Eastern Equine Encephalitis (EEE) has been confirmed in Lambton County, Ontario. A 13 year old Quarter Horse gelding developed generalized ataxia with weakness in the right front and hind limbs on August 29, 2024. He was clinically normal on August 28, 2024. He was treated supportively and remains alive but with some neurologic deficits. Infection with EEE was confirmed on September 19, 2024. The horse is undervaccinated against EEE. This is the 17th case of equine EEE in Ontario in 2024.