Protecting horses against Eastern Equine Encephalomyelitis
Question: How does a horse get Eastern Equine Encephalomyelitis? Is there something I can do to protect my horse against it?
Answer: A viral disease that affects the central nervous system of many species of animals, Eastern Equine Encephalomyelitis is most often detected in birds and horses. Mosquitoes that have become infected by feeding on virus-carrying birds are responsible for transmitting the disease to other birds, horses and people.
Although the name implies it is an "eastern" disease, cases of EEE have been reported in all states east of the Mississippi River and also in a number of western states. The disease took a huge toll on horses in southwest Michigan in 2010, with 133 reported cases. Officials there attributed the outbreak, which was the worst in 30 years, to a huge population of mosquitoes and a growing number of unvaccinated horses.
The clinical signs of EEE are varied, but usually begin with fever, depression and listlessness. Those signs then progress to more serious neurologic signs such as lack of coordination, stumbling, circling, head pressing, coma and usually death.
Unfortunately, once a horse develops these neurologic signs, the disease is fatal 90 percent of the time.
In 2009, Merial introduced RECOMBITEK rWNV-EWT, a combination vaccine that offers aid in preventing against not only EEE, but also West Nile virus, Western Equine Encephalitis virus and tetanus. The American Association of Equine Practitioners considers all of these to be core diseases for which all horses in the United States should be vaccinated.
Besides vaccination, you can also practice good mosquito population management techniques. Minimize the breeding environment by removing sources of standing water such as water buckets, plastic containers, water troughs, wheelbarrows and any other containers or places where water might pool and stagnate.
Decreasing your horse's exposure to mosquitoes is an additional precaution. During peak season, horses should be stabled at dawn and dusk, which are mosquito feeding times. Insect screens and fans can also help minimize mosquito access to your horse.
While the best way to help prevent equine diseases like EEE is to vaccinate, horse owners can also take advantage of Merial's new free "Outbreak Alert" program, which will tell them about the presence of confirmed equine disease in their area. Those who sign up at www.outbreak-alert.com will receive text and/or e-mail notification of disease threats within a 250-mile radius of any ZIP code provided The site also includes maps showing the presence of disease throughout the country and general information about common equine diseases.
Information provided by: April Knudson, DVM, an equine specialist with Merial Veterinary Services. She has a special interest in sport horse lameness and internal medicine. She holds a doctor of veterinary medicine from the University of California-Davis.