BHA officials have said the decision to put Rewilding down at Ascot was the correct one.
Nathaniel win overshadowed
Racing at Ascot was heavily overshadowed on Saturday by the death of the strongly-fancied Rewilding in the feature King George VI And Queen Elizabeth Stakes.
Frankie Dettori's mount, winner of the Dubai Sheema Classic and Prince of Wales's Stakes, broke down badly in the straight, fracturing a cannon-bone and throwing his rider to the ground.
Dettori escaped with what was reported to be just a bruised knee, but Rewilding had to be put down.
Tim Morris, director of Equine Science and Welfare at the British Horseracing Authority, said: "Rewilding suddenly and completely unexpectedly suffered a major fracture of the lower part of his near-fore.
"The horse was caught and examined by the vets immediately, and the decision was made that humane euthanasia was the only option.
"That was done professionally by the vets on the scene. It is a great regret, but it was the right decision for the horse."
Godolphin racing manager Simon Crisford said: "It is a tragedy, unfortunately we lost Rewilding as he had to be put down."
Ascot chief executive Charles Barnett said: "This sort of incident is terribly regrettable, especially on a flagship day like today.
"We express our profound sympathies to Sheikh Mohammed, the Godolphin operation, trainer Mahmood Al Zarooni and jockey Frankie Dettori."
The race was won by Nathaniel, whose trainer John Gosden was one of the first on the scene.
He said: "It was a clean break through the cannon-bone and it's as if he was anaesthetised and didn't feel any pain.
"He was very calm and collected and we held him, but he had to be dealt with because the leg was completely gone.
"People watching must understand that I've seen horses do that galloping in a paddock and it can happen at any time without warning.
"I was quickly out there when he pulled up by the winning post and held him and fed him some grass and he munched away. The horse was very well dealt with by the vet, it was a clean break and a quick end.
"It's a freakish thing, he just put the leg down wrong."
