Ask the Vet: MSM for Horses

Posted on: November 08, 2010 by Dr. Lydia Gray

Is chronic/longterm use of MSM actually detrimental? Laura

Dear Laura,

MSM, or methylsulfonylmethane, is believed to be a source of organic sulfur, required for a number of functions in the body. Sulfur plays critical roles in the formation of protein, connective tissue, immunoglobulins and enzymes. Therefore MSM is thought to support healthy joints; a strong immune system; and resilient skin, coat and hooves. However, MSM may do more than this. I shared a study on MSM in horses in a previous answer that shows it is a powerful antioxidant:

Marañón G, Muñoz-Escassi B, Manley W, García C, Cayado P, de la Muela MS, Olábarri B, León R, Vara E. Acta Vet Scand. 2008 Nov 7;50:45. The effect of methyl sulphonyl methane supplementation on biomarkers of oxidative stress in sport horses following jumping exercise.

There are lots of studies on MSM in humans, ranging from its effects in osteoarthritis to seasonal allergic rhinitis to cancer. For example, here’s the conclusion that this study makes on MSM, which they say is an effective natural analgesic and anti-inflammatory agent:

Usha PR, Naidu MU. Clin Drug Investig. 2004;24(6):353-63. Randomised, double-blind, parallel, placebo-controlled study of oral glucosamine, methylsulfonylmethane and their combination in osteoarthritis.

CONCLUSION: Glu, MSM and their combination produced an analgesic and anti-inflammatory effect in osteoarthritis. Combination therapy showed better efficacy in reducing pain and swelling and in improving the functional ability of joints than the individual agents. All the treatments were well tolerated. The onset of analgesic and anti-inflammatory activity was found to be more rapid with the combination than with Glu. It can be concluded that the combination of MSM with Glu provides better and more rapid improvement in patients with osteoarthritis.

All of these studies in people (lasting from 30 days to 12 weeks) say no major adverse events or side effects were reported. One report I read even said it’s one of the least toxic substances in biology, similar in toxicity to water! Researchers are still looking for harmful effects of short and long-term use of therapeutic doses of MSM, but as of right now none have been found.