Just to go back to my point about captive wolves eating kibble. In my experience it is rare that a wolf can digest kibble and have solid stools with any regularity (no pun intended) if at all and maintain any level of good health. Whether one attempts to raise wolves on kibble from birth or transitioned to it later, diarrhea always seems to be a persistent problem. Even with wolfdogs there seems to be a correlation with the higher percentage wolf content and the tougher ability to digest kibble. Its just a general observational rule of thumb with them and I've seen exceptions to that.
Granted the digestive systems of wild and domestic canines should be much the same especially considering that wolves, dogs, coyotes and jackals can all interbreed with each other and their offspring are fertile as well but anecdotal observation suggests that there are differences. I can't explain it I just know what I have seen. Domestic dogs and feral dogs seem to be garbage disposals that can thrive on a wider variety of foods than their wild counterparts, especially wolves.
I just wish someone could explain why.