Equine Health Solutions | Mosquitos Carry Deadly Diseases

Mosquitoes can transmit viruses that cause encephalitis or “sleeping sickness” infections in horses. These infections attack the brain (and sometimes the spinal cord), causing neurological damage or death. The three mosquito-borne encephalitic diseases of most concern to horse owners are West Nile virus, EEE and WEE.

West Nile virus has been found throughout the continental United States. It kills about one in three clinically affected horses.¹

Eastern equine encephalitis (EEE) is found primarily in the eastern United States and kills 75 to 90 percent of affected horses.²

Western equine encephalitis (WEE) is found primarily west of the Mississippi River and kills up to 50 percent of affected horses.²

Clinical signs for all three diseases are very similar, including:
Stumbling Wandering in circles Walking into objects Partial paralysis Fever Convulsions Coma

1. Larry A. Schuler, et al. Evaluation of an outbreak of West Nile virus infection in horses: 569 cases (2002). JAVMA, Vol. 225, No. 7, October 1, 2004.
2. Les Sellnow. Encephalitis: Many Causes, Deadly Outcome. The Horse. July 1, 2004.