Animal rights campaigners slammed Grand National organisers after a horse died on the first day of the meeting at Aintree on Thursday.
The world famous National will be staged on Saturday, with the welfare of the horses firmly on the agenda after Battlefront became the 23rd horse to die on the Liverpool course since 2000.
Aintree bosses made significant alterations to the course after last year's big race was marred by the death of two horses, According To Pete and Synchronised.
That followed two fatalities in the 2011 race, Ornais and Dooney's Gate.
Old wooden fence frames have been replaced in a bid to make the race easier on the horses.
However, Battlefront was pulled up by jockey Katie Walsh during the fourth race on the course on Thursday.
It came after Walsh defended the sport earlier this week, saying in a magazine interview that the horses were treated better than "many children".
Battlefront had cleared 10 fences in the John Smith's Fox Hunters' Steeple Chase, the first competitive test of significant course changes and new fence frames designed to improve safety.
The cause of his death has not been confirmed but it is thought Battlefront may have suffered a heart attack.
Andrew Tyler, director of Animal Aid, said: "The Aintree authorities and the British Horse Racing Authority have been claiming that major new safety measures and efficiencies would eliminate much of the risk associated with racing on the Grand National course.
"But today's Fox Hunters' Chase, in which Battlefront lost his life, was stomach-wrenchingly chaotic from start to finish.
"Several horses fell or were pulled up, tired and potentially injured.
"It was both utterly depressing and served as confirmation that the Aintree authorities have got it badly wrong once again."