(Brookside) Command Ester-C is a patented, mineralized form of vitamin C. In comparison to ascorbic acid, Ester-C is four times more absorbable and has a neutral pH, which means it will not upset your horse’s stomach or cause ulcers. Vitamin C is important for joint and connective tissue health and is a key anti-oxidant. Useful for stress related conditions, degenerative joint disease, allergies, COPD, heaves, stable cough and respiratory infections. 5,000 mg per serving. Feed 5 grams (about 1/5 ounce) twice daily with feed. Scoop enclosed. Powder.