Decades of inbreeding is causing immense suffering for pedigree dogs, who are plagued by painful and deadly genetic diseases as a result of breeding for appearance, a UK investigation has found.

The BBC documentary Pedigree Dogs Exposed, aired on ABC1 on Thursday, shows boxers suffering from epilepsy and spaniels with brains far too big for their skulls.

Other painful disabilities and deformities, including poor gait and severe heart and respiratory problems, plague purebreds like west highland terriers, golden retrievers and german shepherds.

"We are in effect breeding them to death," dog historian David Hancock said.

University College London professor of genetics Steven Jones says some breeds are paying a terrible price because of inbreeding.

"People are carrying out breeding which would be, first of all, entirely illegal in humans, and secondly is absolutely insane from the point of view of the health of the animals," he said.

The governing body of dogs in the UK, the Kennel Club, sets out breeding standards that require physical traits like short faces, wrinkling, screw-tails and dwarfism, but such traits are causing severe health problems.

Australian National Kennel Council (ANKC) is affiliated with the Kennel Club, and has hired a PR specialist to deal with the fallout from the BBC documentary being aired in Australia.

The ANKC has not yet announced a ban on inbreeding.

The program, which caused a huge public reaction when it was shown in the UK, shows a cavalier king charles spaniel in agony due to syringomyelia, a condition caused by the dog's skull being too small as a result of deliberate inbreeding.

Veterinary neurologist Clare Rusbridge describes the spaniel's brain as a "size 10 foot that's been shoved into a size 6 shoe", which results in neurological damage.

"There are thousands of cavaliers in pain across the world, even at a conservative estimate," she said.

"It's described in humans as one of the most painful conditions you can have; a burning pain, a piston-type headache, abnormal sensations even to the light touch ... even a collar, for example, can induce discomfort for these animals."

The RSPCA points the finger of blame for the high levels of deformities at top dog shows.

Despite the poor health of such dogs, the two-year investigation found affected dogs are are not stopped from competing in prestigious dog shows and the dogs have even gone on to win top "best in breed" prizes.

The program also exposes the common practice of the deliberate mating of dogs which are close related.

After the show was aired in the UK, the Kennel Club banned the practice.

But the ANKC still registers dogs bred from mother-to-son and brother-to-sister matings.

Public reaction

Pedigree Dogs Exposed's airing in Britain last year caused public outrage, and a similar reaction is being anticipated in Australia.

As a result of the program, the BBC walked away from its contract for coverage of Crufts, the Kennel Club's most prestigious dog show.

Both the RSPCA and the ANKC have been vocal in the lead-up to the documentary's broadcast in Australia.

The council said it had hired public relations officer Dr Peter Higgins "for a four-month contract leading up to and after the screening of the program, with the intent of reducing the impact of any fallout".

The council also published the ANKC Vision for the Health and Welfare of Pedigree Dogs in May 2009, which forms the basis for their defence against the program.

The RSPCA welcomes the program's airing in Australia, and says it wants breeders to focus on health, welfare and functionality of dogs, instead of breeding for appearance.

RSPCA chief scientist Dr Bidda Jones says Australia is not immune from the issues highlighted in Pedigree Dogs Exposed.

"Despite all the evidence against inbreeding, the Australian National Kennel Council is still operating a closed studbook system and registering first and second degree matings (mothers with sons, grandfathers with granddaughters), increasing the chances of inherited disorders and making the puppies less resistant to infectious and genetic diseases," Dr Jones said.

A report on pedigree dog breeding in Australia by Jonica Newby will be aired on Catalyst on September 17 at 8.00pm.