West Nile Virus can affect humans, horses, and many types of birds. It is carried by mosquitoes, which become carriers by feeding on infected birds. As of January 2004, the CDC reports only Washington, Oregon, Alaska, and Hawaii have had no human cases of West Nile Virus. There have been no confirmed cases of the virus in Oregon horses, but officials expect that to change this year.

West Nile Affects Equines More Than Other Animals

Symptoms include: loss of appetite, loss of coordination, confusion, fever, stiffness, muscle tremors, and weakness. About one-third of horses that become ill from the West Nile Virus will die

Minimize the Threat of Exposure

The best way to minimize the threat of West Nile Virus to your horses—and to yourself—is to control the mosquito populations and prevent exposure to them. Eliminate the sources of standing water that can serve as a breeding ground for mosquitoes, including old tires, buckets, and other containers. Change water in troughs weekly. Use forced air fans in barns to keep the mosquitoes at bay.

Now is the Time to Minimize

The vaccine requires two doses given three to six weeks apart. Immunity may not be achieved until up to six weeks after the second dose, and some horses may require a third vaccination. An annual booster should be given prior to the start of the mosquito season in your area.