May 20, 2024
Vaccinations Help Protect Horses by Lowering the Risk of Mosquito-Borne Illnesses
Virginia Horse owners should consult with their veterinarian regarding West Nile Virus and Eastern Equine Encephalitis vaccinations
Contact: Michael Wallace

Mosquito season is back in most areas of Virginia. That means it’s time to vaccinate your horses against mosquito-borne illnesses, such as West Nile Virus and Eastern Equine Encephalitis.

Eastern Equine Encephalitis, also called "sleeping sickness,” causes inflammation or swelling of the brain and spinal cord. Symptoms include impaired vision, aimless wandering, head pressing, circling, inability to swallow, irregular staggering gait, paralysis, convulsions, and death. West Nile Virus typically causes inflammation of the brain which leads to a loss of coordination, lack of interest in their surroundings and loss of appetite and can cause the horse to go down and be unable to get up without help.

As the mortality rate for horses with West Nile Virus is 30 percent and up to 90 percent for Eastern Equine Encephalitis. The Virginia Department of Agriculture and Consumer Services (VDACS) encourages equine owners to contact their veterinarian to schedule vaccinations for these diseases.

“Prevention is key to equine health and vaccinations are a great way to provide protection. Vaccinations may be effective for up to a year; however, many veterinarians may recommend vaccination every six months in areas where the disease occurs frequently,” said Dr. Charles Broaddus, VDACS State Veterinarian. “For the vaccine to be effective, it must be given at least two weeks before the horse is exposed to the virus. To stimulate full immunity, horses must be vaccinated twice, about 30 days apart, during the first year of vaccination.”

Humans cannot become infected with Eastern Equine Encephalitis or West Nile Virus by handling an infected horse, nor can a horse acquire the virus directly from another infected horse. However, the presence of an infected horse in an area indicates that mosquitoes carrying these viruses are present, and those insects pose a threat to both humans and horses. Other mosquito prevention methods include:

• Dumping or draining standing water breeding sites for mosquitoes, such as containers and puddles.
• Using insect repellents and removing animals from mosquito-infested areas during peak biting times, usually dusk to dawn.
• Turning off the lights in and around the barn at night.

For more information on WNV or EEE, contact the VDACS Office of Veterinary Services at 804.786.2483 or visit vdacs.virginia.gov/animals-animal-health.shtml.

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