Their very essence is their unchangingness. But this one got me going. Dogs are not really faithful, in the sense of never changing. The oldest breeds, like the mastiff and greyhound, are only a few thousand years old. All the rest were created in the last couple of centuries.
Dogs are inventions, constantly being tinkered with, constantly yielding up new, improved versions.
My bias was that a techno-dog would always be a pale imitation of the real thing. Specifically, he wanted to know if they would be able to talk. Scientists have taught chimpanzees and gorillas to speak in sign. Not having hands, sign language for dogs is probably out. But imagine implanting sensors in the dog's brain, digestive tract, and bloodstream, that are alert to enzymatic changes in the dog's metabolism.