A ruptured cruciate ligament is a painful orthopedic problem that can cause your dog to suddenly start limping on one of its back legs. Though there are many different reasons for limping in dogs, a ruptured cruciate ligament is one of the most common ones. A ruptured cruciate is a painful and immobilizing injury. While not life-threatening, it must be addressed.
What Is a Cruciate Ligament Injury?
Cruciate ligament injury is a problem with the dog's knee joint. The ligaments connect the femur (thigh bone) to the tibia (shin bone). This stabilizes the knee joint. The ligament can rupture completely (complete cruciate tear) or partially (partial cruciate tear.) The complete tear is also called an ACL or CCL tear.
Symptoms of a Cruciate Ligament Injury in Dogs
When the cruciate ligament tears, the tibia moves freely from under the femur, causing pain and lameness. There's one main symptom of this type of injury.
Limping and Lameness
Sudden lameness in a rear leg is often the first sign of injury. The lameness can worsen with activity and improve with rest. If an injury remains unaddressed, arthritic changes occur quickly. This leads to chronic lameness and discomfort. If your dog suddenly shows signs of pain or limping, take it to your vet as soon as possible.
Causes of a Cruciate Ligament Injury
The two main causes of cruciate ligament rupture in dogs are degeneration of the ligament and trauma. Additionally, some dog breeds/types are predisposed to cruciate ligament injuries including rottweilers, Labrador retrievers, Newfoundlands, and Staffordshire terriers.
- Degeneration: Overweight or obese dogs are more prone to this type of injury, as they carry more weight and are prone to ligament degeneration.
- Trauma: A tear can result from an athletic injury in a healthy dog. This could even mean landing "wrong" when running or jumping.
Diagnosing Cruciate Ligament Injury in Dogs
Your veterinarian will be able to diagnose a cruciate ligament injury with a physical exam. The vet will also palpate the knee of the leg that's lame. If there's any further question about the diagnosis, the doctor will take an X-ray. If your dog does have a cruciate injury, talk to your vet about getting a referral to a board-certified veterinary surgeon. There, you can discuss the best option for your dog and your lifestyle.
Although rest and medication may help, surgery is usually recommended to repair the ruptured cruciate ligament. There are several different surgical approaches, each with its pros and cons.
Cruciate Surgery: Extracapsular Repair
In this method, a strong suture is placed to secure the femur and tibia, essentially replacing the function of the torn cruciate ligament. The suture supports the knee joint while scar tissue builds up and the muscles surrounding the knee strengthen. The suture invariably loosens or breaks at some point in the future. It must stay intact for eight to 12 weeks for healing to occur.
This is a relatively quick and uncomplicated procedure with good success rates, especially for smaller dogs. It is less expensive than other methods. Long-term success varies and may be better for smaller dogs.
Cruciate Surgery: TPLO
Another surgical option is the tibial plateau leveling osteotomy (TPLO). This is a more complex procedure than the extracapsular method and requires specific surgical equipment and training.
The TPLO alters the biomechanics of the knee joint, allowing it to function properly without a cruciate ligament. A complete cut is made through the top of the tibia (tibial plateau). The tibial plateau is rotated to change the angle of this portion of the bone. A metal plate is affixed to repair the cut bone. The tibia heals over several months.
Partial improvement can be seen within days; however, full recovery will take several months, so cage rest is essential. Generally, the long-term prognosis is good, and re-injury is uncommon. The plate does not need to be removed unless problems occur later.
As with any surgery, complications are possible, including infection. The TPLO is significantly more expensive than traditional surgery.
Cruciate Surgery: TTA
A third surgical method is the tibial tuberosity advancement (TTA). The details of this method are slightly different from a TPLO, but the TTA still involves cutting the tibia and placement of metal implants.
Some surgeons describe the TTA as a less invasive procedure than the TPLO. The TTA may have a faster recovery than TPLO, as well, though some surgeons see little difference. The dog's anatomy and lifestyle are also deciding factors. The cost of the TTA is comparable to the TPLO.
Prognosis for Dogs With a Cruciate Ligament Injury
In general, the prognosis after surgery is good, with an 85 to 90 percent chance of a return to normal activity levels. Post-surgical medical management consists of multiple steps for your dog's long-term recovery. It helps to know that smaller dogs (weighing less than 25-30 pounds) may fare better than heavier dogs. Medical therapy involves the following:
- Several weeks of cage rest
- Brief, calm leash walks for bathroom breaks only
- Sit-to-stand exercises
- Underwater treadmill therapy and/or swimming
- Veterinary-approved oral anti-inflammatory drugs and supplements to support joint health
Following your vet's recommendations will give your dog the best chance of full recovery with fewer complications. As with any orthopedic surgery, it is common for dogs to develop arthritis in the future. With proper care, your dog can live a full, healthy, and comfortable life.
These dogs may develop osteoarthritis in the affected knee joint. In addition, dogs affected by this injury have a 40 to 50 percent chance of tearing the ligament in their other knee.
How to Prevent a Cruciate Ligament Injury
While a cruciate rupture cannot always be prevented, keeping your dog at a healthy weight and providing plenty of exercise (but not too strenuous) can minimize the risk.
Cranial Cruciate Ligament Disease. American College of Veterinary Surgeons