RSPCA vet Bairbre O'Malley, one of the team at the Harmsworth Memorial Hospital in north London which features on BBC1's Animal Hospital, said: "Films such as Jurassic Park and Teenage Mutant Ninja Turtles have fuelled a demand for reptiles among children which new 'pet supermarkets' have been only too happy to supply. And the sort of men who might in the past have bought an animal with a macho image, such as a Rottweiler, may now choose a reptile or snake instead."
Last month Ms O'Malley attended a course at Whipsnade Zoo aimed at bringing vets up to date with the latest treatments for exotic animals. She said: "The main problems we see are down to bad housing and malnutrition which result from ignorance on the part of owners. People with no experience whatsover can buy a reptile or a snake over the counter, on impulse."
Nearly all the iguanas brought to the Harmsworth had brittle bone diseases, due to dietary deficiencies, and often had broken limbs, Ms O'Malley said.
Most reptiles were dehydrated because of poor diet. Snakes were frequently brought in with burns after lying on incorrectly adjusted heat mats (a condom slipped over the affected area makes an effective lubricated bandage, apparently).
The craze for unusual pets extends beyond reptiles. North American chipmunks - cute, stripey, squirrel-like creatures - are increasingly popular as presents for children. Unfortunately they are very sensitive to high- frequency sounds and can go into shock or suffer heart failure when a TV remote control or burglar alarm is operating. They should therefore only be kept outdoors, said Ms O'Malley.
Dermod Malley (no relation), a vet at Wickford, near Chelmsford, Essex, said: "There has been a phenomenal increase in the past 10 years. I now see at least one reptile, usually an iguana, every day. People can go along to a pet shop and buy a 'starter kit' which consists of a box with a lamp and a reptile in it. This is a hell of a different environment from the canopy of the Central American jungle, which is what these creatures actually need to thrive.
"When people say they are considering buying an iguana I'm tempted to repeat Mr Punch's advice to those about to marry - 'don't'. Certainly don't get one without doing a lot of homework, including reading some expensive books and joining a club such as the British Reptile and Amphibian Society.
"Then you may need to shell out pounds 200 or pounds 300 on a decent vivarium (reptile house) and be prepared for veterinary fees of perhaps pounds 100 a time if the animal gets sick."
Mr Malley said people imagined iguanas to be sleepy, docile creatures because most of those living in Britain were in poor condition. "The healthy adult iguana can be an aggressive bugger," he said. "They can make very engaging pets, but it really does involve a lot of effort on the owner's part."
Mick Powell, secretary of the British Reptile and Amphibian Society, currently shares his house in Barking, Essex, with 30 snakes and reptiles waiting to be re-homed, including a 14ft Burmese python. Most are brought to him by the RSPCA. He gets eight to 10 enquiries a day from worried pet owners.
"Most of the blame lies with the pet shops," he said. "Most of them haven't a clue what they are selling. It's irresponsible to sell a cute 18-inch snake for pounds 60 or pounds 70 which is going to turn into a 10ft python in a couple of years."
The British Reptile and Amphibian Society, 85 Devon Road, Barking, Essex