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Do joint supplements for horses work?

A big market with thin evidence. What the studies on glucosamine, chondroitin, MSM, hyaluronic acid and herbs in horses really show – and why we do not offer a joint module ourselves.

A horse walking in a paddock; study sheets and a neutral closed feed container lie on a bench.
Explanatory illustration · Equivora

Osteoarthritis is not a fringe issue in horses: around 60% of lameness cases involve it, and in horses over 15 years of age the prevalence is above 50% 1. That explains why the market for joint products is so large – and makes it interesting to ask what these products actually do.

The short answer first: for none of the usual active ingredients is there a replicated proof of efficacy on clinical joint endpoints in horses. A systematic review of 22 papers on nutraceuticals for osteoarthritis concluded that the evidence of efficacy is weak; the only exception concerned omega-3-enriched diets in dogs, not horses 2.

Why lab findings and practice diverge

For glucosamine specifically, 15 studies in horses were assessed against a predefined quality score – only 3 reached the 60% threshold. The authors state that the quality of the studies does not allow a reliable interpretation 3. A randomised, placebo-controlled study of 40 older geldings with chronic lameness found no effect over six weeks on lameness grade, gait symmetry or stride length 4.

The most revealing figure comes from pharmacokinetics: when horses are given glucosamine at clinically usual doses, the concentrations reached in the blood and joint fluid are at least 500 times lower than those at which any effects on cartilage cells occur in cell culture; less than 10% of the blood level reaches the joint fluid 5.

The active ingredients one by one

Two details are worth a second look. With chondroitin, the larger of the two fractions tested reached the higher blood levels, not the smaller one 6 – so “low molecular weight” as an advertising term is not a mark of quality. And with omega-3, the source is decisive: the positive finding comes from marine EPA and DHA; plant sources such as linseed oil affect the fatty acid profile differently 7 and are not covered by this result.

IngredientWhat was measured in horsesAssessment
GlucosaminePharmacokinetics and joint levels 5; clinical endpoints 4well studied, no clinical evidence
Chondroitin sulphateAbsorption of two fractions (8.0 and 16.9 kDa) 6absorption proven, efficacy not studied
MSMOxidative stress markers after jumping exercise 9; gene expression in muscle 10not a single joint study in horses
Hyaluronic acid (oral)Joint effusion after OCD surgery in 48 yearlings 11clean positive result – but for a different endpoint
Omega-3 (marine)Inflammatory markers in synovial fluid and plasma in 16 horses with osteoarthritis 12markers, no lameness endpoints
Devil's clawPharmacokinetics of harpagoside in 6 horses 13no efficacy data in horses

Evidence in horses. “What was measured” is the decisive column here – many studies exist, but they measure something other than joint health.

Herbs are relevant for competitions

Devil's claw and willow bark are plants with defined active substances – and that is exactly what makes them borderline cases. Harpagoside from devil's claw can be detected in plasma for up to nine hours after oral administration 13. Willow bark provides the precursor of salicylic acid, which is listed with a threshold value in international competitive sport 14.

There are reviews on the efficacy of devil's claw for osteoarthritis – but in humans, and the methodological quality there is described as weak overall 15. This cannot be transferred to horses. Which withdrawal periods actually apply can be found in the current lists of the FN (German Equestrian Federation) and FEI.

What demonstrably benefits the joints

  • A body condition in the range of body condition score 4–5 out of 9 – excess weight is considered one of the biggest obstacles in managing joint pain 116.
  • Regular exercise: it is necessary for joint homeostasis, while overloading does harm. Changes to the routine should be gradual – a sudden stop in exercise can also worsen existing osteoarthritis 1.
  • Regular hoof care: over a 4–6 week interval, the centre of pressure on the hoof shifts by about 0.5 cm, whereas over eight weeks it shifts by 1.3 cm 17. That is a statement about load distribution, not about treating osteoarthritis.
  • Early veterinary investigation. There is no cure for joint disease in horses; the treatment goals are slowing progression, reducing pain and preserving function – through a multimodal approach that belongs in your vet's hands 18.

Why we do not offer a joint module

Our modules are the result of a calculation: what is supplemented is what is missing from the ration on paper. For glucosamine, chondroitin, MSM or hyaluronic acid, however, there is no requirement value at all in horses that could be covered – they are not essential nutrients. A product containing these substances therefore does not close a gap but aims at an effect.

For us, that is where the remit of a feed ends. A product may contain and declare such substances; it may not claim what they do. Anyone who advertises the effect is, in substance, turning their feed into an unauthorised veterinary medicine 19.

Sources & studies

The content is based on the references listed below. It does not replace individual veterinary or feeding advice.

Show list of sources (19)
  1. Baccarin RYA, Seidel SRT, Michelacci YM, Tokawa PKA, Oliveira TM (2022): Osteoarthritis: a common disease that should be avoided in the athletic horse's life. Animal Frontiers 12(3):25–36Review: around 60% of lameness cases in horses involve osteoarthritis; prevalence over 50% in horses older than 15 years. Exercise is necessary for joint homeostasis, overload is harmful; changes to the exercise routine should be gradual; recommended body condition score 4–5 out of 9
  2. Vandeweerd JM, Coisnon C, Clegg P, Cambier C, Pierson A, Hontoir F, Saegerman C, Gustin P, Buczinski S (2012): Systematic review of efficacy of nutraceuticals to alleviate clinical signs of osteoarthritis. Journal of Veterinary Internal Medicine 26(3):448–456Systematic review of 22 papers (5 in horses, 16 in dogs, 1 in cats), assessed using FDA criteria and a CONSORT-based score. Conclusion: the evidence of efficacy for nutraceuticals is weak – the only exception being diets enriched with omega-3 fatty acids in dogs, not in horses
  3. Pearson W, Lindinger MI (2009): Low quality of evidence for glucosamine-based nutraceuticals in equine joint disease: review of in vivo studies. Equine Veterinary Journal 41(7):706–712Quality assessment of 15 in vivo studies on glucosamine products in horses against a predefined threshold of 60%: only 3 of 15 papers reached it. Conclusion: study quality does not allow a robust interpretation of the reported results
  4. Efficacy of an Oral Chondroprotective Joint Supplement on Stride Length and Gait Symmetry in Aged Geldings with Chronic Lameness (2026). Animals 16(8):1230Randomised, placebo-controlled study in 40 geldings (18 ± 7 years) with chronic lameness (AAEP grade 2–4) over 6 weeks: no treatment effect on subjective lameness grade, objective gait symmetry or stride length
  5. Laverty S, Sandy JD, Celeste C, Vachon P, Marier JF, Plaas AHK (2005): Synovial fluid levels and serum pharmacokinetics in a large animal model following treatment with oral glucosamine at clinically relevant doses. Arthritis & Rheumatism 52(1):181–1918 adult mares, glucosamine hydrochloride 20 mg per kg body weight given nasogastrically or intravenously, sampling of synovial fluid from the carpal joint. The serum and synovial concentrations reached were at least 500-fold below those at which effects on chondrocytes have been described in cell and tissue culture; synovial levels were less than 10% of serum levels
  6. Du J, White N, Eddington ND (2004): The bioavailability and pharmacokinetics of glucosamine hydrochloride and chondroitin sulfate after oral and intravenous single dose administration in the horse. Biopharmaceutics & Drug Disposition 25(3):109–116Pharmacokinetic crossover study on the enteral absorption of glucosamine HCl and low-molecular-weight chondroitin sulphate. Two chondroitin fractions of 8.0 and 16.9 kDa were compared in 10 horses: both are absorbed orally, with the larger fraction reaching significantly higher levels. The glucosamine arm included only 2 horses
  7. Vineyard KR, Warren LK, Kivipelto J (2010): Effect of dietary omega-3 fatty acid source on plasma and red blood cell membrane composition and immune function in yearling horses. Journal of Animal Science 88(1):248–25718 Quarter Horse yearlings: encapsulated fish oil, ground linseed or control for 70 days. Evidence that marine and plant omega-3 sources affect the fatty acid profile differently
  8. Oke S, Aghazadeh-Habashi A, Weese JS, Jamali F (2006): Review of glucosamine-containing oral joint supplements – label claim vs. actual content in the horseOf 23 oral joint products, 9 contained less glucosamine than declared, 4 even less than 30% of the label claim
  9. Marañón G, Muñoz-Escassi B, Manley W, García C, Cayado P, de la Muela MS, Olábarri B, León R, Vara E (2008): The effect of methyl sulphonyl methane supplementation on biomarkers of oxidative stress in sport horses following jumping exercise. Acta Veterinaria Scandinavica 50:4524 show jumpers in competition, three groups (control; MSM 8 mg per kg body weight; MSM plus vitamin C). Endpoints are markers of oxidative stress after exercise – joint or lameness endpoints were not recorded
  10. Barshick MR, Ely KM, Mogge KC, Chance LM, Johnson SE (2025): Methylsulfonylmethane (MSM) Supplementation in Adult Horses Supports Improved Skeletal Muscle Inflammatory Gene Expression Following Exercise. Animals 15(2):215Crossover study in 10 previously untrained Thoroughbred geldings, 21 g MSM per animal per day for 30 days. Endpoints: blood lactate, antioxidant capacity, plasma cytokines and gene expression in muscle – explicitly no joint or lameness endpoints
  11. Bergin BJ, Pierce SW, Bramlage LR, Stromberg A (2006): Oral hyaluronan gel reduces post operative tarsocrural effusion in the yearling Thoroughbred. Equine Veterinary Journal 38(4):375–378Placebo-controlled study in 48 Thoroughbred yearlings after arthroscopic OCD surgery on the hock: 100 mg hyaluronic acid orally daily for 30 days vs placebo; mean effusion score on day 30 0.67 vs 2.05. Post-operative joint effusion was measured, not osteoarthritis or lameness
  12. Manhart DR, Scott BD, Gibbs PG, Coverdale JA, Eller EM, Honnas CM, Hood DM (2009): Markers of inflammation in arthritic horses fed omega-3 fatty acids. The Professional Animal Scientist 25(2):155–16016 horses with existing osteoarthritis, blocked and randomised into two groups of 8; treatment group additionally given 15 g EPA and 19.8 g DHA per day for 90 days. Result: greater decrease in synovial fluid leucocytes and plasma PGE2 compared with control – inflammatory markers, no lameness endpoints
  13. Axmann S, Hummel K, Nöbauer K, Razzazi-Fazeli E, Zitterl-Eglseer K (2019): Pharmacokinetics of harpagoside in horses after intragastric administration of a Devil's claw (Harpagophytum procumbens) extract. Journal of Veterinary Pharmacology and Therapeutics 42(1):37–446 horses in a crossover, Harpagophytum extract given intragastrically at 5 or 10 mg harpagoside per kg body weight; detectable in plasma for up to 9 hours. Pharmacokinetics only – no efficacy data
  14. FEI Threshold Substances List (Anhang zur Equine Prohibited Substances List)Official list of substances with a threshold in international equestrian sport; salicylic acid – the metabolite of salicin from willow bark – is listed there with a threshold. The list is revised annually; the current version always applies
  15. Brien S, Lewith GT, McGregor G (2006): Devil's Claw (Harpagophytum procumbens) as a treatment for osteoarthritis: a review of efficacy and safety. Journal of Alternative and Complementary Medicine 12(10):981–993Review of 14 human studies; methodological quality is described as weak overall. Not transferable to horses – serves solely as context from another species
  16. Henneke DR, Potter GD, Kreider JL, Yeates BF (1983): Relationship between condition score, physical measurements and body fat percentage in mares. Equine Veterinary Journal 15(4):371–372Original publication on the body condition score; bibliographically checked. Its application and limits are additionally supported by horse-specific specialist reviews.
  17. Leśniak K, Williams J, Kuznik K, Douglas P (2017): Does a 4–6 Week Shoeing Interval Promote Optimal Foot Balance in the Working Equine? Animals 7(4):29Observational study of 26 riding school horses: over a 4–6-week interval the centre of pressure shifted palmarly by about 0.5 cm, compared with 1.3 cm over an eight-week interval; the authors recommend not exceeding six weeks
  18. Contino EK (2018): Management and Rehabilitation of Joint Disease in Sport Horses. Veterinary Clinics of North America: Equine Practice 34(2):345–358There is no cure for joint disease in horses; treatment aims are slowing progression, reducing pain and maintaining function through a multimodal approach of medication, intra-articular therapy, management and physiotherapy
  19. Verordnung (EG) Nr. 767/2009Placing on the market and use of feed, labelling and claims; definitions of complete feed (Art. 3(2)(i)) and complementary feed (point (j)), content of feed additives (Art. 8), feeding instructions (Annex II No. 4). Link to the current EUR-Lex consolidated version (as of 26 December 2018).