Mosquito-Borne Illness Doesn’t Horse Around

The tiny mosquito can have a huge impact on your horse’s health. Mosquitoes can transmit Eastern Equine Encephalitis (EEE), a virus that is usually fatal. The disease is most prevalent in the southeastern U.S. during late summer and early fall.

EEE causes inflammation of the brain and spinal cord, and there is no cure.

About 90 percent of horses that contract EEE will die from the disease, even if they receive medical care. Early signs of EEE can occur one to three days after transmission and include depression, loss of appetite and possible fever. As the inflammation of the brain and spinal cord increase, horses develop signs of neurologic disease (i.e. severe depression, circling, irregular gait, headpressing, blindness, seizures, and/or paralysis).

According to Dr. Katie Sheats, an equine specialist at NC State, prevention is key. There is a safe, effective vaccination for EEE, but it is important that the vaccine regimen be properly followed. Horses receiving these vaccinations for the first time should receive a second vaccination four weeks later and then a booster twice annually. In the Southeast, booster vaccinations should be given once in early spring and again in later summer or early fall. Pregnant horses and foals have a slightly different schedule, so check with your veterinarian.

Additionally, owners can reduce horses’ exposure to mosquitoes by eliminating sources of standing water like puddles, installing fans in stalls to maintain air movement, applying permethrin-based insecticides to horses and even using fly sheets to protect horses during pasture turn-out.

And human beings are not immune – although rare, EEE can affect people. So be sure to take measures to avoid mosquito exposure.

Important Note: Any horse exhibiting the behaviors described above should be seen by a veterinarian. Samples from horses suspected of having EEE should be submitted to state diagnostic labs. Reporting this disease to the state veterinarian is mandatory.