The Ontario SPCA is investigating the death of a draft horse at an eastern Ontario fair over the weekend.

The Lyndhurst Turkey Fair in Lyndhurst, Ont., north of Gananoque, said the Percheron horse named Mack died of a heart attack at the fair on Saturday.

"Both Mack and his friend Prince were being rested and watered regularly [that day]," said a statement on the fair's website.

"This death was inevitable."

The fair offered its condolences to the horse's owners, described in the statement as responsible, experienced and respected in the community.

In an email, a spokesperson for the Ontario SPCA said the agency has started an investigation into the circumstances around the horse's death after hearing concerns about it.

The temperature in Lyndhurst reached 30 C on Saturday afternoon.

Draft horses, including the Percheron breed, are large, strong animals traditionally used for farm work.