First, before getting an animal at a pet shop, Stanley advises buyers to closely examine it for any signs of illness. Buyers should look out for indicators such as hair loss, skin infections, coughing, sneezing and eye discharge. 'If you are buying an animal that is kept in a pet shop, use your common sense; some of them are obviously sick. Ask yourself if the animal looks healthy before buying it,' he says.

'Sometimes it's better to go to an animal welfare agency to get a healthy animal because the animal's health is more important than the commercial aspect.'

For those looking to buy a small-sized, or teacup breed, dog at a pet shop, another issue to watch out for is the animal's age. Stanley explains many pet shops will exaggerate a dog's age to fool customers who want very small dogs. For example, a two-month-old teacup poodle is said to be three-months-old, which will make the buyer believe the puppy is closer to its final adult size and smaller than it will actually be.

Stanley says: 'For these dogs, their vaccinations will be out of sync since you are supposed to give them vaccinations at certain ages.'

The former director of veterinary services at the Society for the Prevention of Cruelty to Animals also suggests looking at the dog's teeth for signs of baby teeth, and to contemplate whether the pet shop is truthful about a dog's age.

In the past year, Stanley has seen a number of cases where pet owners wanted to keep their puppy or dog's body size to a minimum so they didn't give them enough food. In addition to potentially harming their growth and health, he says, 'this doesn't do the dog's immune system much good'.

As we all know eating fruits and vegetables are good for us, the veterinarian advises pet owners to think before feeding. Dogs should not be given chocolate, onions or garlic since these are poisonous for canines. As cats are pickier eaters, it's less likely they will consume harmful food.

For food that is fine for animals, quantity should also be considered. 'If you feed a three-kilo dog half a banana, that's equivalent to us eating 10 bananas,' Stanley says.

'The other thing we commonly see [at the hospital] are dogs that are completely spoiled. They get what they want to be fed, and don't eat their own food. Eventually, they stop eating their dog food. Even worse are dogs that are hand fed. People need to be sensible and keep it simple. They should give good quality dog food, avoid giving treats off the table or human food.'

As some owners want their pet to be in tip-top shape, they give supplements and vitamins to boost their health.

Stanley advises that vitamins and bone supplements are unnecessary. 'All you need' is good quality food and water.

Veterinary behaviourist Cynthia Smillie at Animal Behaviour Veterinary Practice suggests that people research the type of pet they want before getting a pet. 'Depending on the breed or mix of breed of a dog, there can be problems [related to its natural behaviour] as a lot of breeds have been bred to do some type of work.'

Smillie says that Border Collies have an innate behaviour of needing to herd; Golden Retrievers and Labradors naturally retrieve prey and Terriers have a need to dig. 'The need to dig by Terriers may be labelled naughty or destructive in the house, but they are meeting a need through a century of breeding,' she explains. 'So for people trying to change or suppress it, you can't do it because it's inbuilt in the breed. The dog may be domesticated but these instincts won't disappear.'

Eventually, the dog's instinctive behaviour, Smillie says, can lead to problems in a family and the owner may not understand what the dog is trying to do.

Hong Kong's only veterinary behaviourist advises owners to choose a dog that will fit their lifestyle. 'Some breeds are aloof, so if you want a friendly and playful dog, they should avoid something like a Samoyed or Husky, which are very reserved,' she says. 'Look at how it will fit in with your circumstances. Are you out all day and work long hours? Then don't get a dog that needs to be bonded to you and close.' She adds that from a behavioural point of view this mismatch between owners and pets 'causes problems'.

Smillie also points out another common problem in Hong Kong. She says some owners are obsessed with washing their dog two to three times a week, which is too often. This may be stripping the skin of all its natural oils and cause skin problems, she says.