Since 6th April 2016, it is now a legal requirement that all dogs must be microchipped. Microchips are about the size of a grain of rice and is usually implanted in the skin between the shoulder blades, ie the scruff of the neck in all mammals. It is a form of identification as it contains an unique number that is registered to your personal details. If your animal is picked up by the dog warden, police, rspca or taken to a vets it can be scanned and reunited with you, every year around 250 000 pets go missing, therefore microchipping is one of the most effective ways of finding your beloved pet.
A microchip is also a legal requirement if you are hoping to travel your pet abroad. Lay people such as those working in rescue centres can train to become a microchip implanter but only Vets can microchip tortoise, reptiles birds and horses.