Why are we asking this now?
It's long been known that pedigree dogs are more likely to suffer from health problems than their mongrel brethren. But a study by scientists at Imperial College, which featured in a BBC1 documentary last night, has revealed just how severe those problems are.
What does the study say?
In a nutshell, that pedigree dogs are much more heavily inbred than had previously been demonstrated, and that that inbreeding causes serious birth defects and abnormalities that can make the animals' lives a misery.
How seriousis the problem?
That depends on the nature of the abnormality: for some breeds, though, their breeding can have appalling consequences. Perhaps the most startling ailment is that suffered by a third of cavalier King Charles spaniels, syringomyelia, which is the result of their brains being too large for their skulls. "The cavalier's brain is like a size ten foot that has been shoved into a size six shoe," says veterinary neurologist Clare Rusbridge. "It is described in humans as one of the most painful conditions you can have, a piston-type headache... If you took a stick and beat a dog to create that pain, you'd be prosecuted. But there's nothing to stop you breeding a dog with it."
Many other breeds suffer similar problems: golden retrievers are prone to cancer, while boxers often suffer from heart disease and epilepsy. The Kennel Club claims that 90 per cent of the British canine population is healthy, and that these kinds of genetic diseases are actually more common in humans than dogs. But there are concerns that the problem will get worse, as an increasingly concentrated gene pool makes the abnormalities even more likely to be passed on.
Some are concerned that dog breeders show little regard for the health of their charges. "I defy anybody to say that they would approve of brother-sister mating or father-daughter mating [in humans]," says geneticist Steve Jones. "And yet if you speak to dog breeders, father-daughter or father-granddaughter mating is common. They must know that this is going to cause problems."
Why are the dogs inbred?
The whole point of the pedigree designation is that it applies to animals which have not had their breed's natural characteristics diluted by cross-breeding with another. The Kennel Club maintains strict pedigree standards that competition dogs are compared to, and, for obvious reasons, breeding close relatives makes it easier to keep dogs close to that template – and helps encourage features that go down well with judges at shows like Crufts. The role Crufts and other competitions have played in encouraging dog breeders to mate close relatives has led the BBC to consider whether it will continue broadcasting the show. "When I watch Crufts, what I see is a parade of mutants," says Mark Evans, chief vet of the RSPCA. "It's some freakish, garish, beauty pageant that frankly has nothing to do with health and welfare."
What other problems do the pedigree standards cause?
As well as the genetic defects like heart disease and epilepsy, the exaggeration of prize-winning features can cause health problems in themselves. These features are often not natural to the breed, but have been exacerbated by years of selective breeding between two dogs that share the same strong characteristics.
The folds of flesh on a bassett hound's legs cause skin complaints; flat-faced pugs have difficulty breathing; prize bulldogs are so oddly proportioned that they often find it impossible to mate or give birth without help.
How long has this been a problem?
The problems began in the 19th century, when dog fanciers began to set down particular physical features that were deemed to be ideal for the breed in question.
In 1864, for instance, Birmingham breeder Jacob Lamphier created the 'Philo-Kuon' standard for bulldogs, decreeing it essential that a bulldog have a deep furrow between its eyes, a recessed nose, and a short, thick neck. Before then, dogs had simply been bred with their practical uses in mind, meaning that their physical capacities were more important than their aesthetic appeal; now, inbreeding is so ubiquitous that the Imperial College researchers estimate the UK's boxer dog population of 20,000 to have the variety of genetic material you would expect to find naturally in a population of about 70.
The Kennel Club, which now governs the pedigree standards in the UK, has been roundly criticised for failing to do enough to solve the problem.
Why is the Kennel Club under fire?
Critics argue that it has not done enough to change the way pedigree dogs are bred. It is against club rules to cross-breed a pedigree dog with a different variety, which makes it hard to see how the gene pool can diversify.
And while many other national kennel clubs have changed their rules to bar incestuous breeding in the face of mounting concerns over the health ramifications, it is still perfectly legitimate in the UK.
In its defence, the club says that inbreeding is an essential tool for the development of breeds. And it points out that it amended pedigree standards 20 years ago to discourage breeders from placing a dog's aesthetic appeal above its health.
In theory, too, unhealthy dogs should not be able to win prizes at dog shows, although many are sceptical about the practical application of that principle. "We recognise the problem," says Club secretary Caroline Kisko. "But it is far less common than it ever was in the past... We are the ones that are trying to put things right."
So how can the problems be solved?
The Imperial college researchers suggest three crucial changes. Since successful competition dogs are likely to be particularly popular breeding stock and will therefore concentrate the gene pool still further, they argue that there should be a limit on how many times any one dog can father a litter.
To combat the problems that arise from a severely limited pool of available animals, they suggest encouraging owners to mate their dogs with animals from abroad. And they say that the breed rules should be relaxed to allow animals to breed outside of their pedigree.
Failing to take such actions may exacerbate the health problems suffered by purebred dogs. "If dog breeders insist on going further down that road," Steve Jones says, "I can say with confidence that there is a universe of suffering waiting for many of these breeds."
Should we be ashamed to watch Crufts?
* It has been known for years that the in-breeding of dogs causes health problems
* Even without scientific evidence, some of the health problems of are obvious
* The dogs have no say in whether they want to be shown, so it's cruel if they're sick
* The scientific evidence is new, and the Kennel Club has promised to consider it
* Ninety per cent of the dogs are said to be healthy – a higher proportion than in humans
* We allow human beauty pageants even though size zero is proven to be unhealthy
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies