From. British Embassy in Madrid.

( Brits in Spain )

Those of you with pets are probably aware that travelling with your cat or dog may have changed from 1 January, depending on where your pet’s passport was issued and where you are travelling to. If you have a pet passport issued by Spain or another EU member state, you can use it to travel with your pet to Great Britain and elsewhere in the EU.

However, a GB-issued EU pet passport is not valid for travel to the EU or Northern Ireland. You should speak to your vet before you travel to get the necessary pet travel documents and ensure you’re compliant with the EU Pet Travel Regulations (https://ec.europa.eu/food/animals/movement-pets_en).

You can find more information about taking your pet from Spain to Great Britain, travelling with your pet in the EU and travelling with your pet to Northern Ireland at https://www.gov.uk/guidance/living-in-spain#pets.