Aintree officials and the British Horseracing Authority are conducting a review of Saturday's Randox Grand National in which the Willie Mullins trained Up For Review suffered fatal injuries.
It was the first fatality in the Grand National since 2012 although two other horses died at last week’s Aintree festival.
Up For Review was brought down by the faller Vintage Clouds at the first fence on Saturday. The obstacle was bypassed by the field on the second circuit.
“Whatever way it happened in the bringing down process he died straight away. By the time the vet got to him he was dead,” Mullins said on Sunday.
An Aintree spokesman said: “All of us at Aintree extend our sympathies to owners Andrea and Graham Wylie and the team behind the horse.
“You have to go back to 2012 since we lost a horse in the Grand National, thanks in part to the huge amount of effort and investment we put into horse welfare.
“However while you cannot remove all risk from our sport, we will analyse what happened an leave no stone unturned in doing so.”
Mullins ran three other horses in Saturday's race with Rathvinden emerging best in third behind Tiger Roll.
“He made little blunders at the water and Valentines but all horses have those. Tiger Roll had little blunders too. It was a great performance by Tiger Roll,” the champion trainer said.
Mullins also didn’t rule out an appearance by Faugheen in next month’s Punchestown festival. The veteran 2015 Champion Hurdle winner was pulled up in Thursday’s Aintree Hurdle and was found to have an irregular heartbeat.
“His heart had gone back to a regular beat by the following day but obviously we will do more tests at home. It can happen once on a day and then never happen again,” he said.
Tiger Roll's National victory gave Gordon Elliott the leading trainer award at Aintree, beating Mullins by four winners to three.
Michael O'Leary's Gigginstown Stud beat the Supreme Racing Club to the owners award on a placings count-back while Robbie Power was top jockey with three winners.
