West Nile Virus (WNV) has been confirmed in the District of Sudbury, Ontario. On August 28, 2025, a 4 year old Quarter Horse mare was noted by the owner to have difficulty loping. Signs progressed to dog-sitting in the paddock, mild ataxia, mildly weak tail pull and hyperesthesia. The mare was treated with anti-inflammatories and is recovering. The horse was not vaccinated against WNV.
This is the seventh 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