Cosequin Helps Navicular Horses, Study Shows

A recently published clinical study conducted at Auburn University Equine Hospital supports the use of the nutraceutical product Cosequin in navicular syndrome cases. Cosequin is manufactured by Nutramax Laboratories.

Navicular syndrome (also known as podotrochleosis) is a significant cause of forelimb lameness in horses. This is a complex condition that involves pathology of the navicular bone, bursa (fluid-filled cushioning sac), and the portion of the deep digital flexor tendon in the area of the navicular bone and bursa. The navicular bone is a sesamoid bone lying beneath the deep digital flexor tendon and articulating with the middle and distal phalanx bones (P2 and P3); the joint space between P2 and P3 is the coffin joint. The deep digital flexor tendon glides over the fibrocartilage-covered surface of the navicular bone and its associated bursa.

The cause of navicular syndrome is not known, but the result is lameness. Many factors can cause the syndrome, such as small blood clots compromising blood flow to the navicular bone, trauma, and certain metabolic conditions. The bony changes seen with navicular syndrome and degenerative joint disease (DJD) are similar; hence it has been suggested that navicular disease be classified as a form of DJD. Because of this, therapies useful for DJD, which include hoof trimming, special shoeing, pharmacologic compounds, and non-pharmacologic nutraceutical agents that support and protect articular cartilage, might prove beneficial in treating navicular syndrome.

Cosequin is a patented formulation of FCHG49 glucosamine hydrochloride, TRH122 low-molecular-weight sodium chondroitin sulfate, and manganese ascorbate. Previous studies conducted at Auburn showed that Cosequin is effective in managing degenerative joint disease in the hock and coffin joint as well as ringbone. Recent cell culture studies conducted by investigators at other veterinary schools using equine cartilage have shown that Cosequin can inhibit the rate of cartilage breakdown. Also, research presented at the 2001 American Association of Equine Practitioners meeting showed Cosequin to be bioavailable in horses (meaning the horse can absorb and use the materials).

The clinical trial at Auburn evaluated 14 horses with confirmed navicular syndrome. This trial was what medical researchers term a randomized, double-blind, placebo-controlled study. This means that horses were randomly assigned to receive either Cosequin or an indistinguishable placebo powder; owners and veterinary investigators were not aware of which compound the horse was receiving. At the beginning of the study and at four and eight weeks into the study, veterinary investigators rated lameness. This lameness index was a tabulated score of standing posture (lameness evident while standing), hoof tester examination, phalangeal flexion test, lameness grades while trotting and longeing, and lameness after warm-up longeing for five minutes. The investigators also assigned a score based on their judgment of response to treatment. Each horse owner rated his or her horse's lameness (rating degree of difficulty in rising, and degree of lameness while standing, walking, trotting, and longeing) and judged his response to treatment once a week.

The results showed a significant improvement in the Cosequin-treated horses' lameness, as scored by both the veterinary investigators and horse owners, and in the clinical condition score given by the veterinary investigators. There were no significant changes in the scores of the horses given the placebo. Cosequin was also shown to be safe in this trial and in a separate safety trial published last month by investigators from the Tufts University School of Veterinary Medicine.

About the Author

R. Reid Hanson, DVM, Dipl. ACVS

R. Reid Hanson, DVM, Dipl. ACVS, joined the surgical faculty at Auburn University in 1992, and is currently a Professor of Equine Surgery and Lameness. He is the author of over 180 scientific articles, abstracts, presentations, and book chapters related to equine surgery, lameness and critical care. Dr. Hanson is also an award-winning speaker, speaking to international audiences about these important topics. In his free time he enjoys competitive swimming and training. More information on Dr. Hanson can be found at

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