“These dogs may also be vulnerable to injury due to their fragile bones, which may even break during normal day to day activities such as jumping and playing.”The RSPCA, the Kennel Club and the Royal Veterinary College have all warned dog lovers against purchasing tiny teacup breeds. They may look adorable – and Paris Hilton has one – but the growing craze for tiny teacup puppies is causing a rise in deformities and illnesses including canine dwarfism, according to many animal welfare bodies.Although they are popular in South Korea and the US, UK breeders have been found breeding dogs to be smaller than is healthy, and this is causing suffering for the puppies and the owners who love them.Dr Rowena Packer, research fellow at the Royal Veterinary College, told The Telegraph of the health problems facing the tiny dogs.She said: “The trend for breeding ‘teacup’ puppies, miniaturised versions of breeds that are already considered small, is a real concern for canine welfare. Although they may be considered cute and baby-like, there are a number of health and behavioural problems associated with their small body size. People in the UK who have bought teacup puppies have found they have become sick and died within a short time after the purchase.Gareth Warton, from Wales, bought his wife, Leah, a teacup Pomeranian for Christmas in 2014.But on Boxing Day she fell ill and, after days of treatment by vets and no improvement the couple made the decision to have her put to sleep. “Evidence from veterinary studies suggests that miniature dog breeds are at an increased risk of a number of health disorders, including patellar luxation, where the dog’s kneecap slips out of place, causing lameness and pain; tracheal collapse, where the windpipe collapses causing coughing and breathing difficulties; dental disease, which may lead to bad breath, but also chronic pain and tooth loss; and syringomyelia, a painful brain disorder where the brain is too big for the relatively small skull. The RSPCA is calling for stricter legislation around the breeding and selling of dogs, including regulating intensive breeding. Dog breeder Jamie Parvizi was sentenced to 33 months in prison at Warrington Crown Court after breeding sick teacup puppies.Natasha Langmaid, also from Wales, bought her puppy, Bailey, in March 2014 for £650 from Parvizi’s home. Within days the tiny dog had fallen ill and needed intensive treatment at a veterinary surgery.To date, he has needed around £7,000 in veterinary treatment which, thankfully, has been covered by insurance.She said: “I have to remember I am one of the lucky ones who bought from these awful people because my fur-baby pulled through. Some others weren’t so lucky.” The animal charity has started to see an increase in the number of popular, fashionable breeds such as teacup dogs coming into its care and has advised people who own teacup dogs not to breed them. Teacup dogs are created when breeders purposefully breed the runts of the litter with each other over and over again, creating dogs which are unnaturally small.The Kennel Club does not recognise teacup breads, partly because of the health problems they suffer.The organisation told The Telegraph: “The Kennel Club does not recognise any teacup breed, and will not record dogs as being teacup on its register. There may be breeders who take care and breed a smaller-than-average dog responsibly, or who mistakenly use the term ‘teacup’ to describe a small dog, but the Kennel Club would advise puppy buyers to take extreme caution if considering buying a dog advertised in this way.”The Kennel Club has advice about the size, shape and conformation of pedigree dogs within its breed standards, which stress that breeders should not exaggerate any characteristics, including those related to size, and puppy buyers are strongly advised to ensure that neither the puppy nor its parents look exaggerated in appearance, before they buy. Any departure from this could lead to serious health problems further down the line.” Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.