EHV-1 Confirmed in Ontario Horse

A case of neurotrophic equine herpesvirus-1 (EHV-1) was recently confirmed in Ontario, Canada, according to an April 30 health alert from Equine Guelph, the horse owners' and care givers' center at the University of Guelph in Ontario.

On May 1, Janet E. Alsop, DVM, Dipl. ABVP, lead regulatory response veterinarian for the Ontario Ministry of Agriculture and Food, told via email that the case was diagnosed in early April. She said the affected horse "deteriorated rapidly and was euthanized within 36 hours of exhibiting initial clinical signs."

"After discussion with the veterinarian, the stable manager voluntarily placed the premises under a self-imposed quarantine to reduce the risk of viral spread," Alsop said. "To date, there have been no further reports of equine illness on the farm."

Although it's not transmissible to humans, EHV-1 is highly contagious among horses and camelids and is generally passed from horse to horse via aerosol transmission (when affected animals sneeze/cough) and contact with nasal secretions. The disease can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy (EHM, the neurologic form).

Myeloencephalopathy is characterized by fever, ataxia (incoordination), weakness or paralysis of the hind limbs, and incontinence. Should a horse that potentially has been exposed to EHV-1 display any of the aforementioned clinical signs, call a veterinarian to obtain samples and test for the disease.

Editor's Note: This story was updated May 1 to include new information provided to

About the Author

Erica Larson, News Editor

Erica Larson, News Editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in three-day eventing with her OTTB, Dorado, and enjoys photography in her spare time.

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