I would try stuffing it with something he's maybe never eaten before, or something that he rarely gets.....something completely irresistable. And, it could be that he'll never chew on a hard rubber type toy. It's just like with kids, even if it's the best toy in the world, not all kids are going to like it. And, with Finn, I buy stuff he can fit in his mouth, but, not that he could swallow.