Shelby has awful breath too and no matter what we try nothing helps. And she will not drink her water if we put additives in it. I know that it isn't her teeth. I do know that she too "eats a snack" from the yard on occasion if we don't clean it up fast enough. But her breath smells even when she has t had a snack for weeks. She is 7 years old and this has been an issue her entire life, so we are not concerned. She has an underbite and as a result her mouth does not close completely and she does not chew her food. I think that is the main culprit of her fragrant breath.