Almost everyone has known someone or heard of someone who has torn their ACL, and it is a common injury among competitive athletes. Cruciate ligament ruptures are relatively common in the canine world as well. A large percentage of the , adult dogs that are seen in the clinic for lameness on a hind limb are diagnosed with a full or partial cruciate ligament rupture.
Each knee joint is supported by two cruciate ligaments- an anterior and a posterior ligament. These ligaments are made up of fibrous tissue and function by connecting the femur to the tibia. These ligaments support the bones above and below the knee joint and allow the knee to bend like a hinge.
Most injuries in dogs occur to the anterior cruciate ligament as the result of some sort of traumatic event, though dogs who are overweight run a much greater risk of this injury. Dogs who are running and suddenly change directions, jump, stop or fall are likely to injury this ligament as a result of twisting the knee joint to the right or left. The injury is extremely painful and usually results in some degree of lameness. Partial tears are possible and the dog may be lame only occasionally, but often times partial tears progress to full ruptures with continued use of the knee joint.
Diagnosing a cruciate ligament tear usually requires at least one radiograph under sedation. Your pet’s veterinarian will attempt to illicit “drawer” in the knee joint. This “drawer” movement is not seen in a stable, healthy knee joint and indicates that the joint has been damaged. Many dogs who have injured their knee are too painful for this manipulation to be performed while they are awake and require a fast-acting IV sedative in order for the veterinarian to perform the evaluation. In some cases “drawer” can not be elicited and a radiograph is necessary to reveal whether or not the ligament has been torn.
In the case of a cruciate ligament tear surgery is usually the best option to give your dog a happy, pain-free life. Most dogs who tear their cruciate ligament are larger dogs who will require a specialty surgery called a TPLO to repair the injury. Older surgical options that involve the replacement of the ligament with an artificial band are not appropriate for medium-large sized dogs. The TPLO surgery is done by a board-certified veterinary surgeon and usually costs between $3,500-$4,000. The rehabilitation period after surgery usually ranges between 2-3 months. If surgery is not an option, treatment with a dog-safe anti-inflammatory pain medication (NOT ADVIL/TYLENOL) coupled with strict cage-rest offer your dog the best chance at minimizing swelling and continued pain in the knee joint.
Regardless of whether the tear is repaired or not the affected joint will likely develop arthritis as your pet ages. A preventative regimen of Glucosamine/Chondroitin supplements and Fish Oils is important to try to delay the onset of arthritis. Additionally, dogs who have ruptured one of their cruciate ligaments are more prone to rupturing the cruciate ligament in their other leg.