Equine herpes myeloencephalopathy has been confirmed in Dufferin County, Ontario. On March 31, 2026, a 14 year old Thoroughbred mare was found down in the field. She was assisted into the barn and then into isolation where she became recumbent with urinary incontinence. Her condition worsened and she was euthanized April 1, 2026. Blood and nasal swab samples were positive for equine herpesvirus 1 (EHV-1) by PCR. Three additional horses were exposed.
The facility owner, working with their veterinarian, has instituted voluntary animal movement restrictions and biosecurity protocols. To see past and present EHV-1 neurologic (EHM) cases in Ontario go to: https://www.oahn.ca/resources/ontario-equine-disease-alerts/ and enter the disease surveillance portal.