That's what the vet thought the first time we told him, but he's always came back negative. He seems to have a perfect bill of health in that regard. He's almost 8 now and he's done this since he was a puppy. We thought he might do it for attention, but I haven't seen behavior like this in any other dog. I also will give you a follow. I always like to stay on top of my pet's health!
Thanks for the suggestions! :)
You are welcom ;) great so.. If your vet did not found nothing probably it could be only a a bad habit. See you !