If you wish to take your pet with you on holiday outside the UK, you will need a Pet Passport. This document identifies the animal by microchip number, description and owner.
Before issuing a passport, your pet will need a rabies vaccination to become eligible for travel. DEFRA provide a broad outline of what is required. In addition, if your pet is flying, some carriers require a Health Certificate to be issued 24 hrs prior to travel. Some countries outside the EU may have their own list of requirements so if you are travelling to far flung corners of the earth it would be wise the check. Airpets will help with this information.
Remember to inform your pet insurers !
I personally do not issue pet passports.
Useful links :