Ultrasonography is widely used in the diagnosis and monitoring of equine tendon injuries. More recently it has been used to perform ultrasound guided intra-lesional administration of growth factor and cell based therapies including autologus bone marrow derived mesenchymal stem cells (BM-MSCs). Re-injury rates in horses following tendon injury are high with conventional treatment, however the use of BM-MSCs has resulted in a significant reduction in tendon re-injury in National Hunt racehorses. This article reviews the methods of tendon ultrasound used in the horse and the techniques used for BM-MSC therapy to treat tendon injury.