Wilson was aged 88 and was based in Fort Erie, Ontario, Canada. He was preparing the gelding Forbidden Dreams for a stakes race when the horse reared up. Witnesses say Wilson was holding the horse's head when he reared, and was struck in the head and chest when the horse came back down.
A spokeswoman for Presque Isle Downs and Casino said on Sunday that Wilson was unresponsive after he was hit and was taken by ambulance to Hamot Medical Center, where he was pronounced dead.
"Jack was a big part of racing at Fort Erie for many years," Herb McGirr Sr. director of operations for Fort Erie, told Canadian Press. "He was well respected by everyone here at the track. This is a huge loss to our community."