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Cruciate ligament rupture

The dog's knee is held together by two cruciate ligaments placed in the center of the joint. The anterior cruciate ligament prevents the tibia from sliding forward and limits rotation of the knee. When this ligament ruptures, the joint beco...

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Definition Signs Causes Diagnosis Treatment Prevention Complications When to see a vet Prognosis FAQ Sources Affected species

What is it?

The dog's knee is held together by two cruciate ligaments placed in the center of the joint. The anterior cruciate ligament prevents the tibia from sliding forward and limits rotation of the knee.

When this ligament ruptures, the joint becomes unstable: with each step, the bony surfaces move relative to each other. It is one of the most common causes of hindlimb lameness in dogs.

In dogs, rupture is rarely a sudden accident in a healthy ligament: most often, the ligament is damaged slowly over weeks or months before giving way, sometimes during a trivial movement.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Related signs — each one links to its page:

Lameness Pain Swelling Fatigue

Lameness of a hind limb, appearing suddenly or developing gradually.

The dog places the tip of the foot on the ground, or carries the paw frankly without pressing.

When sitting, he often extends the affected paw to the side instead of folding it under him.

Swelling of the inside of the knee after a few weeks.

Difficulty jumping in the car, going up the stairs, getting up after a nap.

Clear stiffness upon waking, which eases a little after a few minutes of walking.

A sharp cracking sound can be heard when walking when the meniscus is also injured.

When both knees are affected, there is no longer a clear lameness: the dog walks slowly, with small steps, refuses to play and simply appears "tired" or "aged".

When to consult without delay

This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.

Causes and risk factors

The main mechanism is a progressive degeneration of the ligament, the fibers of which weaken over time until rupture. The exact cause of this wear is not completely understood; the conformation of the knee, the weight and a hereditary component participate in it.

A rupture by true accident also exists: failed landing of a jump, paw caught in a hole, violent twisting of the knee during a race.

Chronic inflammation of the joint also weakens the ligament.

Overweight and obesity: this is the factor over which the owner has the most control.

Large breeds and breeds with high muscle mass, in which the disease is common and often bilateral.

Early sterilization in certain large breeds, which modifies the growth of long bones.

Abnormal knee angles and unstable patella, which unbalance the joint.

“Weekend” type activity: dog sedentary during the week then very suddenly used.

A dog that has already ruptured a cruciate ligament has a significant risk of rupturing the other in the months or years that follow.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

The veterinarian walks and trots the dog to analyze the lameness, then palpates the knee.

Two manipulations look for joint instability: the drawer movement and the tibial compression test. They may require sedation, because a tense dog contracts its muscles and masks the instability.

X-rays are taken: they do not show the ligament itself, but reveal the swelling of the joint, the changes in osteoarthritis and make it possible to measure the bone angles useful for choosing the surgical technique.

The veterinarian also checks the other knee, often already affected without visible signs.

Exploration of the inside of the joint, at the time of surgery or by arthroscopy, makes it possible to check the condition of the menisci.

Treatment

Surgery is the gold standard treatment for most dogs, especially active and medium to large dogs. Several techniques exist: some modify the geometry of the tibia to neutralize instability, others replace the function of the ligament with a band placed outside the joint. The choice is up to the veterinarian depending on the size of the dog, its morphology, its age and its lifestyle.

A damaged meniscus is treated during the same procedure.

Treatment without surgery can be discussed in very small dogs, elderly dogs or in the event of a contraindication to anesthesia: strict supervised rest, weight loss, painkillers and anti-inflammatories prescribed by the veterinarian, then rehabilitation.

Rehabilitation is an essential part of the treatment, operated or not: short walks on a leash, very gradual increase in effort, strengthening exercises, sometimes physiotherapy sessions or water work.

Never give your dog an anti-inflammatory or painkiller intended for humans (ibuprofen, aspirin, paracetamol). These medications can cause stomach ulcers, digestive bleeding and serious kidney or liver damage, sometimes fatal. Only medication prescribed for him, at the dose set by the veterinarian, is safe.

Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.

Prevention

Maintaining a healthy weight is the most effective measure: you must feel the ribs under your hand without pressing, and see a marked waistline seen from above.

Maintain regular physical activity rather than intense and occasional efforts.

Warm up the dog before a sporting activity and avoid repeated jumps on slippery surfaces.

Have any lameness that lasts more than a few days examined quickly: partial damage to the ligament caught early sometimes avoids injury to the meniscus.

Talk to the veterinarian about the right time to spay or neuter a large breed puppy.

Possible complications

Lesion of a meniscus, which causes pain and causes crunching when walking.

Osteoarthritis of the knee: it sets in as soon as the joint becomes unstable and progresses more quickly the longer the instability lasts.

Rupture of the cruciate ligament of the other knee, common because the dog shifts its weight onto it.

Muscle wasting of the affected thigh, which prolongs recovery.

After surgery: infection, delay in bone consolidation or displacement of material, rare but possible.

When to see a veterinarian

Your dog has been limping in one hindquarters for more than two or three days, even if the lameness comes and goes.

He no longer places his paw on the ground at all.

His knee is swollen or hot.

He sits with one hind leg outstretched to the side.

He refuses to jump, climb the stairs or has difficulty getting up.

After an operation: the wound leaks, swells or reddens, or the lameness returns even though it had improved.

Prognosis

With appropriate surgery and rehabilitation carried out to the end, the vast majority of dogs regain comfortable use of the limb and a good quality of life.

Recovery takes time: several weeks of controlled activity, then a gradual recovery over a few months.

Osteoarthritis remains present in the joint in the long term, but it is much better tolerated when the knee has been stabilized and the dog maintained at a correct weight.

Frequently asked questions

My dog limps a little then seems to be better: should I still consult?

Yes. A limp that comes and goes is typical of a partially ruptured cruciate ligament. Waiting for complete rupture exposes you to meniscus injury and more marked osteoarthritis: early consultation broadens the treatment options.

Can we avoid the operation?

In certain very small dogs, in elderly or inactive dogs, treatment without surgery may be enough to regain comfort. In a medium or large dog, surgery generally gives much better results. This is a decision to be made with the veterinarian, taking into account the dog and not just its illness.

Will my dog break the other ligament?

The risk is real, because the ligament of the other knee often wears out by the same mechanism, and because the dog shifts its weight onto it. Monitoring your weight and reporting the slightest limp on the other side allows you to react early.

Can I give him an anti-inflammatory from my pharmacy while waiting for the appointment?

No, never. Ibuprofen, aspirin and paracetamol are dangerous for dogs and can cause digestive ulcers and serious kidney or liver damage. While waiting for the consultation, put him on strict rest on a leash and call the veterinarian.

How long does recovery take?

It is measured in months, not days. The first weeks are devoted to healing and very short outings on a leash, then activity increases in stages according to the protocol given by the veterinarian. Resume too quickly is the main cause of failure.