In Slovenia, microchipping of dogs is obligatory since 2003 and we estimate that over 75% of dogs in the country are microchipped at the moment.
Every microchipped dog also gets EU passport and is entered in central dog register, which is a web portal with detailed contact information of the owner and information about the dog, including rabies vaccinations and possible dog bites of a person. Data is available to practicing clinicians, shelters and other veterinary authorities. With this database at hand, the majority of lost dogs can quickly return to their owners. Besides, it also serves as good control over obligatory rabies vaccination of the dog population.
We find this system very effective since there are no stray dogs in Slovenia.