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Three horses in Oswego County, New York, die of Eastern Equine Encephalitis

The vaccination status of the horses, who all lived on the same farm, is unknown; 13 other horses on the property have been exposed to the virus.

Three horses in Oswego County, New York, died or were euthanatized due to Eastern Equine Encephalitis (EEE) earlier this month. 

A close up silhouette of a mosquito feeding.

EEE is spread primarily mosquitos, which feed on birds who harbor the virus, then transit it to horses. Horses are considered dead-end hosts, meaning they cannot spread it to other animals.

Caused by a virus that is spread mainly by mosquitoes, EEE disease damages a horse’s central nervous system, including the brain and spinal cord. After an initial incubation period of five to 10 days, a horse may at first appear listless and lose his appetite. Within 24 hours, he will show neurological signs such as incoordination, head pressing and seizures. A day later, he may be comatose and unresponsive until death. The disease is fatal in 90 percent of cases and survivors are likely to have lifelong neurological impairment.

According to the Equine Disease Communication Center (EDCC) all three of the New York horses lived on the same farm and were diagnosed within four days of each other. Another 13 horses on the property have been exposed to the virus. The dead horses include a 3-year-old mare who was found recumbent and extremely weak before she died, a 1-year-old stallion who was found dead and an 8-year-old mare  who was euthanized after being unable to stand. The vaccination status of all three horses was unknown. 

The American Association of Equine Practitioners (AAEP) includes EEE on its list of “core vaccines,” which are recommended for the majority of horses.

>>> Click here to read more about EEE vaccination, and all core vaccinations.

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