Horatio Nelson, who stumbled and suffered a broken right foreleg about three-sixteenths of a mile from the finish in Saturday's Vodafone English Derby (Eng-I) at Epsom, was euthanized.
Questions arose about the condition of the Irish-bred son of Danehill because jockey Kieren Fallon had expressed concern about the colt's warm-up prior to entering the starting stall. Horatio Nelson held up the race for several minutes while he was trotted around under the watchful eye of trainer Aidan O'Brien before being allowed to race.
Dr. Peter Webbon, chief executive of the Horseracing Regulatory Authority, told Racing Post
that he was confident that Horatio Nelson was fit to run.
A grim Fallon, who gave up his final mount of the day and left the track early, said: "He was a bit stiff but he was fine when he trotted off. I don't know at what stage it happened. I just heard his leg snap and it's very upsetting."
Fallon pulled Horatio Nelson up shortly after the colt was slightly squeezed between race favorite Visindar and Hala Bek in the straight while making a move inside the two-furlong mark.
Vets and the horse ambulance arrived on the scene immediately but determined that the colt had sustained a fractured leg.
In making the announcement, Webbon, previously the Jockey Club's veterinary director, reported: "(Horatio Nelson) was taken in an ambulance to the treatment center where several X-rays were taken. They revealed major injuries to his right foreleg. He had fractured a cannon bone, a sesamoid bone, and dislocated a fetlock joint.
"There were open wounds and damage to the blood vessels, nerves and ligaments around the joint which were already potentially infected. Five veterinary surgeons were there and they were of the unanimous opinion that the situation was hopeless and it was in the horse's best interests to put him down."
One of the vets, Jenny Hall, was present before the race when Fallon registered his concern.
Webbon told Racing Post
, "Hall discussed the situation with Aidan O'Brien, the trainer, and both were satisfied that the horse was fit to compete. Hall is an extremely experienced vet and O'Brien is an extremely experienced trainer and they would not have allowed the horse to run if they thought its life was being put at risk."
Horatio Nelson's part owner John Magnier expressed satisfaction with the horse's treatment. The colt, who was also owned by Mrs. David Nagle, was a three-time group winner including a victory in the Prix Jean-Luc Lagardere (Fr-I) at Longchamp in October. He won four of seven in his career and earned $488,433.
The HRA planned no further inquiry into the breakdown.