Stem cell therapy has been used for soft tissue injuries, including stifle meniscal lesions following surgical debridement, and for treating tendon injuries. Bone marrow-derived stem cells are reported to achieve improved bone and cartilage effects as compared to fat-derived stem cells. It takes two to three weeks from the time marrow cells are collected from a horse's pelvis or sternum until cells are ready for injection. Dora Ferris, DVM, of the Orthopaedic Research Center at Colorado State University, discussed the use of bone marrow-derived stem cells at the 2009 American Association of Equine Practitioners (AAEP) convention, held Dec. 5-9 in Las Vegas, Nev.

Ferris described evaluating treatment success in a variety of musculoskeletal disorders with a mean follow-up of 21 months (range seven to 39 months) on 101 patients. It should be noted there were no control groups in the study for comparing success between treated and nontreated horses; however, Ferris reported that investigators on previously published studies used controls for horses treated with meniscal, tendon, or ligament injuries. The current study reported that 64% of treated horses returned to full work, while 22% returned to work with increased therapy or at a lesser level, but there was a reported 8% re-injury rate. Fourteen percent did not return to work.

All sport horses and 91% of racehorses with superficial digital flexor tendon injuries returned to work following stem cell therapy. Twenty percent of racehorses that returned to racing following stem cell treatment, rest, and rehabilitation re-injured themselves, whereas 66% of horses experienced re-injury when undergoing conservative treatment or rest and rehabilitation. Encouragingly, Ferris noted that 78% of horses treated for chronic suspensory ligament injuries were able to return to work following stem cell treatment after failing to improve with other conventional treatments.

Veterinarians in this study conducted intra-articular (IA) stem cell therapy mostly on Western performance horses. Of these, 73% returned to work--35% resumed full function and 38% performed with increased maintenance or at a lesser level, although 67% of these were reconditioning with the likelihood of return to full function. Athletic function could not be re-attained by 27%. Fifty-four percent of horses with severe joint injuries returned to work; in comparison, stem cell treatment of horses with minor injuries saw 100% return to work. Three horses experienced transient increased soreness following IA treatment. Severe meniscal injuries appeared more improved with stem cell treatment compared to prior published reports of surgery alone.

Ferris summarized that bone marrow-derived stem cell therapy in this early prospective clinical study encouraged investigators by demonstrated improvement, particularly when compared to previously published reports on conventional treatment results.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care. She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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