What do you get if you cross a cocker spaniel with a poodle? Or a pug with a beagle? Or a poodle with a labrador? This is not the start of a joke - anything but. Designer crossbreed dogs - of whom the puggle and the labradoodle are the most famous examples - are at the centre of a vicious barking match among Britain's canine classes. Ranked on the one side of this row are pedigree breeders, whose champion, the Kennel Club, tomorrow welcomes owners to its annual purebred jamboree, Crufts. On the other are the crossbreeders: owners of pedigree dogs who have seen the British market for designer crosses inflamed in the past three years, and have decided to supply the demand. In fact, the stampede to acquire one has become so furious that puppies now sell for as much as £2,000. "The crossbreed phenomenon seems to be fashion-motivated," says a Kennel Club spokesman. "So we can't condone it. We wouldn't want unscrupulous crossbreeders, who are out to make a fast buck, to compromise the welfare of dogs for purely commercial reasons."