Kentucky animal health officials have confirmed the commonwealth’s third case of equine West Nile virus (WNV) in 2012, according to a statement from Kentucky Equine Programs Manager E.S. "Rusty" Ford.

The affected horse–an unvaccinated 16-month-old Tennessee Walking Horse colt from Warren County–began showing clinical signs on Aug. 13. He presented with inappetance, lethargy, and rear limb ataxia. Diagnostic tests returned today (Aug. 17) indicated the colt was positive for WNV. As of today, his attending veterinarian reports the colt’s health is improving with treatment.

Officials confirmed Kentucky’s first equine WNV case of 2012 on Aug. 3; the affected horse–an unvaccinated yearling Thoroughbred filly from Henderson County–was euthanized Aug. 1. The second case was confirmed Aug 13; the affected horse–an unvaccinated 18-year-old Tennessee Walking Horse gelding from Laurel County–became recumbent and was euthanized Aug. 8.

Clinical signs for WNV include flulike signs, where the horse seems mildly anorexic and depressed; fine and coarse muscle and skin fasciculations (twitching); hyperesthesia (hypersensitivity to touch and sound); changes in mentation (mentality), when horses look like they are daydreaming or "just not with it"; occasional somnolence (drowsiness); propulsive walking (driving or pushing forward, often without control); and "spinal" signs, including asymmetrical weakness. Some horses show asymmetrical or symmetrical ataxia. Equine mortality rate can be as high as 30-40%