The tiny devices, the size of a grain of rice, remain in the animal for life. Another device, the reader, detects the unique number in each chip from outside the dog's body.
In Britain the Kennel Club keeps a database for the 250,000 dogs which have been microchipped, giving their owners' addresses.
Less than 5 per cent of UK dogs have been microchipped to date. The devices, which cost about pounds 20, are injected into the thin layer of fat just below the skin using a special syringe.
Animal welfare organisations have long argued for a compulsory, nationwide registration scheme for all dogs.This would reduce the number of bad, irresponsible owners and strays. They have failed to persuade govern- ment to legislate, except for particularly dangerous breeds like the pit bull.Reuse content