The Daily Mail has a nice piece on Pedigree Dogs Exposed which premiers tonight on BBC One):
Vets describe how virtually all cavalier King Charles spaniels develop life-threatening heart murmurs..
And a third have syringomyelia, an agonising condition caused by them being bred with skulls too small for their brains.
Veterinary neurologist Clare Rusbridge said: 'The cavalier's brain is like a size ten foot that has been shoved into a size six shoe; it doesn't fit.
'It is described in humans as one of the most painful conditions you can have, a piston-type headache. Even a light touch - a collar, for example - can induce discomfort.
'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.'
The programme says the drive for perfection has left golden retrievers prone to cancer, labradors with joint and eye problems, West Highland terriers beset with allergies and boxers at high risk of heart disease, epilepsy and cancer.
Pugs are so inbred that although there are 10,000 in Britain, their DNA could come from just 50.
The Pekingese's squashed face causes breathing difficulties that lead to some airlines refusing to fly them.
So serious are the breathing problems that Danny, the 2003 Crufts winner, sat on an ice pack while being photographed afterwards to stop him overheating.
To ensure desirable traits are passed on, male dogs are being mated with their own daughters, sisters and granddaughters.
Steve Jones, professor of genetics at University College London, said: 'If dog breeders insist on going further down that road, I can say with confidence that there is a universe of suffering waiting for many of these breeds and many, if not most, will not survive.'