West Nile Virus is waking up again, a reminder to keep your horse up-to-date on vaccinations

Amber Betts
WSDA Communications

West Nile virus in Washington is back. Already this year several mosquito pools are testing positive for West Nile virus as well as confirmed human and equine cases.  

Mosquito pools around Washington
state have tested positive for West Nile Virus. 

Mosquito pools in Grant, Franklin, Walla Walla, and Yakima counties have been showing up with positive results for West Nile virus according to the Washington State Department of Health. Due to limited resources, DOH only monitors for West Nile virus in a few counties. This means the virus is likely widespread in our state beyond the above-mentioned counties.

In addition to the mosquito pools detected, there has been a human, two horses in the Yakima County, and one horse in Benton/Franklin County diagnosed with the disease. The status of the person diagnosed with the virus is unknown at this time.

One of the diagnosed horses was euthanized due to ataxia (the loss of full control of bodily movements) and becoming recumbent (the inability to get up without assistance). The vaccine history of the horse is unknown, however, the vaccine is very effective at prevention, and experts believe this horse was most likely unvaccinated or under-vaccinated.

Signs of West Nile virus in horses include: fever, a lack of coordination, urine dribbling, an inability to rise, muscle twitching, and staggering. Other symptoms can include: a fever of 102.5 degrees F or higher, discharge from eyes or nose, limb edema or swelling, spontaneous abortions, or neurologic signs such as an unsteady gait, weakness, and lack of tail tone.

Horses are diagnosed by symptoms and blood testing. There is no treatment except supportive anti-inflammatories.

Don’t wait, please vaccinate

WSDA field veterinarian Dr. Ben Smith said the disease is not always fatal to the infected horse, but most cases that do prove deadly occur in unvaccinated or incompletely vaccinated animals.

“Some animals recover in full, while others have neurological deficits for life or will be unable to get up and must be euthanized,” Dr. Smith said. “About 33 percent of those cases will not survive.”

If your horse is not vaccinated, it will take two injections three weeks apart and a yearly booster. It is never too late.  One vaccination usually will help decrease the severity of disease, but full protection needs a booster at the correct time.

“Please don’t wait,” Smith added. “This infection is very devastating and can be easily prevented with proper vaccination.”

West Nile virus is spread by mosquitoes that have fed on infected birds and while it can sicken people, horses, birds and other animals, it does not directly spread from horses to humans or other animals.

Veterinarians who diagnose potential West Nile virus cases should contact the State Veterinarian’s Office at (360) 902-1878.

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