my purebreed Maltese has diarrhea approx. once a month .I have noticed this pattern for approx. 1 year now.She has received treatment by her Vet.(prophylactics,ie, sulfa med. scientific diet)I have stopped giving her cooked chicken ,small amts with her Iams adult dog food.Last episode was 3 days ago.What can I do? Is this inherent to Maltese?