As the weather warms up across the state and mosquitoes become more prevalent, the Washington State Department of Agriculture is advising owners to make sure their horse’s vaccination is current for protection against West Nile virus (WNV).

In August 2012, a two-year-old gelding pastured near Grandview, Wash., was euthanized after it became ill following a bite from a mosquito infected with WNV. The horse was not vaccinated for the disease.

“It was the only West Nile equine case reported to us last year, but there’s no way to predict the virus won’t return in force this year,” State Veterinarian Leonard Eldridge, DVM, said. “Outbreaks still present a risk.”

West Nile virus is fatal in about one-third of all horses that show symptoms. Horses that become ill show a loss of coordination, loss of appetite, confusion, fever, stiffness, and muscle weakness, particularly in the hindquarters. Infected horses do not spread West Nile virus to other horses or animals