaths were diagnosed
in 2011 (one), 2012 (two), and 2014 (one).
Respiratory and reproductive manifestations of
EHV-1 are well-documented and have long beenrecognized. While viral latency and the productionof a vaccine that produces long-term immunityand confirms better protection continue to bestudied, these syndromes are well understood.
A manifestation of EHV-1 that is less understood is equine herpesvirus myeloencephalopathy(EHM). EHM is a neurologic disease that mani-

fests with acute onset ataxia or paresis, often accompanied by weakness, urinary incontinence,poor tail and anal tone, and tail elevation, either
singly or in combination. EHM can occur as asporadic case of neurologic disease, but often
manifests as an outbreak within a single populationof horses. Outbreaks are often identified in dense
populations of horses, such as at racetracks, horseshows or show barns, riding stables, etc. Generally,
these horses are well-vaccinated and vaccination
seems to be neither protective nor a risk factor.
While the pathology of EHM is well-understood,
the production and development of disease is not
and is the subject of continued research. Preventionof outbreaks of EHM relies on close observationof the horses, including monitoring of rectal temperatures, swift isolation of affected horses, andoften quarantine of the premises.
A constant presence in the horse world, EHV-1
is well known, but many challenges remain.
CONTACT:
Dr. Laura Kennedy(859) 257-8283
drlaurakennedy@uky.edu
University of Kentucky
Veterinary Diagnostic Laboratory
Lexington, Kentucky

KentuckyEquineHerpesvirus-1  .  .  .  .  .  .  . 5M

ore than 100 land-grant colleges and universities have Extension educators whobring research-based information to agricultural
producers and the public, including horse owners. Over the last decade, the university specialists
and educators involved with both equine scienceand disaster education (preparedness, mitigation,
response and recovery) have made significant collaborative strides in developing and publishing
resource information. These efforts include materials on three different platforms: eXtension (thenational Extension website: http://learn.extension.
org), My Horse University (a collaborative effort
between university equine specialists: www.myhorseuniversity.com), and the Extension Disaster
Education Network (EDEN) (collaboration ofdisaster educators across the United States: www.
eden.lsu.edu).
Webinars on animal disaster preparedness andbiosecurity are available on eXtension and My
Horse University (enter “disaster” in the searchengines), along with a wealth of other equine andlivestock information. The EDEN website is anextensive information hub that has disaster-specificinformation (e.g., drought, hurricanes, tornadoes,
animal disease), as well as resources for communities, families, and children dealing with disasters.
A notable effort has been the EDEN Strengthening Community Agrosecurity Preparedness(S-CAP) program, which is a two-day course thatfacilitates emergency managers and agriculture/
livestock owners to evaluate vulnerabilities withincounties and develop enhanced agrosecurity plansto address local needs. This process almost always
includes establishing response and evacuation
guidelines for equine owners. To date, 48 S-CAP
workshops have been conducted, which represent
24 states, 285 counties, and 23.7 million residents.

Universities and partners are incorporating rural
readiness into disaster readiness curricula, which
includes specific materials focused on equine issues
before, during, and after disasters strike. Beneaththe surface of many of the partnerships you willfind delegates from EDEN developing, publishing,and collaborating on new materials on a regularbasis.
It is imperative that information and resources
for horse managers during disasters is bothresearch-based and refereed by experts and civic
authorities for validity. With the popular natureof horses internationally, valid information that isreadily available is critical when crucial incidents
are impending or ongoing. No equine manager
can afford to be basing response on “popular” or“web-based” practices or materials during a crisis.
In most cases equine managers will have an averageof 30 minutes to 2 hours to prepare for a disaster,although in some cases it can be as little as 15
minutes. During two floods and seven wildfires
in the western United States it took an average of
15 minutes per horse to respond to disaster if the
responders were already equipped and organized.
If not ready, the average was closer to one hour per
horse.
For those reasons equine managers should havea disaster plan, equipment, personnel, evacuationroutes, emergency supplies, first-aid kits, andemergency contact information ready at all times.
The eXtension, My Horse University, and EDEN
resources can help utilize the hard-earned, factual
knowledge developed by professionals to reduce
impacts from disasters. Remember: Having a plancan save human and animal lives.
CONTACT:
Scott Cotton(307) 235-9400
Scotton1@uwyo.edu
University of Wyoming Extension Area Educator
EDEN Agrosecurity Delegate
Casper, Wyoming