The 25-year-old Swift County mare had no documented history of WNV vaccination. | Photo: Wikimedia Commons

The Minnesota Board of Animal Health confirmed that a 25-year-old Swift County mare’s owners reported the horse ill in the evening and, by the following morning, she was unable to rise due to the quick progression of neurological signs. The attending veterinarian euthanized the mare due to her clinical signs. The horse had no documented history of West Nile virus (WNV) vaccination.

A blood sample submitted to the University of Minnesota Veterinary Diagnostic Laboratory (MVDL) by the veterinarian and tested using a Plaque Reduction Neutralization Test (PRNT) confirmed exposure to WNV.

Three weeks before this case, another horse on the same property showed similar clinical signs and was euthanized but not tested for WNV. Three horses still on the property appear healthy, and the owner indicated intent to vaccinate them