I had exactly the same issue with my dog - he had chronic diahhrea with no apparent cause. Everything was tried on this dog (including opening him up to see if he had something in him!). What I wound up doing was limiting his food to one item at a time to see if it was the diet - and it was! Rice was one of the big culprits. Also - some of the methods/ingredients in processing foods were really disagreeing with him. Human food was fine with him (as long as it didn't have rice) but processed dog foods sent him running for the yard (including biscuits). In addition to raw meat, I finally found two kibble brands he can eat - Fromm and Go Natural. Also, he is able to have canned tripe (big treat!) Canned Indian food rounds out his diet (most people laugh at this!) Lentils, chickpeas, spinach and paneer all work well for him - and the Indian companies that make it don't use the chemical additives that North American companies do. These can be found in Indian markets as well as specialty food shops. Or you could make your dog some lentil dahl! His biscuits are also now all homemade.