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."
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 th