New York Horse Contracts West Nile Virus

The unvaccinated 8-year-old stallion from Cayuga County was euthanized on July 27.
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A horse in Cayuga County, New York, has died after testing positive for West Nile virus (WNV), the Equine Disease Communication Center (EDCC) reported Aug. 5.

“An unvaccinated 8-year-old stallion was diagnosed with WNV earlier this week,” the EDCC statement said.

The EDCC said the owner first noticed clinical signs on July 25. The horse was holding his head in a fixed, low position and developed fever, ataxia (incoordination), and blindness, the statement said. Despite veterinary treatment, the horse’s condition worsened and he was euthanized on July 27. Tests for Eastern equine encephalitis and rabies were negative, the statement said.

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; 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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Written by:

Erica Larson, former news editor for The Horse, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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