The most common supplements sold as being beneficial for treatment or prevention of arthritis and degenerative joint disease in horses are glucosamine, chondroitin, and methyl sulphonyl methane MSM. Unfortunately, these, and various herbal concoctions also touted, have no sound scientifically valid basis for any beneficial effect.
From a nutrition standpoint, provision in the normal diet of sufficient minerals, particularly calcium & phosphorous in the appropriate ratio (1.8 – 2.2 parts calcium to 1.0 phosphorous) along with adequate trace elements such as copper, zinc, manganese, and vitamin D to support bone growth, density, and remodelling, is the most useful approach to assisting with prevention and management of degenerative joint disease. Nutritional support should be coupled with appropriate exercise, training, and veterinary advice as necessary.