You must take your pet to your vet to get an animal health certificate. You need to do this no more than 10 days before you travel. The certificate needs to be signed by an official veterinarian.
Your pet’s animal health certificate will be valid after the date of issue for:
10 days for entry into the EU or Northern Ireland
4 months for onward travel within the EU
4 months for re-entry to Great Britain
Your pet will need a new animal health certificate for each trip to an EU country or Northern Ireland from Great Britain. For more information visit Defra’s website: https://www.gov.uk/taking-your-pet-abroad