Three New England states have confirmed nine cases of Eastern equine encephalitis (EEE) in horses this year, and none of the horses survived. This suggests that horse owners should take further measures to protect horses against this deadly disease, such as making sure their horses have received EEE vaccinations and reducing mosquito populations around the barn.

A wet and warm spring may have contributed to the New Hampshire’s six reported cases of EEE, explains State Veterinarian Steve Crawford, DVM. Officials reported four cases in Rockingham County, one case in Chichester, and one in Boscawen.

Eastern equine encephalitis is a mosquito-borne viral disease that affects all equine species. After infection, the disease progresses rapidly. Clinical signs might include fever, depression, loss of appetite, progressive central nervous system disorders (lack of coordination, chewing movements, head pressing, ataxia, circling, paddling motion of the forelimbs, and convulsions), blindness, abnormal sensitivity to light and sound, and sudden death. The mortality rate in horses ranges from 75-90%. Vaccines are available, but currently there are no specific treatments for horses contracting EEE.

Last year, New Hampshire reported only three equine cases of EEE. “Historically, the disease crops up in large numbers, with lulls of inactivity in between,” Crawford said