Trainer Nigel Twiston-Davies has insisted the latest horse death on the Grand National course at Aintree was an accident that "could have happened at a park course".

Twiston-Davies today sends out Imperial Commander in the John Smith's Grand National, hoping the horse can become only the third Cheltenham Gold Cup winner in history to triumph in Aintree's top race.

He last night attached no blame to the fences at Aintree after Little Josh was put down following a fall in the Topham Chase that left him with a broken shoulder.

The 11-year-old parted company with rider Sam Twiston-Davies at the 15th fence in the extended two-mile-five-furlong event.

Grand National-winning trainer Twiston-Davies paid tribute to Little Josh, who had career earnings of over £170,000 and won nine races in total, including the 2010 Paddy Power Gold Cup.

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."

All 28 other horses in the race returned safely.

Last year two horses, Synchronised and According to Pete, died after falls in the National itself.

On Thursday, Battlefront was pulled up during the Fox Hunters' Chase and later died.

David Muir, equine consultant for the RSPCA, said of yesterday's death: "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."

Ahead of today's big race, trainer Twiston-Davies is confident 12-year-old Imperial Commander retains all the enthusiasm and ability that saw him claim a famous Gold Cup victory over no lesser horses than Denman and Kauto Star three years ago.

And Twiston-Davies knows what it takes to win the National, having saddled two previous winners in Earth Summit (1998) and Bindaree (2002).

Asked where a victory for Imperial Commander would rank in his career, the Naunton-based handler said: "It wouldn't get any better than that.

"I'm not worried about the statistics. Red Rum won it as a 12-year-old, so there's no reason why we can't do it.

"I think he's as good as ever."

Ted Walsh's Papillon claimed National glory in 2000 and this year he saddles two major contenders in Seabass and Colbert Station.

Seabass was an excellent third 12 months ago and is once again partnered by the trainer's daughter, Katie, while the progressive Colbert Station gets the services of Tony McCoy.

Katie Walsh said: "I'm just hoping to get from fence-to-fence and if he runs the same race as he did last year I'd be over the moon."

Heading the ante-post lists for some time has been the Willie Mullins-trained On His Own, whose only run since falling a year ago was when winning the Boyne Hurdle at Navan in February.