Diagnosing and Treating ACL Injuries in Dogs

Don’t let the title fool you. Most people do not realize anterior cruciate ligament, or ACL, injuries in pets are impossible. The reason is simple: Unlike humans, dogs and cats do not have an ACL. Instead, they have a fibrous band of tissue known as the cranial cruciate ligament (CCL) that connects the two major bones of the knee joint.

While the terminology is different, injuries to this ligament are similar to those of the ACL in humans—and just as common. Most CCL damage is degenerative, though acute injuries can also occur. Both result in pain, lameness, and arthritis within the knee joint, and can contribute to long term problems with mobility if not properly treated.

While CCL injuries can occur in both dogs and cats, they are far more common in dogs. However, if you notice your cat is limping, reluctant to jump to a favorite spot, or having difficulty using one or both hind legs, please contact your primary care veterinarian right away as this could indicate arthritis, a CCL tear, other traumatic injury, thromboembolism, or another serious problem.

Read on to learn more about the role of the CCL in dogs, signs of an injury, and available treatment options.

What Are the Signs of an Injured CCL?

The most common signs of a CCL injury include:

  1. Limping or lameness
  2. Favoring one leg over another
  3. Exercise intolerance, such as reluctance to go on walks or tiring easily
  4. Difficulty climbing stairs
  5. Reluctance to jump into the car or onto furniture
  6. Sitting slowly and not putting the affected leg squarely underneath

While easily spotted by trained eyes, the hallmark signs of a CCL injury are not always noticeable to pet owners and often missed as a result. These signs can also be caused by a number of other conditions, including arthritis, ankle injuries, or hip dysplasia. Fortunately, with a keen sense of observation honed through years of practice, a skilled veterinarian can pick up on even the most subtle clues and help narrow down the cause of discomfort.

How Is a CCL Injury Diagnosed?

Despite their prevalence, CCL injuries are frequently misdiagnosed. In most cases, CCL damage is caused by slow degeneration from a longstanding injury rather than a sudden tear. As a result, ligament injuries are often an underlying source of pain, mobility issues, and arthritis.

While X-rays can provide helpful information, a few minutes with a skilled veterinarian is all that is needed to make a proper diagnosis. During the exam, your veterinarian will observe your dog’s overall mobility and look for signs of discomfort, as well as any fluid or swelling in the knee(s). He/she will also check for a drawer motion, or tibial thrust, which is an abnormal movement to the knee that only occurs if the cranial cruciate ligament has been damaged.

In addition, your veterinarian will assess the body for muscle loss. One leg that is larger than the others may indicate the pet has not been using that leg for some time. He/ she will then examine the other joints of the leg, the bones themselves and the back to check for any discomfort or additional problems.

Once a diagnosis has been made, your veterinarian may refer your pet to a board-certified veterinary surgeon for a consultation on the next steps.

What Are the Treatment Options?

At Central Texas Veterinary Specialty & Emergency Hospital, we typically recommend surgery for dogs with CCL injuries, followed by comprehensive postoperative care. This is the most complete and cost-effective treatment to regain normal use of the leg, resolve pain, and return to a high quality of life. However, it is important to remember that every pet is an individual and not all are ideal candidates for a surgical procedure. Prior to recommending surgery, the surgeon will thoroughly examine your dog to identify any other health issues that need to be addressed. Dogs with spinal cord injuries or hip problems, as well as senior pets with multiple joint issues, may not benefit from surgery. In these cases, pain medication, physical therapy, and other nonsurgical treatment options may be recommended. In addition to reviewing the costs of a surgical procedure, pet parents must also consider their expectations long term after the surgery, as well as their ability to provide the immediate postoperative care 

Types of CCL Surgery

There are three primary types of surgery that restore stability to the knee joint:

  • Extracapsular repair: This procedure aims to artificially replace the ligament with a heavy nylon suture across the outer part of the joint. The goal of this procedure is to make your pet comfortable with return to low stress activities like walking.
  • Tibial Plateau Leveling Osteotomy (TPLO): Rather than attempting to replace the CCL, this procedure actually changes the mechanics of the joint so the ligament is no longer needed. Cutting the tibia bone allows for a more “level” surface that prevents the femur from sliding forward and stabilizes the joint. The goal of this procedure is to return normal function and full athletic activity like chasing squirrels, jumping on and off the coach, jogging or anything more strenuous than a short walk.
  • Tibial Tuberosity Advancement (TTA): This procedure is similar to the TPLO, but has a longer recovery time.  It provides a comfort and activity level similar to the extracapsular repair. The goal is to eliminate the sliding movement and stabilize the joint by realigning the two bones connecting the knee joint. This is done by cutting the top of the tibia and moving it forward. 

What Can Dog Owners Expect from CCL Surgery?

Every pet owner has a different expectation for CCL surgery: Some are happy if their dog can hop onto the couch and go in and outside with reasonable comfort, while others expect their dogs to be running partners. Your surgery team will communicate the best outcomes based on your dog’s condition and make personalized recommendations for postoperative care; however, most dogs will enjoy pain-free mobility within several months if the recommended postoperative care is provided.

How Can I Help My Dog Recover from CCL Surgery?

It is important for pet owners to realize that CCL injuries do not heal, as blood carrying nutrient-rich oxygen no longer flows to the ligament. Therefore, recovery is a matter of controlled expectations and following the surgeon’s recommendations to help your dog feel his best. The mainstay of CCL surgery recovery is exercise restriction. Your dog will not be able to go on long walks or visits to the dog park for roughly two months after surgery, and will need to be confined to allow the healing process to occur and minimize complications. Physical therapy is recommended for every surgery patient as it helps speed the recovery process and improves knee use immediately and for the long term. Recheck appointments with the surgeon are also critical to evaluate your pet for any potential problems during recovery.

Nonsurgical Options for CCL Injuries

Nonsurgical options for CCL injuries include:

  • Weight loss: Extra pounds put additional pressure on the joints, so weight management through nutrition and exercise is key.
  • Long-term pain medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) can help take the edge off your pet’s pain.
  • Rest: Reducing your dog’s activity will help slow further injury and decrease the pain. 
  • Physical therapy: Rehabilitation and hydrotherapy (water therapy) can improve your dog’s range of motion and slow the progression of other concerns, like arthritis.
  • Braces: Braces try to immobilize the knee and ankle to relieve pain; however, they provide only minor support. It is important to select one specifically designed for dogs for best results.
  • Laser therapy: Also known as cold laser therapy, this noninvasive procedure uses deep-penetrating light to stimulate cell regeneration and increase blood circulation.
  • Acupuncture: Acupuncture can be used to stimulate the nervous system, reduce inflammation, and promote healing. These modalities may also be used adjunctively in surgical patients to promote healing.

*It is important to note that the pain, limping and decreased use of your pet’s leg is due to the abnormal movement of the bones in the knee when the ligament is torn  This abnormal movement causes rubbing of the cartilage of the joint which will lead to arthritis.  If the abnormal motion is not stopped by replacing or mimicking the ligament internally or changing the mechanics within the knee, the pain and arthritis will continue to get progressively worse. The abnormal motion can also cause the meniscus within the knee to tear 


If you notice your dog is limping or has long-term pain or mobility issues, please call your primary care veterinarian right away. Ask them if you need the help of the skilled veterinary specialists at Central Texas Veterinary Specialty and Emergency Hospital.