New California Equine WNV Case Brings State Total to 18

The California Department of Food and Agriculture (CDFA) confirmed one additional case of equine West Nile virus (WNV) today (Sept. 24), according to a statement on the organization's website.

"On Sept. 24, 2012, the CDFA Animal Health Branch confirmed one additional case of WNV in an 18-month-old unvaccinated filly located in Fresno County," the statement read. "The horse is recovering."

"For 2012, a total of eighteen (California) horses have been confirmed positive for WNV," the statement continued. "The positive horses are located in the following counties Butte, Calaveras, Fresno (3), Glenn, Kern(2), Merced, Sacramento(2), San Joaquin (2), Shasta (3), Stanislaus and Yolo counties. Five of the positive horses have been euthanized.

"The CDFA continually monitors and investigates equine neurologic cases for the presence of WNV in California," the statement concluded. "The CDFA urges horse owners to consult their veterinarian concerning a WNV vaccination program to ensure maximum protection of their horses."

Clinical signs for WNV include flu-like 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 (incoordination on one or both sides, respectively). Equine mortality rate can be as high as 30-40%.

The American Association of Equine Practitioners recommends all horses be vaccinated against WNV at least annually and possibly more frequently, depending upon geographic location. Many veterinarians are urging horse owners to ensure their animals' WNV vaccines are up to date, given the rise in case numbers this year.

The USDA Animal and Plant Health Inspection Service reported 87 cases of WNV in U.S. horses in 2011, with 15 of those cases being identified in California horses.

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, and enjoys photography in her spare time.

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