Dogs in some pet shops are being deliberately underfed, experts say.
Some shops starved puppies to boost sales, hoping the pets' ravenous behaviour would be mistaken by customers as friendliness, said Dr Frank DeGroot of the Victory Animal Clinic.
'The shops probably feed dogs only half the amount of food required. Feeling hungry, the pets may lick the clients who think them friendly when they're actually looking for food. It helps to sell them,' said Dr DeGroot.
The vet, who has frequent contact with shops, said he heard of the practice four years ago.
'I know the practice is still going on. The treatment of puppies by some pet shops is very bad compared to overseas,' he said, adding that most dogs in shops were underweight.
Another vet, Mark O'Byrne from Mid-Levels Veterinary Centre, said: 'I've heard about this practice. Unfortunately, it's quite common in Hong Kong.' Dr Hugh Stanley, a vet for eight years, put the ill-treatment down to shop owners' poor knowledge.
'The practice may be on purpose, but I think it's a matter of ignorance and misconception.' Underfed dogs became susceptible to disease and reached adulthood at a later age, said Dr DeGroot.
Many shops also told pet buyers to feed the animals less than recommended amounts.
'I often have clients coming to me with puppies that are very thin. They said the pets shops told them to feed the pets twice a day, which is not enough,' said Dr Stanley.
Three-month-old puppies should be fed four times a day, with as much as they can eat in 20 minutes each time.
One-year-old dogs can be fed twice a day.
Dr Stanley said staff might believe it was less appealing to buy a dog that needed a lot of feeding.
A reporter, posing as a customer at a Wan Chai pet shop, was advised to feed a three-month-old Pekinese only twice a day.
'Though vets suggest four times, it's unlikely you have so much time for feeding. Most of the dogs in our shop eat two meals a day, which is okay,' said the sales assistant.
At another shop, two puppies in an open box were trembling and cuddled up to each other to withstand the blast of strong air-conditioning.
A staff member acknowledged the pets were freezing, saying he had forgotten to refill a hot water bag on which the puppies lay.
Pets in some shops were in small cages and one shop owner admitted she seldom let the animals out.
Dr Tony Holmes of Green Cross Veterinary Clinic said he once treated a dog from a pet shop which had suffered injuries from its confinement.
'It couldn't walk properly or go upstairs because it had been kept in a cage for months,' he said.
Dr Stanley said while conditions in pet shops had improved in recent years, premises could still be a magnet for infectious diseases.
An Agriculture and Fisheries Department spokesman said vets should report any problems. 'We have recently drafted a letter to encourage vets to report things to us.'