Butte County officials are urging owners to vaccinate horses for West Nile virus (WNV), a mosquito-borne illness.

Horses are at higher risk for WNV because they spend most of their time outdoors, including dusk and dawn, when mosquitos capable of transmitting WNV are most active. Horses are often pastured in areas near standing water where mosquitos breed, such as ponds, troughs, and irrigation run-off.

Last year Butte County had more infected mosquitoes than previously reported. Officials expect the rate of WNV to be significant, as well.

Annual WNV vaccination is recommended for horses, ideally, prior to mosquito season, which runs May through October in Butte County. Several vaccines are available for horses, so it’s advisable to check with your veterinarian to discuss the best option for your horse