An advisory from the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) indicates that the agency received notification Aug. 9 that a horse residing in the United Counties of Stormont, Dundas, and Glengarry, Ontario Canada, tested positive for Eastern equine encephalitis (EEE).

"The 12-year old unvaccinated gelding with no travel history was euthanized following the sudden onset and progression of fever and neurological signs," the advisory said. "The horse presented with signs of nystagmus and strabismus (abnormal eye position and movement) along with ataxia (wobbly gait) and eventual recumbency. A post-mortem examination was performed at the Animal Health Laboratory in Kemptville, Ontario and EEE was confirmed by testing of brain tissue."

The advisory indicates that EEE has been present in Ontario's horse population since 1938, and that one case was confirmed last year.

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