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