Boost your horse's immune system with herbs! This formula may also help with coughing. Stress, injury or fatigue can sometimes lower your horse's immune system. Recent studies suggest that even arthritis is due to a low functioning immune system. Give a quick boost with Immune Secret! INGREDIENTS: SIBERIAN GINSENG, YUCCA, ROSEHIPS, OLIVE LEAF, GARLIC, L-GLUTAMINE. 30 Servings.