Two yearling Quarter Horse fillies from Monroe County are the first Wisconsin horses to test positive for Eastern equine encephalitis (EEE) this year, the Wisconsin Department of Agriculture, Trade and Consumer Protection reported July 28.

One horse died and the other was euthanized.

Because EEE normally emerges in mid- to late summer and remains a threat until the first killing frost, veterinarians are encouraged to discuss vaccination and mosquito abatement with their horse-owning clients.

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