Little Josh put down
Little Josh was put down after breaking his shoulder in the John Smith's Topham Chase at Aintree on Friday.
The Nigel Twiston-Davies-trained gelding parted company with rider Sam Twiston-Davies in the extended two-mile-five-furlong event, run over the Grand National course.
Little Josh had previously shown smart form over the big fences, finishing seventh when favourite for this race a year ago and winning the Grand Sefton Chase in December.
He fell on his next appearance at Cheltenham, was pulled up in the Denman Chase at Newbury and then finished down the field on his only subsequent outing in a Warwick handicap chase in February.
A tweet from Aintree racecourse read: "We can sadly confirm that Little Josh broke a shoulder in the Topham Chase. He was treated immediately but needed to be humanely put down."
Professor Chris Proudman, veterinary advisor to Aintree, said: "We are sad to confirm that is has been necessary to humanely put down Little Josh on welfare grounds, as a result of his fall at the 15th fence in the John Smith's Topham Chase.
"He received immediate veterinary attention for a broken shoulder, but this injury was not treatable and it was the necessary course of action."
All 28 other horses in the race returned safely.
John Baker, Aintree and North West Regional Director for Jockey Club Racecourses, said: "I would like to extend our sympathies to the connections of Little Josh following his fall in the John Smith's Topham Chase.
"We have made significant improvements in safety at the course, but we also recognise that jump racing carries risk you can never completely remove from the sport."
Aintree said jockey Liam Treadwell received medical assessment on course and was taken to hospital for further assessment. Andrew Lynch was being assessed in the medical centre on course.
Grand National-winning trainer Twiston-Davies paid tribute to Little Josh, and did not attribute blame to the much-scrutinised fences.
He said: "He's gone out doing what he loved the most, he's jumped round those fences before and it's one of those things.
"It could happen anywhere, it could happen at home and it's not the fences - it could have happened at a park course.
"It's desperate, as he is one of Sam's favourite horses and he has been a great servant."
David Muir, equine consultant for the RSPCA, said: "I'm not here to defend the death of any horse, but I'm not going to condemn the efforts to make the course better either.
"The horse didn't appear to take off, he went through the fence, and until I see the result of the post-mortem and am in full possession of the facts, I'm not going to say what happened."