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Joint Disorders in Cats


Joseph Harari


Topic Resources


Displacement of the Kneecap (Patellar Luxation)

This hereditary disorder is caused by abnormal development of the kneecap (patella). Displacement of the kneecap can be associated with multiple deformities of the hindlimb, involving the hip joint, femur, and tibia. Cats of any age can be affected.

Signs vary based on the severity of the displacement. In mild cases, lameness occurs infrequently, and the kneecap can be manually displaced but easily returned to normal position. As displacement becomes more severe, the dislocated kneecap is more often out of place, the limb is consistently lame, and bone deformities may be seen. Veterinarians can often feel the displacement. X-rays can help your veterinarian see what effects this has had on the limb.


Hip Dysplasia


Osteoarthritis (Degenerative Joint Disease, Degenerative Arthritis)

The joint cartilage in freely moving joints may degenerate over time, leading to loss of joint movement and, in many cases, pain. Joint degeneration can be caused by trauma, infection, the body’s own immune system, or malformation during development. This leads to inflammation of the joint membrane, continued cartilage destruction and inflammation, and abnormal joint function. The condition is common in cats but it may not be noticed because cats often hide signs of pain. Approximately 60 to 90% of older cats have osteoarthritis.


Treatments can be either medical or surgical. Medical therapy may include weight loss (when appropriate), controlled exercise on soft surfaces, warm compresses of the affected joint, and the use of appropriate drugs to reduce pain and inflammation. Other treatments, such as joint fluid modifiers, may help prevent cartilage degeneration. Surgical options include joint fusion, joint replacement, cutting of the joint, and amputation. The outlook for recovery depends on the location and severity of the joint disease.

Septic Arthritis


Signs of septic arthritis include lameness, swelling, pain of affected joint(s), fever, listlessness, loss of appetite, and stiffness. X-rays may reveal increased fluid within the joint in early cases and degenerative joint disease in longterm conditions. Laboratory tests on fluid removed from the joint may help to confirm the diagnosis and identify the cause. Blood tests may also be necessary.


Immune-mediated Arthritis

The body’s own immune system can cause inflammation of joints (immune-mediated arthritis). It generally affects several joints. In some types of immune-mediated arthritis, joint cartilage and bone beneath the cartilage is destroyed. Feline progressive polyarthritis, which resembles rheumatoid arthritis in people, is an example of the type of arthritis that destroys joint cartilage and bone beneath the cartilage. Systemic lupus erythematosus is the most common form of arthritis that causes inflammation of the joint without destruction of cartilage and bone. This condition may affect other organ systems, including the skin.

Signs of immune-mediated arthritis include lameness, pain and swelling in multiple joints, fever, a general feeling of illness, and persistent loss of appetite. These signs commonly come and go. In addition to signs, the diagnosis is aided by x-rays, biopsy of joint tissue, blood tests, and examination of joint fluid (commonly called a joint tap).

Treatment involves anti-inflammatory medications and chemotherapeutic drugs. The outlook for recovery is uncertain. Relapses are relatively common, and the cause of the reactions is often unknown.

Cancerous Arthritis

This type of arthritis is most commonly caused by a tumor known as a synovial cell sarcoma. It is the most common cancerous (malignant) tumor involving the joints. Signs include lameness and joint swelling. X-rays show soft-tissue swelling and a reaction around the bone. A biopsy reveals evidence of a soft-tissue tumor. When diagnosed, spread of the cancer to the lungs has already occurred in about 25% of animals. Amputation of the limb is usually recommended to alleviate pain and, if possible, prevent spreading.

Joint Trauma

Several types of joint trauma can affect the joints in cats, including cranial cruciate ligament tears and palmar carpal ligament breakdown.

Cranial Cruciate Ligament Tear


Signs include lameness, pain, joint swelling, fluid buildup, and a grating sound when the joint is moved. In addition, the joint may appear to be abnormally loose. Partial tears are characterized by a reduced ability to move the joint, especially bending it. X-rays may show excessive fluid in the joint and signs of arthritis. Testing of fluid removed from the joint or arthroscopy (examining the joint with a specialized camera) may also be used to help diagnose the condition.


Joint Fractures

The shoulder, elbow, carpal (wrist), hip, stifle (knee), and tarsal (ankle) joints are those most commonly involved in fractures due to injury. In young animals, the portion of the bone where growth occurs—called the growth plate and usually located at the ends of the bones—is weak compared with adjacent bones, ligaments, and joint membranes, making this area more prone to injury.

Signs of joint fractures include lameness, pain, and joint swelling. If the injury affects an active growth plate, limb deformities can result. X-rays and computed tomography (CT) scans are used to confirm and locate the fracture.

The goal of treatment is to allow the fracture to heal in proper alignment while maintaining joint and limb functions. This is usually done by holding the fracture in place internally with pins, wires, or screws to stabilize it. The outlook for recovery is good as long as damage to the joint is not severe.

Palmar Carpal Ligament Breakdown


Dislocation of the Hip




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