Officials at the New York Department of Agriculture and Markets (NYDAM) have confirmed two horses with West Nile virus (WNV). The horses reside on farms in Lewis and Yates counties.

The Lewis County horse, an 8-year-old mare, began showing signs consistent with WNV on Sept. 18. Her signs included facial twitching, hyper-reactivity, dog sitting, and recumbency (down and unable to rise).

The horse from Yates County, a 13-year-old gelding, began experiencing clinical signs, which included hypersensitivity to touch, crossing his forelegs, severe agitation, and recumbency on Sept. 23.

Neither horse was vaccinated against WNV. Both are reportedly recovering.

About West Nile Virus

WNV transmission occurs when infected mosquitoes feed on animals, as well as humans, after having fed on infected birds.

Clinical signs of WNV in horses include:

• Mild anorexia and depression
• Fine and coarse muscle and skin fasciculation;
• Hyperesthesia (hypersensitivity to touch and sound);
• Changes in mentation (mentality), when horses look like they’re daydreaming or “just not with it”;
• Occasional drowsiness;
• Propulsive walking (driving or pushing forward, often without control);
• 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%. The American Association of Equine Practitioners includes WNV as one of the core diseases all horses should be vaccinated against at least annually.