“The California Department of Food and Agriculture (CDFA) has confirmed the first case of West Nile virus (WNV) in a horse in 2012, according to a statement on the organization’s website.
“On July 26, 2012, the CDFA Animal Health Branch confirmed the first positive equine West Nile virus case in Stanislaus County,” the statement read. “The 2-year-old unvaccinated filly displaying severe neurologic signs was euthanized.”
In a blog post published today (July 31), California State Veterinarian Annette Whiteford, DVM, said, “Each year, we find ourselves using this sad occasion to remind horse owners to have their animals vaccinated. It offers them maximum protection against the disease. And once vaccinations occur, horse owners should be checking regularly with their veterinarians to make sure they stay current.”
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 USDA Animal and Plant Health Inspection Service reported 83 cases of WNV in U.S. horses in 2011, with 15 of those cases being identified in California horses.”