The athletic abilities of horses mean that they are at high risk of musculoskeletal problems. Injuries and diseases of the joints are a common problem in ridden and driven horses and ponies; therefore maintenance of healthy joints is paramount in the minds of horse owners.
Joints contain cartilage and synovial fluid, both of which are shock absorbing and reduce friction during joint movement. Cartilage does not have its own blood supply and relies on healthy synovial fluid for its nutrition. During inflammation or other damage, joint cartilage and synovial fluid can be detrimentally affected, leading to a cascade of inflammation, degradation of cartilage and loss of synovial fluid.
Feeding compounds that could have a beneficial effect on the ability of cartilage to withstand wear and tear and avoid the damaging effects of inflammation would be worthwhile, but these compounds must be absorbed, get to the site of the joint and have a therapeutic effect.
Chondroitin sulphate and glucosamine-sulphate and –hydrochloride are commonly used joint supporting supplements for horses. Both – in theory – get to the joint and promote healthy cartilage and synovial fluid.
Chondroitin is a large complex molecule belonging to a group called glycosaminoglycans, and it is found naturally in cartilage, skin, and connective tissue. Researchers have shown that low-molecular weight chondroitin is absorbed in horses after oral supplementation. Chondroitin is sourced from bovine trachea, pig or shark cartilage or whale septum, so it is a good idea to ask a supplement supplier where they source their chondroitin from. And if you wish to feed your horse a vegetarian diet, then chondroitin is not an option.
Its mode of action is believed to be a replacement of the proteoglycans in articular cartilage, which are lost in damage and/or inflammation, an anti-inflammatory effect and inhibition of enzymes involved in cartilage breakdown – effects which have been backed up by laboratory research.
Studies of horses investigating the effects of oral supplementation of chondroitin have been promising, but all have used combinations of chondroitin with glucosamine. Authors of two research trials investigating the results of feeding a glucosamine chondroitin combination to 25 horses with degenerative joint disease, and to 14 horses with navicular syndrome, found significant improvements in lameness in both trials. The DJD trial was not blinded, however, and nor was it crossover but the navicular trial was placebo-controlled (Hanson et al, 1997). Another trial (double-blind placebo-controlled) investigated stride characteristics in 20 veteran horses fed a chondroitin-glucosamine combination and found significantly increased stride length (Forsyth et al, 2006).
Authors of a review of in vivo (laboratory) research papers concluded that the quality of research was not of a high enough standard to make meaningful conclusions and recommended further research (Pearson & Lindinger, 2009). In conclusion, more high quality research is required in horses to determine the usefulness of chondroitin alone as a joint-supporting supplement. In the meantime, several grams of chondroitin should be fed over the long term and the horse owner should be aware of the source of the chondroitin in the supplement of their choice.
Forsyth, R. K. et al, (2006) Double blind investigation of the effects of oral supplementation of combined glucosamine hydrochloride (GHCL) and chondroitin sulphate (CS) on stride characteristics of veteran horses. Equine Veterinary Journal. 38(Supplement 36): 622-625
Hanson, R. R. et al, (1997) Oral Treatment With a Glucosamine-Chondroitin Sulfate Compound for Degenerative Joint Disease in Horses: 25 Cases. Equine Practice. 19(9): 16-20
Hanson, R. R. et al, (2001) Oral treatment with a nutraceutical (Cosequin) for ameliorating signs of navicular syndrome in horses. Veterinary Therapeutics. 2(2): 148-159.
Pearson, W. & Lindinger, M. (2009) Low quality of evidence for glucosamine-based nutraceuticals in equine joint disease: review of in vivo studies. Equine Veterinary Journal. 41(7): 706-712.