Veterinary interest in MSM has increased over recent years. However, MSM has been used on horses for nearly 20 years. In 1983 John Metcalf, DVM, a well-known equine practitioner, started his evaluation of MSM to treat a variety of illnesses in horses, including chronic muscle soreness, epiphysitis, acute laminitis, pleuritis, recurring digestive tract disorder and arthritis. He has published his positive findings in several studies in peer-reviewed scientific periodicals, and generally emphasizes that MSM is of great value in maintaining the general health of horses.