Tomlyn Nutri-Cal for Dogs & Cats www.petco.com - $9.49 Product Description: Quality nutrition energizer for picky eaters. High-calorie palatable dietary supplement in a low-volume form is highly palatable. Provides an added source of energy for cats and hunting and working dogs. RattyRat's Review: If you have a rat that is having trouble keeping weight on, for what ever reason, this is a good product to use. It is full of vitamins, and calories, and contains an appetite stimulant. Try introducing this product to your rats when they are younger and healthy so that they learn to love the flavor. Once a month give them a few licks of it, or use it in the "hiding food" game and put dabs of it around their play area.