The return of West Nile virus to California this year is renewing calls for horse owners to make sure the animals are vaccinated.

So far in 2010, four horses have been diagnosed with the disease in Sacramento, San Joaquin, and Madera counties. The horses were unvaccinated or incompletely vaccinated.

“Outbreaks of West Nile virus are still a risk for horses,” said California State Veterinarian Richard Breitmeyer. “Horse owners should contact their veterinarians as soon as possible to ensure vaccination status is current. If people get the necessary shots for their horses now, the animals will have optimal protection against the disease.”

Signs of West Nile virus include stumbling, staggering, wobbling, weakness, muscle twitching, and the inability to stand.

Horses contract the disease from carrier mosquitoes and are not contagious to other horses or people. Not every horse exposed to the virus dies.

The California Department of Food and Agriculture is cooperating with the California Department of Public Health to detect and respond to the disease in California.

For more information: www.cdfa.ca.gov/ahfss/Animal_Health/WNV_Info.html.