Animal welfare at the Grand National has come under scrutiny again after a horse died on the first day of the meeting at Aintree.
Battlefront was pulled up - or withdrawn from competition - during the fourth race by jockey Katie Walsh and later collapsed and died.
It came after Ms 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. A further five horses fell in the race, although none was significantly injured.
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."
Animal protection charity Peta said the death was "shamefully predictable yet entirely avoidable."
A spokesperson said "Profit is still allowed to trump concern for the horses' very lives, and the animals fare in a way that would be unthinkable if the racers were human.
"Why doesn't the British Horseracing Authority just dig holes on the course for the animals to stumble into and then bury the fallen animals on the track to save time? The Grand National is nothing but a national disgrace that is only "grand" if you are not a horse or a caring human being."
Battlefront was the 23rd horse to die on the Grand National course since 2000, Animal Aid said.
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 with "Easyfix plastic birch", dressed with spruce.
Aintree said the new fences were "kinder if the horse makes a mistake". The height of the fences remains the same.
The start of the Grand National course has also been moved 90 yards further away from the grandstands and the crowds.
John Baker, regional director north west of Jockey Club Racecourses, expressed his sympathies to Battlefront's owners and trainers, adding: "You can never remove all risk from horse racing, as with any sport.
"However, welfare standards are very high and equine fatalities are rare, with 90,000 runners each year with a fatality rate of just 0.2%.
"The Grand National is woven into the fabric of British culture and, while the race is designed to be a unique and tough test, Aintree ensures it is as fair and as safe as possible.
"Nothing has greater importance to Aintree than the safety and welfare of the horses and riders. The racecourse constantly strives to improve this further."
More than 150,000 race goers will descend on Aintree over the three day meeting, building up to the world-famous Grand National steeplechase on Saturday.