Although horse owners continue to administer oral joint health supplements (OJHS), a substantial proportion of these products are substandard in quality, efficacy, and safety, according to a presentation given at the 2008 American Association of Equine Practitioners convention, held Dec. 6-10 in San Diego, Calif. Wayne McIlwraith, BVSC, PhD, DSc, FRCVS, Dipl. ACVS, reviewed use of these products from a paper he co-authored with Stacey Oke, DVM, MSc.

Manufacture of OJHS is mostly an unregulated industry with widespread lack of quality control, including improper labeling practices (with incorrect, incomplete, or misleading analysis of content), lack of standardization of appropriate therapeutic dosing, and the potential for contamination with dangerous substances, such as heavy metals, pesticides, dimethyl sulfoxide (DMSO), or other compounds prepared in the manufacturing plant. More than one-third of the products do not meet label claims. In addition, McIlwraith is concerned that there is no mandatory federal recording of adverse event occurrence with these products. And, there is no incentive to perform any in vivo (in the live horse, as opposed to samples in a lab setting) research because there are no requirements to demonstrate product efficacy.

There is also no reported information on interaction of OJHS with other pharmaceutical medications or with herbal preparations, plus not all side effects of OJHS have been recorded in veterinary literature or are well-understood. For example, there is some concern that glucosamine has the potential to increase insulin resistance, which is of great concern in geriatric horses, particularly those at risk for laminitis.

Previous studies on some OJHS might have yielded favorable results, however McIlwraith explained that many studies are lacking in the scientific method that requires controls, placebos, and objective information gathering important to validating a research project. There are only a limited number of peer-reviewed publications on in vivo findings regarding equine OJHS. It is also valuable to ascertain what company might be funding research of a product so there is as little conflict of interest as possible.

OJHS are perceived by horse owners as safe and an economical alternative to intra-articular or intramuscular joint therapies. The general impression has been that these products are therapeutic for treatment of osteoarthritis, for postoperative or post-traumatic management, and they might have preventive applications. One canine study involved feeding a glucosamine/chondroitin sulfate combination in advance of inducing osteoarthritis and found that dogs pre-treated for three weeks had less joint inflammation than those not receiving the supplement. If the product was given following induction of osteoarthritis, then no improvement was seen, suggesting that there might be a lag time between administration and clinical effects. McIlwraith suggests that prophylactic use of OJHS is theoretical and requires further investigation.

In a controlled study at Colorado State University testing the effect of avocado and soybean unsaponifiable extracts (ASU), researchers found a significant decrease in cartilage erosion in horses with experimentally induced osteoarthritis that were given the extracts, although there were no differences in pain or lameness. Although not identical, a similar form of the studied ASU product has been added to Cosequin (produced by Nutramax), but no data on this product has yet been attained in live horse models.

McIlwraith recommended seven ACCLAIM steps for selection of a supplement:

  • A name you recognize Do you recognize the manufacturer's name as an established company?
  • Clinical experience Have the products been tested in clinical trials with reports in peer-reviewed journals?
  • Contents Are the contents clearly indicated on the product label?
  • Label claims Are the product label claims based on scientific study results?
  • Administration directions Are administration recommendations clear and easy to follow?
  • Identification of lot Is there an identification of lot number, tracking system, and quality control?
  • Manufacturer information Is manufacturer and contact information included on the label?

Finally, McIlwraith stressed the value of an evidence-based approach to clinical trials using these products. Veterinarians and consumers should demand high-quality research that carefully analyzes product value by using a diligent scientific method.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her recent book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care (available at or by calling 800/582-5604). She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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