Equine herpes myeloencephalopathy has been confirmed in the Regional Municipality of Waterloo, Ontario. On October 28, 2025, a 17 year old Thoroughbred mare was examined by a veterinarian for limb edema ("stocked up" ) and was walking stiffly. This progressed to difficulty urinating and ataxia within hours. She was referred to an equine hospital where she was diagnosed with EHV-1 neurologic disease (equine herpes myeloencephalopathy) on October 29, 2025. The horse is affected and alive.
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.