If your dog is lost, you need to make both a police report, and, assuming it's chipped and registered locally, inform the chip registrars. This notification has to be made to the Microchipping Office at the Veterinary Regulation Directorate on +356 2292 5301 or email@example.com, and has to be done within 48 hours. They will then inform the sanctuaries, vets and the animal welfare department.
If your dog isn't chipped, you still need to make a police report, but you will need to inform all the sanctuaries, vets and the animal welfare department yourself.
Animal Welfare can be informed in the following ways
All dogs 4 months and older must be microchipped, and at any age wear an ID tag on their collar/harness when in public. Having no chip or no ID tag is punishable by a €300 fine. You also significantly reduce the chances of getting your dog back if you don't.