Dog ACL Injuries

Updated April 17, 2017

An ACL, or anterior cruciate ligament, is an essential part of the composition of a dog's knee. Located towards the front of the knee, the ACL joins the tibia and femur of the leg. When it is ruptured, the two bones are able to move back and forth, typically causing extreme discomfort and pain. Unfortunately, the most effective way in which to treat an ACL that is completely torn is through surgery.

The Facts

A ruptured ACL typically occurs when a dog's knee experiences too much twisting and ultimately tears, usually when the dog slips, gets hit by a car or suddenly turns when running. In addition, the ACL can deteriorate progressively over time due to obesity. The excess weight on the knee causes the ACL to become weaker and weaker until it eventually tears. Dogs that are prone to this type of ACL degeneration include St. Bernards, Rottweilers, Labrador Retrievers, Bichon Frises and Newfoundlands. In addition, dogs that suffer from luxating patellas are also prone to ACL ruptures, as well.


A dog that has a ruptured ACL will stumble and limp suddenly or hold the leg of the affected knee off of the ground at an odd angle, states Furthermore, the knee may appear swollen and the dog may intermittently place weight on the leg, but hold it up again. Exercise typically worsens the pain, while rest helps to relieve it.


A veterinary examination is necessary in order to diagnose a ruptured anterior cruciate ligament. The doctor will observe the way in which the dog walks and will palpate the leg and knee. The doctor will typically place one hand on the dog's femur and the other on the tibia and check for a "drawer movement," a specific sensation similar to the closing of a drawer that a knee with a ruptured ACL will display. Many dogs who come to the vet with ACL injuries are often nervous, painful and cautious; therefore, it is often difficult for the doctor to accurately manipulate the leg because of this. The vet may need to ultimately sedate the dog in order to accurately palpate the leg. In addition, the doctor may take radiographs to access the amount of arthritis present in the knee.


Surgery is typically indicated for the treatment of ruptured anterior cruciate ligaments. There are three surgery options that are available and each has their own benefits that are specific to a dog's circumstances, suggests However, if the ACL is only partially torn or the dog is older or has health issues that prevents it from going under anaesthesia safely, medical treatment is often used to heal the ACL injury. Swimming, low-impact exercises and pain management are often the most effective type of non-surgical treatment. Unfortunately, when an ACL is left to heal on its own without the aid of surgery, arthritis typically sets in. In addition, because the dog places most of its weight on the non-injured leg, that knee typically becomes weak and is prone to suffer an ACL tear, as well.


Unfortunately, it is not practical for a dog to wear a knee brace for the prevention of ACL ruptures, as it is with humans. However, keeping weight off of your dog will lessen the chances of an ACL injury. Improving your dog's physical condition will also help to prevent ACL damage. Exercising with your dog progressively will help to condition its knee and build its strength to protect itself against damage.

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