Horses hit hard with West Nile virus in northeastern WA

Mike Louisell
Communications

Photo credit: Erin Danzer

Ten confirmed cases of West Nile Virus in horses have been detected so far this year in Washington, with the most recent cases in Stevens, Pend Oreille, Lincoln and Spokane counties. Warmer weather seems to have prompted the spread of mosquitoes carrying the West Nile virus into these northeastern parts of Washington.

The first case of the year came in late July involving a horse in Grandview, Yakima County, the state’s traditional hotspot for the West Nile virus. Since then, the Washington Animal Disease Diagnostic Laboratory (WADDL), operated by Washington State University in Pullman, has reported nine additional horse cases to WSDA.

The cases include:

• A horse in Creston, Lincoln County, in guarded condition. It had not been vaccinated for West Nile virus.
• A horse in Sprague, Lincoln County, in fair condition. It was vaccinated as a foal and yearling. 
• A horse near Elk, Stevens County, has been euthanized. It was not vaccinated.
• A horse in Kettle Falls, Stevens County, in guarded condition. It was not vaccinated.
• A horse in Colville, Stevens County, in fair condition. It was vaccinated.
• A horse in Newport, Pend Oreille County, is in fair condition. It was not vaccinated.
• A horse in Cheney, Spokane County, is in fair to good condition. It was not vaccinated.
• A horse in Cheney, Spokane County, died recently. Tissue tested positive for West Nile virus. Vaccination history unknown.
• A horse in Deer Park, Spokane County, is in fair condition. It was not vaccinated.
• The horse in Grandview, Yakima County was showing neurologic signs including stumbling and difficulties eating when the case was reported in late July. It was not vaccinated. It was the first horse report for 2016.

Washington had 36 confirmed cases of horses with West Nile virus last year, leading the nation with nearly 17 percent of confirmed equine cases. The 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 risk of a horse becoming ill lingers into fall.

Vaccinations against West Nile virus and reducing mosquito populations are the main strategies for protecting your horse. Spring is the best time for the vaccination but some veterinarians say it’s never too late to vaccinate for some protection against the virus.

Other tips include:
• Remove standing water from yards and barns that can serve as a breeding ground for mosquitoes, including old tires and garbage that may be rain soaked.
• Change water at least weekly in troughs or bird baths.
• Keep horses in stalls or screened areas during early morning and evening hours when mosquitoes are most active.
• Put fans inside bars and stalls to maintain air movement.

Visit our West Nile virus webpage for more on protecting your horse against this disease.