The Canadian Animal Health Surveillance System has confirmed that two horses have been identified with the neurologic form of Equine Herpesvirus in a stable in the Saint-Lazare region of Montérégi, QC. One vaccinated horse was severely affected and had to be euthanized; the other animal has been quarantined. The recent entry of a new horse into the stable without prior quarantine is one of the risk factors responsible for this outbreak.

Equine herpesvirus type 1 is highly contagious and can manifest as respiratory, neurological and abortion disorders. Horses can shed the virus and contaminate other horses without showing visible signs of the disease. A sick horse that has shown symptoms usually remains contagious for 1 to 2 weeks (maximum 21 days) after their disappearance.

Symptoms of the neurological form of the disease and the degree of severity of infection are variable between horses and can be manifested by fever, decreased appetite, depression, mild to severe incoordination of movements (more often marked in the hind limbs), urinary incontinence, loss of tail tone, etc. Euthanasia of severely affected horses is sometimes necessary. This depends on various factors, including the presence of a highly pathogenic viral strain.

For more information about EHM, click here for the Factsheet.