Sounds like a bulldog puppy, lol. It does stop eventually. Just be consistent. We tried everything from saying "NO", yiping loudly. Grabbing his jaw when he bit, time outs, ignoring and walking away, replacing our hand with a toy and whatever else we could think of and Tonka only came back at us harder and more aggressive. To this day the only thing that works ( and very well) is shaking coins in a coke can. Now all we have to do is reach for the can and he stops immediately and sits. Just have to find what your pup responds to. Tonka went into this obsessed state and it was all about breaking his concentration, which the coins do great. Also, I will not play tug with him ( though he tries) as I find it makes his obsessing worse. If he starts pulling on a toy in my hand I drop it immediately and he gets the idea and calms down.