As a veterinarian and lifelong dog lover, one of the most common and painful injuries I see in my canine patients is a torn cranial cruciate ligament (CCL), also known as the anterior cruciate ligament (ACL) in humans. This injury can strike dogs of all ages and sizes, from playful puppies to senior couch potatoes.
A torn ACL not only limits a dog‘s mobility and quality of life, but also predisposes them to debilitating osteoarthritis later on. While there are surgical options to repair the damaged ligament, many dog owners wonder if their furry friend can recover without going under the knife.
As someone who has both treated hundreds of dogs with ACL tears and navigated this injury with my own beloved pup, I want to share the most up-to-date veterinary knowledge and guidance to help you make the best decision for your dog. Let‘s start with a closer look at what the ACL is and how it can be damaged.
Anatomy of the Canine ACL
The knee joint (stifle) is a complex hinge between the femur (thigh bone) and tibia (shin bone). Unlike human knees, dog stifles have two long, crossed ligaments called the cranial cruciate ligament and caudal cruciate ligament that provide essential stability.
The ACL runs from the back of the femur to the front of the tibia, preventing the tibia from sliding forward. It is one of the most important stabilizers of the knee joint, which has no interlocking bones and would otherwise be quite unstable. [^1^]
When the ACL is torn or ruptured, the joint becomes unstable and the bones rub against each other, causing pain, inflammation, and eventually arthritis. The meniscus, a crescent-shaped cartilage cushion between the bones, can also be torn secondary to ACL injury.
How Common Are ACL Tears in Dogs?
According to a study by the Journal of the American Veterinary Medical Association, ACL tears are the most common orthopedic injury in dogs, affecting an estimated 1.4-4.9% of all dogs. [^2^] However, certain breeds are significantly more prone to this injury:
| Breed | Incidence of ACL Tear |
|---|---|
| Neapolitan Mastiff | 12.9% |
| Akita | 10.7% |
| Saint Bernard | 9.1% |
| Rottweiler | 8.6% |
| Newfoundland | 8.1% |
| Chesapeake Bay Retriever | 7.8% |
| Labrador Retriever | 4.8% |
| Golden Retriever | 3.2% |
| Chihuahua | 1.9% |
Large and giant breeds tend to have the highest incidence, likely due to a combination of genetics, conformation (straight hind legs), and the mechanical stress of their weight. Interestingly, female dogs are up to twice as likely to suffer ACL tears compared to males. [^3^]
In my experience, most dogs who tear one ACL will eventually injure the other side as well – often within the first year. One retrospective study found that 54% of dogs ruptured the contralateral ACL within 2.5 years of initial injury.[^4^] This highlights the importance of preventive measures and addressing any underlying risk factors.
What Causes ACL Tears in Dogs?
While human ACL tears are almost always due to a sudden, traumatic injury, dogs tend to experience a slow degeneration of the ligament over time. This chronic weakening is caused by a perfect storm of factors including:
- Genetics and breed predisposition
- Poor physical conditioning and muscle tone
- Obesity and excess weight
- Knee joint conformation (straight hind legs)
- Chronic stress from high-impact activities
Eventually, the degenerated ligament may tear partially or completely. While a dog might suddenly become lame after jumping or rough play, chances are the underlying damage has been accumulating long before any symptoms appeared.
In the cases of acute ACL tears in dogs, they are often a combination of chronic degeneration and a sudden twisting motion or awkward landing that causes the weakened ligament to rupture.
Symptoms of an ACL Tear
If your dog has injured their ACL, you may notice some or all of the following signs:
- Sudden hindlimb lameness (not putting weight on a back leg)
- Sitting with the affected leg extended out to the side
- Stiffness after rest that improves with light activity
- Clicking sound when walking
- Pain when touching the knee joint
- Swelling or thickening of the joint
- Visible discomfort when rising or climbing stairs
In some cases, owners report hearing their dog yelp or cry out during activity and then start limping. While this can indicate the moment of injury, it‘s important to remember the ACL has likely been degenerating for some time.
Diagnosing an ACL Tear
If you suspect your dog has torn their ACL, it‘s crucial to get them evaluated by a veterinarian as soon as possible. Delaying treatment can worsen joint damage and arthritis.
During the orthopedic exam, your vet will feel for knee instability, swelling, and pain. The most telling sign of an ACL tear is the "cranial drawer sign" – when the tibia can be abnormally pulled forward in relation to the femur.
Sedation or anesthesia may be necessary to check for a drawer sign in anxious or large dogs. X-rays are also often recommended to assess the joint and rule out other injuries. Advanced imaging like CT or MRI can be used to confirm a partial ACL tear.
Once diagnosed, you and your vet can discuss whether surgical or non-surgical treatment is right for your dog. The decision depends on several key factors:
- Size and weight of your dog
- Partial or complete tear
- Age and overall health
- Desired level of function and activity
- Financial considerations
Non-Surgical Treatment for ACL Tears
If your dog is small (generally under 30 lbs), a senior, or has health issues that preclude anesthesia, conservative treatment may be an option to discuss with your vet. It tends to be most successful for dogs with a partial ACL tear or an incomplete rupture that just needs scar tissue stabilization.
Non-surgical treatment aims to reduce pain and inflammation, build muscle strength, and promote healing of the compromised ligament. It typically involves a multi-pronged approach:
- Strict rest and confinement (no running, jumping, stairs, or off-leash activity) for 6-8 weeks
- Anti-inflammatory pain medications like NSAIDs
- Joint supplements (glucosamine, chondroitin, omega-3 fatty acids)
- Physical therapy exercises to maintain muscle mass and flexibility
- Range of motion exercises
- Controlled leash walks
- Swimming
- Balance board work
- Use of a custom stifle brace to stabilize the joint
- Weight management if needed
- Alternative therapies like acupuncture or cold laser
The goal is for scar tissue to form over the tear and stabilize the joint enough for pain-free, functional movement. In one study of non-surgical treatment for dogs under 15 kg, 85.7% regained acceptable function. However, their long-term osteoarthritis risk was still higher than dogs treated surgically.[^5^]
It‘s important to note that non-surgical treatment requires significant dedication from the owner in terms of strictly limiting their dog‘s activity for at least 2-3 months. Even then, there is a risk the conservative approach will fail and surgery will still be necessary.
Surgical Treatment Options
For most dogs, especially large and active breeds, surgery is still the gold standard to achieve a dynamically stable joint and reduce the risk of arthritis. The goal is to restore function by replacing the ruptured ACL with an artificial ligament and/or modifying the joint biomechanics so the ACL is no longer necessary.
The three most common techniques are:
- Lateral suture/extracapsular repair: A strong suture is placed outside the joint capsule to mimic the ACL. Best for dogs under 50 lbs.
- Tibial plateau leveling osteotomy (TPLO): The tibia is cut and rotated to change the joint angle, making the ACL unnecessary. Ideal for active dogs over 50 lbs.
- Tibial tuberosity advancement (TTA): The front of the tibia is advanced forward to stabilize the joint without the ACL.
Your veterinarian or veterinary surgeon can help determine which procedure is best for your dog based on their individual anatomy and lifestyle. In general, TPLO and TTA have slightly better success rates than lateral suture for large dogs.[^6^]
Regardless of technique, ACL surgery requires an extensive recovery period. Your dog will need to be strictly rested for the first 2-3 months with gradual introduction of low-impact exercise. Physical therapy is essential for regaining muscle strength and joint mobility.
Most dogs can return to normal activities within 4-6 months, but it can take up to a year to fully recover. Lifelong joint supplements and weight management are also crucial for preventing arthritis.
Preventing ACL Tears
While some ACL degeneration is inevitable, especially in predisposed breeds, there are steps you can take to reduce your dog‘s risk:
- Keep your dog slim and trim. Obesity increases the load on the knee joint and is a major risk factor for ACL tears.
- Provide consistent, low-impact exercise. Regular leash walks, swimming, and controlled play help maintain strong muscles, ligaments, and joint stability.
- Use ramps or stairs. Especially for at-risk breeds, raised food bowls and ramps for furniture/cars can reduce stress on the knee joint.
- Consider joint supplements. Glucosamine, chondroitin, and omega-3s can support healthy cartilage and reduce inflammation. Start them early if your dog is predisposed to ACL issues.
- Work with a canine rehabilitation specialist. For dogs recovering from ACL surgery or those with conformational risks, a certified rehab practitioner can design a personalized conditioning program.
The Emotional Toll of ACL Injury
As a veterinarian, I know all too well the heartbreak of watching a once-active dog struggle with the pain and immobility of an ACL tear. It‘s a difficult journey for both the dog and their devoted owner.
Many of my clients express guilt that they didn‘t notice the early warning signs or do enough to prevent the injury. Others are overwhelmed by the financial burden of surgery and the time commitment of recovery.
It‘s important to remember that ACL tears are incredibly common and rarely anyone‘s fault. The best thing you can do is educate yourself, work closely with your veterinarian, and focus on giving your dog the best possible quality of life.
There is no one-size-fits-all approach to treating ACL tears in dogs. While surgery remains the recommended choice, especially for larger breeds, conservative management can be effective for some dogs when coupled with dedication and patience.
No matter which path you choose, know that your love and commitment to your dog‘s well-being is the most essential ingredient for a successful recovery. With the right plan and plenty of TLC, your furry friend can get back to doing what they love on four healthy legs.
