* Dietary Supplement * Pet Vitamins * Chewable * Dog and Puppy Formula From playful pup to mature dog and all stages in between, give your pet Vita Treat Pet Vitamins. FOS (Fructooligosaccharides derived from natural plant sources) are all natural carbohydrates found in a variety of fruits, vegetables, and grains. FOS selectively promote the growth of beneficial bacteria in the intestines. FOS are produced naturally and contain no additives.