The Equine Disease Communication Center (EDCC) reported Aug. 15 that a third Wisconsin horse has tested positive for Eastern equine encephalitis (EEE).

“The horse was an unvaccinated 9-year-old Quarter Horse mare from Monroe County,” the EDCC said on its website. “The horse acted depressed during the afternoon of Aug. 6, then began showing neurologic signs and was down by that evening. She was euthanized the next day.”

All three equine EEE cases confirmed in Wisconsin this year have been in Monroe County horses, the EDCC said.

A viral disease, EEE affects the central nervous system and is transmitted to horses by infected mosquitoes. 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. 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