Hi everyone! I have a 9-month-old male gsd and he loves chewing on bones! I'm having trouble finding a bone that will last him more than 3 minutes. I have tried various ones at Walmart that claim to be "long-lasting" but have not found one yet. I am really into rawhide-free and natural ingredients, something he won't have a problem digesting even though he does not have a sensitive tummy. Any suggestions are helpful, thanks!