Glucosamine is a popular nutritional supplement that horses are fed in hopes of protecting them from osteoarthritis. Researchers studying the mechanisms of osteoarthritis have identified several compounds, called markers, that are unique to the cartilaginous joints. Increased concentrations of these markers in the blood signify damage to cartilage and/or bone. Recently, a group of researchers from Michigan State University set out to investigate the benefits of glucosamine by testing its effect on the concentrations of three markers of early joint disease.

Standardbreds just beginning race training were divided into two groups. One group received glucosamine hydrochloride at the dosage recommonded on the label of a commercial glucosamine product (4 grams twice a day). The placebo group was given glucose (sugar) at the same dosage. Horses were put on a training regimen for 48 weeks, with periodic blood sampling.

During race training, all horses had an increased concentration of a marker of bone remodeling. A second marker, signifying cartilage damage, was also increased in both groups, but only during the latter half of the training period. The concentration of the third marker, an indicator of bone resorption, remained unchanged in all horses. The authors concluded that glucosamine had no recognizable effect on cartilage protection at the dosage administered. This conclusion was supported by the fact that there was no difference in the changes of concentration of the three markers of osteoarthritis between the treatment and placebo groups.

Caron, J.P.; Peters, T.L.; Hauptman, J.P., et al. American Journal of Veterinary Research, 63 (8), 1106-1110, 2002