One of the most common injuries that causes hind leg lameness in dogs is cranial cruciate ligament (CCL) rupture. The most typical scenario is a middle aged or older, often overweight, large breed dog that suddenly does not want to bear weight on one of his hind legs. Sometimes dogs will turn the affected leg slightly so that the knee points away from the body. If the injury occurs when a person is nearby, he or she may report that the dog was running around normally and suddenly yelped and held up a back leg.
Why Owners Should Be Concerned
The cranial cruciate ligament is an essential part of the knee’s architecture. When it is no longer functioning correctly, the joint becomes unstable. This can quickly lead to the development of osteoarthritis as the body attempts to stabilize the joint on its own. Both the initial injury and the arthritis pain that follows are very painful.
If a dog’s CCL ruptures because of a traumatic injury, the problem will likely only affect one leg. However, if a dog has cranial cruciate ligaments that have weakened over time (e.g., as a result of obesity, hypothyroidism, conformational abnormalities, and/or a genetic predisposition), it is very common for both legs to develop CCL ruptures over the course of several months to years.
Diagnosing a CCL Rupture
To diagnose a CCL rupture, a veterinarian will start by watching a dog walk and then feel for abnormalities in the affected leg and try to pinpoint the source of the problem. If the knee seems to be the primary suspect, the vet will then check for a “drawer sign.” This is an abnormal movement of the knee that occurs when the cranial cruciate ligament is ruptured. Most dogs need to be sedated for this part of the exam so they do not feel pain. Pain causes muscles to tense, which makes the drawer sign hard to observe.
If the CCL is completely ruptured, the drawer sign is readily evident and the diagnosis is clear. In some cases, however, the CCL may only be partially torn or stretched, and the drawer sign may not be as apparent. Your veterinarian may also want to take an X-ray of the affected knee to look for more evidence of a ruptured CCL and to evaluate the degree of arthritis that may have already set in.
Surgery is the treatment of choice for a complete cranial cruciate ligament rupture. Several different types of surgery are available, and the best option depends on a dog’s size, an owner’s finances, and the veterinarian’s experience. Talk to your veterinarian or make an appointment with a veterinary orthopedic surgeon to get the details. In general, repairing a CCL rupture as soon as possible will minimize the severity of osteoarthritis that develops in the future.
If surgery to repair a ruptured CCL is not viable, a stifle brace can help keep the knee somewhat stable as scar tissue and the normal healing process take place. When used consistently, a brace may help decrease the degree of arthritis that develops in the injured joint. Owners need to be committed to monitoring their dogs for injuries associated with the brace (e.g., pressure sores) and preventing excess activity, which will negate any benefit associated with this option.
Physical therapy, pain relief, canine anti-inflammatories, and supplements to promote joint repair are all vital to treating both partial and complete CCL ruptures whether or not surgery is performed or a brace is employed. Weight loss and exercises to strengthen the tissues within and around the knee can go a long way toward reducing knee stress and returning a dog to normal activity levels after an injury occurs. Talk to your veterinarian about what program is right for your dog.