Hi Chris-
Have you ever heard of a Kong, a rubber toy with a hollow center? I occasionally will “stuff” one with wet kibble and pumpkin. Then put it in the freezer. My dogs love them and they do last a while as well, if you freeze them til the contents are completely frozen.
Here is a link: http://www.aspca.org/pet-care/virtual-pet-behaviorist/dog-behavior/how-stuff-kong-toy
I have heard chicken feet are good also. I have tried tracheas and they seemed a little too greasy and gave my dogs loose stools.
