Apprentice jockey Valerie Nagle was knocked unconscious when the horse she was riding fell during a race at Churchill Downs on Saturday.
Nagle, 23, a native of Ireland and former dressage rider, was aboard Derby City Slew in the fourth race. The horse was near the lead when it tumbled face first coming around the final turn of the five-furlong sprint. Nagle was thrown to the track and lay motionless on her back as an ambulance sped to her aid.
The horse, a 2-year-old dark bay colt making his fourth start in just over two months, broke a bone in its left front leg and was euthanized on the track.
Nagle was taken to Caritas Medical Center, where she was undergoing tests Saturday night, track officials said.
Nagle, riding in her first meet at Churchill Downs after racing in Keeneland's spring meet, won Saturday's second race aboard 20-1 long shot Wieuca Run.