MSM & Hyaluronic Acid for Dogs: Do They Help Joints?

MSM (methylsulfonylmethane) and hyaluronic acid appear in a large share of dog joint chews, usually alongside glucosamine and chondroitin. We found no controlled trial of MSM on its own in dogs, and the only controlled canine trial of oral hyaluronic acid on its own measured markers in joint fluid, not pain or lameness. Positive results for products that contain them come from multi-ingredient formulas, where the effect cannot be credited to either ingredient.

Key takeaways

• MSM: no dog trial of MSM alone. Human knee-osteoarthritis trials at 3–6 g a day found modest pain improvements; a systematic review found no definitive evidence.
• Oral hyaluronic acid: a randomized, double-blind trial in 55 dogs after cruciate surgery found favorable joint-fluid biomarker changes, not clinical outcomes.
• Injected hyaluronic acid is a veterinary procedure with its own evidence; it says nothing about chews.
• Positive trials of combination products cannot be credited to MSM or hyaluronic acid.
• Omega-3, green-lipped mussel and UC-II have stronger canine evidence.

What are MSM and hyaluronic acid?

MSM is a sulfur-containing compound found in small amounts in foods and made synthetically for supplements. The rationale is that sulfur is part of cartilage building blocks and that MSM may have anti-inflammatory effects in laboratory studies.

Hyaluronic acid (HA) is a large sugar molecule that gives joint fluid its slippery, cushioning quality. Supplements usually contain sodium hyaluronate, sometimes of a stated molecular weight. Whether HA taken by mouth reaches joints in useful amounts is still debated; most of the evidence for HA in joints comes from injections.

MSM: what the evidence shows

In dogs

We searched for placebo-controlled trials of MSM on its own in dogs with osteoarthritis and did not find any. Dog joint products contain MSM almost always in combination with glucosamine and chondroitin, and trials of those combinations do not separate MSM’s contribution. Glucosamine–chondroitin itself has disappointing controlled evidence: see Does glucosamine help dogs with osteoarthritis?.

In people

• A 2006 randomized, double-blind pilot trial in 50 adults with knee osteoarthritis gave 6 g of MSM a day for 12 weeks and reported lower pain and better physical function scores than placebo.
• A 2011 randomized, double-blind trial in 49 adults (3 g twice daily for 12 weeks) reported small improvements in pain and function.
• A systematic review of MSM and its parent compound DMSO concluded there was no definitive evidence that MSM benefits osteoarthritis, and a meta-analysis of three trials (326 patients) found reductions in pain that were statistically significant but not clinically meaningful.

Human doses (3–6 g a day for an adult) are far larger per kilogram than the few hundred milligrams in a typical dog chew, so even the human results do not tell us what a dog chew does.

Oral hyaluronic acid: what the evidence shows

A 2021 prospective, randomized, double-blind trial enrolled 55 dogs undergoing tibial tuberosity advancement surgery for cranial cruciate ligament rupture. Thirty received a branded oral HA product and 25 a placebo for 10 weeks after surgery. In the HA group, hyaluronic acid concentration in joint fluid rose and paraoxonase-1, a marker associated with inflammation, fell; in the placebo group joint-fluid HA declined. The authors concluded oral HA “may be effective” for managing stifle osteoarthritis.

What the trial did not show is less pain, better weight bearing or less lameness: the outcomes were laboratory markers after surgery. That is useful early evidence that oral HA is absorbed and has some joint effect, but under our rating rules biomarker changes are not clinical benefit.

Combination products with hyaluronic acid

A 2022 randomized, placebo-controlled, double-blind trial in 40 dogs with osteoarthritis tested a supplement containing Boswellia serrata, chlorophyll, green tea extract, glucosamine, chondroitin sulfate, hyaluronic acid and non-hydrolyzed type II collagen for 60 days. Combining veterinary and owner assessments, the product reduced pain and clinical signs. With seven actives, the trial cannot say what hyaluronic acid contributed.

Injected hyaluronic acid is different

Veterinarians sometimes inject hyaluronic acid directly into arthritic joints. Randomized trials of injections exist, but an injection delivers HA into the joint at doses no chew can match. Injection evidence should never be quoted as support for an oral supplement.

Safety

MSM has been well tolerated in human trials at several grams a day, and oral HA is generally considered low risk. Dog-specific safety data for both are limited. The practical risks are indirect: relying on a chew while pain goes untreated, or doubling up on multiple joint products. Chews are also a source of calories, which matters because extra weight worsens arthritis — see the body condition score tool.

How to read the label

• Is each active listed in mg per chew? Many chews list MSM and HA inside a “joint blend” without amounts.
• For HA, is the form and source stated (sodium hyaluronate, molecular weight, branded ingredient)? The canine trial tested a specific branded product.
• What else carries the formula? If you are buying for evidence, look for EPA/DHA, green-lipped mussel or UC-II at studied amounts; use the joint dose checker to compare labels with study doses.

For a full checklist, see How to check a dog joint supplement label.

Dog Supplement Facts evidence status

INSUFFICIENT for both.

For MSM, there is no canine trial of the ingredient alone, and human evidence is modest and inconsistent. For oral hyaluronic acid, the one canine trial of the ingredient alone measured biomarkers, not clinical outcomes, and positive clinical trials involve multi-ingredient products. Under our rating rules, both are insufficient. This does not mean they are harmful or certainly ineffective; it means the evidence does not show that they help.

When to see a veterinarian

Limping that lasts more than a few days, reluctance to jump or climb stairs, or stiffness after rest are signs of pain. Effective, well-studied treatments exist, including weight management, exercise plans, anti-inflammatory drugs and anti-NGF antibody therapy. A supplement is an add-on at most.

Related Dog Supplement Facts content

• Omega-3 Fish Oil for Dogs With Osteoarthritis
• UC-II for Dogs
• Dog Joint Supplements: What Matters
• Best-selling dog joint supplements vs the evidence

References

1. Kim LS, et al. Efficacy of methylsulfonylmethane (MSM) in osteoarthritis pain of the knee: a pilot clinical trial. Osteoarthritis Cartilage. 2006;14(3):286–294. PMID: 16309928. https://pubmed.ncbi.nlm.nih.gov/16309928/
2. Debbi EM, et al. Efficacy of methylsulfonylmethane supplementation on osteoarthritis of the knee: a randomized controlled study. BMC Complement Altern Med. 2011;11:50. doi:10.1186/1472-6882-11-50
3. Brien S, et al. Systematic review of the nutritional supplements dimethyl sulfoxide (DMSO) and methylsulfonylmethane (MSM) in the treatment of osteoarthritis. Osteoarthritis Cartilage. 2008. https://www.oarsijournal.com/article/S1063-4584(08)00066-6/fulltext
4. Brien S, et al. Meta-analysis of the related nutritional supplements dimethyl sulfoxide and methylsulfonylmethane in the treatment of osteoarthritis of the knee. Evid Based Complement Alternat Med. 2011. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3135791/
5. Serra Aguado CI, et al. Effects of oral hyaluronic acid administration in dogs following tibial tuberosity advancement surgery for cranial cruciate ligament injury. Animals. 2021;11(5):1264. doi:10.3390/ani11051264
6. Efficacy of a dietary supplement in dogs with osteoarthritis: a randomized placebo-controlled, double-blind clinical trial. PLoS One. 2022. PMID: 35171954. doi:10.1371/journal.pone.0263971