The New Mexico Department of Health announced Aug. 20 a Valencia County horse has been diagnosed with West Nile virus (WNV) infection and is recovering.

“August and September are typically when we see the highest number of West Nile virus cases in both people and horses in New Mexico,” said Department of Health Secretary Retta Ward, MPH. “However, the mosquito populations are very high this year because of the extensive rainfall in many areas of the state.”

West Nile is transmitted to horses via bites from infected mosquitoes. 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%.

The clinical signs of WNV can be consistent with other important neurologic diseases such as equine encephalitis, rabies, and equine herpesvirus; therefore it is important to work with your veterinarian to get an accurate diagnosis through laboratory testing