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