Dog Knee Joint Problems

The onset of knee joint problems in dogs usually happens very quickly, when the dog becomes lame or begins limping and shows reluctance to bear weight on the involved leg. These issues often present particular problems to owners: pain for the dog and the expense of treatment and repair.

  1. Function

    • The knee joint in dogs is the largest joint in the dog's body and carries most of its body weight. It comprises the patella (kneecap), which resides in a groove at the base of the femur--the largest leg bone--and the ligaments and tendons that hold the femur, patella and tibia (the shinbone) together. The knee is able to bend in only one direction, and when any of its elements becomes dysfunctional, the result is a limping, painful dog.

    Types

    • Dogs suffer two major types of knee problems.

      The first is a cruxiate ligament injury, usually occurring in middle-aged, obese dogs that hyperextend the joint while exercising after a period of inactivity. The cruxiate ligament consists of two separate ligaments that cross behind the patella and hold it in place. When either of these two structures becomes injured, the knee can pop out of place. This type of traumatic injury also occurs in some athletic dogs and may result in degeneration of the joint after just a few weeks without treatment.

      Patellar luxation is the dislocation of the kneecap from the groove where it resides--usually without involvement of the ligaments. Resulting from trauma or congenital deformities, the symptoms of luxation can be intermittent as the patella slips in and out of place. It often starts in puppyhood and may grow progressively worse as the dog ages.

      Other kinds of knee joint problems include osteoarthritis; sprains; muscle, tendon and ligament strains; and infections. Any type of joint problem in dogs needs diagnosis and treatment by a licensed veterinarian.

    Diagnosis

    • Veterinarians typically use a series of radiographs and flexation tests to diagnose any kind of knee joint disease. X-rays show any kind of anatomic deformity and displacement of the kneecap. Vets also sometimes palpate the dog's joint and patella to see if they display any dislocation as it occurs. Veterinarians then might recommend an MRI of the affected joint, but this usually happens only if the problem is acute and traumatic.

    Prevention and Solution

    • The best prevention of any sort of knee-joint problem is to keep a dog active and slim. Because obesity is a factor, a high fiber, low carbohydrate diet is useful in managing a weight gain as the dog ages. Some owners add a chondroitin/glucosamine supplement to their aging dog's food to improve joint flexibility. Treatment of cruxiate ligament injury and patellar luxation usually requires surgical stabilization of the knee. The veterinarian normally removes any kind of damaged tissue before securing any parts of the damaged joint. Owners must limit their dogs' exercise and jumping for several weeks after surgery. Veterinarians usually place a supportive bandage over the area and recommend pain and anti-inflammatory medications. They may also recommend physical therapy and weight reduction.

    Considerations

    • Although cruxiate ligament injuries normally occur in overweight, middle-aged or highly athletic dogs, patellar luxation can happen to any animal. Often the kind of luxation diagnosed and its treated depend on the size of the animal. Regardless of the diagnosis, a dog's knee problems usually result in some degree of degenerative bone disease as the dog ages.