West Nile Virus Confirmed in Yakima County Horse
A case of West Nile virus, a potentially fatal disease in horses, has been confirmed in a Yakima County horse. The owner of a 7-year-old Quarter horse gelding is monitoring the horse's progress for recovery. Other than being supportive, the Washington State Department of Agriculture says there is no effective treatment for the horse.
The horse, recently pastured in Outlook, had no history of travel out of the area and has no vaccination history.
The Washington Animal Disease Diagnostic Laboratory in Pullman reported the positive test results to the State Veterinarian’s Office on Sept. 25. It is the only confirmed case of West Nile virus in a Washington horse this year.
West Nile virus is spread by mosquitoes that have fed on infected birds. The disease sickens people, horses, birds and other animals, but it does not spread from horses to people or other animals.
West Nile virus is fatal to horses in about a third of the cases where clinical signs are apparent, although most horses do not become ill and show no symptoms at all. Horses that do become ill can appear to be displaying loss of coordination, loss of appetite, confusion, fever, stiffness, and muscle weakness, particularly in their hindquarters.
Washington had 72 West Nile virus cases in horses in 2009, but none in 2010 or 2011. Last year, a horse pastured near Grandview was euthanized after it became ill with the disease.
The State Veterinarian’s Office recommends spring as the best time to vaccinate horses against West Nile virus or obtain booster shots. Veterinarians who learn of potential West Nile Virus cases in horses or other animals should contact the State Veterinarian’s Office at (360) 902-1881.