Casein is the active ingredient in QCHEFS Natural Dental Chews dog treats. Casein is a digestible, lactose-free, milk-based protein that contains essential amino acids. Casein is hypoallergenic and remineralizes tooth enamel while reducing oral bacteria, plaque and tartar, according to the manufacturer. The chews are gluten free, antibiotic-free, hormone free, lactose-free with no additives, salt or sugar.