On Oct. 29, a 6-year-old Percheron mare in Christian County, Kentucky, tested positive for West Nile virus (WNV). The unvaccinated mare developed clinical signs on Oct. 21, including muscle fasciculations and recumbency. She is now deceased.
This is Kentucky’s 15th confirmed equine WNV case in 2025.
EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.
WNV 101
West Nile virus is transmitted to horses via bites from infected mosquitoes. Not all infected horses show clinical signs, but those that do can exhibit:
- Flulike signs, where the horse seems mildly anorexic and depressed;
- Fine and coarse muscle and skin fasciculation (involuntary twitching);
- Hyperesthesia (hypersensitivity to touch and sound);
- Changes in mentation (mental activity), when horses look like they’re daydreaming or “just not with it”;
- Occasional drowsiness;
- Propulsive walking (driving or pushing forward, often without control); and
- Spinal signs, including asymmetrical weakness; and
- Asymmetrical or symmetrical ataxia.
West Nile virus has no cure. However, some horses can recover with supportive care. Equine mortality rates can reach 30-40%…