“It’s just a belief that this is what a perfect German Shepherd looks like,” he said.
“The decision to stop breeding them like this is not just one that can be taken by breeders or the Kennel Club, but by the general public.
“If they refuse to buy these dogs then the breeders will stop breeding them.”
German Shepherds were originally bred as a medium-sized dog for herding work until their popularity as a guard dog led to them being bred for a larger size and aggressive demeanour.
“If people think something like a sloped back is good then they will think that more of it is better,” said Dr O’Neill.
The Kennel Club ruled this year that dogs can only be exhibited at Crufts if they are able to “stand freely” and balance while both pasterns – the lower part of the leg – are vertical.
A spokesman welcomed today’s report, saying the German Shepherd was one of the organisation’s seventeen breeds involved in the Breed Health and Conservation Plan.