Mine is on Raw, he's been fed raw since about 9 months and he's now nearly 8. He eats a variety of things, tinned sardines/pilchards, raw eggs, natural yoghurt, garlic, cottage cheese, chicken wings, tripe, chicken, lamb, beef, liver, plus supplements -organic apple cider vinegar, keepers mix, fish body oil, vit E.
He does well on this and has had no problems, the end product (being polite!) is much smaller and firmer on a raw diet. There shouldn't be any constipation, if there is it is because there is too much bone in the diet and you need to cut back on the bone and include more meat.
Karen & Reggie (GSD)