BAR-CODED tins of beans are no longer a novelty - but dogs?

Coding is the latest solution to the problem of keeping tabs on the dog population and more than 120,000 British dogs already have their own unique, scannable code number.

Since 1930, owners have been required by law to put collars and tags on their dogs. But the RSPCA does not believe this is adequate and Terence Beat, its chief veterinary officer, points out that tags can be lost and that anyone abandoning a dog would be more than likely to remove its tag.

The RSPCA would like to see every dog in the country fitted with a microchip. The Identichip, manufactured in the United States, was introduced in Britain in 1989. More than 800 veterinary practices and 230 charities supply them.

For a fee of pounds 25 the microchip, about the size of a grain of rice, is injected painlessly into the back of the dog's neck, between the shoulder blades.

Encoded into the chip is a unique number which can be picked up by a scanner. The number is lodged in a central computerised database, with the name and address of the owner, the dog's age, breed, colour, vaccinations and so on. If the information changes, the chip stays in and data is simply updated on the computer.

A dog taken to a vet, the police, or a warden can be identified immediately if it has a chip, by a scanner and a call to the register. A national scheme could bring the price down.

The RSPCA now microchips every animal it re- homes, with the new owners having to pay the fee. Some local authorities are following suit, waiving a reclamation fee and charging for micro-chipping instead.

Bristol City Council, in conjunction with the local RSPCA, has been running a voluntary system of microchip registration. Between July 1992 and June 1993, of 1,797 stray dogs found, 822 had chips, enabling 733 dogs to be reclaimed within a day.

Brian Leonard, spokesman for the Kennel Club, is dubious. 'I would like to see a long term study of the effects on dogs. A non-intrusive procedure would be better.'

Terence Beat says: 'We handle up to 50,000 dogs a year, the majority of whom have a home but no identification and we can do nothing.'

Dogs with permanent chips on their shoulders could well be the answer.

(Photograph omitted)