What is the best chew toy for a 80lb shepherd who seemingly and easily chews through the nylabones. Ivery gotten him the dinosaur ones and had to throw them out as they are now missing heads and tails. I got him a new tough big enough today and he is chewing that up bad already too. He is an EPI dog and on limited Ingredient food so my options for chews for him around limited to one's like the nylabone etc. I just need one he actually can't chew through lol. Thanks!!