Farm Talk

August 4, 2009

EEE report good reason to vaccinate horses

by Donald Stotts

Recent reports of several horses in Texas dying from Eastern Equine Encephalitis serve as a reminder that Oklahoma horse owners should make sure their horses are vaccinated.

“We’ve always recommended that horse owners in Oklahoma vaccinate for it as a preventive measure,” said Dr. Carolynn MacAllister, Oklahoma State University Cooperative Extension veterinarian.

The State Veterinarian’s Office with the Oklahoma Department of Agriculture, Food and Forestry is unaware of any EEE cases in Oklahoma as of this writing.

EEE is spread by mosquitoes. OSU veterinarians and equine specialists recommend that horses be vaccinated to protect against mosquito-born diseases such as West Nile Virus and Eastern and Western Equine Encephalitis as part of their routine health care program.

“It takes a week to 10 days after vaccination for a horse to develop protective antibodies,” she said. “Booster shots should be administered as directed to maintain the highest level of protection.”

Symptoms of EEE include confusion, erratic behavior, staggering and even collapsing. A blood test is needed to confirm the diagnosis. Approximately half of infected horses will survive provided they get timely and appropriate supportive care.

“An infected horse will not spread EEE, WEE or West Nile Virus to humans,” MacAllister said. “Humans can be infected with these diseases, but the source of the virus is not horses. Rather, an infected horse acts as a sentinel that the disease may be in your area. Mosquitoes are the culprit.”

Dave Freeman, OSU Cooperative Extension equine specialist, said there are management steps that horse owners should take in addition to vaccination of animals.

“Police your property and drain sources of stagnant water where mosquitoes can breed,” he said. “Make sure to use approved products that kill mosquito larvae in water sources such as troughs, ponds and even fountains, if applicable, taking care to always follow label directions. Consider sheltering horses at night.”

And don’t forget the personal management: Avoid being outside at night or at dawn, when mosquitoes are most active, and wear protective clothing such as long sleeves and pants whenever possible. Protect yourself from mosquito bites with a repellant containing DEET.

“It’s important not to panic just because EEE cases have been confirmed across the Red River,” MacAllister said. “Having grown up in Texas, I can attest to it being a problem that crops up from time to time, as it does in many southern states that have significant mosquito populations. The key is to practice good management, for your horse and yourself.”

In addition to Texas, EEE cases have been reported this year in Florida, Louisiana, Missouri and Virginia.