Cruciate Ligament Rupture in Dogs: From Diagnosis to Recovery

Dr Andrew

11 Oct 2023

📖 Key Takeaways

Cruciate ligaments are essential for knee stability in pets, and their rupture leads to instability of the knee and serious mobility issues, mainly seen in certain breeds with a genetic predisposition.
The start of a cruciate ligament rupture is often gradual, starting with ligament deterioration that might get worse during physical activities, sometimes without obvious triggering events.
Treatment can range from medication to complex surgeries to restore joint stability and the leg’s function.
Post-treatment care is vital, involving physiotherapy, controlled exercise, and sometimes ongoing medication to help recovery and prevent it from happening again.
Fetch covers the cost of diagnosis and treatment for cruciate ligament injury and rupture, as long as it’s not a pre-existing condition.
Fetch offers FastClaims where we check your pets history for pre-existing conditions, so you know exactly what you are covered for.

You may have noticed your dog hesitating a bit before leaping off the stairs, or maybe they have been favouring one leg over the other recently. These could be the signs of a cruciate ligament rupture, a common but serious issue that mainly affects dogs.

What Are Cruciate Ligaments and Why Are They Important for Your Dog?

Picture your dog running, each leap and bound is supported by bones and muscles of their hind limbs, and at the centre, holding things together inside their knee, are the cruciate ligaments. There are two crossed (or cruciate) ligaments, known as cranial and caudal, that are preventing the lower part of your dog’s back leg from falling forward when weight is applied to their leg. Sometimes, the cranial ligaments can rupture, causing pain and affecting the mechanics of your dog’s leg. Once the ligament is ruptured or weakened, your dog’s knee becomes unstable and can become painful when putting weight on their leg.

It usually starts with a gradual wearing down of the ligament. This deterioration might be slow, leading to a gradual stretching or partial tear of the ligaments. Most times, the rupture happens during a regular play session or exercise, nothing out of the ordinary, but it's the result of an ongoing deterioration process.

The damage caused in the joint and the resulting inflammation is likely to start the development of osteoarthritis. You can read about it here.

Which Dog Breeds are More Susceptible to Cruciate Ligament Ruptures?

Some breeds, like Retrievers, Boxers, and Rottweilers, tend to be more predisposed to this condition. Genetics and biomechanics together increases the risk of a cruciate rupture. And it doesn't stop there; a rupture in one ligament significantly increases the risk of it in the other ligament. This is another good reason to be proactive if your dog has any lameness issues and to follow recovery and prevention instructions from your vet.

Fetch covers the cost of diagnosis and treatment for cruciate ligament injury and rupture, with no additional sub-limits, as long as it’s not a pre-existing condition

What Are the Signs of a Cruciate Ligament Rupture in Dogs?

There is quite a wide range of signs your dog might show with a cruciate ligament injury. It could range from a subtle limp in their hind leg all the way to an inability to put any weight on the leg.

Common signs of cruciate ligament rupture are:

Progressively worsening limp over time, which is aggravated by exercise
Your dog might have a few episodes of limping after they’ve been exercising, which gets better after resting
Your dog might start limping suddenly right after something strenuous or twisting their leg
Holding the affected leg in a partially bent position (flexion) while standing.
Walking by only putting a very small amount of weight on the back and only touching the tip of the toes on the ground
Stiffness when getting up after exercising and resting
Not wanting to exercise as much or as long
Refusing to jump, or not jumping properly

There are other signs that aren’t as obvious that you could also look for such as a swollen knee, especially on the inside of the leg and after some time, a reduction in the size of the muscles in the thigh (muscle atrophy). If your dog has an cruciate injury on one knee, you might be able notice that from behind, the affected leg is thinner than the other.

Remember, early detection could help reduce impact of other issues like arthritis.

How Do Veterinarians Diagnose Cruciate Ligament Ruptures?

Your vet usually starts by asking what you what you’ve noticed, and especially when (exercise, getting up etc) you’ve noticed it. They will examine your dog when it's standing, then walking to look for any lameness. Vets also check for other signs like muscle wasting followed by a hands on exam to feel for laxity in the knee, any pain or swelling in the joint. The next step is usually imaging, such as X rays. Your vet will look for signs of inflammation in the knee joint, and in the soft tissues surrounding it as well as other potential issues that could cause pain and lameness in your dog’s knee. Vets typically start with X-rays under sedation, meaning your dog will receive some drugs to make them relax for short period of time. Having X-rays done under sedation allows your vet to take a better quality X-ray, without movement blur and with a better positioning. Advanced imaging techniques like MRI or ultrasound scans might be used sometimes to allow a more detailed view of the joint.

What are the treatment options available for Cruciate Ligament Ruptures in dogs?

Treatment options range from rest and anti-inflammatory medications to more advanced surgeries. Depending on your dog’s size and the seriousness of the rupture, your vet will recommend the best course of action.

There are two main routes, surgery or non-surgical management.

Non-surgical management relies on medications and life style changes. In cases of partial tears, stretching, or ligament strain, initial treatment often includes rest, anti-inflammatories, and painkillers to reduce swelling and alleviate pain. This approach is typically used for about a week before reassessing. This may be recommended for elderly dogs when surgery isn't recommended. Lifestyle changes are often part of treatment, including weight and exercise management to avoid unnecessary stress on the joint. Walks on a lead, swimming and physiotherapy exercises are good, but perhaps not things like fetching or jumping. Stairs or jumping in and out of the car could be an issue as well.

Several surgeries can restore function of the back leg. The choice of surgery sometimes depends on the dog's size. Small dogs can get procedures to place strong sutures to replace the cruciate ligament. For larger breed dogs, who carry more weight sutures may not be strong enough. They may need surgeries that change the biomechanics or the joint, ie: changing the direction of the forces to re-stabilise the knee:

Tibial Wedge or Closing Wedge Osteotomy (TWO/CWO): Involves removing a wedge of bone from the front of the tibia, securely plating it back together to change the angle of the tibia (lower leg bone)
Tibial Tuberosity Enhancement (TTA): This surgery involves cutting and repositioning the point where the patellar ligament attaches to the tibia (lower leg bone), using metal plates or a cage
Modified Maquet Procedure (MMP): Similar to TTA
Centre of Rotational Angle (CORA) Based Levelling Osteotomy (CBLO): Involves cutting and repositioning the top of the tibia to correct the rotational angle of the knee. It's suitable for large and young dogs
Tibial Plateau Levelling Osteotomy (TPLO): This surgery also focuses on changing the tibial plateau's angle, but this is not suitable for young growing dogs

During the surgery, your vet will also examine the knee joint and check for injuries to the meniscus (the cartilaginous cushioning at the end of the leg bone). You might hear your vet mention meniscal injury or meniscal tear. These injuries are frequently associated with cruciate ligament ruptures and need to be treated surgically. Your vet will remove the parts of the menisci that have been damaged and are causing pain and inflammation inside the knee joint of your dog.

Long-term medications such as anti-inflammatories, medication to support the joint or nutraceuticals (like joint supplements) may also be recommended for dogs that already developed a degree of osteoarthritis - many dogs may benefit from the latter.

What Should You Expect During Your Dog's Recovery from a Cruciate Ligament Surgery?

Post-treatment, it's a journey of patience, attention and care. Physiotherapy, consistent and controlled exercise, and weight management are essential to recovery. A slow reintroduction to normal activity levels, under careful guidance by your vet, is recommended.

Medications or joint supplements may also be necessary to minimize long-term damage to the knee and help support joint health.

Conclusion

Being proactive is key if you ever notice your dog limping or not wanting to exercise as much as usual. Prompt treatment helps minimise discomfort or pain, and can reduce further damage in the injured leg or from developing on the other side.

Fetch covers the cost of diagnosis and treatment for cruciate ligament injury and rupture, as long as it’s not a pre-existing condition.