EQUINE | Equine Disease Update
“With adequate preplanning and an action plan, risks
and response times can be reduced,” said Traub-Dargatz.
“In addition, early recognition and swift action in man-
aging suspect cases is key to reducing spread of disease.”
Handling a Diarrheal Outbreak
Diarrhea associated with infectious gastrointestinal (GI)
disease can be lifethreatening due to secondary devel-
opment of laminitis and vascular thrombosis (blood
clot). Diagnosing its cause and stopping its spread can
be difficult because few facilities use optimal manage-
ment and prevention practices.
Scott Weese, DVM, DVSc, Dipl. ACVIM, a professor in the
departments of Pathobiology and Infection Control at
the Ontario Veterinary College, in Canada, provided key
tips for handling infectious diarrhea.
When walking into a facility with suspected GI disease,
the first and most important step is separating clinically
affected horses from the rest of the herd.
“It is imperative to reduce transmission of pathogens by
personnel, fomites (objects), or other animals,” he said.
Step two, said Weese, is cohorting, which involves sepa-
rating horses into groups based on risk status: diseased,
exposed, and unexposed. Even within the diseased and
exposed groups, individual isolation is ideal, although
often not implemented at many facilities. When in
doubt about grouping a horse, default to the highest
risk group that is reasonable.
Once you’ve cohorted and instituted treatment, infec-
tion control response can continue. Strategies include:
• Establishing an investigation team;
• Conducting diagnostic testing;
• Making containment and isolation recommenda-
tions; and
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After quarantine is lifted, reviewing the outbreak to
prevent future issues.
Summing up, he said to implement biosecurity mea-
sures pre-emptively, as infectious disease is an ever-
present risk.
Stemming Spread of Respiratory Diseases
Disease spreads invisibly, often thanks to horses shed-
ding disease but not showing signs. Leading causes of
these outbreaks include equine herpesvirus-1 and -4
(EHV-1, -4) and equine influenza virus, as well as equine
arteritis virus and strangles.
Peter Morresey, BVSc, Dipl. ACT, ACVIM, of Rood & Riddle
Equine Hospital in Lexington, Kentucky, described how
to investigate and control infectious respiratory disease
outbreaks. He first reviewed what questions to ask:
• What is the cause of the disease?
• When did infectious and clinically affected cases ap-
pear?
• How long will it take for the disease to spread
through the exposed population?
• How long will naive populations—never exposed
to the disease—remain at risk once sick horses have
recovered?
• Will any horses become “reservoirs” for disease, in-
termittently shedding the disease-causing organ-
ism in the future?
• When is it safe to transport, breed, show, or sell re-
covered and/or exposed horses without risk of dis-
seminating disease?
• Will the disease-causing pathogen persist in the en-
vironment (on surfaces)?
“Controlling an infectious respiratory disease involves
two main strategies: isolation of affected individuals and
identifying then segregating horses exposed to clinical
cases,” he said.
• Equine Health Update •