During spring, summer, and fall months, the mosquito population increases and with that increase in population, the dangers of horses and humans becoming infected with mosquito-borne diseases also increases.
Blood engorged mosquito
Mosquitoes that have become infected by feeding on virus-carrying birds are responsible for transmitting diseases to other birds, horses and people.
© 2013 by PD-USGOV-HHS-CDC
April Knudson, DVM, is 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. Below, she answers a question about the danger of 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 (EEE) 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 last year, 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.1 Unfortunately, once a horse develops these neurologic signs, the disease is fatal 90 percent of the time.
Combination vaccines that offer aid in preventing not only EEE, but also West Nile virus (WNV), Western Equine Encephalitis (WEE) virus and tetanus are available. The American Association of Equine Practitioners (AAEP) 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 prevent equine diseases like EEE is to vaccinate, horse owners are encouraged to reduce the number of mosquitoes around their properties by eliminating standing water in yards and making sure all windows and doors have screens that are in good repair to prevent mosquitoes from getting inside. In addition,
- Dispose of used tires, tin cans, plastic containers, ceramic pots or similar containers in which water collects.
- Drill holes in the bottoms of recycling containers that are kept outdoors. Make sure roof gutters drain properly and clean clogged gutters in the spring and fall.
- Turn over plastic wading pools and wheelbarrows when not in use, and change the water in bird baths twice a week.
- Clean vegetation and debris from the edges of ponds.
- Clean and chlorinate swimming pools, outdoor saunas and hot tubs, and drain water from pool covers.
Eastern Equine Encephalitis is a viral disease spread by mosquitoes that can affect people and horses. People who are infected may suffer a range of symptoms, from no symptoms to a mild, flu-like illness with fever, headaches and fatigue to serious illness involving seizures and, in rare cases, coma and death.
Article is based on an edited press release provided by Merial which was acquired by Boehringer Ingelheim in 2017