A colt was fatally injured at Keeneland in a crash that also left his jockey Adam Breschizza with an injured left clavicle.
The death of Triggerman is the track's third since the fall meet opened on Friday.
Keeneland says in a statement that Triggerman injured his front left leg in a 1-mile turf race on Wednesday. It did not specify where the 3-year-old bay colt was euthanized, but the race chart said he "went wrong late in the stretch" and was vanned off.
Keeneland medical director Barry Schumer says Breschizza was stable upon being discharged from the track's first aid station. The rider, who has three Grade 3 victories this year, was transported to the University of Kentucky's Chandler Hospital for evaluation.
On Friday, filly Stella D'Oro was euthanized after sustaining a "catastrophic injury" in the fourth race. Fast Dreamer was vanned off after the fifth race with an injured right front leg and was euthanized.