I am a big advocate for Brewer's yeast. Avoid the kind with garlic since it can cause gas. The Brewer's yeast can be purchase both at petstores or at Health Food stores (in powder form). It works great for their coats and shedding. Continued use is supposed to help with fleas as well. You can't smell it but the fleas do and keep off. Read the instructions and modify as needed. The powder form is easier to put on food. Good luck