Racehorses, greyhounds, and competitors in track and field events in human sports medicine are frequently hampered by acute tendon injury. Various projects in the Comparative Orthopaedics Laboratory have identified predisposed regions for tendon damage, and identified growth factor and matrix changes that are key targets in the rehabilitative period. This information has provided a window of opportunity for enhanced repair through the use of cell injections, growth factor supplementation, and gene-enhanced mechanisms to further drive tendon repair. These projects aim to restore the elastic function through enhanced local repair of the tendon. Supplementation with adult stem cells derived from bone marrow or fat, and more recently carrying genes coding for additional growth factors, all show promise to return athletes that had previously been forced into retirement.