Clare - that is great to hear you got a shelter dog, Penny was a shelter dog too. She is getting older, almost 10, but very small dog. We have switched both our dogs over to grain free dog food as well. I think the primary reason for her bad breath is she has OCD when it comes to licking, I mean she will lick the floor, your pants, your face, her blankets, pretty much anything! Also, with her old age, her teeth are not in good shape. Totally agree on diet though. Being diabetic I try to eat the same way, grain free, doesnt always happen, but try to stick to the 80/20 rule. Eat as best I can 80% of the time :) thanks for the comment.