The Ontario Ministry of Agriculture and Food and Rural Affairs (OMAFRA) was notified on September 23, 2021 regarding a positive test result for EHV-1 from a mare that was euthanized on September 20 due to acute neurologic disease (severe ataxia progressing to recumbency). The mare was located at a boarding facility in the Ottawa region. The facility owner voluntarily implemented movement restrictions on September 17, 2021 after a different mare was referred to a veterinary facility in another province for assessment and treatment of ataxia. The boarding facility is under veterinary supervision. At this time, no other horses have shown clinical signs related to EHV-1 infection.