Pet Points: Treating torn knee ligaments in dogs

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Many student and professional athletes are going through surgery and rehabilitation for knee ligament injuries as sports seasons come to a close. Just a few weeks ago, Pittsburgh Penguins' center Evgeni Malkin ruptured his anterior cruciate ligament, an injury that will keep him out of the lineup for the rest of the season. Skiers are also prone to this injury.

While pets frequently injure their ACLs while running, jumping or doing other athletic activities, some of these injuries occur with only moderate exercise and may be due to underlying problems in the knee joint, or concurrent medical conditions.

Overweight dogs are more susceptible to this injury, and conditions such as Cushing's syndrome (an excess of cortisone in the body) can also weaken the ligaments and make a dog more prone to injury. The cruciate ligaments permit the knee to be stable while allowing bending as a hinge joint. When dogs overstress this ligament, it can slowly fray or completely tear.

Dogs with this injury visit the veterinarian because they are not bearing weight on the hind leg or with a light toe touching. When we examine a dog for this injury, the crucial test is to see if the tibia and femur abnormally shift forward and back on each other. This is known as cranial drawer motion. Certain breeds are more commonly seen with this injury such as retrievers, mastiffs, Newfoundlands, Rottweilers and many smaller breeds.

After making a diagnosis, the veterinarian will help the client determine the need for surgery in their pet. In many cases surgical stabilization is most appropriate to prevent severe arthritis from developing in the joint over time. The younger and larger the dog the more critical it is to surgically stabilize the joint. An athletic dog will also require surgery in order to regain full function.

My own dog, Vern, was older when he ruptured his ACL. Due to his other health issues we did not do surgery on him. Vern had a history of severe kidney disease and also had severe elbow dysplasia. He regained some function in his leg but continued to limp. However, he did reach the typical lifespan for a Bernese mountain dog. His "sister" Vicky was an active Jack Russell. She tore her ACL running with other dogs at the park. After surgery she regained full function and was active for many years.

Some primary care veterinarians will perform cruciate ligament repairs with varying degrees of success. Our office refers these cases to surgical specialists because of the extra training and expertise they have.

Dr. Anthony Pardo, a board certified veterinary surgeon in the North Hills, believes that surgery is usually needed to return a dog to his or her pre-injury function. Smaller dogs may be helped with a nylon suture technique to replace the function of the ligament. In athletic dogs and in active, large-to-giant-breed dogs, procedures such as the Tibial Plateau Leveling Osteotomy or Tibial Tuberosity Advancement are often recommended to stabilize the joint. These newer, more complex techniques aim to make the joint stable by changing the shape of the top of the tibia (shin bone) to eliminate the forces that used to be controlled by the cruciate ligament. In that way, the joint can now be stable and fully functional without an ACL.

During TPLO surgery, a special saw is used to make a curved cut in the tibia just below the knee joint. The top of the bone is then realigned to a neutral position and secured there with screws and a metal bone plate so that the bone can heal as strong as it once was. After a short stay in the hospital, the dog can go home without a bandage or cast but with medications for pain control and strict instructions for complete rest.

Dogs seem to recover from these surgeries quite well and start to use the operated leg within a few days. Any of the surgical techniques require eight weeks of very limited activity to allow the knee to heal, with a gradual return to normal exercise over another four to six weeks. Physical rehabilitation with treadmills or swimming therapy may be helpful for specific cases.

If dogs with ACL injuries are to have a chance of a full recovery, it is critical that the proper diagnosis is made and treatment initiated early. Any rear leg lameness should be evaluated by a veterinarian without delay.

Dr. Gerson is a veterinarian and founder of the Point Breeze Veterinary Clinic. His column will appear biweekly. The intent of this column is to educate pet owners. Consultation with a veterinarian is necessary to diagnose and treat individual pets. If you have a question you'd like addressed in Pet Points, e-mail . Please include your name and municipality or neighborhood.


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