Regional News

Washinton confirms first equine West Nile virus case of 2017

Aug 10, 2017

The Washington State Department of Agriculture (WSDA) was notified that a 10-year-old quarter horse in the town of Four Lakes, Spokane County, is the first horse in the state to contract West Nile virus this year. The horse, which was unvaccinated for the disease, is reported to have coordination problems with its rear legs and muscle tremors, but is improving.

Washington State University’s Washington Animal Disease Diagnostic Laboratory in Pullman reported the positive test results to WSDA’s State Veterinarian’s Office this week.

WSDA confirmed 27 equine West Nile virus cases last year. Seven of those horses died or were euthanized. In all, 10 counties reported West Nile virus cases involving horses last year, including Benton, Franklin, Grant, Kittitas, Lincoln, Okanogan, Pend Oreille, Spokane, Stevens and Yakima counties. Spokane County lead with eight cases.

“Horses can still benefit from first-time vaccinations or an annual booster vaccination,” State Veterinarian Dr. Brian Joseph said. “It’s never too late to vaccinate your horse, but it’s more effective to do it earlier than now.”

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 directly from horses to people or other animals.

The disease is fatal to horses in about a third of the cases in which clinical signs are apparent, although most horses do not become ill and show no symptoms. 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.

Prevention strategies

Spring is the best time to vaccinate horses against West Nile virus or obtain an annual booster shot. Besides vaccination, horse owners can reduce mosquito populations and their possible breeding areas. Recommendations include removing stagnant water sources, keeping horses inside during insects’ feeding times, typically early in the morning and evening. Consider using equine-approved mosquito repellants, place fans inside barns or stalls to maintain air movement, and avoid using incandescent bulbs inside stables at night.

Veterinarians who learn of potential West Nile virus cases in horses or other animals should contact the State Veterinarian’s Office at (360) 902-1878.