Some fear the British bulldog - symbol of defiance - could vanish
The Kennel Club has introduced new standards for 209 breeds, following concerns about ill health in pedigree dogs caused by years of in-breeding.
Last year, the RSPCA pulled out of Crufts, saying breeding to exaggerate certain features, such as bulldogs' jowls, had led to painful deformities.
Now new rules designed to prevent exaggeration and incestuous breeding have been brought in.
Ryan O'Meara, from the K9 dog magazine, said the changes were long overdue.
"When we breed dogs to a set of physical standards and ignore the health consequences, it's really unforgivable," he told the BBC News website.
The Kennel Club is changing its guidelines defining which features dogs should have to be classed as pedigree.
In future, the bulldog must be leaner and will no longer be encouraged to have heavy jowls and deep, overhanging wrinkles in its skin.
Rules now state "skin may be slightly wrinkled," but "must never adversely affect or obscure eyes or nose". Wrinkles which lead to "pinched nostrils" - potentially affecting breathing - "are unacceptable and should be heavily penalised".
But while they are aimed at making animals healthier, the change has angered the British Bulldog Breed Council, which fears the loss of a breed emblematic of defiance and pugnacity.
Chairman Robin Searle told the Times newspaper: "What you'll get is a completely different dog, not a British bulldog."
Other breeds altered include the German shepherd, whose forelegs must not be weak and overlong because it would "affect a dog's working ability," and the chow chow which "must not have so much coat as to impede activity or cause distress in hot weather".
Mr O'Meara said the bulldog was "a vivid illustration of how wrong we can get it".
"Bulldogs have been bred to a point where they die at about seven years of age - in human terms that's just 45 or 46," he said.
"They can't breathe properly. They can't support themselves because their heads are too big. They have terrible skin conditions.
"The public must be educated to see dogs not for their aesthetic appeal but to think about their health."
He said people "shouldn't be scared or snobbish about interbreeding".
"All dogs are one species and all breeds are man-made. They wont die out because we made them. It's like saying i-pods could die out.
"We have to start cross-breeding more in order to reconstruct these dogs and improve genetic diversity."
The Kennel Club said breed standards had been revised to exclude "anything that could in any way be interpreted as encouraging features that might prevent a dog breathing, walking and seeing freely".
Judges at licensed dog shows have been instructed to choose only the healthiest dogs as champions. Any animals at Crufts that show signs of ill-health are to be expelled.
Any dogs that are the product of incestuous breeding are also banned from registering, although this does rely on owners providing accurate information about their animals.
Cavalier King Charles Spaniels are also said to suffer health problems
A spokeswoman for the club said: "It's going to take time, several generations, to have an effect, but we think these exaggerated features can eventually be bred out altogether."
RSPCA chief veterinary adviser Mark Evans said the ban on incestuous breeding was "brilliant news," but the changes to breeding standards "don't appear to be radical enough to really make a difference".
"We also question how the standards may be interpreted in the show ring," he said.
Last year, a BBC programme, Pedigree Dogs Exposed, found animals suffering acute health problems, and following its airing, the broadcaster pulled out of showing Crufts in 2009.
The Kennel Club lodged a complaint about the programme with Ofcom, accusing the documentary of bias.