Veterinarian: Keep Horses' Vaccines Current

Veterinarian: Keep Horses' Vaccines Current

“Now is an especially good time to vaccinate or give a booster on previously vaccinated horses," Parr said.

Photo: Erica Larson, News Editor

It’s mosquito-carried disease season and horses need to be protected. Boyd Parr, DVM, South Carolina state veterinarian and director of Clemson University Livestock Poultry Health (LPH), recommends owners keep their horses' vaccinations for Eastern equine encephalitis (EEE), West Nile virus (WNV), and rabies current.

“South Carolina’s first 2013 case of EEE was confirmed in June,” said Parr. “Now is an especially good time to vaccinate or give a booster on previously vaccinated horses. Vaccination is very important in our coastal counties because the majority of last year’s cases were identified there.”

In 2013, South Carolina led the country with 49 confirmed cases of equine EEE, which is a serious mosquito-borne illness in horses that also can affect humans. It is preventable by vaccination in horses. Horse owners should consult with their veterinarians to be sure vaccinations against both EEE and WNV are up-to-date.

None of the horses infected during 2013 had been vaccinated effectively according to a review of vaccination history reported to Clemson LPH.

The EEE virus is maintained in nature through a cycle involving the freshwater swamp mosquito, Culiseta melanura, commonly known as the blacktailed mosquito.

“Two to three days after becoming infected with EEE virus, a mosquito becomes capable of transmitting the virus,” said Adam Eichelberger, DVM, Dipl. ACT, who oversees the LPH animal health programs. “Infected mosquitoes that feed on both birds and mammals can transmit the disease to horses and humans.”

A viral disease, EEE affects the horse's central nervous system. The course of EEE can be swift, with death occurring two to three days after onset of clinical signs despite intensive care. Horses that survive might have long-lasting impairments and neurologic problems. Clinical signs of EEE include moderate to high fever, depression, lack of appetite, cranial nerve deficits (facial paralysis, tongue weakness, difficulty swallowing), behavioral changes (aggression, self-mutilation, or drowsiness), gait abnormalities, or severe central nervous system signs, such as head-pressing, circling, blindness, and seizures.

Nine out of every 10 horses infected with EEE virus die from the disease. In South Carolina last year, 48 of the 49 of the confirmed cases died from the EEE infection.

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