Swanson Lake, a 3-year-old filly, was pulled up by jockey James Graham about 100 yards past the finish line after placing fourth in the $120,000 race Saturday. She was vanned off the track.
Dr. Will Farmer, the track's equine medical director, said Swanson Lake sustained โa significant injury to the left hind leg.โ Upon further diagnostics, it was deemed inoperable and the filly was euthanized.
Trained by Mike McCarthy, Swanson Lake was winless in two career starts and had earnings of $9,200. She is owned by BG Stables.
Earlier Saturday in Baltimore, a horse trained by eventual Preakness winner Bob Baffert was injured in a race on the event's undercard and was euthanized.
A horse died May 14 after a race at Churchill Downs.
Two horses were euthanized after being injured in races hours before the Kentucky Derby on May 6.
Five others were euthanized after training and racing incidents at the track in the days leading up to the Derby.
Trainer Saffie Joseph Jr. was indefinitely suspended by Churchill Downs during Derby week after two of his horses collapsed on the track and died. Kentucky racing officials also scratched his Derby entry, Lord Miles.