Cruciate ligament injuries often cause lameness in dogs |

Cruciate ligament injuries often cause lameness in dogs

Ron Carsten, DVM, Ph.D, CVA
Integrative Pet Vet

One of the most common causes of lameness and pain in the hind leg of the dog is a torn cruciate ligament. Cruciate ligaments in the dog knee have a similar but more complex function than those in the human knee. Basically, cruciate ligaments provide important knee support. The ACL (anterior cruciate ligament), or more correctly termed the CCL (cranial cruciate ligament) in the dog, prevents forward motion of the tibia (bone below the knee) with respect to the femur (bone above the knee). In addition, the CCL limits over straightening of the knee and rotation of the tibia.

In the dog, the CCL can be partially torn or completely torn resulting in partial or complete instability. CCL damage can occur from trauma like an acute injury or long-term or chronic degeneration. A partially torn CCL occurs in 25-30 percent of dogs. Frequently the partial tear progresses to a full tear. A damaged CCL leads to instability and degenerative changes within a few weeks of injury. Degeneration can progress to severe within a few months. Over 50 percent of dogs with a torn CCL will also experience a torn or damaged meniscus, the fibrocartilage pad in the knee.

Traumatic tearing of the normal CCL occurs in only about 20 percent of dogs. Interestingly, it has been estimated that in a normal CCL, it requires a force 4 times the body weight of the dog to cause a tear. In the remaining 80 percent of dogs, tears occur with much less force in a CCL that has undergone long-term chronic degeneration. Unfortunately, because degeneration plays a role in a large number of dogs, 40-60 percent of dogs will eventually experience a torn CCL in the other leg.

Factors that contribute or predispose to ligament degeneration include aging, obesity, poor physical condition, abnormal confirmation, disuse, immune mediated damage, and genetics factors. Degeneration related to aging is more significant in dogs over 30 pounds and over 5 years of age. Abnormal confirmation such as bowlegged, knock-kneed, or having straight knees and hocks predisposes to CCL rupture. Some dog breeds like the Rottweiler, Newfoundland, Staffordshire Terrier, Mastiff, Akita, Saint Bernard, Chesapeake Bay Retriever, and Labrador Retriever are more commonly affected. A genetic mode of inheritance has been identified in the Labrador Retriever.

The signs of CCL injury include difficulty rising from sitting, reduced activity, varying severity of lameness, loss of muscle mass, thick area on the inside of the knee, pain, and stiffness. Keep in mind that these signs are not specific to CCL injury and can be caused by other problems. Therefore, it is important to have a thorough examination that may include X-rays. Complete tears are generally straightforward to diagnosis while the partial tears can be more challenging. An increased cranial draw motion (tibia slides forward abnormally) is consistent with CCL tear. In addition, there is often increased fluid in the joint.

Optimal treatment of the torn CCL depends on the dog’s activity level, size, age, knee conformation, and amount of knee instability. Surgical stabilization is generally thought to be the best approach. There are a number of surgical techniques that are commonly used and are generally selected based on the size of the dog and the surgeon’s preference. The goal for surgery is to stabilize the knee so that degeneration is eliminated or its rate of progression significantly slowed. However, surgery is not practical for all dogs due to health concerns associated with anesthesia risk or financial reasons. When surgery is not practical, some dogs can be kept comfortable using a custom made knee brace. These are designed to provide support during activity, but are not intended to be worn continuously. Partial tears may benefit from prolotherapy.

In addition to surgery or a knee brace, there are a variety of nutriceutical products, supplements, and herbs that can be used to help manage inflammation, pain, and reduce degeneration of the joint. For example, glucosamine and chondroitin products reduce the damaging effects of inflammation on the cartilage surface in the joint. Fish oil and herbs like boswellia help to reduce inflammation. Manual therapies may be indicated to help maintain appropriate alignment of the back and pelvis because there is additional stress in these areas during times of lameness. Non-steroidal anti-inflammatory drugs like Rimadyl help to reduce inflammation and pain. Acupuncture and therapeutic laser can be used to reduce pain and improve healing after surgery. A rehabilitation program can be beneficial after surgery.

If you have concerns or questions about your dog, contact your veterinarian for further information.

Ron Carsten, DVM, PhD, CVA, CCRT was one of the first veterinarians in Colorado to use the integrative approach, has lectured widely to veterinarians, and has been a pioneer in the therapeutic use of food concentrates. He has a Doctor of Veterinary Medicine, a Ph.D. in Cell and Molecular Biology, and is a Certified Veterinary Acupuncturist and Canine Rehabilitation Therapist. He practices integrative veterinary medicine in Glenwood Springs.

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