Dr. Sonja Egan:

It absolutely is but, ultimately, it is the legal obligation of the passport-issuing authority to register the animals if they receive an application. Ultimately, if the passport-issuing authority receives an application with a new microchip for an adult, it will process that application. It is up to the breeder to decide whether it wants to enter the animal on an identity document passport. If the animal in question had a new microchip inserted and a new set of markings done by the vet, and the vet signed off on this and sent it to the passport-issuing authority in the North, it goes off that application in good faith because it was signed off by a vet.