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Reviewed in November 2026

Microchip and registration: what it is, who fits it and how to change the details

The microchip is your pet's ID card, but it only works if the details in the register are up to date. What you need to know and what people forget most.

What it is

A chip the size of a grain of rice that the vet places under the skin. It has a number that is read with a scanner and is linked to your details in the companion animal register of your autonomous community.

Who has to have one

Dogs, cats and ferrets have to be identified with a microchip (Ley 7/2023, the Animal Welfare Act, and regional rules). Your community may also require other species to be identified. Keeping it identified and traceable is an obligation (Ley 7/2023, art. 24.2.f).

What people forget most

  • Changing the phone number and address when you move or change number. Otherwise, the chip is useless.
  • Changing the registered owner if you adopt or buy an animal: it has to be in your name.
  • If you move to another autonomous community, registering the animal in the new register.
  • Reporting its death when it dies.

How it is done

It is almost always handled by your vet, who has access to the register. The regional registers are connected through the Red Española de Identificación de Animales de Compañía (REIAC), so a lost animal can be identified even if it turns up in another community.