MADISON, Wis. – The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) confirms that an unvaccinated yearling Standardbred gelding in Trempealeau County has tested positive for West Nile Virus (WNV). It is the state’s first confirmed case of WNV in a horse this year.
Symptoms of WNV in horses include fever, incoordination, hind-end weakness, depression, loss of appetite, muscle tremors, teeth grinding, inability to swallow, head pressing, excessive sweating, and going down with an inability to rise. The disease can cause brain inflammation in horses and people, and it is fatal in 30% to 40% of horses showing signs of illness.
While humans can be infected by WNV, the virus does not pass directly between people and horses. The only route of transmission is from a mosquito bite. Mosquitoes transmit the virus from birds, which serve as natural reservoirs for WNV. Since humans and equines acquire WNV from mosquitoes, the threat of WNV normally occurs when mosquitoes are most active, from mid-to-late summer until the first killing frost.
DATCP encourages equine owners to speak with their veterinarians about vaccinating their horses for WNV. The American Association of Equine Practitioners (AAEP) recommends vaccinating for both WNV and Eastern Equine Encephalitis as part of the core vaccine protocol, meaning all horses should be vaccinated for these diseases.
Horse owners also can protect their animals by limiting exposure to mosquitoes. More information on WNV and tips for minimizing mosquito exposure can be found at https://datcp.wi.gov/Pages/Programs_Services/HorsesEEEWNV.aspx.