The Ontario Ministry of Agriculture Food and Rural Affairs has issued a disease advisory to Ontario equine veterinarians about West Nile virus (WNV), but not in response to cases of WNV in Ontario horses. In fact, to date, there have been no reported cases in horses in the province this year. However, no reported cases only means no horses have become sick and WNV infection has been considered and WNV testing has been performed. It doesn’t mean that no horses in the province have been infected, and as much as anything else, the advisory is a reminder to be aware of WNV and ensure that potential cases are properly tested.

While not anywhere near as bad as the situation in some US states, Ontario has had a larger than expected number of human WNV infections this year, and it’s reasonable to assume that many equine infections have (and will) also occurred. Since the end of August is typically the start of the WNV season in horses in Ontario, the next few weeks will tell us a lot about the state of this disease in horses in the province this year.