Just to add if you are planning to fly your cat/dog over to Spain or back again you need to check the routes and airlines. There are only certain airlines and routes you can use. Again it's all on the Defra website. Airlines have their own policy, and you may need to have a private health certificate. This is basically a letter from the vet to say the animal is fit to fly. The cost is cheaper for the pet you are travelling with them than if they fly alone.