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State veterinarian: horse owners should vaccinate for West Nile virus

OLYMPIA — Washington’s state veterinarian is reminding horse owners that it is mosquito time and vaccinations or booster shots are needed to protect horses from West Nile virus (WNV). Veterinarians have had great success with vaccines offering protection against WNV, a potentially fatal disease in horses.

With warmer weather and mosquito season approaching, horse owners should plan to protect their horses as soon as possible even though no equine cases of WNV were confirmed here last year, says State Veterinarian Dr. Leonard Eldridge. Two human cases of WNV were reported last summer in Washington and health officials detected the virus in two dead birds and more than 100 mosquito samples.

Washington led the nation in confirmed equine cases in 2009 (72 cases) and 2008 (41 cases).

“Much as I’d like to, I can’t fully explain why we had such high figures for several years and zero horse cases confirmed in 2010,” Eldridge said. “I do believe West Nile virus is a continuing threat and getting the vaccine now can help horse owners avoid grief down the road. There is no guarantee the virus won’t return and there already have been reports of cases outside of Washington this year.”

WNV is spread by mosquitoes that have fed on an infected wild bird. The disease can sicken people, horses, many types of birds and other animals. Infected horses do not spread the disease to other horses or animals.

Eldridge said that the majority of WNV cases in horses are preventable with vaccination. Vaccinating a horse or getting the proper booster injections is the best way to help protect the animal and prevent greater expense from treating a horse infected by the disease. Infected horses that do become ill show a loss of coordination, loss of appetite, confusion, fever, stiffness and muscle weakness, particularly in the hindquarters.

“I’d urge horse owners to consult with their private veterinarian for recommendations on a complete immunization and animal health program,” Eldridge said. “Owners should not wait until positive cases are reported in their area, since it can take several weeks for an animal to be fully protected by a vaccine.”

Eldridge also recommends that horse owners take measures to reduce mosquito populations. Recommendations include:

• Removing standing water from yards and barns
• Removing old tires and garbage that may be rain soaked
• Changing water at least weekly in troughs or bird baths
• Keep horses in stalls or screened areas during the early morning and evening hours when mosquitoes are the most active and feeding.

Veterinarians who learn of potential WNV cases in horses or other animals should contact the State Veterinarian’s Office at (360) 902-1881.

State and local health departments, mosquito control districts, other state agencies and volunteers work together on environmental monitoring and prevention measures for the virus. Additional information on WNV can be found at the state Department of Health Web site (www.doh.wa.gov/WNV).

Note: The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service maintains a Web site showing states with West Nile virus equine cases in 2010 and earlier years.

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