Last Night's TV: No prizes for the pedigree chumps

Judging from last night's Pedigree Dogs Exposed, the very worst thing you can have stirred into your genetic mix – far more debilitating than a disease-bearing gene – is human self-regard and vanity. Nature, after all, has its ways of getting around defective genes, so that only the fittest survive. But nature has no answer to the inbred self-righteousness of many dog breeders, a species dedicated to the creation and maintenance of canine cartoons. If it's desirable for your particular breed cartoon to have a flat upturned nose, then that's what you'll get, even if – as in the case of many pedigree pugs – half of your soft palate is pushed down your throat as a result. And if the cartoon requires a pertly cute little skull shape, you'll get that, too, and you'll just have to put up with the fact that there's no longer quite enough room for your brain, so that you may end up in twitching agony with a disease called syringomyelia.

Jemima Harrison's powerful film began with some case studies of cavalier spaniels, which had suffered from this disease – known to be a problem for the breed – and I imagine it will have gone off like a bomb in quite a few British living rooms. I wouldn't count myself as a dog lover. In fact, I only recently qualified as a dog tolerator, after several unrewarding years of intimacy with a wire-haired fox terrier. So if this footage can make me angry, I don't like to think what it will do to viewers with a more heartfelt interest in canine welfare.

The burden of Harrison's film was simple. There are rising levels of disease and distress in pedigree breeds as humans tinker with their genetic make-up to suit their own entirely artificial notion of "breed purity". And the Kennel Club – keeper of the flame of breed type and promoter of dog-show ideals – is not doing nearly enough to prevent the pain and suffering continuing. The case of Rhodesian ridgebacks neatly exemplifies the problem. For the Kennel Club, and ridgeback breeders, the dogs' spinal ridge is "the escutcheon of the breed", an indispensable element of any prize-winning dog. In scientific terms, though, the ridge is also a marker of disease and spinal deformity, and breeding for more prominent ridges has led to an increasing number of dogs with spinal problems. Left to their own devices, the dogs would soon put this right, but ridgeback breeders take care that puppies born without a ridge don't contaminate the gene pool with their unsightly good health. This isn't always easy, given the perverse reluctance of some vets to kill healthy puppies. "We do have trouble nowadays with the young vets who tend to see everything in black and white," said one ridgeback breeder. "'It's a healthy, beautiful puppy, there's nothing wrong with it except that it hasn't got a ridge,'" she continued, parodying their woolly-minded soft-heartedness. In many cases, the disease is intimately knitted together with the characteristics that have been decreed "desirable". George the pug, a hairy collage of physical abnormalities, demonstrated the point nicely. Pugs are supposed to have tightly curled tails, but breed for that and you get twisted spines thrown into the mix for free. George's spine kinked like a crank handle, but it hadn't stopped him qualifying for Crufts, and Harrison had come up with several cases here in which breeders were knowingly breeding from dogs with serious genetic disorders, a situation that the Kennel Club appears to have done little to prevent.

Harrison's most potent evidence, though, was the contrast between Victorian specimens of various breeds, and their grotesquely exaggerated modern counterparts. The Victorian basset hound was unmistakably still a dog, sturdy and handsome. The modern show basset – draped with folds of skin and belly scraping the ground – is a sideshow freak. This was a film that should have legislative consequences, and in the meantime the BBC itself might like to reflect on how it contributes to the problem with its uncritical coverage of Crufts, the Olympics of engineered disability.

At the other Olympics, the commentators are pacing themselves for the tricky middle stretch. "Adrian, if the Olympics were a 400-metre race on the track, we'd be just about to head up to the first bend," said Hazel, as the morning's coverage began. No obvious signs of exhaustion yet, which is frankly astonishing to this particular viewer, though even I felt invigorated by two British triumphs in the "Who Can Ride Slowest Without Falling Off the Bike" finals. Unfortunately, an earlier attempt to understand the rules of the madison – a bicycle race more intractably complicated than a Balkan peace summit -- meant I had to withdraw injured before the final tape.