Treatment of Cruciate Ligament Tears in Dogs

What is a cruciate ligament? 

Dogs have similarities to people in how their joints are stabilised and move. In people, the anterior cruciate ligament (ACL) is commonly injured during sporting activities involving rapid stopping or changes of direction.

In dogs, a ligament in the stifle (knee joint) performs a very similar function. It is called the cranial cruciate ligament.

How does the cranial cruciate ligament become damaged in dogs?

In most dogs, the ligament begins to deteriorate over time. There have been many investigations into the underlying reasons for this, but the causes are not completely clear.

The ligament typically develops a partial tear over time. As the tear worsens, so does the degree of lameness. An acute, complete tear can also occur during vigorous activity, such as chasing a ball or running at the beach.

For many of these dogs, X-rays reveal signs of an existing joint problem that preceded the activity that appeared to cause the injury.

What else can happen when a dog tears the cranial cruciate ligament?

There are other structures in the stifle (knee) joint that help to stabilise the joint and distribute pressure between the tibia (shin bone) and femur (thigh bone). The most important of these are known as the menisci. 

The meniscus on the inside of the joint (medial meniscus) is the most frequently damaged cartilage. It is more likely to be damaged when the cranial cruciate ligament is completely torn.

How is a dog assessed for treatment of cranial cruciate ligament problems?

A consultation and physical examination are the first steps. The veterinarian will discuss the symptoms you have noticed, how they have progressed and your dog’s general health. They will also watch your dog move to identify which legs show signs of problems.

Around 20% of dogs with cranial cruciate ligament problems have both hind legs affected when assessed. The veterinarian will then feel the knee and apply pressure in various directions to assess whether the ligament has been damaged.

X-rays are typically recommended after the examination. These help rule out other causes of lameness, identify signs of cruciate ligament disease and, in some cases, plan surgery.

The cruciate ligament itself cannot be seen on an X-ray, so the diagnosis is based on the findings from both the physical examination and X-rays.

What are the treatment options for a cruciate ligament tear in dogs?

Treatment for cranial cruciate ligament disease is typically surgical. An older study suggests that around 20% of dogs can manage with medical treatment alone. Non-surgical treatment may also be advised if significant health issues mean an anaesthetic is not in the patient’s best interest. However, most dogs develop progressive arthritis when cranial cruciate ligament disease is left untreated.

Regardless of the surgical technique selected, the inside of the joint should be examined during surgery. This confirms that the ligament is torn and allows any damage to the meniscal cartilage to be assessed and treated. An untreated meniscal injury typically leads to ongoing lameness after surgery.

Arthroscopy uses a camera and small instruments to examine the joint and treat meniscal damage. It provides better visualisation than opening the joint completely and supports a faster recovery. It requires specific training and is typically available in referral surgical centres such as Veterinary Specialist Services.

What surgical techniques are used?

There are several surgical options available. In humans, some of a hamstring tendon is used to replicate the damaged ligament. With good rehabilitation over 9-12 months, this can become similarly effective to the original ligament.

Unfortunately, this approach is not reliably successful in dogs, largely because confinement and rehabilitation are more difficult than in people.

The most commonly recommended procedures for most patients are Tibial Plateau Levelling Osteotomy (TPLO) or Triple Tibial Osteotomy (TTO). These procedures change the way the knee joint functions, allowing it to remain stable without relying on the damaged cruciate ligament.

TPLO involves making a cut in the tibia (shin bone) and adjusting the angle of its upper surface. A bone plate and screws hold the bone in its new position while it heals.

Research supports TPLO as the best option for most dogs, with a very high proportion of patients returning to athletic, active function. It can be performed on dogs across a wide range of sizes. At VSS, patients weighing from 2 kg to more than 100 kg have been treated using this procedure.

For some patients weighing less than 15 kg, an alternative called an extracapsular suture is used. This involves placing a prosthetic stabiliser around the outside of the joint.

What should we expect after surgery?

The initial postoperative period focuses on pain management and recovery from the procedure. Most dogs receive multiple pain medications and, in some cases, antibiotics.

Dogs need to be confined for at least six weeks, and sometimes up to 12 weeks, to reduce the risk of damage to the surgical repair. Controlled walking on the operated leg is important to help recovery, following the instructions provided by the surgical team.

Most dogs are walking consistently on the leg with an obvious limp by two weeks after surgery, and with a mild limp by six weeks. Around 80% of the improvement occurs within the first 12 weeks, with further improvement taking place over the remainder of the year.

Most dogs return to a high level of athletic activity, although osteoarthritis can still occur. A structured physiotherapy programme has been shown to improve the rate of recovery, alongside a comprehensive approach to arthritis management. Your family vet can help develop an ongoing arthritis management plan.

A plan should also be made to watch for signs of complications. The most common complications include bacterial infection, subsequent damage to the meniscal cartilage, or damage to the surgical repair if the dog is too active after surgery.

Most complications can still be managed to achieve a successful result.

For fixed-price TPLO surgery packages, hospital locations and consultation bookings, visit our dog knee surgery page.

For more information about the treatment and management of cruciate ligament tears, or advice on a specific case, please contact our surgery team on 1800 442 648