Oral Joint Health Supplements

 

Abstract: Oral joint health supplements are popular in the equine industry despite, in many cases, a lack of understanding of the chemistry, pharmacology (particularly safety), and appropriate dosages of these products among owners and trainers. The most popular ingredients include glucosamine, chondroitin sulfate, and methylsulfonylmethane; however, a multitude of alternative supplements, including cetyl myristoleate, hyaluronic acid, ester-C, devil’s claw, yucca, garlic, and avocado/soybean unsaponifiable extracts, are also widely available. In this article, the most up-to-date information regarding the chemistry, pharmacokinetics (primarily absorption), safety, and dosing of oral joint health supplements is relayed in a practical manner. This information can help clinicians educate clients regarding the use of supplements to ensure that horses derive as much benefit as possible.
Complementary and alternative medical therapies, including the use of oral nutritional supplements, have become increasingly popular in the veterinary community, particularly the equine industry.1 Among these, joint health supplements are ubiquitously employed.1 Oral joint health supplements are popular not only because of the high incidence of osteoarthritis (OA; degenerative joint disease) in the equine population but also because of limitations of conventional medical treatment.
Despite the widespread availability and administration of oral nutritional supplements, these products are not considered to be drugs by the FDA. As a result, nutritional supplements, including equine oral joint health supplements, are poorly regulated and typically lack important pharmacologic information, such as absorption, distribution, metabolism, excretion, recommended dosages, and safety information. This dearth of basic scientific information makes it challenging for practicing veterinarians to identify quality oral joint health supplements.
Comprehensive reviews have been published regarding the medical management of equine OA2 and the use of nutraceuticals in horses with OA3 (both of these reviews include an up-to-date description of the pathophysiology of OA) as well as future OA management strategies.4 Together, these lay an excellent foundation for this discussion, which focuses on the rationale for the administration of various oral joint health supplements, including glucosamine, chondroitin sulfate, methylsulfonylmethane (MSM), and avocado/soybean unsaponifiable (ASU) extracts, either alone or in combination products, to horses with OA. This article examines the chemistry of articular cartilage and some oral joint health supplement components and presents the most up-to-date and relevant pharmacologic information available. This should allow practicing equine veterinarians to remain current with the ever-increasing information regarding oral joint health supplements and to facilitate product, formulation, and dosing decisions.