Michigan Department of Agriculture and Rural Development (MDARD) officials have confirmed three horses in three separate counties with Eastern equine encephalomyelitis (EEE) and suspect that a fourth horse succumbed to the disease on Aug. 22. Affected counties include Clare, Montcalm, and Newaygo.

The Montcalm County horse, an undervaccinated yearling filly of unspecified breed, experienced onset of clinical signs on Aug. 17. Signs included ataxia (loss of control of bodily movements), circling, and dull mentation. She was confirmed positive on Aug. 24 and was subsequently euthanized.

On Aug. 18, a Newaygo County horse and a Clare County pony began showing clinical signs. The horse, a 4-year-old draft mix gelding, experienced ataxia, fever, and hind-end weakness and was euthanized.

The 3-year-old pony mare from Clare County experienced ataxia, circling, head-pressing, and tremors. Veterinarians confirmed her positive on Aug. 24. The pony, which was undervaccinated, is deceased. An additional Clare County horse that is suspected to have EEE experienced similar clinical signs and died on Aug. 22 within 36 hours of showing signs of illness