West Nile virus (WNV) has been confirmed in one horse in Kittitas County, Washington.
The 14-year-old Quarter Horse gelding did not travel outside of Kittitas County, the Washington State Department of Health confirmed. This is the second confirmed equine case of WNV in Kittitas County; the first case was confirmed in 2008.
The Washington State Department of Health indicates that, statewide, WNV infections have been identified in 10 horses in Kittitas County, Yakima County (2), Grant County (2), Benton County (2), Lincoln County, Adams County, and Franklin County) thus far in 2015. In addition, at press time, there have been 14 cases of WNV in humans in Washington 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%.
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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 accura