Jockey Corey Nakatani was thrown from his mount when it fell in the third race Monday at Del Mar.
Tirpitz fell on the stretch turn, tossing Nakatani to the turf. The 3-year-old gelding and the jockey lay on the turf near the rail while the race finished. Track workers rushed to hold up green screens that shielded the horse and jockey from the view of fans.
Trained by J. Eric Kruljac, Tirpitz was loaded onto an ambulance and later euthanized.
Nakatani was taken to a hospital for further examination after being removed from his three remaining mounts on the final day of Del Mar's summer meet. The 44-year-old jockey has won three riding titles at the seaside track.