Whether you call it chronic arthritis, osteoarthritis (OA) or degenerative joint disease (DJD), it is one of the most common causes of lameness problems in the horse or other equine...more. DJD is troubling because it is a progressive disorder and can become an exercise limiting lameness of the horse over time. For decades the mainstay of DJD treatment has been oral non-steroidal anti-inflammatory drugs like phenylbutazone and intra-articular steroid therapy and these are still some of the most useful treatments for keeping horses comfortable and working albeit often at a reduced work load...more.

Since the 1980's the benefits of various oral joint health nutraceuticals have been advertised for use in horses and equines with arthritis and have been advertised as a cure for arthritis in horses. These product's ingredients include:

• chondroitin sulfate (CS)
• glucosamine (GL)
• hyaluronic acid (HA)
• methylsulfonylmethane (MSM)
• avocado soybean unsaponifiables (ASU's)

While early studies seem to indicate a benefit from some of these products, legitimate questions remain. DJD is a difficult disease to study because of the normal waxing and waning nature of the disease. This is also a disease that has a high positive placebo effect. In experiments where placebos are also administered often a positive effect is noted, making the significance of the trial drug harder to evaluate. As a result the results of the research was in question and whether the medication was absorbed at all in a useful form caused many to ask, "is there a real benefit or not". Also of concern was the exact nature of the substance itself. These products were manufactured from a bewildering variety of natural substances including mussels, harvested cadaver cartilage, and cock's comb. These natural products are then chemically broken down to produce a large array of chemicals including various forms of chondroitin sulfates which include glucosamine and the polymer hyaluronate.

Ned Tijdschr Geneeskd. 2006 May 20;150(20):1105-7. Effectiveness of dietary supplements in patients with osteoarthritis: the doubt persists Lems WF, Bijlsma JW.; VU Medisch Centrum, afd Reumatologie 4A42, Amsterdam. Earlier studies with glucosamines in patients with osteoarthritis have shown conflicting results. A placebo-controlled randomized trial was now carried out in 1583 patients with osteoarthritis. The primary endpoint was a 20% reduction in knee pain between baseline and week 24 according to the 'Western Ontario and McMaster Universities arthritis index'(WOMAC)-score. No statistically significant difference was found between the groups using placebo (60% response), glucosamine (64%), chondroitin sulphate (65%) or combination therapy (67%). The results of this trial do not support the hypothesis that glucosamines have a positive effect on symptoms in patients with osteoarthritis of the knee. However, (a) the chance of a statistically significant difference decreases with increasing magnitude of the placebo response, (b) there was a statistically significant reduction in the patients with moderate to severe pain, (c) when the pain was assessed with the more sensitive 'Outcome measures in rheumatology clinical trials (OMERACT) - Osteoarthritis Research Society International (OARSI)-score, there was a better response in the group given combined treatment, (d) the data on radiological progression and the effects on cartilage markers must still come in, and (e) the efficacy may have been higher if a different dietary supplement had been used. These questions on the design and the robustness of the study indicate that further studies are necessary.

Despite these questions a whole human and horse industry grew up around hundreds of different products with a number of different ingredients, each promising remarkable benefits. These products were not cheap. In spite of these questions and the cost, horse owners bought them and continue to use them today. It does seem that these products have the potential for improving joint health in horses but the optimal chemical composition including the relative proportions of ingredients, and proper dosages are still unanswered questions. This article discusses the current evidence on the use of these products, potential modes of action, and makes recommendations for the use of such products.