Washington State Veterinarian Joe Baker, DVM, is urging owners to vaccinate their horses for West Nile virus (WNV).

Thirty-six horses tested positive for the virus in 2015. By comparison, only five cases were reported positive in 2014, all in Eastern Washington.

The state veterinarian’s office is part of the Washington State Department of Agriculture (WSDA) and monitors cases of animal diseases, including West Nile virus. The West Nile virus vaccine has proven to be effective if administered to horses early enough for protection before mosquito season.

“The virus activity varies greatly from year to year, but the risks are real, so I recommend protecting your horses with West Nile virus vaccine,” Baker said. “Most active cases of West Nile virus in Washington tend to develop in the southcentral counties when warmer weather starts growing the mosquito population