As spring brings warmer, wetter conditions ideal for mosquito activity, animal health officials are urging horse owners to vaccinate against West Nile virus (WNV) and Eastern Equine Encephalitis (EEE)—two deadly diseases spread by mosquitoes.

Even with relatively few cases last year, early detections as soon as January show the need for vigilance. Unvaccinated horses face a 90% mortality rate for EEE and 30–40% for WNV.

Vaccination is key—but mosquito control matters too. Mosquitoes like the black-tailed Culiseta melanura carry these viruses and thrive in swampy or stagnant water.

What owners should do:

• Vaccinate horses annually, ideally before peak mosquito season
• Drain stagnant water around barns and paddocks
• Report neurologic symptoms to your veterinarian immediately

Early symptoms may include stumbling, circling, depression, and muscle twitching. Fast action can save lives.