The cranial cruciate ligament (CCL) (also referred to as the anterior cruciate ligament in people), is a tough, fibrous band found within the knee. This ligament attaches the femur (thigh bone) to the tibia (shin bone) and in doing so provides stability of the knee joint. We often hear of cruciate injury causing career threatening injury in our top sports stars, with it being a particularly common footballer’s injury. A bad tackle for example may cause the ligament to rupture and this is solely down to excessive trauma. The situation in our dogs is quite different and acute trauma is rarely the cause of CCL injury, but rather degeneration of the ligament over time, somewhat akin to the fraying of a rope. We don’t know the precise cause of degenerative CCL disease but genetic factors play a role, with certain breeds being predisposed (including Labradors, Rottweilers, Boxers, West Highland White Terriers and NewFoundlands). The genetic influence also leads to many dogs suffering CCL disease in both hind legs, often while still relatively young. Other factors also play a role such as obesity, individual conformation, hormonal imbalances and certain inflammatory conditions of the joint.