Oregon state veterinarian recommends West Nile vaccinations

Jun 3, 2011
by WLJ

Horse owners in Oregon are once again advised to help protect against West Nile Virus by vaccinating their animals and taking steps to control mosquitoes this spring and summer. State Veterinarian Don Hansen of the Oregon Department of Agriculture says it is very likely some cases of the disease will be reported in Oregon this year, and that owners of horses need to consider taking steps to protect their horses.

“Vaccination against the disease provides good protection against West Nile,” says Hansen. “It is important for horse owners to vaccinate animals before the mosquito season gets into high gear.”

The vaccine for horses is available through local veterinarians and many veterinary supply stores.

Oregon became one of the last states to report the presence of West Nile Virus when the disease was confirmed in 2004. The incidence of the virus in horses has dropped over the last couple of years. However, the risk is still present, especially following a wet spring in Oregon.

Insect control on individual animals remains a good preventative measure against the virus. Insect repellents applied to animals according to label directions, screened housing at night, and controlling exposure to mosquitoes at dusk and dawn can all work to limit the possibility of infection. Reduction of mosquito breeding sites is also effective in controlling the spread of the disease. Any source of stagnant water is important. Tires, wading pools, wheelbarrows, birdbaths, or wherever water can stand for more than four days is a potential breeding site. Local vector control districts can offer ad vice and assistance.

Infected wild birds are the source of West Nile Virus. Mosquitoes bite infected birds and then can potentially transmit the infection to horses and humans. The disease does not transmit from horse to horse or human to human. A bite by an infected mosquito is the only known route of transmission.

A low percentage of mosquitoes carry the virus and a low percentage of horses bitten by infected mosquitoes become ill. But a horse showing signs is a serious situation. The disease causes inflammation of the brain and about one-third of affected horses die. Symptoms include stumbling, lack of coordination, weakness in the legs, depression, muscle twitching, and death.

For more information, contact Don Hansen, state veterinarian, at 503/986- 4680. — WLJ