There are no specific formalities for bringing pets into Greece. In compliance with World Health Organisation (WHO) requirements, pets (dogs and cats) entering or departing Greece must have a health certificate that the pet is in good health, free from infectious disease, and has had a rabies inoculation not more than 6 days before arrival or departure. The certificate must be validated by the appropriate medical authority in the country, where travel begins. Animals entering should bear either a clearly readable tattoo or an electronic identification system.
Generally, the standard requirements for bringing a pet into Greece are, that your pet must be micro-chipped and registered, and must have had a rabies vaccination within the last 12 months, but more than 30 days ago. Throughout the EU there are standard rules for the issuing of a PET passport and animals travelling within the EU are required to have one. If your pet originated from the UK, has a passport and had the required jabs before leaving which have been kept up to date by a local vet, then there isn’t any problem about quarantine on returning.
On the other hand, as Greece does not currently belong to the pet passport scheme, if your animal comes from Greece it will be required to go into quarantine on arrival in the UK.
Pets must be transported by an authorised carrier. Greece national carier, Olympic Airways and other international scheduled airlines will transport pets to Greece. Depending on the airline, you may be able to have your pet travel on the same flight, either in the cabin or in the cargo hold. The airline may consider a pet transported this way as excess baggage and charge you accordingly. Do not assume that you can take your pet on the same flight with you. You must confirm this in advance with your airline. As a rule animals weighing 100 lbs. or more will travel as cargo even if they are transported on the same flight as you.
The other option is to arrange for your pet to be transported on a separate flight as air cargo shipment. In this case you do not have to accompany your pet, however, you need to make arrangements for picking it up at the destination. Be aware that the cost of this service is generally considerably higher than excess baggage.