For horses kept in the Tidewater area of Virginia, veterinarians recommend vaccination against mosquito-borne disease every six months. Anyone keeping horses in mosquito-infested areas of North America should heed this recommendation.

The Virginia Department of Agriculture and Consumer Services (VDACS) today announced the second case of Eastern Equine Encephalitis (EEE) in a Virginia horse this year. Both cases were in Suffolk County, a mosquito-breeding area. Fortunately, the horse, a Thoroughbred, had been vaccinated and is recovering.

Symptoms include impaired vision, aimless wandering, head pressing, circling, inability to swallow, irregular staggering gait, paralysis, convulsions and death. Once a horse has been bitten by an infected mosquito, it may take three to ten days for signs of the disease to appear.

Without vaccination, the mortality rate for horses is high—from eight to ninety percent. Vaccines are generally effective in drastically reducing the incidence of both EEE and West Nile Virus (WNV) in horses.

To stimulate full immunity, horses must be vaccinated twice in the first year of vaccination, about thirty days apart. The vaccines are effective for six to twelve months, so horses should be re-vaccinated at least annually.

For more information, horse owners may contact VDACS’ Office of the State Veterinarian at 804.692.0601 or consult their local veterinarian.

Posted July 12, 2016