Trot Insider has received an update on the equine herpes outbreak reported from a facility in Northumberland County, Ont. last week.

The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) learned on April 16 that a horse had been removed from the Northumberland facility where cases of equine herpes myeloencephalopathy (EHM)—caused by equine herpesvirus-1 (EHV-1)—have been diagnosed. Shipment of the horse, which is now located at a vacant farm in the Municipality of Kawartha Lakes, is contrary to the veteraniary advice and the voluntary animal movement restrictions implemented by the facility owner.

OMAFRA reminds horse owners that it is critical to abide by the biosecurity protocols and animal movement restrictions in place when EHM is diagnosed from a facility. All protocols aim to curb the transmission of EHV-1, which risks spreading to other farms and horses if owners decide to ship a carrier of—or a horse potentially exposed to—the virus. In 2021, 12 facilities in Ontario have been affected by EHV-1 and all owners abided by the protocols in place.

As of April 16, the Equine Disease Communication Center only reports three confirmed cases of EHV-1 from the Northumberland outbreak, with one of those cases diagnosed in a mare from neighboring Durham County that had left the facility on April 1.

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

EHV-1 infection is immediately notifiable by laboratories to OMAFRA under the Animal Health Act. 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.

Because a fever (greater than 101.5 °F or 38.6 °C) may be the first indication of infection, 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 this from other serious diseases such as rabies.

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 people and horses where EHV-1 has been diagnosed. Any person leaving a facility to care for or be in contact with horses elsewhere should change their clothes, shoes/boots and wash their hands before leaving the property. 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.

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 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.

► OMAFRA - Preventing Disease Spread - Personal Hygiene and Disinfectants around Horse Barns

► OMAFRA - Horses - Health Management and Biosecurity

► CFIA - National Farm and Facility Level Biosecurity Standard for the Equine Sector

► Equine Guelph - Equine Biosecurity Risk Calculator

► Alberta Veterinary Medical Association and Alberta Equestrian Federation - Equine Biosecurity Principles and Best Practices

(with files from OMAFRA)