A:Well your dog is getting to an old age... But my family member has an 15 year old dog and his hearing is VERY bad. He will not bark much any more. So it could be possible that he has gone def. You could test this by going near him but to where he cant see you and clap your hands, if he turns he isnt def of course. If he just lays there then maybe he is either just old and lazy or def. Hope i helped 
