Fatter dogs have been linked to breathing problems associated with breeds like the French bulldogDrew Angerer/Getty

Judges at Crufts have been told to avoid giving prizes to “fat little Frenchies” when the world’s biggest dog show opens on Thursday.

The move follows growing criticism from vets and animal campaigners about the apparent genetic defects suffered by pedigree dogs such as some French bulldogs.

The Kennel Club, which runs Crufts, confirmed that this year judges had been told not to pick “fat little rotund Frenchies” — as research shows fatter dogs are more likely to suffer breathing problems associated with flat-faced breeds including pugs and bulldogs. Instead judges have been told to choose skinnier winners.

By next year campaigners hope that a working group on which the Kennel Club is represented will have come up with new standards by which to judge…