Anterior Cruciate Ligament (ACL) Rupture in Dogs

German Shepherd

One of the most common types of orthopedic lameness that we see is rupture of the Cranial (Anterior) Cruciate Ligament (ACL). Factors such as anatomy, obesity, athleticism, degeneration of the ligaments, and arthritis probably all play a role in this disease process. Dogs, like humans, can develop bad knees, especially in their senior years.

The general rule of thumb is that ruptured CCLs should be repaired in all dogs, unless there is some extenuating circumstance.


To diagnosis a ruptured CCL we start with palpation of the knee. Physical exam will reveal instability, pain, and swelling. Radiographs of both the knees and hips will be taken in nearly all instances. X-rays will help confirm the diagnosis and rule out other problems. Additionally, the radiographs will measure the knee, determining the proper size implants for the corrective surgery that will stabilize the knee.


All dogs with a ruptured cruciate ligament should be treated surgically. The sooner a knee can be repaired, the better. Left untreated, most dogs develop severe degenerative joint disease (arthritis) and meniscal tears, resulting in chronic pain. As the dog favors the affected leg and puts more weight on the unaffected leg, the chances of developing a second cruciate ligament rupture increases.

Surgical Repair Options

Guy with Tan Dog

The best choice of procedures largely depends on the size of your dog. Dogs 50 pounds or less typically do well with a somewhat less aggressive, traditional type of surgical repair. There are minor variations of this procedure and you may see it referred to as a Flo technique, lateral imbrication, or tight rope procedure. Dogs in the 50-60 pound range and up are better served with one of the more advanced procedures, TTA or TPLO.

If you have a large breed dog that has been diagnosed with a CCL tear, visit our page that discusses the TPLO procedure.

Learn more by downloading these useful handouts.

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