I am not sure with the civilian dogs however when the services train the dogs the handler is always there. The handler eats, drinks and sleeps with the dog.
When the handler leaves the military the dog is considered not able to be retrained so there is a choice. Put the dog down or let the dog retire with the handler. At least that was how it was in my younger days.
Yeah, but you’re talking about military attack and guard dogs, not drug-sniffing dogs. The drug dogs come fully trained and then the handler has to be trained to the dog, so they can change handlers easily. Many drug dogs are adopted by civilians when the retire.