Protect Horses Against Mosquito-Borne Diseases

Several equine neurologic diseases are spread by mosquitoes. These include West Nile virus, eastern equine encephalomyelitis, and western equine encephalomyelitis in North America, and Ross River virus, Kunjin virus, and Murray Valley encephalitis virus in Australia.

Horse owners can follow these management steps to reduce the risk for these diseases.

1. Vaccinate. Check with a veterinarian to determine which mosquito-borne illnesses can be prevented by vaccination. The best time of year to vaccinate and the number of boosters per year will vary based on climate, anticipated size of the local mosquito population, and other factors. Remember that it takes some time for the horse to develop full immunity after being vaccinated, so injections should be scheduled well before the onset of warm weather.

2. Eliminate breeding areas. Mosquitoes lay eggs in still water, and only a small amount of water is needed. Drinking bowls for pets, birdbaths, water standing in a blocked gutter, and storm drainage in a shallow ditch or tire track are all ideal breeding areas. Water containers should be emptied and refilled daily to prevent development of larvae, and frequent property surveys should be conducted to find and deal with all standing water near barns and pastures.

3. Think about turnout places and times. Though mosquitoes can appear at any time of the day, they are most active at dawn and dusk. These insects don’t like moving air and will be somewhat less likely to bite horses that are kept in barns equipped with fans to keep the air stirring. If possible, horses should be turned out in fields that are not close to swampy or wet areas.

4. Use sprays, wipes, and sheets. Physical or chemical barriers will help to keep mosquitoes from landing on a horse’s skin. Insect-repelling sprays and wipes need to be applied frequently for the best effectiveness. Fly sheets, scrim leg wraps, and mesh facemasks also offer some protection.