Everything that we don't eat, the dogs do. There's a deer backbone and hocks in the back yard right now they're probably working on as I speak. Everything. Organs, hides and fur, bones, tendon, etc. I have an audience in the kitchen when I grind because they know I toss up the silverskin and other crap that plugs up the grinder. I can basically just throw the scraps in the air and it vanished before hitting the ground.
All the trim and bloodshot too - is good dog food.
Oh, and I've fed 'em grouse, duck, partridge, goose, squirrel, rabbit, deer, bear, wolf, beaver, caribou, but not moose yet. Maybe next year. Never had an issue with bones getting stuck in the digestive tract in decades of dogs. A lot of dogs are aggressive eaters and "wolf" down food without chewing it. I wouldn't give a dog like that a lot of bones. They do that when they feel their food is in jeopardy of being taken from them. Mark my words, that's the root of it every dog I've ever seen inhale food. It's insecurity with their position.