Cranial Cruciate Ligament Ruptures in Dogs

dog

Labrador retrievers, rottweilers, golden retrievers, boxers, and pit bulls. If you own one of these or another large-breed dog, you should know that your dog is at risk of rupturing one or both of its cranial cruciate ligaments. This time of year, veterinarians see more dogs coming in limping or holding up a leg. If it’s a rear leg, the first thing we think about is a cranial cruciate rupture. What exactly is this? Is it preventable? And if it happens, what does it mean for the dog?

There are two tough fibrous bands of tissue that cross inside the knee joint: the cranial and the caudal cruciate (cross-shaped) ligaments. They span from one side of the femur (the bone above the knee joint) to the tibia (the bone on the bottom of the knee joint). The cranial cruciate ligament attaches to the front of the tibia and the caudal attaches to the back of the tibia. These ligaments stabilize the knee (stifle) and prevent the tibia from slipping forward out from under the femur. If the cranial cruciate ligament (CrCL or CCL) tears or ruptures, the knee joint is suddenly unstable and very painful.

Trauma and degenerative changes are the main causes of a CCL rupture. In young, athletic large-breed dogs, we often see ruptures after the dog has been playing roughly or very energetically and takes a bad step, injuring the knee. Older dogs—often those that are overweight—can have weakened ligaments that slowly stretch over time. These weak ligaments can partially tear and, eventually, break down completely. In these dogs, there isn’t usually anything that precedes the complete rupture. It might occur just walking down some stairs or jumping off the couch. Degenerative disease can occur in both large- and small-breed dogs.

If your dog is suddenly holding up a leg, you should take him to your veterinarian. All the joints in the leg will be moved and felt for swelling, inflammation, and pain. Sometimes a limp is due to an injury on the pad or a broken toenail. Some dogs just over did it playing and running and are sore. Many times, your dog may be started on an anti-inflammatory medication and a week of rest to see if the limp goes away.

One of the things your vet will do is look for a “drawer” sign in the stifle. Because the cruciate ligaments keep the tibia in place, if one is ruptured, the tibia will slide out a little bit from the femur—sort of like a drawer being opened. Because the knee can be very painful and swollen, sedation of your dog may be necessary. This is also a good time to get an x-ray of the knee to look for other signs of a CCL rupture—inflammation in the joint or changes in the bone that occur with long-standing problems. An x-ray also allows the vet to make sure there isn’t a bone tumor or fracture that could cause pain and limping.

Once a CCL rupture is diagnosed, your vet will discuss the different options for treatment and repair. In an older, fairly inactive small-breed dog, treatment could be cage rest, restricted activity, and anti-inflammatory pain medication for about four months. Physical rehabilitation would also be helpful, as well as weight loss; over 50 percent of overweight dogs that have one CCL rupture will rupture the other side within a year.

For a larger dog, surgery is the best option. While there are some companies that make braces, they aren’t recommended long term. Dogs don’t tolerate them well; they’re hard to put on correctly; and they don’t help with meniscal tears (the meniscus is cushioning cartilage in the stifle), which are present in the majority of dogs with a CCL rupture. There are a number of different CCL surgeries. Historically, most dogs had an extracapsular repair, where a strong suture is passed behind the knee and through a drilled hole at the front of the tibia. This basically acts as the cranial cruciate ligament, providing stabilization to the knee. This is a good choice for older, fairly inactive dogs. Over time, however, the suture will break down, and if the dog is too active, the scar tissue around the knee will also break down, leading to lameness again.

The tibial-plateau-leveling osteotomy (TPLO) and the tibial tuberosity advancement (TTA) are surgical procedures that change the angle of the femur and tibia. By changing the angles and, thus, the biomechanics of the stifle, the natural weight-bearing of the dog stabilizes the knee joint. Both procedures require the tibia to be cut and metal implants placed. Dogs have a quicker recovery with these advanced surgeries compared to the extracapsular repair, and three to four months after surgery, the dog can be back to full activity. These surgeries do require a very experienced surgeon with special training in the techniques and are more expensive than the extracapsular repair. Physical rehabilitation is also recommended to get the dog back up to full speed.

Is there anything that can be done to prevent a CCL rupture? My first recommendation if you have a large-breed dog is to invest in pet insurance before there’s a problem. Surgeries can run $5,000 to $6,000 or more for repair of one knee, and there’s a good chance the other one will rupture in the future.

There’s a lot of research into early spay/neutering and orthopedic problems in large-breed dogs. There are a lot of things that contribute to orthopedic problems—genetics, weight, repetitive activity, etc.—not just early neutering. This is a topic best discussed with your veterinarian, weighing the pros and cons of waiting to fix your dog.

One of the most important risk factors for knee injuries is weight. If you can’t easily feel your dog’s ribs or they don’t have a waist when viewed from the top and a nice abdominal tuck when viewed from the side, they’re overweight. Trust me when I say labradors shouldn’t look like coffee tables. Your vet should be able and willing to discuss diets, calories, and ways to help your dog slim down. Now is the time to talk to your veterinarian about ways to keep your dog healthy and active, not when your dog comes in from playing in the yard holding up a rear leg.

Photograph by Brenda Eckhardt

Lori Scarlett, DVM, is the owner and veterinarian at Four Lakes Veterinary Clinic. For more information, visit fourlakesvet.com .