West Nile Virus (WNV) has been confirmed in Grey County, Ontario. On September 20, 2025, a 3 year old Quarter Horse filly was referred to an equine hospital due to acute onset of neurologic signs (ataxia). The horse is recovering. The horse was not vaccinated against WNV.
This is the 8th confirmed case of equine WNV in Ontario this year. To see past and present WNV cases in Ontario go to: https://www.oahn.ca/resources/ontario-equine-disease-alerts/ and enter the disease surveillance portal.