Why there are MSM horse supplements

21st December 2012
Beryl Shuttleworth
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MSM has become extremely popular amongst horse owners. Amongst other claims, MSM is believed to:

  • moderate allergic reactions,
  • calm upset stomachs,
  • correct mineral imbalances,
  • kill some parasites,
  • relieve pain and inflammation, and lastly,
  • be a natural antimicrobial and antioxidant.


Double Blind Trials

Now, being a natural sceptic myself, this looks to me like some supplier of MSM claiming to have discovered a “wonder drug”. So, I did some research to see whether any of these claims could be scientifically substantiated. To my surprise, I found that all of these claims were actually true and had been tested to work.

Double blind studies have been done on horses and humans which prove this.This is where two groups of patients are given either a placebo (no MSM) or MSM and their responses are measured. Neither the scientists conducting the trial nor the patients taking the medicine know who is taking placebo and who is taking the drug.

At the end of the trial, it is made known which group is which and responses are compared. In the trials that I looked at, an 80% improvement was shown in the group taking MSM, compared to the group taking placebos.


The history of MSM is interesting. It dates back to a chemist called Herschler who worked for a paper- processing company. His boss asked him to investigate possible uses for one of the company’s by-products, DMSO.

Herschler found that DMSO decreased inflammation and pain when applied to horse’s swollen legs. Although it became quite popular, there were some disadvantages to using DMSO:

  • It’s effect is transient, as it leaves the tissue very fast
  • There are possible toxicity problems
  • It causes bad breath
  • It causes dry, itchy skin
  • It stinks!

Herschler then decided to experiment with a molecule called MSM, which had a stabilising oxygen atom bound to the sulphur of the DMSO. This small change in molecular structure resulted in many positive advantages:

  • It had long-term therapeutic values
  • It is very untoxic (similar to water)
  • No bad breath, itchy skin or stink
  • Biochemistry

Although it is not known exactly how MSM works, it is assumed to be because it is a source of sulphur. Animals can’t use sulphur on its own, and MSM (which contains a sulphur molecule) can be easily used in the body. Sulphur is a very fragile element and, although it is present in big quantities in fresh foods, (eg. fresh hay), even minimal processing (eg. cutting and drying of hay) or storage causes the suplhur to be lost. This means that most horses (and humans) are deficient in sulphur. MSM can correct this imbalance by supplying sulphur in a form which is easy to use.


Together with his veterinarian friend, Dr Metcalf, Herschler continued to experiment. This is what he found:

  • Both men suffered from respiratory allergies. When they dosed themselves with MSM, the allergy disappeared. When they stopped taking it, the allergy returned.
  • Dr Metcalf’s labrador was able to stop her daily dose of four bute tablets per day when given MSM.
  • Dr Metcalf’s daughter’s showjumper became a different horse (no tail swishing, ears back or refusing) when put on MSM. He since had a lot of success with MSM in treating back pain in jumpers and race horses, especially with sacroiliac problems.

Fast-growing foals often develop epiphysitis, especially when their diet is too protein rich. This is a painful inflammatory condition when the foal’s body grows faster than his bones can develop to support the weight. A small amount of MSM fed daily can prevent this.

Further problems that were cured were: severe diarrhea in a valuable Arab stallion, gastric ulcers in foals, lameness, internal parasite (worm) infestations.


Dr Metcalf is quick to point out that MSM must not be regarded as a cure-all. “We must determine the cause of discomfort and make sure the cause no longer exists. Obviously, if there are joint chips in a horse’s knee, you might get temporary relief from MSM, but it isn’t going to make him sound.”

He also cautions people to always consult their doctor or vet before starting to use MSM.

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