Rare, insect-borne illnesses kill at least 3 MN horses, officials say

Three cases of relatively rare infectious illnesses have killed horses across Minnesota in recent weeks, the state Board of Animal Health said Monday.

The deaths include a 14-year-old Belgian mare in Otter Tail County euthanized after being diagnosed with Eastern equine encephalitis. The previous last case in Minnesota dates back to 2001.

A suspected West Nile virus infection forced a vet to euthanize another horse in Swift County in July.

Both of those diseases are thought to be carried by mosquitoes.

A horse in Pine County was euthanized after being diagnosed with equine infectious anemia, which is often spread by large biting flies. Only a few dozen cases of that disease are reported nationwide each year, said Dr. Courtney Wheeler, a senior veterinarian with the Board of Animal Health.

"In the 1970s, this disease was far more common, with as many as 10,000 cases nationwide. So we've done a really good job from a regulatory standpoint, of getting this disease under control, because states have multiple requirements for testing horses," Wheeler said.

Wheeler said vaccines are available for West Nile and equine encephalitis, but that horse owners should stay vigilant about protecting their animals.

“Limiting contact with mosquitoes and horses is key with these vector-borne diseases,” she said. Owners, she added, should install window screens and make sure animals are inside during dawn and dusk hours, which are peak mosquito time.