A 2-year-old gelding in Benton County, Washington, tested positive for West Nile virus (WNV) after being severely ataxic and eventually passing away before confirmation. The horse was unvaccinated at the time.
EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.
WNV 101
West Nile virus is transmitted to horses via bites from infected mosquitoes. Symptoms include flulike signs, muscle twitching, hypersensitivity, changes in mentation, drowsiness, propulsive walking, and spinal signs. Mortality rates can be as high as 30-40% with no known cure, but some horses can recover with supportive care.
Vaccination is an effective prevention method for WNV. Horses should receive annual booster shots or two boosters annually in areas with prolonged mosquito seasons. Unvaccinated horses require a two-shot series. Owners should also take measures to reduce mosquito populations and limit exposure, such as removing stagnant water sources, cleaning water containers regularly, keeping animals indoors during peak mosquito activity times, and using approved mosquito repellents for horses.