An 8-year-old mare in Aiken has been euthanatized after contracting Eastern equine encephalitis (EEE), according to the Equine Disease Communication Center. The EDCC reported the case on December 2 and noted that the mare had been vaccinated. This is the 16th case of EEE reported in that state this year. 

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.

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.