West Nile virus tips for horses, donkeys and mules

West Nile virus has had a significant impact on the health of horses, donkeys and mules. Although the virus is no longer an emerging disease in the United States, it remains a serious threat. As many as 30 to 40 percent of equids that develop signs of WNV infection die.

Equine owners should work with their veterinarians to vaccinate their animals against West Nile virus. Vaccination is the most effective way to protect horses, donkeys and mules from the virus. The virus is spread through the bite of infected mosquitoes, and the mosquito acquires the virus most commonly from infected birds. WNV is not spread as a result of contact with an infected horse.

Equines with WNV may need to be hospitalized and may need assistance with a sling to stand for a period of time. Treatments include anti-inflammatory drugs and fluids, and sometimes products that provide antibodies to the virus are appropriate.

In temperate climates, most equine WNV cases are recognized in the late summer. In addition to vaccinating, the chances of a horse becoming infected can be reduced by minimizing their exposure to mosquitoes.

Useful tips include keeping them indoors during dawn and dusk when mosquitoes are most active; eliminate standing water near horses and change birdbath water and water in tanks at least weekly; use a fan on stabled horses; use insect repellents with permethrin or 35 percent DEET; install incandescent bulbs around the inside and outside of the stable; remove any dead birds from the area.

Several different types of vaccinations for the prevention of WNV infection in equids are available through veterinarians. Vaccine guidelines are available at the American Association of Equine Practitioners website at www.aaep.org.

This information is provided as a service of Colorado State University veterinarians.

Date: 9/4/09