The Equine Disease Communication Center has reported five new cases of equine West Nile virus (WNV) in Utah. Three horses in Cache County and two horses in Weber County have tested positive for the virus.
EDCC Health Watch is a marketing program by Equine Network that uses information from the Equine Disease Communication Center (EDCC) to create and share verified equine disease reports. The EDCC is a nonprofit organization supported by industry donations to provide accessible infectious disease information.
WNV 101
West Nile virus is transmitted to horses through mosquito bites. Symptoms in infected horses may include flulike signs, muscle twitching, hypersensitivity, changes in mentation, drowsiness, propulsive walking, and ataxia.
- Flulike signs, mild anorexia, and depression;
- Muscle and skin twitching;
- Hypersensitivity to touch and sound;
- Changes in mental activity;
- Occasional drowsiness;
- Propulsive walking;
- Spinal weakness;
- Ataxia.
There is no cure for West Nile virus in horses, but supportive care can help some recover. Mortality rates can be as high as 30-40%.
Vaccines have been shown to be effective in preventing WNV. Horses should receive annual booster shots, with some veterinarians recommending biannual boosters in areas with prolonged mosquito seasons. Unvaccinated horses will require a two-shot series within a three- to six-week period.
In addition to vaccinations, owners can reduce mosquito exposure by eliminating stagnant water sources, cleaning water containers regularly, keeping horses indoors during peak mosquito times, and using approved mosquito repellents for horses.

