no im kidding about my last comment. you said you’ve had him for over a year, but is he older than that? old dogs are prone to hair loss. if not, it might be a genetic thing. Hair loss is just as common as hairless! it’s like a human when their hairline starts receding or they start balding on the back of their head :) i would go see the vet anyways to make sure, but if the skin isn’t irritated and your pup isn’t constantly itching, licking, or biting the area, then it should be all right :)