Kentucky Reports Tenth Equine WNV Case of 2013

Kentucky Reports Tenth Equine WNV Case of 2013

For horses residing in the northern United States veterinarians recommend vaccinating in the spring prior to peak mosquito levels. In the south, where mosquito populations are present year-round, horses might be vaccinated more frequently.

Photo: Anne M. Eberhardt/The Horse

The Kentucky State Veterinarian's office announced today (Oct. 16) that a Union County horse has tested positive for West Nile virus (WNV), the tenth confirmed case of the virus in the commonwealth this year.

A statement from Kentucky Equine Programs manager E.S. "Rusty" Ford relayed that the 3-year-old Quarter Horse gelding began showing mild ataxia (incoordination) and fine muscle fasciculation (twitching) on Oct. 11. As of Oct 15, the gelding's condition was improving, and he has a favorable prognosis for recovery, the statement said.

"Through mid-October, we are continuing to see equine cases of West Nile virus develop, particularly in western Kentucky and in non-vaccinated animals," Ford said. "Each of the 10 cases diagnosed and reported in Kentucky this year involve animals that had not been immunized to prevent infection."

Nine of the WNV-affected horses are reportedly recovering or have recovered; one affected horse was euthanized.

WNV is a viral disease transmitted to horses by infected mosquitoes. Clinical signs of WNV include flulike signs, where the horse seems mildly anorexic and depressed; fine and coarse muscle and skin fasciculation; 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 rates can be as high as 30-40%.

Studies have shown that the WNV vaccine has a substantial effect on preventing disease. The American Association of Equine Practitioners (AAEP) recommends vaccinating all foals and horses against WNV. For horses residing in the northern United States veterinarians recommend vaccinating in the spring prior to peak mosquito levels. In the south, where mosquito populations are present year-round, horses might be vaccinated more frequently. In addition to geography, age and exposure play an important role in deciding how often to vaccinate horses. The AAEP's complete vaccination guidelines are available online

The United States Department of Agriculture Animal and Plant Health Inspection Service reported 627 cases of WNV in U.S. horses in 2012; 13 cases were reported last year in Kentucky.

About the Author

Erica Larson, News Editor

Erica Larson, news editor, 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 three-day eventing with her OTTB, Dorado.

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