When a 1,000-pound racehorse breaks down on slender legs while running about 35 mph, the damage can be temporary or as tragic as it was with Go for Wand in the Breeders' Cup Distaff on Saturday.
Some horses take missteps and go on to race again, although usually against cheaper competition.
Others have to be destroyed.
In the serious cases, no one is sure what snaps first, but the result usually is a breakdown in the horse's suspensory apparatus and sesamoid bones.
When running at full speed, the extra steps that a horse takes when falling or pulling up cause further breakdown.
"If the sesamoid bones are shattered, sometimes they look like a bag of finely crushed ice," a local veterinarian said yesterday.
"You can't put those bones back together. Sometimes you can fuse other bones together, but they [the horses] can never race again. They would only be saved for stud."
When they awaken after surgery, racehorses often thrash around on the operating table, tearing up the work that has been done to save their injured legs.
When Go for Wand fell in front of the Belmont Park grandstand, it reminded observers of Ruffian, an unbeaten filly who broke down at Belmont in 1975 during the first half-mile of a match race with Kentucky Derby winner Foolish Pleasure.
Ruffian was humanely destroyed.
"Go for Wand wasn't injured any worse than Ruffian was," veterinarian Dr. Alex Harthill said.
"I'll never forget the night we operated on Ruffian. The injury was just so bad that it looked like she had no chance, but there were children outside the [vet] hospital rooting for her. There were nuns and even a priest.
"We had to try something. We put the leg back as best we could, but when she woke up, she thrashed around so bad we had to put her down [destroy her]."
Ruffian had been eased by jockey Jacinto Vasquez in the race, but her leg still was badly damaged. "The reason he [Vasquez] was able to pull her up was that it was in the first half-mile and she was still fresh," Harthill said. "Go for Wand was about to finish the race and she was tired. That's why she fell."