Diagnosis: ACL Rupture
Most football fans (and players) know what the ACL is. This tiny ligament, the anterior cruciate ligament, is an important part of the stabilization of the knee joint. Just like human athletes may injure this ligament, canine athletes (and maybe even those not so athletically inclined) can injure this ligament.
ACL is an acronym for anterior cruciate ligament. Ligaments attach bone to bone, while tendons attach muscle to bone. The anterior cruciate ligament is an important part of the stabilizing structure of the knee, or stifle. There is also a posterior cruciate ligament, but this one ruptures less frequently. The cruciate ligaments cross each other, forming an “X” inside the joint. They connect the femur to the tibia and maintain the stability of the joint from front to back. Two other important parts of the knee joint are the menisci. A meniscus is a cartilage pad that acts as a cushion between the femur and the tibia.
Dogs can rupture or tear this ligament, resulting in joint pain and swelling. This often occurs in exercise that involves jumping or a sudden change in terrain (such as stepping in a hole). Labrador Retrievers seem to have a genetic predisposition for weak cruciate ligaments and can rupture the ACL in both hindlegs.
Immediate diagnosis and treatment is necessary to preserve the health of the joint as much as possible. Dogs that rupture their ACL will have what is called a positive cranial drawer sign. What this means is that pressure on the lower part of the leg will move it forward, in front of the upper part of the leg. Clinical history, presence of drawer sign, and radiographic evidence of the injury are all used to diagnose a cruciate ligament tear. In addition to injuring or tearing the ACL, many dogs also tear one of their menisci. Tearing one of them results in even more severe pain and often a “clicking” noise when the dog is walking.
Medical therapy may be used to control the pain, but the joint must be surgically repaired to prevent severe arthritis from developing. There are two common surgical procedures that can be performed to stabilize the joint. For large dogs (the ones that most commonly suffer from this injury), there is one type of repair that is most successful. This is called a tibial plateau leveling osteotomy, or TPLO. This procedure should only be perfomed by veterinarians that have completed a training course, or by board certified veterinary surgeons.
With proper surgical repair, the time before arthritis sets in is prolonged. The use of nutritional supplements like glucosamine and chondroitin may help soothe the joint and delay the onset of painful arthritis even more than surgery alone. However, at some point, it is likely that these dogs will need some anti-inflammatory therapy to eliminate pain from arthritis.
Please note that this information does not replace onsite, professional, veterinary care. It is solely for educational purposes. Your pet's medical condition should be evaluated by a veterinarian before any medical decisions are implemented. If there is a potentially life-threatening emergency involving your pet, take your pet to a veterinarian or veterinary facility immediately.
Veterinary Technical Services Department