Joint Health for Horses Ages 6 and Up. Nutrition is a pro-active way to keep joints from deteriorating even during heavy work. As horses progress in their athletic careers, you may need to use a different set of nutrients to address thinning of the joint fluid or damage to the cartilage while still providing solid nutrition and plenty of antioxidants to prevent any further damage. Depending on whether your horse is experiencing any changes in their joints, you may need to offer cartilage support in the form of a joint supplement.