Now is good time to vaccinate your horse for West Nile virus | Department of Agriculture

Published 3:42 pm Monday, April 13, 2015

As a mild winter has given way to spring and temperatures rise in our state, can mosquitoes be far behind? The Washington State Department of Agriculture (WSDA) is advising horse owners to make sure their horse’s vaccination is current for protection against West Nile virus.

The disease is potentially fatal to horses and is spread by mosquitoes that have fed on infected birds. While West Nile virus can sicken people, horses, birds and other animals, it does not spread from horses to people or other animals.

“With mosquito season approaching, now is the time to schedule a visit with your veterinarian to protect against West Nile virus,” said State Veterinarian Dr. Joe Baker. “Do it before mosquitoes are active since it takes time for the vaccine to provide maximum protection for your horse.”

Horses require two doses of the vaccine initially, and then boosters at least annually.

The virus appeared in at least five equine cases last year, including horses in Benton, Franklin, Grant, Okanogan and Yakima counties. The first case wasn’t reported until mid-August.

The disease 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. But horses that do become ill often display loss of coordination, loss of appetite, confusion, fever, stiffness, and muscle weakness, particularly in their hindquarters.

To reduce the risk, WSDA advises owners to keep horses indoors during the peak mosquito activity times of dawn and dusk, eliminate any sources of standing water nearby and even check areas where rain water may accumulate, like old tires or bird baths. It also helps to refresh the water in water troughs weekly.

Veterinarians who learn of potential West Nile virus cases should contact the State Veterinarian’s Office at (360) 902-1881.

Visit WSDA’s West Nile virus webpage or the state Department of Health for more information on the disease.