Do you know that cranial cruciate ligament (CCL) injuries are one of the most commonly seen sporting dog injuries seen by veterinarians?
If you’re in dog sports, chances are you know someone whose dog has suffered CCL injury. Have you ever found yourself asking how a CCL injury occurs and how you can make every best attempt to prevent your dog from suffering this injury?
In this week’s blog, we take a deep dive into CCL injuries, how they occur, what to look out for, and how a CCL injury does not mean the end of your dog’s sporting career.
What is the Cranial Cruciate Ligament?
Ligaments are bands of tough elastic tissue around the joints of the body. They play a role in connecting bone to bone, supporting the joints, and keeping bones where they should be.
There are five main ligaments that support the knee joint.
In dogs, the most common knee injury is a tear or rupture of the cranial cruciate ligament. In humans, the ligaments are called the anterior and posterior cruciate ligaments which is why sometimes you’ll hear a CCL injury be incorrectly referred to as an ACL injury. The forces applied to the joint during weight bearing are vastly different between dogs and humans. When we stand, our hips, knees, and ankle joints are perpendicular to our primary weight bearing surface (the feet) meaning there is limited stress placed on our knee ligaments. Our dogs however, stand on their toes with the ankle elevated and their knee forward and bent. Weight bearing creates a shear force that pushes the femur down the slope of the tibia. The main job of the CCL is to resist this force and is called into action whenever our dog is standing or bearing weight.
How do CCL injuries occur?
The knee is a hinged joint held together by ligaments which makes it more unstable than other areas of the body which are connected by interlocking bones. Most commonly, CCL tears are caused by a combination of many factors, including aging/degeneration of the ligament, obesity, poor physical condition, conformation, genetics and breed. Meaning, the ligament injury is a result of slow degeneration that has been taking place over many months or years versus an acute (sudden) trauma to an otherwise healthy ligament. The knee is designed to go back and forth but has little ability to move side-to-side.
Let’s dive a bit deeper into the possible causes of a CCL injury:
Signs and Symptoms of CCL Injuries
The presentation of a CCL injury will largely depend on whether the injury is partial, or a complete rupture. Here are some commonly seen signs:
How to Determine if your dog has a CCL injury?
If you suspect your dog has a CCL injury then it's time to visit a vet or canine PT for an examination. If left untreated, a torn cruciate ligament can lead to degenerative joint disease, decreased mobility, and pain. Your health professional will take you through a full assessment of your dog to determine if they have a CCL injury and its severity.
During the assessment, the following will be evaluated:
The Cranial Drawer Test – one hand stabilizes your dog’s femur while manipulating/moving the tibia with the other. If the tibia moves forward, known as a positive drawer because of the way the bone moves similar to a drawer being opened, the ligament is ruptured. In the videos below you can see my client's Australian Shepherd Lily have a drawer test performed on both her knees.
Lily, owned by John Martin, is now 3 months post TPLO surgery and back to all of her regular activities!
Cranial Tibia Thrust - Stabilize the dog’s femur with one hand, while flexing the ankle with the other. In dogs with a ruptured cranial cruciate ligament, the tibia will display forward motion upon flexion of the ankle joint.
It is possible for a dog to show a false negative from these tests if they are quite painful and guarding their knee. In these cases, radiographs can help in confirming the diagnosis. Radiographs can also help confirm the presence of joint effusion/swelling which indicates a problem within the joint.
How is CCL treated?
There are two routes you can take for treating a CCL injury; surgery or conservative management. There are MANY factors that will weigh in on which path you choose! This discussion should be had with your rehabilitation/veterinarian team to determine the best course of action for your dog.
It is important to consider that not all dogs are surgical candidates. Some dogs may not be good surgical candidates due to:
The goals for rehabilitation should globally be focused on: reducing pain, promoting healing, building muscle mass and promoting muscular development, joint stability, body awareness and flexibility. The focus should be on a return to function, prevention/delay of degeneration of joint disease (e.g. arthritis) and improving overall health and fitness.
Rehabbing the Sporting Dog with CCL
A cookie-cutter approach to rehab will on put our dog at a disadvantage and prolong their recovery. Although there are a lot of protocols that exist on how to best rehab a dog post CCL injury, one should always consider the individual dog and how they are presenting. Time does not dictate where a dog should be on the spectrum of their rehabilitation journey. Yes, there are “guidelines” or “expectations” of where a dog should fall, however, the rehabilitation process should always focus on the individual needs of the dog and treatment progressions should be based on dog’s abilities, pain, range of motion, strength and functional capabilities.
The sporting dog with a CCL injury is very different from the pet dog with a CCL injury and should be treated as such. For sporting dogs, I recommend a much more intense and longer rehab approach as these dogs are working towards a return to sport and will face greater physical demands on their body in the future. Whether a dog is coming for post-operative rehab or conservative management of their CCL injury, our first goal is to complete a thorough assessment of the dog to determine their baseline function and build a plan for their rehabilitation process. The goals of this stage include focusing on increasing ROM, increase muscle function and weight bearing, improving proprioception and decreasing pain and joint swelling. An important mantra to keep in mind is that “movement is medicine,” and we want to ensure our dogs keep moving in a way that is appropriate for their stage of healing and recovery. Crate rest is a thing of the past!!! Research has shown that dogs placed on strict crate rest post-TPLO were 2.9 times more likely be categorized as having an unacceptable function at 8 weeks than dogs who participated in a supervised physical rehabilitation program (Romano 2015).
Rushing headlong into exercise without careful consideration of our dog’s current physical ability will only risk further injury or slow the healing process. During this initial and crucial stage, lifestyle management is always discussed. This includes a review of the dog’s home environment (e.g. increase carpets and mats to prevent slipping, no access to stairs) and discussions around factors that can cause re-injury to either the affected or unaffected limb (e.g. jumping, rough play with other dogs, longer walks on uneven terrain, twisting motions).
As your dog progresses through their rehabilitation journey a variety of techniques may be used by your rehabilitation provider to speed and support tissue healing and function. These techniques could include: manual therapy (e.g. soft tissue massage, myofascial release, cross friction massage, joint mobilizations), modalities (e.g. laser, PEMF, EMS, Assisi loop) and gradual/progressive exercise program to maximize ROM, weight bearing, strength, flexibility, and body awareness.
The return to functional activities (e.g. longer leash walks, proper positioning with sits/downs and navigating stairs) will depend largely on the individual dog’s stage of healing and recovery. Progressive exercises will begin to be introduced – these exercises look to make sure our recovering dog is ready to meet the demands of life. Our goals at this stage is to ensure that limb circumference is symmetrical (remember that it’s not uncommon to see a size difference between limbs with a CCL injury), gait has returned to normal, and that the surgical limb (if post-op) is fully healed.
A common question I get asked is when should I be progressing my dog’s exercises?
Once muscles fall into a comfort zone and workouts are no longer challenging the body begins to plateau and stops building muscle. This signifies that it’s time to begin increasing the challenge to our dogs. Unchallenged muscles can also begin to degrade; limiting your dog's recovery. To continue challenging our dog's healing tissue we need to add other demands to the musculoskeletal system. This continues to build muscle and allows us to see if the existing injury will reappear with increased demands. There are several ways we can add challenge to a workout:
One of the biggest concerns I see in my practice is owners worry that their dog’s injury will reappear once the dog returns to sport. If we have successfully completed a return to sport program, the risks are dramatically reduced!
Is there always a chance of another potential injury? Perhaps, but this is the risk of playing dog sports, or any sport for that matter! However, if your dog has successfully completed a progressive and high-level conditioning program geared to mimic the movements seen in your dog sport, you are setting up your dog for success. At this stage, we stress your dog’s body to prepare them for a return to sport and constantly evaluate how their bodies are handling the increase in demands. This can be fine-tuned and tailored throughout the rehabilitation process. Setbacks are expected in the rehabilitation process but can help give valuable information to owners and their rehab team on the dog’s readiness to return to sport. We do this so that by the time you get back to the performance ring you have the peace of mind and confidence in knowing your dog's injury has fully healed and can meet the demands of their sport.
The focus on return to sports should include elite level conditioning exercises for strength and balance, jumping exercises, sport specific training, quick directional changes/pivots, interval training, sprints, power/plyometric focused exercises and cardiovascular endurance.
Once your dog has graduated from their return to sport program, owners will continue to have regular follow-ups with their canine PT to ensure that their dog is continuing to improve and is not showing early signs of a potential issue. It is likely that a dog with a CCL injury will still develop arthritis later in life. However, by keeping up with a conditioning program post-injury you’ll better prepare your dog for this challenge and delay the onset.
A CCL injury can take almost a year to heal. A study of agility dog with CCL tears treated with a TPLO surgery found that average time for a return to sport post-surgery was 7.5 months (Heidorn 2018). The other risk in recovery is that many dogs with a CCL injury will rupture the CCL in the other leg (statistics tell us that 40-60% of the dogs).
Another option to aid in the healing process and manage the injury is the use of a stifle orthotic (knee brace). Braces are a popular management tool for dogs with CCL injuries. Research has shown that braces help with proprioception and joint position sense, reduces fatigue and permits the injured limb to relax (Canapp, 2018). A study also found that there was a 3% difference in weight bearing when the dog was wearing a knee brace suggesting that a custom canine stifle orthotic allows for improved weight bearing in dogs with unilateral CCL tear (Carr 2016). If you choose to have your dog wear a brace it’s crucial that you make sure the brace is properly fitted to your dog. This is where your rehab team can help! Bracing may also not be a good option for dogs with a torn meniscus as the compressive forces of the knee still cause quite a bit of pain for the meniscus. Remember, when using a brace watch for potential complication such as: persistent lameness, skin lesions, and intolerance. If you would like more information on bracing, I recommend OrthoPets.
As a rehab specialist, my preferred treatment for injuries is preventing them in the first place! Now that we know how a CCL injury occurs and how we rehab it lets take a look at how we prevent it from happening in the first place!
There are a couple key things we can do NOW to prevent CCL injuries in our sport:
A final word...
Recovery from a CCL injury can be a long and confusing process. Having specific guidance from a trusted rehabilitation professional can make the world of a difference at getting your canine companion back to their old self again and to the activities they love.
Having a support system around you can greatly help in the recovery process by giving you the tools to help support your dog in the rehabilitation path you have chosen. If your dog has been diagnosed with CCL or if you would like to introduce your dog to a conditioning program to help prevent a future injury please don’t hesitate to reach out to me about building a program and treatment plan!
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Carr, B.J., Canapp Jr, S.O., Meilleur, S., et al., The use of canine stifle orthotics for cranial cruciate ligament insufficiency Veterinary Evidence, 1(1), pp. 1-13, 2016.
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