If you bring a dog or cat into Malta which was chipped overseas, it's vital to get the chip locally registered via a local vet, or the chip will show as unregistered. This is not done by the vet who inspects the animal on arrival in Malta. If you have not received a certificate in the post from the Malta chip registrar, typically within a couple of weeks, then almost certainly your dog is not registered on the Maltese chip register, which is the only place animal welfare or sanctuaries would check.
It is also a legal requirement to register the chip here if the dog is in the country for over 90 days, and for any dog to wear an ID tag whenever in a public place.
Certificates are NOT currently sent out for cats.