Contains the highest quality vitamin C available. Vitamin C is a water soluble antioxidant that helps to eliminate damaging free radicals while improving overall health. What is Ester-C. Ester-C is a unique form of vitamin C containing non-acidic mineral ascorbates and natural metabolites (powerful boosters that help your pet's body efficiently absorb vitamin C). Patented Ester-C is the "ingredient of choice" for many supplements. Guaranteed Analysis: Analysis per 11cc scoop, Ascorbic Acid* - 875 mg. Ingredients: *Calcium Ascorbate (source of Vitamin C), Dextrose, Rice Flour, Calcium Carbonate, and Natural Apple Flavoring. Directions: One 11 cc scoop of Ester-C Plus per 1000 pound horse per day. One ounce supplies 875 mg of Vitamin C.