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

Therapeutic ShoeingA

pplying shoes to the feet of horses has been acommon practice for over 1,000 years, while
the first horseshoes may have been used as much as
2,500 years ago. Generally, the feet of domesticatedhorses are trimmed to balance and reduce excessive
hoof length, and, in many cases, horseshoes areapplied as an aid for traction, protection, and to
reduce wear of the hoof wall. Therapeutic horseshoeing, therapeutic farriery, corrective shoeing,
and podiatry are some of the terms that have beenused to describe the care of a horse’s hoof to address abnormal conditions beyond this common
practice. Since many farriers use various shoes,pads, and application methods, therapeutic shoeing is practiced by most farriers at various levels.
It could also be argued that basic horse shoeing istherapeutic in nature.
There are various certifications and endorsements that farriers can acquire from a handful of
farrier organizations, indicating specialty or ability.
These involve additional training, apprenticeships,
case studies, and testing. Additionally, there areveterinarians who are trained farriers with experience and specialty achieved beyond the scope ofwhat is provided in vet school. Depending on client base, geography, experience, and preference,veterinarians and farriers often specialize in certain
disciplines or breeds.
As much as 80% of equine forelimb lamenessis due to problems involving the feet. Some of theusual conditions where therapeutic horseshoeing
is utilized include laminitis and founder, naviculardisease, hoof cracks and defects, coffin bone injuries or disease, infections such as canker, white linedisease and abscesses. Soft tissue injuries involving
tendons and ligaments as well as diseases involving
bone and joints can also be addressed with modulation of the foot even though these injuries may belocated further up the leg. For example, shoeing
applications to reduce strain on a suspensory ligament can greatly improve healing and comfort forsuspensory desmitis. Conformational abnormalities may be accommodated with proper attention.
Each breed and discipline also has a set of nuancesand problems specific to the group. The farrier ispart of a team which also includes the horse, owner,trainer, grooms, and veterinarian. This team approach is never more evident than when a horse
has an injury or disease. Occasionally, multiple
farriers or veterinarians will work together on acase via referral or consultation. It is important
to note that an accurate diagnosis is essential for
successful treatment.
Shoeing has evolved from the use of standard
steel “keg” horseshoes. Manufacturing technology has brought a multitude of therapeutic shoes
to market. A farrier can also modify pre-made orbuild shoes from scratch to custom fit each footand need. In addition to steel and aluminum;
plastics, fabrics, composites, epoxy and acrylic
adhesives, and even wood is often utilized. Pads
and impression support materials have evolved,
offering different application methods, hardness,and even incorporated medications tailored to
the needs at hand. Although craftsmanship andskill in building a foot appliance is important, theknowledge of how therapy will affect the horse(positive or negative) in every aspect is imperative.
An example is how a wide-webbed shoe with a pad
and rolled toe and branches might benefit a horsewith navicular pain but will reduce traction andseal a sole from air causing other concerns that
may result in different problems.
Therapeutic goals may include protection ofinternal or external injuries and wounds, stabilization of the hoof capsule, orthotic support, modification of static and dynamic biomechanics of the
foot-ground interface, and protection or supportof structures above the hoof. To properly address
the needs of the condition and the horse, one musthave an intimate understanding of the anatomic,
physiologic and biomechanical relationships of thefoot and leg. There should be an understanding of
the disease process at hand. One application for acertain problem may be detrimental for another.
This is the main reason that a farrier and veterinarian are most efficient when they have a goodworking relationship.
CONTACT:
Josh Zacharias, DVM, MS, DACVS, DACVSMR
zachariasdvm@gmail.com
Countryside Large Animal Veterinary Service
Greeley, Colorado

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

JULY 2020
Volume 29, Number 3

C O M M E N TA RY
IN THIS ISSUECOMMENTARY: continued from the front page

be employed at racetracks, equine sporting events,
sales, etc. The economic fallout from this pandemic
also has affected people who buy horses or wager
at racetracks.
Horse breeding has been allowed to take placesubject to stringent precautionary measures toprevent further spread of SARS-CoV-2. This ispredicated on maintaining an enhanced level ofbiosecurity in all aspects of breeding shed activity and in following approved standard practices
including social distancing by personnel. While
much attention has been focused on centers ofhorse racing and breeding across the country, thefinancial repercussions of COVID-19 have also
been acutely felt by owners of smaller horse farms/

businesses, etc., whose livelihoods are dependent
on the sustainability of the equine industry.
It is way too soon to predict what the overall
impact of the pandemic will have on the nation’s
equine industry in all its aspects from racing,equestrian events, horse shows, breeding, sales,
and a variety of ancillary businesses. What iscertain, however, is that the horse industry willsurvive and, given time, thrive again and regain its
former prominence and importance to the nation’s
economy.
CONTACT:
Peter J. Timoney, MVB, MS, PhD, FRCVS
ptimoney@uky.edu(859) 218-1094
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, KentuckyS

ince discovery of the novel coronavirus (SARSCoV-2), causal agent of the highly contagious
Commentaryand frequently life-threatening disease of humans
designated COVID-19 in December 2019, theInternational
virus has spread very rapidly around the globe. The
First Quarter2020  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2 exponential increase of cases in affected countries
and the alarming case-fatality rate has resulted
Acute Respiratory
Distress .  .  .  .  .  .  .  .  .  .  .  .  .  . 3 in a pandemic of unprecedented proportions, interms of its health and economic impact on humanpopulations worldwide.
National
Of the seven coronaviruses known to infect
Vesicular
Stomatitis .  .  .  .  .  .  .  .  .  .  . 4 humans, three are of major public health significance: severe acute respiratory syndrome (SARS),
Therapeutic
Shoeing .  .  .  .  .  .  .  .  .  .  .  .  . 5 Middle East respiratory syndrome (MERS), andcoronavirus 2019 (COVID-19). Other membersof the coronavirus family can cause respiratory or
intestinal disease in a range of domestic species, including horses, swine, cattle, cats, dogs and chickens. SARS-CoV-2 is genetically and otherwise
uniquely distinct from these other coronaviruses,
none of which are known to be human pathogens.
There are many aspects of the biology of SARSCoV-2, including its host range, epidemiology,
pathogenesis, and nature of the immune responseto the virus, that remain to be fully elucidated.
The pandemic of COVID-19 has had significant implications for the U.S. horse industry. A
point of continuing concern for many in theindustry is whether SARS-CoV-2 is capable ofCollege of Agriculture, infecting and perhaps causing disease in horses.
Food and Environment At the present time, there is no evidence conDepartment of
firming the susceptibility of horses to infection.
Veterinary Science
This is supported by the outcome of a recent
study undertaken to determine conservation of
the angiotensin-converting enzyme 2 (ACE2)
across 410 vertebrates including 252 mammalian
species, and the likelihood of it functioning as a
Lloyd’s—An international
insurance market for
SARS-CoV-2 cell receptor. The horse was ranked
bloodstock and otherlow risk in predicted susceptibility to infection
specialist insurance.

NIAID-RML

5

The novel coronovirus that causes COVID-19.

based on the binding characteristics of its ACE2
compared to the human homologue. In the current absence of any information to the contrary,
it is not possible to speculate on the potential riskof horse-to-horse transmission of the virus andwhether horses might play a role in transmitting
the virus back to humans.
Aside from the primary consideration of its
potential to affect the health of the horse, COVID-19 has had a major impact on the economyof the horse industry in Kentucky and the USA.
Virtually all sectors of the industry have been
negatively influenced by the current pandemic.
Racing, equestrian events, and horse shows havebeen cancelled or postponed to a later date. Horsesales and other ancillary businesses have been similarly affected. This has inevitably resulted in layoffs
or furloughing of workers who would otherwise
continued on the back page

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

N AT I O N A L

First Quarter 2020

T

Equine Disease Quarterly
Editors

Peter Timoney
Alan Loynachan
Rebecca Ruby

Staff

Diane Furry
Tawana Brown
Dennis Duross

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
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.
The Republic of South Africa (RSA) confirmed
the occurrence of African horse sickness at expectedlevels within endemic areas of eight of the nine
provinces. The highest number of cases were recorded in Gauteng Province; none were confirmed
in Western Cape Province.
African horse sickness was also reported forthe first time in Thailand. Three outbreaks wereconfirmed, involving 78 cases with 57 fatalities.
An outbreak of Venezuelan equine encephalomyelitis was confirmed by Belize. Four of fiveunvaccinated horses died from the disease.
France, the Netherlands, and the USA recorded
outbreaks of equine influenza. The number ofoutbreaks included four in France (one to 20
cases per outbreak), two in the Netherlands (three
to five cases per outbreak), and nine in the USA,
where the disease is endemic. The number of cases
per outbreak varied from three to 30, with many
unvaccinated against the disease.
Strangles is considered endemic in most countries with reports from Belgium (two outbreaks),
France (20 outbreaks), the Netherlands (24 outbreaks), Switzerland (four outbreaks), and the USA(16 outbreaks in 11 states).
Equine herpesvirus 1 (EHV-1) related diseases
were recorded by Belgium, France, Canada, theNetherlands, Switzerland, the UK, and the USA.
Respiratory disease outbreaks were confirmed in
Belgium (two), France (three), the Netherlands(one), and the USA (six). Abortion due to EHV1 was reported by Belgium (four outbreaks, one
involving six cases), Canada (one outbreak), theNetherlands (five outbreaks), the UK (four outbreaks), and the USA (eight outbreaks of abortion/
neonatal disease, one involving four cases). EHV1 neurologic disease was confirmed by Canada(one case), the Netherlands (two outbreaks, one
involving two cases and the second, seven cases),
Switzerland (single case), the UK (three outbreaks,
one involving nine cases), and the USA (seven outbreaks, with two each in California and Virginia).

Numerous countries recorded outbreaks ofequine herpesvirus 4 respiratory disease. These
included Argentina (one outbreak in five to sevenmonth old foals), Belgium (one outbreak), France(18 outbreaks, mostly single cases), the Netherlands (two outbreaks), Spain (one case), Switzerland (two outbreaks, one involving co-infection
with EHV-1), and the UK (five outbreaks, twolinked to new arrivals).
France reported finding the carrier state in threestallions infected with equine arteritis virus.
Equine infectious anemia was confirmed in
Canada (a case of subclinical infection) and theUSA (three outbreaks, with single cases in California and Texas and three cases in Iowa).
The RSA was the only country to report thepresence of equine piroplasmosis. Isolated cases
were diagnosed throughout the country.
Two outbreaks of leptospiral abortion wererecorded by Belgium, both involving single casesof the disease.
The USA reported a significant number of casesof nocardioform placentitis/abortion. Of 256 cases
confirmed, 147 represented cases of placentitis
and 109 where the placentitis was accompanied
by submission of a fetus or neonate. Amycolatopsis
was implicated in 98 cases and Crossiella equi in
65 cases.
A fatal case of Tyzzer’s disease (Clostridium
piliforme) infection was confirmed in a foal in
Kentucky, USA.
The USA reported a non-fatal case of equine
coronavirus infection in a gelding in Arizona.
Rotavirus infection in foals was diagnosed by
France (two outbreaks), Spain (one case), and theUSA (one case).
The USA reported 10 cases of Lawsonia enteropathy due to Lawsonia intracellularis infection in
the first quarter of 2020. It also confirmed detection of Clostridium perfringens in 24 foals originating in Kentucky and Indiana, and Clostridium
difficile in 16 foals in Kentucky; these included two
toxin Type A strains and two toxin Type B strains.
The RSA recorded cases of equine encephalosis
in seven of the country’s nine provinces, with over
100 cases diagnosed in Gauteng Province.

Equine Acute Respiratory Distress SyndromeA

cute respiratory distress syndrome (ARDS)
causes rapidly progressive and severe respiratory failure and is associated with high mortality
in affected patients. First described in critically ill
humans more than 50 years ago, ARDS is now
recognized as a rare cause of respiratory failure inseveral veterinary species including horses, where
it is referred to as veterinary ARDS (VetARDS).
ARDS and VetARDS develop as a complication when a primary disease or injury triggers
overwhelming and uncontrolled inflammationin the lung. This inflammatory response causes
the hallmark features of ARDS: severe pulmonary
damage and edema, respiratory dysfunction, andprofound hypoxemia (low oxygen in the blood).
Pneumonia and conditions associated with severe
systemic inflammation, such as sepsis, represent themost common risk factors for ARDS and VetARDS.
Other potential risk factors include smoke inhalation, severe trauma, aspiration of stomach contents,
and near drowning.
In horses, VetARDS is a rare, but distinct, clinical condition in foals younger than nine monthsof age. Previously, this condition was referred to asacute interstitial or bronchointerstitial pneumonia.
Bacterial pneumonia is the most common predisposing cause of VetARDS in these foals. There
does not appear to be a single bacterial pathogen
associated with VetARDS in foals but Rhodococcus
equi, Klebsiella sp. and Streptococcus sp. have all
been identified with VetARDS. Sepsis represents
the most likely risk factor in neonatal foals andconditions consistent with VetARDS have beenreported in adult horses after smoke inhalation ornear drowning.
A definitive diagnosis of VetARDS can bechallenging, and distinguishing VetARDS fromsevere bacterial pneumonia may not be possible.
The specific criteria established for the diagnosis
of ARDS in veterinary species include recent
onset of clinical signs (< 72 hours), exposure to a
known risk factor, radiographic changes consistent
with widespread pulmonary damage and edema,
evidence of severe hypoxemia on blood analysis,
and if possible, inflammatory changes identified
on respiratory fluid analysis. These diagnostic
criteria apply to all veterinary species with minor

modifications existing only for neonatal foals lessthan one week of age. Specific postmortem diagnostic criteria also exist for animals that succumb
to VetARDS.
Foals with VetARDS present with a sudden
onset of severe and rapidly progressive respiratory distress that may follow a recent historyof pneumonia. Other nonspecific findings on
physical examination can include fever, abnormallung sounds, increased heart rate, and depression.
Radiographic or ultrasound examination of thelungs is recommended. Blood laboratory analysis
is useful to detect and monitor hypoxemia. Other
laboratory findings vary but are typically consistent
with inflammation or other disease process. Additional diagnostics should focus on identifying
any underlying primary disease.
Regardless of age, the goals of treatment forhorses with VetARDS include addressing any
underlying primary disease, controlling inflammation, improving oxygenation, and providing
supportive care. These cases require prompt andintense management. In humans with ARDS,
lung-protective mechanical ventilation is the
only therapy that has resulted in reduced mortality. Unfortunately, this is not feasible for the vast
majority of horses with this condition. Intranasal
oxygen supplementation, administration of antiinflammatory medications (e.g. corticosteroids)
and antibiotics, and appropriate nutritional andintravenous fluid support represent the mainstayof therapy for most horses with VetARDS.
The prognosis for recovery from VetARDS is
guarded. Survival rates of 60% have been reported
in older foals but are often lower in neonatal foals.
With appropriate treatment, survivors typicallystabilize or improve within a few days. Whilethe impact of this condition on future athletic
performance is unknown at this time, limited
reports suggest that recovered foals can go on tohave successful athletic careers.
CONTACT:
Kara Lascola, DVM, MS, DACVIM
Kml0068@auburn.edu(334) 844-4490
College of Veterinary Medicine,
Department of Clinical Sciences
Auburn University
Auburn, Alabama

Mitigation Strategies to Prevent
Vesicular Stomatitis Virus Transmission to Equids

V

Muzzle lesion in VS affected equid.

DR. PIPER NORTON

esicular stomatitis (VS) is a viral disease ofhorses and other livestock caused by vesicularstomatitis virus (VSV), which is endemic in southern Mexico and only occasionally moves northward into the United States. The clinical disease
is characterized by vesicular (blister-like) lesions
on the muzzle, lips, tongue, ears, udder, sheath,or coronary bands. While the lesions usually healon their own, some horses require supportive care.
A 2019 outbreak of VSV was the largest in recent
history with 1,144 premises affected in eight states(Colorado, Kansas, Nebraska, New Mexico, Oklahoma, Texas, Utah, and Wyoming). VS returned
this year on April 13, 2020, with equine premisesin Arizona, New Mexico, and Texas affected. Expansion of the disease to other states is expected
this summer. Taking steps now to prevent VSVtransmission on equine premises is imperative tolimit the spread.
VSV is spread two ways; natural transmission
by insect vectors or direct contact with infectedanimals. Mitigation strategies targeting insect vectors and implementation of biosecurity to prevent
contact with infected animals and contaminatedfomites (shared water troughs, feed buckets, tack,or equipment) are thought to be the best methodsof disease prevention. Known competent insect
vectors include black flies (Simulium spp.), sandflies (Lutzomyia spp,), and biting midges (Culicoides spp.), but other insects may also transmit thedisease.
These insect vectors emerge in specific habitats,which helps target implementation of mitigation
strategies. Sand flies prefer dry areas, such as treeholes, rock crevices, and animal burrows. Biting
midges prefer wet areas, such as wet leaves andmud around ponds or troughs. Black flies preferflowing water, such as irrigation ditches, rivers, or
streams. Adult flies move outward from these areas.
Some can only fly short distances (sand flies), butothers fly longer distances (black flies) or travel onwind currents (black flies, midges). Seasonality ofthe vectors coincides with warmer months, springthrough fall, but midges can be more cold-hearty
and occasionally transmit VSV in winter. Preferred
feeding/biting times vary, with sand flies being

night feeders, biting midges feeding around sunrise
and sunset, and black flies feeding during the day.
Vector mitigation strategies should be considered at the neighborhood, premises, barn, andanimal level. At the neighborhood level, keep
animals away from insect emerging sites suchas moving water and standing water during theinsect seasons. Alternatively, time the rotation ofanimals through pastures to avoid grazing near astream returning to base flow after reaching peakrunoff, a time of black fly emergence. If possible,
move animals to higher-elevation pastures during
the vector season. At the premises level, removing
manure regularly, maintaining sloped and welldrained footing around water sources, and keeping
surrounding vegetation mowed will also reduce
insect vectors.
At the barn level, move animals indoors duringvector feeding times or provide access to a run-in
shed for pastured horses. Installing mesh nettingor repellent-treated fabrics on barn openings canfurther prevent vector entry. Minimizing the useof bright lights at night and adding fans blowing
down onto horses can also be preventive. At the
animal level, topical insecticides and repellents
reduce exposure to biting insects, but repeatedapplication is necessary and must be combinedwith insect mitigation at the other levels to beeffective. Using fly sheets, masks, leg wraps, andear covers with or without repellent fabric are also
animal-level mitigations, but these must cover theareas where VSV lesions occur. Therefore, chemical
repellents may need to be used in conjunction withfly sheets and masks to protect the muzzle and lips.
Mitigation strategies and biosecurity measuresat multiple levels are needed to provide adequate
protection from VSV. For more information access“Management Strategies for Reducing the Risk of
Equines Contracting Vesicular Stomatitis Virus in
the Western United States” at the following link:
https://doi.org/10.1016/j.jevs.2020.103026
CONTACT:
Angela Pelzel-McCluskey, DVM, MS, Equine Epidemiologist
Angela.M.Pelzel-McCluskey@aphis.usda.gov(970) 494-7391
USDA-APHIS-Veterinary Services
Fort Collins, Colorado

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

N AT I O N A L

First Quarter 2020

T

Equine Disease Quarterly
Editors

Peter Timoney
Alan Loynachan
Rebecca Ruby

Staff

Diane Furry
Tawana Brown
Dennis Duross

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
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.
The Republic of South Africa (RSA) confirmed
the occurrence of African horse sickness at expectedlevels within endemic areas of eight of the nine
provinces. The highest number of cases were recorded in Gauteng Province; none were confirmed
in Western Cape Province.
African horse sickness was also reported forthe first time in Thailand. Three outbreaks wereconfirmed, involving 78 cases with 57 fatalities.
An outbreak of Venezuelan equine encephalomyelitis was confirmed by Belize. Four of fiveunvaccinated horses died from the disease.
France, the Netherlands, and the USA recorded
outbreaks of equine influenza. The number ofoutbreaks included four in France (one to 20
cases per outbreak), two in the Netherlands (three
to five cases per outbreak), and nine in the USA,
where the disease is endemic. The number of cases
per outbreak varied from three to 30, with many
unvaccinated against the disease.
Strangles is considered endemic in most countries with reports from Belgium (two outbreaks),
France (20 outbreaks), the Netherlands (24 outbreaks), Switzerland (four outbreaks), and the USA(16 outbreaks in 11 states).
Equine herpesvirus 1 (EHV-1) related diseases
were recorded by Belgium, France, Canada, theNetherlands, Switzerland, the UK, and the USA.
Respiratory disease outbreaks were confirmed in
Belgium (two), France (three), the Netherlands(one), and the USA (six). Abortion due to EHV1 was reported by Belgium (four outbreaks, one
involving six cases), Canada (one outbreak), theNetherlands (five outbreaks), the UK (four outbreaks), and the USA (eight outbreaks of abortion/
neonatal disease, one involving four cases). EHV1 neurologic disease was confirmed by Canada(one case), the Netherlands (two outbreaks, one
involving two cases and the second, seven cases),
Switzerland (single case), the UK (three outbreaks,
one involving nine cases), and the USA (seven outbreaks, with two each in California and Virginia).

Numerous countries recorded outbreaks ofequine herpesvirus 4 respiratory disease. These
included Argentina (one outbreak in five to sevenmonth old foals), Belgium (one outbreak), France(18 outbreaks, mostly single cases), the Netherlands (two outbreaks), Spain (one case), Switzerland (two outbreaks, one involving co-infection
with EHV-1), and the UK (five outbreaks, twolinked to new arrivals).
France reported finding the carrier state in threestallions infected with equine arteritis virus.
Equine infectious anemia was confirmed in
Canada (a case of subclinical infection) and theUSA (three outbreaks, with single cases in California and Texas and three cases in Iowa).
The RSA was the only country to report thepresence of equine piroplasmosis. Isolated cases
were diagnosed throughout the country.
Two outbreaks of leptospiral abortion wererecorded by Belgium, both involving single casesof the disease.
The USA reported a significant number of casesof nocardioform placentitis/abortion. Of 256 cases
confirmed, 147 represented cases of placentitis
and 109 where the placentitis was accompanied
by submission of a fetus or neonate. Amycolatopsis
was implicated in 98 cases and Crossiella equi in
65 cases.
A fatal case of Tyzzer’s disease (Clostridium
piliforme) infection was confirmed in a foal in
Kentucky, USA.
The USA reported a non-fatal case of equine
coronavirus infection in a gelding in Arizona.
Rotavirus infection in foals was diagnosed by
France (two outbreaks), Spain (one case), and theUSA (one case).
The USA reported 10 cases of Lawsonia enteropathy due to Lawsonia intracellularis infection in
the first quarter of 2020. It also confirmed detection of Clostridium perfringens in 24 foals originating in Kentucky and Indiana, and Clostridium
difficile in 16 foals in Kentucky; these included two
toxin Type A strains and two toxin Type B strains.
The RSA recorded cases of equine encephalosis
in seven of the country’s nine provinces, with over
100 cases diagnosed in Gauteng Province.

Equine Acute Respiratory Distress SyndromeA

cute respiratory distress syndrome (ARDS)
causes rapidly progressive and severe respiratory failure and is associated with high mortality
in affected patients. First described in critically ill
humans more than 50 years ago, ARDS is now
recognized as a rare cause of respiratory failure inseveral veterinary species including horses, where
it is referred to as veterinary ARDS (VetARDS).
ARDS and VetARDS develop as a complication when a primary disease or injury triggers
overwhelming and uncontrolled inflammationin the lung. This inflammatory response causes
the hallmark features of ARDS: severe pulmonary
damage and edema, respiratory dysfunction, andprofound hypoxemia (low oxygen in the blood).
Pneumonia and conditions associated with severe
systemic inflammation, such as sepsis, represent themost common risk factors for ARDS and VetARDS.
Other potential risk factors include smoke inhalation, severe trauma, aspiration of stomach contents,
and near drowning.
In horses, VetARDS is a rare, but distinct, clinical condition in foals younger than nine monthsof age. Previously, this condition was referred to asacute interstitial or bronchointerstitial pneumonia.
Bacterial pneumonia is the most common predisposing cause of VetARDS in these foals. There
does not appear to be a single bacterial pathogen
associated with VetARDS in foals but Rhodococcus
equi, Klebsiella sp. and Streptococcus sp. have all
been identified with VetARDS. Sepsis represents
the most likely risk factor in neonatal foals andconditions consistent with VetARDS have beenreported in adult horses after smoke inhalation ornear drowning.
A definitive diagnosis of VetARDS can bechallenging, and distinguishing VetARDS fromsevere bacterial pneumonia may not be possible.
The specific criteria established for the diagnosis
of ARDS in veterinary species include recent
onset of clinical signs (< 72 hours), exposure to a
known risk factor, radiographic changes consistent
with widespread pulmonary damage and edema,
evidence of severe hypoxemia on blood analysis,
and if possible, inflammatory changes identified
on respiratory fluid analysis. These diagnostic
criteria apply to all veterinary species with minor

modifications existing only for neonatal foals lessthan one week of age. Specific postmortem diagnostic criteria also exist for animals that succumb
to VetARDS.
Foals with VetARDS present with a sudden
onset of severe and rapidly progressive respiratory distress that may follow a recent historyof pneumonia. Other nonspecific findings on
physical examination can include fever, abnormallung sounds, increased heart rate, and depression.
Radiographic or ultrasound examination of thelungs is recommended. Blood laboratory analysis
is useful to detect and monitor hypoxemia. Other
laboratory findings vary but are typically consistent
with inflammation or other disease process. Additional diagnostics should focus on identifying
any underlying primary disease.
Regardless of age, the goals of treatment forhorses with VetARDS include addressing any
underlying primary disease, controlling inflammation, improving oxygenation, and providing
supportive care. These cases require prompt andintense management. In humans with ARDS,
lung-protective mechanical ventilation is the
only therapy that has resulted in reduced mortality. Unfortunately, this is not feasible for the vast
majority of horses with this condition. Intranasal
oxygen supplementation, administration of antiinflammatory medications (e.g. corticosteroids)
and antibiotics, and appropriate nutritional andintravenous fluid support represent the mainstayof therapy for most horses with VetARDS.
The prognosis for recovery from VetARDS is
guarded. Survival rates of 60% have been reported
in older foals but are often lower in neonatal foals.
With appropriate treatment, survivors typicallystabilize or improve within a few days. Whilethe impact of this condition on future athletic
performance is unknown at this time, limited
reports suggest that recovered foals can go on tohave successful athletic careers.
CONTACT:
Kara Lascola, DVM, MS, DACVIM
Kml0068@auburn.edu(334) 844-4490
College of Veterinary Medicine,
Department of Clinical Sciences
Auburn University
Auburn, Alabama

Mitigation Strategies to Prevent
Vesicular Stomatitis Virus Transmission to Equids

V

Muzzle lesion in VS affected equid.

DR. PIPER NORTON

esicular stomatitis (VS) is a viral disease ofhorses and other livestock caused by vesicularstomatitis virus (VSV), which is endemic in southern Mexico and only occasionally moves northward into the United States. The clinical disease
is characterized by vesicular (blister-like) lesions
on the muzzle, lips, tongue, ears, udder, sheath,or coronary bands. While the lesions usually healon their own, some horses require supportive care.
A 2019 outbreak of VSV was the largest in recent
history with 1,144 premises affected in eight states(Colorado, Kansas, Nebraska, New Mexico, Oklahoma, Texas, Utah, and Wyoming). VS returned
this year on April 13, 2020, with equine premisesin Arizona, New Mexico, and Texas affected. Expansion of the disease to other states is expected
this summer. Taking steps now to prevent VSVtransmission on equine premises is imperative tolimit the spread.
VSV is spread two ways; natural transmission
by insect vectors or direct contact with infectedanimals. Mitigation strategies targeting insect vectors and implementation of biosecurity to prevent
contact with infected animals and contaminatedfomites (shared water troughs, feed buckets, tack,or equipment) are thought to be the best methodsof disease prevention. Known competent insect
vectors include black flies (Simulium spp.), sandflies (Lutzomyia spp,), and biting midges (Culicoides spp.), but other insects may also transmit thedisease.
These insect vectors emerge in specific habitats,which helps target implementation of mitigation
strategies. Sand flies prefer dry areas, such as treeholes, rock crevices, and animal burrows. Biting
midges prefer wet areas, such as wet leaves andmud around ponds or troughs. Black flies preferflowing water, such as irrigation ditches, rivers, or
streams. Adult flies move outward from these areas.
Some can only fly short distances (sand flies), butothers fly longer distances (black flies) or travel onwind currents (black flies, midges). Seasonality ofthe vectors coincides with warmer months, springthrough fall, but midges can be more cold-hearty
and occasionally transmit VSV in winter. Preferred
feeding/biting times vary, with sand flies being

night feeders, biting midges feeding around sunrise
and sunset, and black flies feeding during the day.
Vector mitigation strategies should be considered at the neighborhood, premises, barn, andanimal level. At the neighborhood level, keep
animals away from insect emerging sites suchas moving water and standing water during theinsect seasons. Alternatively, time the rotation ofanimals through pastures to avoid grazing near astream returning to base flow after reaching peakrunoff, a time of black fly emergence. If possible,
move animals to higher-elevation pastures during
the vector season. At the premises level, removing
manure regularly, maintaining sloped and welldrained footing around water sources, and keeping
surrounding vegetation mowed will also reduce
insect vectors.
At the barn level, move animals indoors duringvector feeding times or provide access to a run-in
shed for pastured horses. Installing mesh nettingor repellent-treated fabrics on barn openings canfurther prevent vector entry. Minimizing the useof bright lights at night and adding fans blowing
down onto horses can also be preventive. At the
animal level, topical insecticides and repellents
reduce exposure to biting insects, but repeatedapplication is necessary and must be combinedwith insect mitigation at the other levels to beeffective. Using fly sheets, masks, leg wraps, andear covers with or without repellent fabric are also
animal-level mitigations, but these must cover theareas where VSV lesions occur. Therefore, chemical
repellents may need to be used in conjunction withfly sheets and masks to protect the muzzle and lips.
Mitigation strategies and biosecurity measuresat multiple levels are needed to provide adequate
protection from VSV. For more information access“Management Strategies for Reducing the Risk of
Equines Contracting Vesicular Stomatitis Virus in
the Western United States” at the following link:
https://doi.org/10.1016/j.jevs.2020.103026
CONTACT:
Angela Pelzel-McCluskey, DVM, MS, Equine Epidemiologist
Angela.M.Pelzel-McCluskey@aphis.usda.gov(970) 494-7391
USDA-APHIS-Veterinary Services
Fort Collins, Colorado

2

3

4

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

N AT I O N A L

First Quarter 2020

T

Equine Disease Quarterly
Editors

Peter Timoney
Alan Loynachan
Rebecca Ruby

Staff

Diane Furry
Tawana Brown
Dennis Duross

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
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.
The Republic of South Africa (RSA) confirmed
the occurrence of African horse sickness at expectedlevels within endemic areas of eight of the nine
provinces. The highest number of cases were recorded in Gauteng Province; none were confirmed
in Western Cape Province.
African horse sickness was also reported forthe first time in Thailand. Three outbreaks wereconfirmed, involving 78 cases with 57 fatalities.
An outbreak of Venezuelan equine encephalomyelitis was confirmed by Belize. Four of fiveunvaccinated horses died from the disease.
France, the Netherlands, and the USA recorded
outbreaks of equine influenza. The number ofoutbreaks included four in France (one to 20
cases per outbreak), two in the Netherlands (three
to five cases per outbreak), and nine in the USA,
where the disease is endemic. The number of cases
per outbreak varied from three to 30, with many
unvaccinated against the disease.
Strangles is considered endemic in most countries with reports from Belgium (two outbreaks),
France (20 outbreaks), the Netherlands (24 outbreaks), Switzerland (four outbreaks), and the USA(16 outbreaks in 11 states).
Equine herpesvirus 1 (EHV-1) related diseases
were recorded by Belgium, France, Canada, theNetherlands, Switzerland, the UK, and the USA.
Respiratory disease outbreaks were confirmed in
Belgium (two), France (three), the Netherlands(one), and the USA (six). Abortion due to EHV1 was reported by Belgium (four outbreaks, one
involving six cases), Canada (one outbreak), theNetherlands (five outbreaks), the UK (four outbreaks), and the USA (eight outbreaks of abortion/
neonatal disease, one involving four cases). EHV1 neurologic disease was confirmed by Canada(one case), the Netherlands (two outbreaks, one
involving two cases and the second, seven cases),
Switzerland (single case), the UK (three outbreaks,
one involving nine cases), and the USA (seven outbreaks, with two each in California and Virginia).

Numerous countries recorded outbreaks ofequine herpesvirus 4 respiratory disease. These
included Argentina (one outbreak in five to sevenmonth old foals), Belgium (one outbreak), France(18 outbreaks, mostly single cases), the Netherlands (two outbreaks), Spain (one case), Switzerland (two outbreaks, one involving co-infection
with EHV-1), and the UK (five outbreaks, twolinked to new arrivals).
France reported finding the carrier state in threestallions infected with equine arteritis virus.
Equine infectious anemia was confirmed in
Canada (a case of subclinical infection) and theUSA (three outbreaks, with single cases in California and Texas and three cases in Iowa).
The RSA was the only country to report thepresence of equine piroplasmosis. Isolated cases
were diagnosed throughout the country.
Two outbreaks of leptospiral abortion wererecorded by Belgium, both involving single casesof the disease.
The USA reported a significant number of casesof nocardioform placentitis/abortion. Of 256 cases
confirmed, 147 represented cases of placentitis
and 109 where the placentitis was accompanied
by submission of a fetus or neonate. Amycolatopsis
was implicated in 98 cases and Crossiella equi in
65 cases.
A fatal case of Tyzzer’s disease (Clostridium
piliforme) infection was confirmed in a foal in
Kentucky, USA.
The USA reported a non-fatal case of equine
coronavirus infection in a gelding in Arizona.
Rotavirus infection in foals was diagnosed by
France (two outbreaks), Spain (one case), and theUSA (one case).
The USA reported 10 cases of Lawsonia enteropathy due to Lawsonia intracellularis infection in
the first quarter of 2020. It also confirmed detection of Clostridium perfringens in 24 foals originating in Kentucky and Indiana, and Clostridium
difficile in 16 foals in Kentucky; these included two
toxin Type A strains and two toxin Type B strains.
The RSA recorded cases of equine encephalosis
in seven of the country’s nine provinces, with over
100 cases diagnosed in Gauteng Province.

Equine Acute Respiratory Distress SyndromeA

cute respiratory distress syndrome (ARDS)
causes rapidly progressive and severe respiratory failure and is associated with high mortality
in affected patients. First described in critically ill
humans more than 50 years ago, ARDS is now
recognized as a rare cause of respiratory failure inseveral veterinary species including horses, where
it is referred to as veterinary ARDS (VetARDS).
ARDS and VetARDS develop as a complication when a primary disease or injury triggers
overwhelming and uncontrolled inflammationin the lung. This inflammatory response causes
the hallmark features of ARDS: severe pulmonary
damage and edema, respiratory dysfunction, andprofound hypoxemia (low oxygen in the blood).
Pneumonia and conditions associated with severe
systemic inflammation, such as sepsis, represent themost common risk factors for ARDS and VetARDS.
Other potential risk factors include smoke inhalation, severe trauma, aspiration of stomach contents,
and near drowning.
In horses, VetARDS is a rare, but distinct, clinical condition in foals younger than nine monthsof age. Previously, this condition was referred to asacute interstitial or bronchointerstitial pneumonia.
Bacterial pneumonia is the most common predisposing cause of VetARDS in these foals. There
does not appear to be a single bacterial pathogen
associated with VetARDS in foals but Rhodococcus
equi, Klebsiella sp. and Streptococcus sp. have all
been identified with VetARDS. Sepsis represents
the most likely risk factor in neonatal foals andconditions consistent with VetARDS have beenreported in adult horses after smoke inhalation ornear drowning.
A definitive diagnosis of VetARDS can bechallenging, and distinguishing VetARDS fromsevere bacterial pneumonia may not be possible.
The specific criteria established for the diagnosis
of ARDS in veterinary species include recent
onset of clinical signs (< 72 hours), exposure to a
known risk factor, radiographic changes consistent
with widespread pulmonary damage and edema,
evidence of severe hypoxemia on blood analysis,
and if possible, inflammatory changes identified
on respiratory fluid analysis. These diagnostic
criteria apply to all veterinary species with minor

modifications existing only for neonatal foals lessthan one week of age. Specific postmortem diagnostic criteria also exist for animals that succumb
to VetARDS.
Foals with VetARDS present with a sudden
onset of severe and rapidly progressive respiratory distress that may follow a recent historyof pneumonia. Other nonspecific findings on
physical examination can include fever, abnormallung sounds, increased heart rate, and depression.
Radiographic or ultrasound examination of thelungs is recommended. Blood laboratory analysis
is useful to detect and monitor hypoxemia. Other
laboratory findings vary but are typically consistent
with inflammation or other disease process. Additional diagnostics should focus on identifying
any underlying primary disease.
Regardless of age, the goals of treatment forhorses with VetARDS include addressing any
underlying primary disease, controlling inflammation, improving oxygenation, and providing
supportive care. These cases require prompt andintense management. In humans with ARDS,
lung-protective mechanical ventilation is the
only therapy that has resulted in reduced mortality. Unfortunately, this is not feasible for the vast
majority of horses with this condition. Intranasal
oxygen supplementation, administration of antiinflammatory medications (e.g. corticosteroids)
and antibiotics, and appropriate nutritional andintravenous fluid support represent the mainstayof therapy for most horses with VetARDS.
The prognosis for recovery from VetARDS is
guarded. Survival rates of 60% have been reported
in older foals but are often lower in neonatal foals.
With appropriate treatment, survivors typicallystabilize or improve within a few days. Whilethe impact of this condition on future athletic
performance is unknown at this time, limited
reports suggest that recovered foals can go on tohave successful athletic careers.
CONTACT:
Kara Lascola, DVM, MS, DACVIM
Kml0068@auburn.edu(334) 844-4490
College of Veterinary Medicine,
Department of Clinical Sciences
Auburn University
Auburn, Alabama

Mitigation Strategies to Prevent
Vesicular Stomatitis Virus Transmission to Equids

V

Muzzle lesion in VS affected equid.

DR. PIPER NORTON

esicular stomatitis (VS) is a viral disease ofhorses and other livestock caused by vesicularstomatitis virus (VSV), which is endemic in southern Mexico and only occasionally moves northward into the United States. The clinical disease
is characterized by vesicular (blister-like) lesions
on the muzzle, lips, tongue, ears, udder, sheath,or coronary bands. While the lesions usually healon their own, some horses require supportive care.
A 2019 outbreak of VSV was the largest in recent
history with 1,144 premises affected in eight states(Colorado, Kansas, Nebraska, New Mexico, Oklahoma, Texas, Utah, and Wyoming). VS returned
this year on April 13, 2020, with equine premisesin Arizona, New Mexico, and Texas affected. Expansion of the disease to other states is expected
this summer. Taking steps now to prevent VSVtransmission on equine premises is imperative tolimit the spread.
VSV is spread two ways; natural transmission
by insect vectors or direct contact with infectedanimals. Mitigation strategies targeting insect vectors and implementation of biosecurity to prevent
contact with infected animals and contaminatedfomites (shared water troughs, feed buckets, tack,or equipment) are thought to be the best methodsof disease prevention. Known competent insect
vectors include black flies (Simulium spp.), sandflies (Lutzomyia spp,), and biting midges (Culicoides spp.), but other insects may also transmit thedisease.
These insect vectors emerge in specific habitats,which helps target implementation of mitigation
strategies. Sand flies prefer dry areas, such as treeholes, rock crevices, and animal burrows. Biting
midges prefer wet areas, such as wet leaves andmud around ponds or troughs. Black flies preferflowing water, such as irrigation ditches, rivers, or
streams. Adult flies move outward from these areas.
Some can only fly short distances (sand flies), butothers fly longer distances (black flies) or travel onwind currents (black flies, midges). Seasonality ofthe vectors coincides with warmer months, springthrough fall, but midges can be more cold-hearty
and occasionally transmit VSV in winter. Preferred
feeding/biting times vary, with sand flies being

night feeders, biting midges feeding around sunrise
and sunset, and black flies feeding during the day.
Vector mitigation strategies should be considered at the neighborhood, premises, barn, andanimal level. At the neighborhood level, keep
animals away from insect emerging sites suchas moving water and standing water during theinsect seasons. Alternatively, time the rotation ofanimals through pastures to avoid grazing near astream returning to base flow after reaching peakrunoff, a time of black fly emergence. If possible,
move animals to higher-elevation pastures during
the vector season. At the premises level, removing
manure regularly, maintaining sloped and welldrained footing around water sources, and keeping
surrounding vegetation mowed will also reduce
insect vectors.
At the barn level, move animals indoors duringvector feeding times or provide access to a run-in
shed for pastured horses. Installing mesh nettingor repellent-treated fabrics on barn openings canfurther prevent vector entry. Minimizing the useof bright lights at night and adding fans blowing
down onto horses can also be preventive. At the
animal level, topical insecticides and repellents
reduce exposure to biting insects, but repeatedapplication is necessary and must be combinedwith insect mitigation at the other levels to beeffective. Using fly sheets, masks, leg wraps, andear covers with or without repellent fabric are also
animal-level mitigations, but these must cover theareas where VSV lesions occur. Therefore, chemical
repellents may need to be used in conjunction withfly sheets and masks to protect the muzzle and lips.
Mitigation strategies and biosecurity measuresat multiple levels are needed to provide adequate
protection from VSV. For more information access“Management Strategies for Reducing the Risk of
Equines Contracting Vesicular Stomatitis Virus in
the Western United States” at the following link:
https://doi.org/10.1016/j.jevs.2020.103026
CONTACT:
Angela Pelzel-McCluskey, DVM, MS, Equine Epidemiologist
Angela.M.Pelzel-McCluskey@aphis.usda.gov(970) 494-7391
USDA-APHIS-Veterinary Services
Fort Collins, Colorado

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

Therapeutic ShoeingA

pplying shoes to the feet of horses has been acommon practice for over 1,000 years, while
the first horseshoes may have been used as much as
2,500 years ago. Generally, the feet of domesticatedhorses are trimmed to balance and reduce excessive
hoof length, and, in many cases, horseshoes areapplied as an aid for traction, protection, and to
reduce wear of the hoof wall. Therapeutic horseshoeing, therapeutic farriery, corrective shoeing,
and podiatry are some of the terms that have beenused to describe the care of a horse’s hoof to address abnormal conditions beyond this common
practice. Since many farriers use various shoes,pads, and application methods, therapeutic shoeing is practiced by most farriers at various levels.
It could also be argued that basic horse shoeing istherapeutic in nature.
There are various certifications and endorsements that farriers can acquire from a handful of
farrier organizations, indicating specialty or ability.
These involve additional training, apprenticeships,
case studies, and testing. Additionally, there areveterinarians who are trained farriers with experience and specialty achieved beyond the scope ofwhat is provided in vet school. Depending on client base, geography, experience, and preference,veterinarians and farriers often specialize in certain
disciplines or breeds.
As much as 80% of equine forelimb lamenessis due to problems involving the feet. Some of theusual conditions where therapeutic horseshoeing
is utilized include laminitis and founder, naviculardisease, hoof cracks and defects, coffin bone injuries or disease, infections such as canker, white linedisease and abscesses. Soft tissue injuries involving
tendons and ligaments as well as diseases involving
bone and joints can also be addressed with modulation of the foot even though these injuries may belocated further up the leg. For example, shoeing
applications to reduce strain on a suspensory ligament can greatly improve healing and comfort forsuspensory desmitis. Conformational abnormalities may be accommodated with proper attention.
Each breed and discipline also has a set of nuancesand problems specific to the group. The farrier ispart of a team which also includes the horse, owner,trainer, grooms, and veterinarian. This team approach is never more evident than when a horse
has an injury or disease. Occasionally, multiple
farriers or veterinarians will work together on acase via referral or consultation. It is important
to note that an accurate diagnosis is essential for
successful treatment.
Shoeing has evolved from the use of standard
steel “keg” horseshoes. Manufacturing technology has brought a multitude of therapeutic shoes
to market. A farrier can also modify pre-made orbuild shoes from scratch to custom fit each footand need. In addition to steel and aluminum;
plastics, fabrics, composites, epoxy and acrylic
adhesives, and even wood is often utilized. Pads
and impression support materials have evolved,
offering different application methods, hardness,and even incorporated medications tailored to
the needs at hand. Although craftsmanship andskill in building a foot appliance is important, theknowledge of how therapy will affect the horse(positive or negative) in every aspect is imperative.
An example is how a wide-webbed shoe with a pad
and rolled toe and branches might benefit a horsewith navicular pain but will reduce traction andseal a sole from air causing other concerns that
may result in different problems.
Therapeutic goals may include protection ofinternal or external injuries and wounds, stabilization of the hoof capsule, orthotic support, modification of static and dynamic biomechanics of the
foot-ground interface, and protection or supportof structures above the hoof. To properly address
the needs of the condition and the horse, one musthave an intimate understanding of the anatomic,
physiologic and biomechanical relationships of thefoot and leg. There should be an understanding of
the disease process at hand. One application for acertain problem may be detrimental for another.
This is the main reason that a farrier and veterinarian are most efficient when they have a goodworking relationship.
CONTACT:
Josh Zacharias, DVM, MS, DACVS, DACVSMR
zachariasdvm@gmail.com
Countryside Large Animal Veterinary Service
Greeley, Colorado

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

JULY 2020
Volume 29, Number 3

C O M M E N TA RY
IN THIS ISSUECOMMENTARY: continued from the front page

be employed at racetracks, equine sporting events,
sales, etc. The economic fallout from this pandemic
also has affected people who buy horses or wager
at racetracks.
Horse breeding has been allowed to take placesubject to stringent precautionary measures toprevent further spread of SARS-CoV-2. This ispredicated on maintaining an enhanced level ofbiosecurity in all aspects of breeding shed activity and in following approved standard practices
including social distancing by personnel. While
much attention has been focused on centers ofhorse racing and breeding across the country, thefinancial repercussions of COVID-19 have also
been acutely felt by owners of smaller horse farms/

businesses, etc., whose livelihoods are dependent
on the sustainability of the equine industry.
It is way too soon to predict what the overall
impact of the pandemic will have on the nation’s
equine industry in all its aspects from racing,equestrian events, horse shows, breeding, sales,
and a variety of ancillary businesses. What iscertain, however, is that the horse industry willsurvive and, given time, thrive again and regain its
former prominence and importance to the nation’s
economy.
CONTACT:
Peter J. Timoney, MVB, MS, PhD, FRCVS
ptimoney@uky.edu(859) 218-1094
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, KentuckyS

ince discovery of the novel coronavirus (SARSCoV-2), causal agent of the highly contagious
Commentaryand frequently life-threatening disease of humans
designated COVID-19 in December 2019, theInternational
virus has spread very rapidly around the globe. The
First Quarter2020  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2 exponential increase of cases in affected countries
and the alarming case-fatality rate has resulted
Acute Respiratory
Distress .  .  .  .  .  .  .  .  .  .  .  .  .  . 3 in a pandemic of unprecedented proportions, interms of its health and economic impact on humanpopulations worldwide.
National
Of the seven coronaviruses known to infect
Vesicular
Stomatitis .  .  .  .  .  .  .  .  .  .  . 4 humans, three are of major public health significance: severe acute respiratory syndrome (SARS),
Therapeutic
Shoeing .  .  .  .  .  .  .  .  .  .  .  .  . 5 Middle East respiratory syndrome (MERS), andcoronavirus 2019 (COVID-19). Other membersof the coronavirus family can cause respiratory or
intestinal disease in a range of domestic species, including horses, swine, cattle, cats, dogs and chickens. SARS-CoV-2 is genetically and otherwise
uniquely distinct from these other coronaviruses,
none of which are known to be human pathogens.
There are many aspects of the biology of SARSCoV-2, including its host range, epidemiology,
pathogenesis, and nature of the immune responseto the virus, that remain to be fully elucidated.
The pandemic of COVID-19 has had significant implications for the U.S. horse industry. A
point of continuing concern for many in theindustry is whether SARS-CoV-2 is capable ofCollege of Agriculture, infecting and perhaps causing disease in horses.
Food and Environment At the present time, there is no evidence conDepartment of
firming the susceptibility of horses to infection.
Veterinary Science
This is supported by the outcome of a recent
study undertaken to determine conservation of
the angiotensin-converting enzyme 2 (ACE2)
across 410 vertebrates including 252 mammalian
species, and the likelihood of it functioning as a
Lloyd’s—An international
insurance market for
SARS-CoV-2 cell receptor. The horse was ranked
bloodstock and otherlow risk in predicted susceptibility to infection
specialist insurance.

NIAID-RML

5

The novel coronovirus that causes COVID-19.

based on the binding characteristics of its ACE2
compared to the human homologue. In the current absence of any information to the contrary,
it is not possible to speculate on the potential riskof horse-to-horse transmission of the virus andwhether horses might play a role in transmitting
the virus back to humans.
Aside from the primary consideration of its
potential to affect the health of the horse, COVID-19 has had a major impact on the economyof the horse industry in Kentucky and the USA.
Virtually all sectors of the industry have been
negatively influenced by the current pandemic.
Racing, equestrian events, and horse shows havebeen cancelled or postponed to a later date. Horsesales and other ancillary businesses have been similarly affected. This has inevitably resulted in layoffs
or furloughing of workers who would otherwise
continued on the back pageEquine Disease Quarterly Newsletter
Department of Veterinary Science
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, Kentucky 40546-0099

Therapeutic ShoeingA

pplying shoes to the feet of horses has been acommon practice for over 1,000 years, while
the first horseshoes may have been used as much as
2,500 years ago. Generally, the feet of domesticatedhorses are trimmed to balance and reduce excessive
hoof length, and, in many cases, horseshoes areapplied as an aid for traction, protection, and to
reduce wear of the hoof wall. Therapeutic horseshoeing, therapeutic farriery, corrective shoeing,
and podiatry are some of the terms that have beenused to describe the care of a horse’s hoof to address abnormal conditions beyond this common
practice. Since many farriers use various shoes,pads, and application methods, therapeutic shoeing is practiced by most farriers at various levels.
It could also be argued that basic horse shoeing istherapeutic in nature.
There are various certifications and endorsements that farriers can acquire from a handful of
farrier organizations, indicating specialty or ability.
These involve additional training, apprenticeships,
case studies, and testing. Additionally, there areveterinarians who are trained farriers with experience and specialty achieved beyond the scope ofwhat is provided in vet school. Depending on client base, geography, experience, and preference,veterinarians and farriers often specialize in certain
disciplines or breeds.
As much as 80% of equine forelimb lamenessis due to problems involving the feet. Some of theusual conditions where therapeutic horseshoeing
is utilized include laminitis and founder, naviculardisease, hoof cracks and defects, coffin bone injuries or disease, infections such as canker, white linedisease and abscesses. Soft tissue injuries involving
tendons and ligaments as well as diseases involving
bone and joints can also be addressed with modulation of the foot even though these injuries may belocated further up the leg. For example, shoeing
applications to reduce strain on a suspensory ligament can greatly improve healing and comfort forsuspensory desmitis. Conformational abnormalities may be accommodated with proper attention.
Each breed and discipline also has a set of nuancesand problems specific to the group. The farrier ispart of a team which also includes the horse, owner,trainer, grooms, and veterinarian. This team approach is never more evident than when a horse
has an injury or disease. Occasionally, multiple
farriers or veterinarians will work together on acase via referral or consultation. It is important
to note that an accurate diagnosis is essential for
successful treatment.
Shoeing has evolved from the use of standard
steel “keg” horseshoes. Manufacturing technology has brought a multitude of therapeutic shoes
to market. A farrier can also modify pre-made orbuild shoes from scratch to custom fit each footand need. In addition to steel and aluminum;
plastics, fabrics, composites, epoxy and acrylic
adhesives, and even wood is often utilized. Pads
and impression support materials have evolved,
offering different application methods, hardness,and even incorporated medications tailored to
the needs at hand. Although craftsmanship andskill in building a foot appliance is important, theknowledge of how therapy will affect the horse(positive or negative) in every aspect is imperative.
An example is how a wide-webbed shoe with a pad
and rolled toe and branches might benefit a horsewith navicular pain but will reduce traction andseal a sole from air causing other concerns that
may result in different problems.
Therapeutic goals may include protection ofinternal or external injuries and wounds, stabilization of the hoof capsule, orthotic support, modification of static and dynamic biomechanics of the
foot-ground interface, and protection or supportof structures above the hoof. To properly address
the needs of the condition and the horse, one musthave an intimate understanding of the anatomic,
physiologic and biomechanical relationships of thefoot and leg. There should be an understanding of
the disease process at hand. One application for acertain problem may be detrimental for another.
This is the main reason that a farrier and veterinarian are most efficient when they have a goodworking relationship.
CONTACT:
Josh Zacharias, DVM, MS, DACVS, DACVSMR
zachariasdvm@gmail.com
Countryside Large Animal Veterinary Service
Greeley, Colorado

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

JULY 2020
Volume 29, Number 3

C O M M E N TA RY
IN THIS ISSUECOMMENTARY: continued from the front page

be employed at racetracks, equine sporting events,
sales, etc. The economic fallout from this pandemic
also has affected people who buy horses or wager
at racetracks.
Horse breeding has been allowed to take placesubject to stringent precautionary measures toprevent further spread of SARS-CoV-2. This ispredicated on maintaining an enhanced level ofbiosecurity in all aspects of breeding shed activity and in following approved standard practices
including social distancing by personnel. While
much attention has been focused on centers ofhorse racing and breeding across the country, thefinancial repercussions of COVID-19 have also
been acutely felt by owners of smaller horse farms/

businesses, etc., whose livelihoods are dependent
on the sustainability of the equine industry.
It is way too soon to predict what the overall
impact of the pandemic will have on the nation’s
equine industry in all its aspects from racing,equestrian events, horse shows, breeding, sales,
and a variety of ancillary businesses. What iscertain, however, is that the horse industry willsurvive and, given time, thrive again and regain its
former prominence and importance to the nation’s
economy.
CONTACT:
Peter J. Timoney, MVB, MS, PhD, FRCVS
ptimoney@uky.edu(859) 218-1094
Maxwell H. Gluck Equine Research Center
University of Kentucky
Lexington, KentuckyS

ince discovery of the novel coronavirus (SARSCoV-2), causal agent of the highly contagious
Commentaryand frequently life-threatening disease of humans
designated COVID-19 in December 2019, theInternational
virus has spread very rapidly around the globe. The
First Quarter2020  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2 exponential increase of cases in affected countries
and the alarming case-fatality rate has resulted
Acute Respiratory
Distress  .  .  .  .  .  .  .  .  .  .  .  .  . 3 in a pandemic of unprecedented proportions, interms of its health and economic impact on humanpopulations worldwide.
National
Of the seven coronaviruses known to infect
Vesicular
Stomatitis .  .  .  .  .  .  .  .  .  .  . 4 humans, three are of major public health significance: severe acute respiratory syndrome (SARS),
Therapeutic
Shoeing .  .  .  .  .  .  .  .  .  .  .  .  . 5 Middle East respiratory syndrome (MERS), andcoronavirus 2019 (COVID-19). Other membersof the coronavirus family can cause respiratory or
intestinal disease in a range of domestic species, including horses, swine, cattle, cats, dogs and chickens. SARS-CoV-2 is genetically and otherwise
uniquely distinct from these other coronaviruses,
none of which are known to be human pathogens.
There are many aspects of the biology of SARSCoV-2, including its host range, epidemiology,
pathogenesis, and nature of the immune responseto the virus, that remain to be fully elucidated.
The pandemic of COVID-19 has had significant implications for the U.S. horse industry. A
point of continuing concern for many in theindustry is whether SARS-CoV-2 is capable ofCollege of Agriculture, infecting and perhaps causing disease in horses.
Food and Environment At the present time, there is no evidence conDepartment of
firming the susceptibility of horses to infection.
Veterinary Science
This is supported by the outcome of a recent
study undertaken to determine conservation of
the angiotensin-converting enzyme 2 (ACE2)
across 410 vertebrates including 252 mammalian
species, and the likelihood of it functioning as a
Lloyd’s—An international
insurance market for
SARS-CoV-2 cell receptor. The horse was ranked
bloodstock and otherlow risk in predicted susceptibility to infection
specialist insurance.

NIAID-RML

5

The novel coronovirus that causes COVID-19.

based on the binding characteristics of its ACE2
compared to the human homologue. In the current absence of any information to the contrary,
it is not possible to speculate on the potential riskof horse-to-horse transmission of the virus andwhether horses might play a role in transmitting
the virus back to humans.
Aside from the primary consideration of its
potential to affect the health of the horse, COVID-19 has had a major impact on the economyof the horse industry in Kentucky and the USA.
Virtually all sectors of the industry have been
negatively influenced by the current pandemic.
Racing, equestrian events, and horse shows havebeen cancelled or postponed to a later date. Horsesales and other ancillary businesses have been similarly affected. This has inevitably resulted in layoffs
or furloughing of workers who would otherwise
continued on the back page

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

N AT I O N A L

First Quarter 2020

T

Equine Disease Quarterly
Editors

Peter Timoney
Alan Loynachan
Rebecca Ruby

Staff

Diane Furry
Tawana Brown
Dennis Duross

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
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.
The Republic of South Africa (RSA) confirmed
the occurrence of African horse sickness at expectedlevels within endemic areas of eight of the nine
provinces. The highest number of cases were recorded in Gauteng Province; none were confirmed
in Western Cape Province.
African horse sickness was also reported forthe first time in Thailand. Three outbreaks wereconfirmed, involving 78 cases with 57 fatalities.
An outbreak of Venezuelan equine encephalomyelitis was confirmed by Belize. Four of fiveunvaccinated horses died from the disease.
France, the Netherlands, and the USA recorded
outbreaks of equine influenza. The number ofoutbreaks included four in France (one to 20
cases per outbreak), two in the Netherlands (three
to five cases per outbreak), and nine in the USA,
where the disease is endemic. The number of cases
per outbreak varied from three to 30, with many
unvaccinated against the disease.
Strangles is considered endemic in most countries with reports from Belgium (two outbreaks),
France (20 outbreaks), the Netherlands (24 outbreaks), Switzerland (four outbreaks), and the USA(16 outbreaks in 11 states).
Equine herpesvirus 1 (EHV-1) related diseases
were recorded by Belgium, France, Canada, theNetherlands, Switzerland, the UK, and the USA.
Respiratory disease outbreaks were confirmed in
Belgium (two), France (three), the Netherlands(one), and the USA (six). Abortion due to EHV1 was reported by Belgium (four outbreaks, one
involving six cases), Canada (one outbreak), theNetherlands (five outbreaks), the UK (four outbreaks), and the USA (eight outbreaks of abortion/
neonatal disease, one involving four cases). EHV1 neurologic disease was confirmed by Canada(one case), the Netherlands (two outbreaks, one
involving two cases and the second, seven cases),
Switzerland (single case), the UK (three outbreaks,
one involving nine cases), and the USA (seven outbreaks, with two each in California and Virginia).

Numerous countries recorded outbreaks ofequine herpesvirus 4 respiratory disease. These
included Argentina (one outbreak in five to sevenmonth old foals), Belgium (one outbreak), France(18 outbreaks, mostly single cases), the Netherlands (two outbreaks), Spain (one case), Switzerland (two outbreaks, one involving co-infection
with EHV-1), and the UK (five outbreaks, twolinked to new arrivals).
France reported finding the carrier state in threestallions infected with equine arteritis virus.
Equine infectious anemia was confirmed in
Canada (a case of subclinical infection) and theUSA (three outbreaks, with single cases in California and Texas and three cases in Iowa).
The RSA was the only country to report thepresence of equine piroplasmosis. Isolated cases
were diagnosed throughout the country.
Two outbreaks of leptospiral abortion wererecorded by Belgium, both involving single casesof the disease.
The USA reported a significant number of casesof nocardioform placentitis/abortion. Of 256 cases
confirmed, 147 represented cases of placentitis
and 109 where the placentitis was accompanied
by submission of a fetus or neonate. Amycolatopsis
was implicated in 98 cases and Crossiella equi in
65 cases.
A fatal case of Tyzzer’s disease (Clostridium
piliforme) infection was confirmed in a foal in
Kentucky, USA.
The USA reported a non-fatal case of equine
coronavirus infection in a gelding in Arizona.
Rotavirus infection in foals was diagnosed by
France (two outbreaks), Spain (one case), and theUSA (one case).
The USA reported 10 cases of Lawsonia enteropathy due to Lawsonia intracellularis infection in
the first quarter of 2020. It also confirmed detection of Clostridium perfringens in 24 foals originating in Kentucky and Indiana, and Clostridium
difficile in 16 foals in Kentucky; these included two
toxin Type A strains and two toxin Type B strains.
The RSA recorded cases of equine encephalosis
in seven of the country’s nine provinces, with over
100 cases diagnosed in Gauteng Province.

Equine Acute Respiratory Distress SyndromeA

cute respiratory distress syndrome (ARDS)
causes rapidly progressive and severe respiratory failure and is associated with high mortality
in affected patients. First described in critically ill
humans more than 50 years ago, ARDS is now
recognized as a rare cause of respiratory failure inseveral veterinary species including horses, where
it is referred to as veterinary ARDS (VetARDS).
ARDS and VetARDS develop as a complication when a primary disease or injury triggers
overwhelming and uncontrolled inflammationin the lung. This inflammatory response causes
the hallmark features of ARDS: severe pulmonary
damage and edema, respiratory dysfunction, andprofound hypoxemia (low oxygen in the blood).
Pneumonia and conditions associated with severe
systemic inflammation, such as sepsis, represent themost common risk factors for ARDS and VetARDS.
Other potential risk factors include smoke inhalation, severe trauma, aspiration of stomach contents,
and near drowning.
In horses, VetARDS is a rare, but distinct, clinical condition in foals younger than nine monthsof age. Previously, this condition was referred to asacute interstitial or bronchointerstitial pneumonia.
Bacterial pneumonia is the most common predisposing cause of VetARDS in these foals. There
does not appear to be a single bacterial pathogen
associated with VetARDS in foals but Rhodococcus
equi, Klebsiella sp. and Streptococcus sp. have all
been identified with VetARDS. Sepsis represents
the most likely risk factor in neonatal foals andconditions consistent with VetARDS have beenreported in adult horses after smoke inhalation ornear drowning.
A definitive diagnosis of VetARDS can bechallenging, and distinguishing VetARDS fromsevere bacterial pneumonia may not be possible.
The specific criteria established for the diagnosis
of ARDS in veterinary species include recent
onset of clinical signs (< 72 hours), exposure to a
known risk factor, radiographic changes consistent
with widespread pulmonary damage and edema,
evidence of severe hypoxemia on blood analysis,
and if possible, inflammatory changes identified
on respiratory fluid analysis. These diagnostic
criteria apply to all veterinary species with minor

modifications existing only for neonatal foals lessthan one week of age. Specific postmortem diagnostic criteria also exist for animals that succumb
to VetARDS.
Foals with VetARDS present with a sudden
onset of severe and rapidly progressive respiratory distress that may follow a recent historyof pneumonia. Other nonspecific findings on
physical examination can include fever, abnormallung sounds, increased heart rate, and depression.
Radiographic or ultrasound examination of thelungs is recommended. Blood laboratory analysis
is useful to detect and monitor hypoxemia. Other
laboratory findings vary but are typically consistent
with inflammation or other disease process. Additional diagnostics should focus on identifying
any underlying primary disease.
Regardless of age, the goals of treatment forhorses with VetARDS include addressing any
underlying primary disease, controlling inflammation, improving oxygenation, and providing
supportive care. These cases require prompt andintense management. In humans with ARDS,
lung-protective mechanical ventilation is the
only therapy that has resulted in reduced mortality. Unfortunately, this is not feasible for the vast
majority of horses with this condition. Intranasal
oxygen supplementation, administration of antiinflammatory medications (e.g. corticosteroids)
and antibiotics, and appropriate nutritional andintravenous fluid support represent the mainstayof therapy for most horses with VetARDS.
The prognosis for recovery from VetARDS is
guarded. Survival rates of 60% have been reported
in older foals but are often lower in neonatal foals.
With appropriate treatment, survivors typicallystabilize or improve within a few days. Whilethe impact of this condition on future athletic
performance is unknown at this time, limited
reports suggest that recovered foals can go on tohave successful athletic careers.
CONTACT:
Kara Lascola, DVM, MS, DACVIM
Kml0068@auburn.edu(334) 844-4490
College of Veterinary Medicine,
Department of Clinical Sciences
Auburn University
Auburn, Alabama

Mitigation Strategies to Prevent
Vesicular Stomatitis Virus Transmission to Equids

V

Muzzle lesion in VS affected equid.

DR. PIPER NORTON

esicular stomatitis (VS) is a viral disease ofhorses and other livestock caused by vesicularstomatitis virus (VSV), which is endemic in southern Mexico and only occasionally moves northward into the United States. The clinical disease
is characterized by vesicular (blister-like) lesions
on the muzzle, lips, tongue, ears, udder, sheath,or coronary bands. While the lesions usually healon their own, some horses require supportive care.
A 2019 outbreak of VSV was the largest in recent
history with 1,144 premises affected in eight states(Colorado, Kansas, Nebraska, New Mexico, Oklahoma, Texas, Utah, and Wyoming). VS returned
this year on April 13, 2020, with equine premisesin Arizona, New Mexico, and Texas affected. Expansion of the disease to other states is expected
this summer. Taking steps now to prevent VSVtransmission on equine premises is imperative tolimit the spread.
VSV is spread two ways; natural transmission
by insect vectors or direct contact with infectedanimals. Mitigation strategies targeting insect vectors and implementation of biosecurity to prevent
contact with infected animals and contaminatedfomites (shared water troughs, feed buckets, tack,or equipment) are thought to be the best methodsof disease prevention. Known competent insect
vectors include black flies (Simulium spp.), sandflies (Lutzomyia spp,), and biting midges (Culicoides spp.), but other insects may also transmit thedisease.
These insect vectors emerge in specific habitats,which helps target implementation of mitigation
strategies. Sand flies prefer dry areas, such as treeholes, rock crevices, and animal burrows. Biting
midges prefer wet areas, such as wet leaves andmud around ponds or troughs. Black flies preferflowing water, such as irrigation ditches, rivers, or
streams. Adult flies move outward from these areas.
Some can only fly short distances (sand flies), butothers fly longer distances (black flies) or travel onwind currents (black flies, midges). Seasonality ofthe vectors coincides with warmer months, springthrough fall, but midges can be more cold-hearty
and occasionally transmit VSV in winter. Preferred
feeding/biting times vary, with sand flies being

night feeders, biting midges feeding around sunrise
and sunset, and black flies feeding during the day.
Vector mitigation strategies should be considered at the neighborhood, premises, barn, andanimal level. At the neighborhood level, keep
animals away from insect emerging sites suchas moving water and standing water during theinsect seasons. Alternatively, time the rotation ofanimals through pastures to avoid grazing near astream returning to base flow after reaching peakrunoff, a time of black fly emergence. If possible,
move animals to higher-elevation pastures during
the vector season. At the premises level, removing
manure regularly, maintaining sloped and welldrained footing around water sources, and keeping
surrounding vegetation mowed will also reduce
insect vectors.
At the barn level, move animals indoors duringvector feeding times or provide access to a run-in
shed for pastured horses. Installing mesh nettingor repellent-treated fabrics on barn openings canfurther prevent vector entry. Minimizing the useof bright lights at night and adding fans blowing
down onto horses can also be preventive. At the
animal level, topical insecticides and repellents
reduce exposure to biting insects, but repeatedapplication is necessary and must be combinedwith insect mitigation at the other levels to beeffective. Using fly sheets, masks, leg wraps, andear covers with or without repellent fabric are also
animal-level mitigations, but these must cover theareas where VSV lesions occur. Therefore, chemical
repellents may need to be used in conjunction withfly sheets and masks to protect the muzzle and lips.
Mitigation strategies and biosecurity measuresat multiple levels are needed to provide adequate
protection from VSV. For more information access“Management Strategies for Reducing the Risk of
Equines Contracting Vesicular Stomatitis Virus in
the Western United States” at the following link:
https://doi.org/10.1016/j.jevs.2020.103026
CONTACT:
Angela Pelzel-McCluskey, DVM, MS, Equine Epidemiologist
Angela.M.Pelzel-McCluskey@aphis.usda.gov(970) 494-7391
USDA-APHIS-Veterinary Services
Fort Collins, Colorado