Two Horses Struck by EEE in Ontario

In a concerning development, two horses in Ontario have tested positive for Eastern equine encephalitis (EEE), raising alarms across the equine community. The horses, residing in the Regional Municipality of Halton and Renfrew County, displayed severe health symptoms that led to tragic outcomes.

Tragic Health Declines

In Halton, a 16-year-old draft mare who had not been vaccinated developed alarming neurological symptoms on August 21. Sadly, despite immediate intervention, she was euthanized just one day later. Similarly, an 8-year-old draft mare in Renfrew County, who was under-vaccinated, showed acute signs on August 4 and died on the same day.

A Growing Concern in 2025

These two cases contribute to a troubling total of seven confirmed EEE cases in Ontario horses this year alone, highlighting an urgent public health issue in the region.

What is EEE?

Eastern equine encephalomyelitis is caused by the Eastern equine encephalitis virus, primarily hosted by wild birds. The virus is transmitted through mosquitoes that feed on infected birds, posing a threat not just to horses but also to humans. Fortunately, horses do not spread the virus to one another or to humans, but the high mortality rate associated with EEE makes it a significant concern.

Stay Safe!

As the threat of EEE looms, it’s crucial to take preventive measures against mosquito-borne diseases. Regular vaccination for horses and reducing mosquito habitats around living areas can make a significant difference in curbing outbreaks and protecting both animals and humans.