Neurologic EHV-1 Identified in Quebec Horse

Neurologic EHV-1 Identified in Quebec Horse

The neurologic EHV-1 virus.

Photo: George P. Allen, PhD

One mare is dead and two horses are showing neurologic signs in an outbreak of the neurologic form of equine herpesvirus-1 (EHV-1) in Quebec, Canada, that has left more than 50 horses in quarantine.

A 12-year-old Canadian Horse mare showed signs of illness last week, including fever, lethargy, and difficulty standing and walking, according to treating veterinarian Isabelle Morin, DVM, of the Clinique Vétérinaire Sagamie in Alma, Quebec. The horse then "rapidly deteriorated" over the next 24 hours and was unable to stand. She was humanely euthanized.

Necropsy results confirmed the presence of neurologic EHV-1, Morin said. All 53 remaining horses at the Bédard Quarter Horse riding stable in Chicoutimi, Quebec, were immediately placed in quarantine by their veterinarians and their owner.

Two horses have since shown signs of the disease, including fever, ataxia (incoordination) in the hind legs, and bladder complications, said Morin. However, their condition is currently stable, and care takers are "hopeful" for a full recovery.

On-site care takers, including riding instructors, are observing the horses at regular intervals throughout the day and taking rectal temperatures at least twice a day, according to Laurie Michaud, one of the club's instructors. "We're remaining very attentive and watchful for any slight change in any of the horses," she said.

The origin of the outbreak is still unclear, according to Morin. Samples have been sent to a laboratory in Ontario for strain analysis, which could provide clues into how the virus arrived at the Bédard premises. The analyses are still under way, and no preliminary results have been released.

The mare that was euthanized had competed regularly for several years at a national level, but she had not competed recently, according to Michaud.

During the quarantine, the stable's activities are continuing, including riding classes and a full-time school for children pursuing equestrian sports, Michaud said. "But no horses are coming in or (going) out until the quarantine is lifted."

The quarantine--which is not obligatory, as EHV is not a reportable disease in Quebec--will continue until no horses have shown positive symptoms for 28 days, Morin said.

"We have posters up all around our stables and at the entrance, to make sure everyone knows," Michaud said. "Since it's not a reportable disease, we want to do what we can to keep this outbreak contained as much as possible."

Although it's not transmissible to humans, EHV-1 is highly contagious among horses and camelids, and it 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 equines, 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 with potential EHV-1 exposure display any of the aforementioned clinical signs, a veterinarian should be called to obtain samples and test for the disease.

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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