Spontaneous rupture at the distal part of the gastrocnemius tendon (GT) is the second most common non-traumatic tendon injury in dogs, whereas the other strands of the common calcaneal tendon do not seem to have a predisposition to rupture. In order to discover why we investigated the common calcaneal tendons of 63 dogs microscopically and biomechanically. Both the gastrocnemius and superficial...