Why do you suggest they may be quarantined. The point of the Pet Passport is to ensure they are rabies free (and treated for ticks, fleas and worms). A dog or cat coming from UK to France with a Pet Passport would not have to be put in quarantine. My dog has travelled between UK and France on a Pet Passport for 9 years. Can you explain to me why you mention quarantine please?
Sorry, just re-read the question and the writer refers to pets from OUTSIDE the EU. My mistake.