Since the start of last year, they have been responsible for just under half the 119 reported incidents of dog bites here.

Bigger dogs such as German shepherds, rottweilers, bull dogs and Siberian huskies accounted for less than 20 per cent of the cases.

The proportion has been on the rise in the last few years.

Small dogs have been responsible for 35 per cent of the 236 incidents of people being bitten by dogs from 2005 till now, according to statistics from the Agri-Food and Veterinary Authority (AVA).

Small-dog bites accounted for 28 per cent of the bite incidents in 2005, 32 per cent in 2006, 45 per cent last year and 42per cent so far this year.

Bigger dogs accounted for just over 20per cent of the cases from 2005 till now.

In the wake of new rules being proposed by the AVA to make training compulsory for rottweilers, some professional trainers and enthusiasts are suggesting that it be made compulsory for other dogs, including small dogs too.

Dog trainer Patrick Wong, who trains 500 to 600 dogs a year, said even small dogs can be aggressive and attack people.

'Any dog can be territorial and defensive,' Mr Wong, 48, said.

The AVA said that current dog licensing laws here do not make it compulsory for dogs to undergo obedience training - just like most other countries.

The head of AVA's centre for animal welfare and control, Mr Madhavan Kannan, said: 'Generally, in view of their size and strength, dogs of a bigger breed can cause more serious injuries than a smaller breed. However, the seriousness of the injury would also depend on where a dog bites a person.'

The AVA's recommendations on obedience training for rottweilers are based on the recent spate of 'vicious attacks' by rottweilers on people and other dogs both here and in other countries.

There have been 11 cases of rottweilers attacking people here since 2005.

Mr Kannan said: 'The rottweiler is a large and powerful dog...The person handling such a dog should have it obedience-trained in order to exercise proper control of the dog.'

Rottweilers are also required by law to be muzzled and leashed when in a public place.

'A slip made could be fatal to another person or animal,' Mr Kannan added.

In any case, there are far more instances of small dogs biting because there are more of them here, especially since big dogs are not allowed to be kept in Housing Board flats.

Dog breeders and vets estimate that small dogs make up 75 per cent of the 53,000 licensed dogs in Singapore, or about 40,000. If this is right, then they actually bite less than their population would suggest.

There are about 323 licensed rottweilers and 300 German shepherds here.

While the number of biting incidents involving small dogs has been going up, such bites are far less likely to cause the damage that a bite from a medium-sized or large dog would cause.

Veterinarian Wendy Chee, 27, from the James Tan Veterinary Hospital said: 'The muscular power and strength of a bigger dog's jaw and size of its teeth mean that its bite could cause much deeper wounds than a small dog's.'

Professional trainer Josiah Gan, 40, said the force of a big dog's bite can break a bone 'whereas a small dog's bite is not enough to hurt a person beyond minor bleeding of the skin'.

Having said that, certain breeds of small dogs are known to be less docile than others, said Dr Chee, who was herself bitten by a neighbour's Jack Russell recently. 'These are typically high-

energy dogs which are built to be territorial and bark excessively,' she said.

In many countries, Jack Russells are bred in farms to hunt rodents and pests. 'They need to be constantly active, and can get frustrated if kept indoors too much,' Dr Chee said.

Vets and trainers said small dogs are no less aggressive and may have as high a propensity to bite.

Even if they do not inflict as much damage, it is a good idea that small dogs also attend obedience training, they said.

Singapore German Shepherd Club president Kabir Singh said: 'Given that Singapore is a densely populated country with a high degree of interaction between humans and pets, obedience training for all dogs will address and reduce incidents of dog-related injuries.'