Veterinarian formulated and recommended for all classes of horses. Ester-C Plus is the highest quality Vitamin C available. Vitamin C is a water soluble antioxidant that helps protect against free radicals that cause cellular damage while improving overall health. The Ester-C manufacturing process neutralizes the acidity of ascorbic acid and maximizes the formation of mineral ascorbates and Vitamin C metabolites that speed the absorption of Vitamin C.