Does your Pit have a food allergy? Is that why he's not doing as well on the Canidae? Nature's Recipe is not that good of food, check out the sticky I have posted in the health section of the list that the Whole Dog Journal published reagrding premium foods. Obviously it would be a lot easier to have all 3 on the same food, but it may not be possible depending on your Pit's allergy. A lot of dogs have issues with corn, so definitely steer clear of any food containing corn. A good substitute is Lamb & Rice, or duck.