Franklin Co., Wash., Horse Euthanized after Contracting WNV

Franklin Co., Wash., Horse Euthanized after Contracting WNV

WNV is a viral disease transmitted to horses by infected mosquitoes.

Photo: Photos.com

A 10-year old mare from north Pasco is the second case of equine West Nile virus (WNV) reported in Washington this year, according to an Oct. 10 statement from the Washington State Department of Agriculture. The horse was euthanized.

The horse was not vaccinated for the disease and had not left the state. Washington State University’s Animal Disease Diagnostic Laboratory in Pullman reported the positive test results to the state veterinarian’s office earlier this week.

The only other confirmed case of WNV in a Washington horse this year was reported in late September for a horse pastured in Outlook in Yakima County

“A killing frost will reduce the likelihood of further cases for the year,” said Acting State Veterinarian Paul Kohrs, DVM. “Horse owners in areas of the state where this disease will overwinter should consider vaccinating for West Nile in 2014 at least a month before the onset of the mosquito season.”

WNV is a viral disease transmitted to horses by 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 drowsiness; propulsive walking (driving or pushing forward, often without control); and "spinal" signs, including asymmetrical weakness. Some horses show asymmetrical or symmetrical ataxia (incoordination). Equine mortality rate can be as high as 30-40%.

Washington had 72 equine WNV cases in 2009, but none in 2010 or 2011. In 2012 a horse pastured near Grandview was euthanized after it contracted the disease.

Veterinarians who learn of potential WNV cases in horses or other animals should contact the state veterinarian’s office at 360/902-188.

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