News Release
California Department of Food and Agriculture
Media Contact:
Steve Lyle, Office of Public Affairs, (916) 654-0462,
Release #04-022
Eight cases in horses so far this year, five deaths

SACRAMENTO – Eight horses in California have contracted West Nile Virus in recent weeks, underscoring the need for horse owners to check with their veterinarian about vaccinations and to practice mosquito control measures. Five of the horses have been euthanized. None of the five had been vaccinated.

Seven of the cases were in Riverside County. The other case was in San Bernardino County. The outbreak of the disease is likely to continue into late fall.

“West Nile Virus vaccinations for horses have never been more important,” said California State Veterinarian Dr. Richard Breitmeyer. “If people get the necessary booster shots for their horses now, or even just start the vaccination series, horses that may otherwise die can still be protected this season. Horse owners should contact their veterinarian as soon as possible.”

Signs of West Nile Virus include stumbling, staggering, wobbling, weakness, muscle twitching or inability to stand. Horses contract the disease from carrier mosquitoes and are not contagious to other horses or to people. Not every horse exposed to the virus will develop symptoms. Of the horses that do, approximately 30 percent will die.   

CDFA has collaborated with state, federal and local agencies to detect and respond to the disease in California. CDFA has recently produced and distributed public service announcements about West Nile Virus and has taken a public education program directly to the equine community over the last several years. More information is available online at



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California Department of Food and Agriculture Office of Public Affairs
1220 N St., Ste. 214, Sacramento, CA 95814