Differences Between ACL & CCL in Dogs

The interior of both the dog and human knees contains a pair of ligaments that link the bones above and below the knee joint and hold them firmly together. In the human, these ligaments are named the anterior cruciate ligament and the posterior cruciate ligament. These same two ligaments, which perform the identical function in the dog's knee are called the cranial cruciate ligament and the caudal cruciate ligament.

  1. Structure of the Knee

    • The knee is the flexible joint between the large bone of the upper leg -- the femur -- and the two smaller bones of the lower leg -- the tibia and fibula. Linking these bones together is a set of four ligaments, which are tough strands of connective tissue fibers with rope-like characteristics. Two of these ligaments are outside of the joint itself and two others are contained within the joint capsule.

    Ligament Names Reflect Their Anatomical Position

    • When anatomists first named the ligaments of the knee, they referred to them by their anatomical position. In the human knee, the internal ligaments cross one in front of the other and are therefore named the anterior cruciate ligament, which is the Latin for front crossing ligaments, and the posterior cruciate ligament, which is the Latin for rear crossing ligament. This reflects our upright posture.

    Canine Ligament Names Reflect Their Four-Legged Stance

    • Because dogs do not stand upright, their front facing, or anterior surface, would not be same as a humans. Instead, the forward facing surface of a dog is the head. Anatomists refer to the head as the cranial region. Because the front-facing surface of the dog is the cranial surface, the ligament within the knee that crosses in front is named the cranial cruciate ligament, not the anterior cruciate ligament as it is in humans.

    CCL Injuries are Common

    • CCL injuries are fairly common in domesticated dogs. As in humans, tearing the CCL is more common in female dogs. Dogs that are overweight are also at greater risk of injury to the CCL. Large breeds are more susceptible than smaller breeds. If left untreated, a torn CCL will continue to degenerate over time. For minor CCL injures, rest and limited physical activity is recommended. For more serious tears or complete ruptures, surgery may be required.