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MSM for Horses With PSSM and Other Muscle Sore Horses: Promising Help for Liver and Muscle Health

MSM for Horses: PSSM horses, liver health, sore muscles
MSM for Horses: PSSM horses, liver health, sore muscles

Our Experience With MSM Plus Research Articles Regarding MSM, Liver Health, PSSM Horses and Rhabdomyolysis

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MSM for horses: (above) Jax in April 2017 after a month or so on high MSM – from my notes “Has been bright-eyed and looking good the last couple days. The 4 days before today were all long, technical trail rides except the 3rd ride, which was medium-long and flat. 4th ride had lots of mud which was no problem for him. Standing with back legs separate instead of severely cowhocked as he has been since the vet trip 3 weeks ago (and before at times).”

A while back I found an older article about the benefits of MSM for horses with sore muscles (the very definition of PSSM horses, but not specific to PSSM horses). It was quite interesting, as I’d had my horse on MSM for about 2 weeks at that point and he was doing wonderfully – going on long trail rides daily and muscles were softer than they’ve been in years. Here’s one of the most interesting bits I found in the article:

“The results showed that all of the horses receiving MSM had dramatic improvement in three ways. Thermography showed less inflammation and soreness, particularly through the back and hind end. [emphasis mine]  (The change was faster and more dramatic for the horses on the higher dose.) Additionally, their serum chemistry demonstrated significant drops in two crucial parameters: AST (aspartate aminotransferase) and CK (creatine kinase), tests that indicate metabolites from muscle damage. Finally, all treated horses improved their average training time–group two (the lower dose) by two seconds, and group three by 2.62 seconds.” 1

MSM seems to help with Jax’s energy levels, back pain, overall inflammation, and exercise tolerance.  After reading the above article I was giving 28g of MSM daily, and he started tolerating the cold weather so much better than he did without MSM (cold weather is a massive trigger for him and many PSSM horses, even blanketed, and the winter before this had been horrible – Update 2021 – with the right blanketing winter is no problem for Jax!). 

After quite a few months, I noticed Jax’s manure had a horrible sulfur smell, and started reducing MSM with no setbacks.  Eventually I took him off completely and he did great for quite a few months (over the summer, when him and many PSSM horses are least symptomatic).  

He did really well for a while, but started having back pain again.  I went back through my notes and decided to add MSM back in October 2017, and after a few days his back pain was much better.  So, twice after adding MSM I noticed a major difference in muscle pain/stiffness.  However when that sulfur smell returned I worried about stomach health, as MSM can be an irritant, so I removed it again and he did fairly well being on it for short spurts for the next year or two.

MSM for horses: I either buy Animed MSM for my horses, or I buy human grade MSM from Bulk Supplements. Since I now need smaller amounts of MSM (only occasional use) buying the large bulk tubs of MSM for horses no longer makes sense! See MSM on Bulk Supplements’ website.

MSM for Horses: Liver Health

PSSM horses can sometimes have liver complications, as muscle disorders are hard on both liver and kidneys. In mid-2018, I decided to try a liver herb for Jax – milk thistle in human doses.  He had his worst laminitis episode yet (he’s prone to low grade laminitis and gets a mild case around June of every year).  This was not a bad case of laminitis, but it persisted despite my normal trim, boot, epsom salt poultice regimen that usually has him feeling better within a couple of days. 

The episode finally stopped when I removed milk thistle from his diet, leading me to believe he had a massive toxic dump that affected his hooves.  Despite the hoof issues, Jax’s muscles were better than ever!  I put him on milder liver herbs in hopes of keeping his muscles moving forward while stopping the effects on his hooves and it worked beautifully.  By late 2019 I was able to put him on milk thistle on occasion with no issues, supporting the idea that the 2018 episode was due to liver detox rather than a milk thistle sensitivity or allergy. 

At this point, I had no idea that MSM helps the liver, and he had been off it for at least 6 months.  I find it interesting that MSM has such a healing effect on the liver and was amazing for Jax’s muscles, and that herbs specific for liver health did the same.  Since it is known that rhabdomyolysis affects the liver enzymes, it makes sense that some of the “symptoms of PSSM horses” could actually be stressed liver symptoms.

As of April 2020, he now gets around 10g of MSM on occasion to keep inflammation at bay and to help any liver issues that may creep up. [Update Feb. 2023 – he gets MSM on occasion as needed now – See Jax’s updated diet here].

MSM for horses: Jen and Jax, as he’s starting to feel more physically comfortable with PSSM management and an anti-inflammatory diet, his personality is really starting to come out again.

One more note on our use of MSM: I no longer use the full horse dose of MSM for horses unless they really need a large amount; like herbs, I prefer to use smaller doses, so maybe a teaspoon a day instead of the recommended tablespoon in Animed’s MSM.


1. MSM Helps Sore Muscles on [I read this article with PSSM horses in mind, but it’s interesting for any/all horses!]

2.   Effect of Methylsulfonylmethane Pretreatment on Aceta-minophen Induced Hepatotoxicity in Rats – “Conclusion: Our findings suggest that MSM pretreatment could alleviate hepatic injury induced by acetaminophen intoxication, may be through its sulfur donating and antioxidant effects.”

3.   Hepatoprotective effect of methylsulfonylmethane against carbon tetrachloride-induced acute liver injury in rats – “Pre-treatment with MSM (400 mg/kg) inhibited the increases of serum ALT and AST activities… On the other hand, MSM raised SOD and CAT activities as well as CYP2E1 level in liver tissues. The present study shows that MSM possesses a hepatoprotective effect against CCl₄-induced liver injury in rats. This protective effect might be through its antioxidant, anti-inflammatory and antiapoptotic properties.” [AST is a muscle enzyme that raises after a PSSM episode – if MSM inhibits that raise, maybe this is part of the reason MSM can help sore muscles – but stopping a tie up? Also SOD is an amazing antioxidant that does seem to help PSSM horses.] Information in [] mine.

  • 3a.   Effects of Cu/Zn superoxide dismutase on strain injury-induced oxidative damage to skeletal muscle in rats – “The results showed that plasma levels of SOD, glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC) in SOD group were significantly higher than in the saline group on day 3 or 7, while the plasma creatine kinase (CK) and malondialdehyde (MDA) were lower in the SOD group than in the saline group. The histological examination of muscle sections revealed a lower degree of damage in the SOD group in which the expression level of desmin was higher than in the saline group. It is suggested that SOD supplement may attenuate strain-induced muscle damage and facilitate its regeneration.”

4.   Methylsulfonylmethane suppresses hepatic tumor development through activation of apoptosis

5.   WebMD – “Common complications of rhabdomyolysis [or tying up as it’s called with PSSM horses] include very high levels of potassium in the blood, which can lead to an irregular heartbeat or cardiac arrest and kidney damage (which occurs in up to half of patients). About one in four also develop problems with their liver. A condition called compartment syndrome may also occur after fluid resuscitation. This serious compression of nerves, blood vessels, and muscles can cause tissue damage and problems with blood flow.” Information in [] mine.

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