Equine arthritis, also known as degenerative joint disease (DJD) afflicts many horses. It is a condition characterized as a slowly developing chronic disease of the joint in which the cartilage wears down, resulting in pain and subsequent lameness. Aside from a proper exercise program, there are other forms of preventative care, which includes supplements. These supplements include glucosamine and chondroitin, which targets joint health. Before you add any supplement to your horse's diet, be sure to consult your veterinarian. (petMD)