Oklahoma Horse Owners Encouraged to Vaccinate Against WNV

Oklahoma Horse Owners Encouraged to Vaccinate Against WNV

Horses that have not already been vaccinated this year for EEE or other mosquito-borne diseases are at greater risk, but it is not too late to vaccinate.

Photo: Anne M. Eberhardt/The Horse

The Oklahoma Department of Agriculture, Food, and Forestry’s Animal Industry Services is encouraging horse owners to take precautions and vaccinate their animals to protect against the West Nile virus (WNV) and Eastern equine encephalitis (EEE).

In years past, Oklahoma averaged approximately 40 equine cases per year of the potentially deadly mosquito-borne diseases. There were no reported human deaths in 2016; however, the state health department recently reported the first human West Nile death in 2017.

The bird population serves as the reservoir for the viruses and mosquitos then transmit the virus to horses and humans. Mosquitos most likely to transmit WNV and EEE lay their eggs in small pools of standing water. Once the adult mosquito hatches, they can become infected with both WNV and EEE after feeding on an infected host, such as a bird carrying the virus. Within 10 to 14 days, the mosquito can transmit the virus to both humans and horses.

“Signs of West Nile virus include weakness, fever, incoordination, seizures, blindness, and difficulty getting up,” said Assistant State Veterinarian Michael Herrin, DVM. “There are several vaccines available, and we are encouraging horse owners to visit their veterinarians and determine the vaccination protocol that will best fit their operations.”

Horses that have not already been vaccinated this year for WNV or EEE are at greater risk, but it is not too late to vaccinate. Horses that have been vaccinated in past years will need an annual booster shot; in areas with a long mosquito season, veterinarians might recommend two boosters per year—one in the spring and one in the fall. However, if an owner did not vaccinate their animal in previous years, the horse will need the two-shot vaccination series within a three- to six-week period.

In addition to vaccinations, horse owners also need to reduce the mosquito populations and their possible breeding areas. Recommendations include removing stagnant water sources, keeping animals inside during the bugs’ feeding times, which are typically early in the morning and evening, and using mosquito repellents.

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