'Chinchillas won't greet you when you come home. You can't even hold them in your arms because they would run away,' says Chan, an office worker. 'So I kept them in a cage and played with them for one hour or so after I returned from work.'

But Chan developed an allergy, which was aggravated by the chinchillas. So three months ago she decided to hand them to the Agriculture, Fisheries and Conservation Department (AFCD).

'I felt a bit upset when I surrendered Fa Fa and Fai Chai. But my allergy problem deteriorated this year, with bouts of sneezing and even fever,' she says. 'I had no alternative.'

Such a rationale gets short shrift from animal welfare groups which say Fa Fa and Fai Chai will likely be among the tens of thousands of creatures expected to be put down by the department this year.

One in eight families in Hong Kong keep a pet at home, according to the latest official figures, but 7.6 per cent eventually give up those pets, often on trivial grounds.

Reasons given range from losing their fondness for the pet (21.2 per cent), fed-up with having to deal with animal droppings (18 per cent) and shortage of space as the pet grows bigger (17.6 per cent). Other reasons include financial problems (10.2 per cent), lack of time to care for the animal (8.6 per cent), the pet's ageing (7.4 per cent), pet shedding hair (7.4 per cent) and a new baby in the family (5.6 per cent).

'Keeping a pet should be a lifelong commitment,' says Rebecca Ngan Yee-ling, communications manager for the Society for Prevention of Cruel to Animals (SPCA). 'You would not leave your family members if they were old and sick. If you truly loved your pets, you would try to overcome all barriers, such as health problems and housing restrictions.

'Owners who abandon their pets are like people who want to break up with their partners. But in the case of animals, such a decision is cruel and unfair,' says Ngan. 'Your pet may only be a part of your life, but you are their entire life. To a pet, it would likely be the end of the world if owners decide to give them up.

'It's often hard to find a new owner for the abandoned animal. Even if they were lucky enough to find a new home, it's not easy for them to integrate into a new family.'

A seven-year-old cat which was recently surrendered by its owner after five years was lucky to be adopted early this month, she says. 'Seven cat years is about fiftysomething in human terms - middle-aged. But most people look for tiny, cute kittens. It is very difficult for an old cat to find a new home.'

Shops such as Love Pet Pet in Causeway Bay, which recently launched a scheme to allow potential owners to keep an animal for a two-week trial period, are likely to further erode any sense of commitment, welfare groups say.

But the pet shop says the scheme is designed to protect consumers if the pet becomes sick and would also deter them from dumping the animal.

'Owners should learn to take care of their pets when they're sick too,' Ngan says. 'Even if the animal is well during the two weeks, it will still grow old and sick one day. Besides, it's stressful for the animals to keep moving from one family to another in trial adoptions.'

Keeping pets is a relatively recent trend in Hong Kong - 'it has became popular only in the past 10 to 20 years,' Ngan says - and many owners tend to view their pets as commodities rather than part of the family.

'While some people are devoted to their pets, many regard them as status symbols and only want pedigreed animals. They would proudly walk their terrier or Pekinese, but rarely brag about a mongrel,' she says.

'But even pedigreed pets are abandoned once owners lose interest. We get dogs such as Cocker Spaniels and Dalmatians here, too.'

The odds that an abandoned animal would get a new lease of life with a good owner are slim. The SPCA received 9,251 surrendered animals, including 2,833 dogs and 5,190 cats between April 2005 and March this year. Among the abandoned pets were rabbits, guinea pigs, chinchillas and birds. And in the first six months of this year alone, the AFCD took in 6,300 dogs and 3,000 cats.

Some owners don't even bother to hand in unwanted pets. The SPCA recently received a snake which its owner had placed in a tank beside a playground. 'Some just leave their pets in front of our office and run away,' Ngan says. 'Others threaten to dump their animal in the street if we don't take them in.'

The sheer number of unwanted pets means most eventually have to be put down - animal welfare groups simply don't have the space and resources to tend to them. In the first six months of this year, the government has already had to kill 10,400 animals, including 5,100 dogs and 2,250 cats. Meanwhile, in the 12 months to March, the SPCA had to put down 372 animals that it could not find homes for because of such factors as serious illnesses and behaviour problems.

'We try to give the pets every opportunity to find new homes. However, it's inhumane to keep them in such a small space indefinitely, especially those unlikely to find new owners,' Ngan says.

Yet owners often refuse to recognise that to desert their pets - even if left at a place such as the SPCA - is often to condemn the animals to death. 'Some people return to abuse us after they learn that the animals they abandoned were put down,' Ngan says.

The Society for Abandoned Animals doesn't put down creatures it can't find homes for, but space at its 'orphanage' in Yuen Long is limited. The society keeps 190 dogs, 60 cats and 15 rabbits, and some farm animals, including a pig, two chickens and five goats.

But the centre has been filled to capacity for the past seven years, with another 1,400 animals on the waiting list, says chief executive officer El Chan Suk-kuen.

She was particularly distressed when an expatriate adopted two dogs from the centre only to give them up two years later when he moved to Dubai.

'He would not allow his pet indoors and argued that it would be inhumane to bring the dogs to such a city with such a hot climate as he would not allow his pets to stay indoors. I was really upset by his explanation,' Chan says.

'It's wrong for people to treat animal welfare organisations as a fail-safe solution so they can feel better about deserting their animals,' she says.