Theo’s favorite treats (not including human food) are bully sticks. He can gnaw on them for hours. I first heard of them while reading, “How to Raise the Perfect Puppy” by Cesar Millan. I am a huge Dog Whisperer fan and he highly recommends them.
You can purchase them from almost any dog store but I buy mine at Petco. Do yourself a favor and AVOID looking up what it is actually made of… yuck!