"Pedigree dogs have been bred to emphasise certain physical features," noted the experts at the RSPCA. Yet, the role of selective breeding has caused a number of problems for the dog and its owners.

Most Bulldog and French Bulldog breeds have been bred to have large heads (too large in comparison to their small hips), which means the mother typically needs a cesarean to give birth to her litter.

More worrisome, some puppies may become lodged in the mother's birth canal, endangering her life. This risk to life also applies to the Mastiff breed, who might require surgery to give birth – a risky procedure that can be expensive.

Certain dogs have been bred to have wrinkled, folded or "loose" skin, making them at high risk of painful infections and inflammation. Dog breeds at risk of itchy and sore skin include the Shar Pei and Neapolitan Mastiff.

Moreover, infolding eyelids may irritate and scratch the eye, which can feel uncomfortable and cause unnecessary pain.

The Hairless Chinese Crested dog is vulnerable to heat exposure and sunburn; consequently, this leads to an increased risk of cancer. And the dense coat of Chow Chows mean they are at risk of overheating in the sun, which can be dangerous.

Breeds bred to have short, flat faces can suffer from "severe breathing difficulties", heatstroke and fainting.

The RSPCA added: "Some dogs' nostrils and windpipes are so narrow they need surgery just so they can breathe properly." Breeds affected include the Pug and Pekingese.

Dogs bred to be very large and heart can suffer from hip dysplasia, lameness and arthritis; breeds include St Bernard and Dogue de Bordeaux.

Then the Dachshund, because of its long body and short legs, is prone to "painful and debilitating spinal problems"; this is also true of the Corgis.

And up to 70 percent of Cavaliers develop painful "syringomyelia, which is a hereditary brain condition common in toy dogs bred with skulls that are too small for their brains".

Dogs at risk of severe health problems and expensive veterinary bills

• Bulldog
• French bulldog
• Mastiff
• Shar pei
• Neapolitan Mastiff
• Hairless Chinese crested
• Pug
• Pekingese
• Chow chow
• St Bernard
• Dogue de Bordeaux
• Dachshunds
• Corgis
• Cavaliers

The RSPCA said: "We believe that all those who breed dogs - whether pedigree, purebred or crossbreed - should prioritise health, welfare and temperament over appearance. This will help protect the welfare of both the parents and puppies."