I tried to switch my cats from Felidae to Chicken Soup since the latter is available locally. They have been on it for a while now but several of the cats stools still seem much looser than I would like and are discolored- same result some of my sister's cats had on it. But when my husband accidentally picked up a bag of CS light formula and fed it too them their stools went back to normal. Why would the result be so different between the regular and the light? Would the amount of fiber in the light make a difference? Is there something I should be looking for (or avoiding) if I try to go with another brand locally?