The time to protect horses from West Nile virus (WNV) is now, said David Wong, DVM, MS, Dipl. ACVIM, assistant professor of equine medicine at Iowa State University’s Veterinary Medical Center.

“The peak of West Nile season is August and September,” said Wong. “Horse owners should have their animals vaccinated now to protect them against the virus.”

West Nile virus (WNV) is a mosquito-borne illness that first hit the East Coast in 1999 and spread west across the United States. The virus causes encephalitis (inflammation of the brain). Clinical signs of WNV infection in horses include ataxia (incoordination), lethargy, weakness, muscle twitching, and partial paralysis. Although there is no cure for WNV, there is an effective vaccine.

“The best protection against WNV is vaccination,” Wong said. “Horse owners should be vigilant about getting their animals regular booster shots to keep them protected. Wong also recommends that horse owners empty standing water from unused buckets and other areas around horses to reduce potential mosquito breeding sites. Mosquitoes are most active at dusk and dawn so, if possible, keep horses in the barns during those times to reduce the risk of exposure to infected mosquitoes