California Confirms Equine WNV Cases

California animal health authorities confirmed the state's sixth case of equine West Nile virus (WNV) for 2013 on Aug. 13, according to a statement on the California Department of Food and Agriculture (CDFA) website.

"On Aug. 13, 2013, the CDFA Animal Health Branch confirmed one additional case of West Nile virus (in) a two-and-a-half month old Quarter Horse filly in Stanislaus County," the statement read. "Both mare and foal were unvaccinated. The positive filly is recovering."

The statement noted that WNV-positive horses were located in Kern, Riverside, Sacramento (2), and Stanislaus (2) counties, and that four of the six positive horses were euthanized.

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 United States Department of Agriculture Animal and Plant Health Inspection Service reported 627 cases of WNV in U.S. horses in 2012; 22 cases were reported last year in California.

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 eventing with her OTTB, Dorado.

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