Current situation

On January 5th, 2023, the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) was notified of a confirmed case of equine herpes myeloencephalopathy (EHM), caused by equine herpesvirus-1 (EHV-1) infection, at a premises in Wellington County.

EHV-1 does not pose a threat to public health or food safety.

A mature mare was examined and treated by a veterinarian after presenting with incoordination, which rapidly deteriorated. The premises is under veterinary supervision, including biosecurity protocols, and voluntary movement restrictions have been implemented by the facility manager.

EHV-1 infection is immediately notifiable by laboratories to the Office of the Chief Veterinarian for Ontario under the Animal Health Act, 2009. Attending veterinarians concerned about potential cases of EHV-1 infection may contact an OMAFRA veterinarian through the Agricultural Information Contact Centre at 1-877-424-1300.

Clinical signs

A fever (greater than 101.5°F or 38.6°C) may be the first indication of infection, therefore, the temperature of potentially exposed animals should be monitored and recorded twice daily for 21 days and any abnormalities discussed with a veterinarian. Neurological signs, if they develop, may include loss of balance, hind-limb weakness, difficulty urinating, decreased tail tone, depression and being down and unable to rise. It is important that a veterinarian assess horses demonstrating neurological signs since it can be difficult to distinguish these from other serious diseases such as rabies.

Biosecurity

EHV-1 infection is easily spread to other horses by nose-to-nose or close contact with an infected horse, by sharing contaminated equipment including bits, buckets and towels or by the clothing and hands of people who have recently had contact with an infected horse. It is important, therefore, to restrict movement for 21 days of both horses and people who have worked with them, where EHV-1 has been diagnosed. Any person moving between equine facilities should change their clothes, shoes/boots and wash their hands. Facility owners should also inform all service providers that have attended the facility within the previous week, including, but not restricted to, veterinarians, farriers, feed suppliers and transporters, of the presence of the virus at the facility so they can take appropriate precautions.

Prevention

Biosecurity is key to preventing spread of EHV-1. Implementing routine biosecurity measures is the best way to minimize viral spread and should be in place at all times to prevent a disease outbreak. Such measures include hand hygiene and basic cleaning and disinfection practices. Horses that have been shipped long distances to the facility should be segregated for 14 days prior to entering the general population.

EHV-1 vaccines marketed for prevention of respiratory disease may reduce viral shedding but are not protective against developing the neurological form of the disease in the vaccinated animal.

Additional information