Immune-mediated Polyarthritis

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Immune-mediated Polyarthritis

By: Dr. Douglas Brum

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Section: Overview

Immune-mediated joint disease is a condition in which the immune system is stimulated to cause an inappropriate inflammatory response in one or usually multiple joints. The condition is sometimes termed idiopathic immune-mediated polyarthritis, reflecting an unknown cause of the condition that involves multiple joints.

Inflammation of the lining of the joints causes an increase in white blood cells in the joint fluid. This causes joint swelling and pain.

As with most diseases of the immune system, female animals are at increased risk of getting the disease. The disease is also most commonly seen in younger to middle-aged animals. All breeds may be affected.

What to Watch For

A stiff stilted gait

Reluctance to walk or stand

Swelling of one or more joints, which may also feel warm

Shifting or multiple leg lameness

Fever

Anorexia

Lethargy

Diagnosis

A complete physical and orthopedic exam

Complete blood test (CBC)

Biochemical profile

Urinalysis with culture and sensitivity

Arthrocentesis of the affected joints by inserting a needle into the joint space and aspirating a sample of synovial fluid. Microscopic cytology examination of the fluid is required to evaluate for any abnormalities. The fluid is also cultured.

X-rays of the affected joint or joints

Chest and abdominal X-rays

Immune profile-includes rheumatoid factor (RF) and antinuclear antibody (ANA)

Infectious disease titers including Lyme disease, ehrlichia and Rocky Mountain spotted fever

Treatment

Treatment with immunosuppressive drugs is the main therapy. Prednisone is usually the drug of choice, although other immunosuppressive drugs may be added to the treatment if needed.

Intravenous fluid support may be required in debilitated animals.

Home Care and Prevention

Carefully monitor your pet for improvement or deterioration. Animals tend to respond to therapy quickly, but relapses may occur, especially as drug dosages are decreased. Drugs need to be slowly decreased over time. Careful communication with your veterinarian is essential.

Animals on immunosuppressive therapy are more susceptible to infection and need to be monitored closely for changes in behavior, appetite or general condition. Periodic blood tests are needed when animals are on certain immunosuppressive drugs.

Initially, strict rest is recommended, but as your pet improves, normal activity may resume.

There are no known measures that can be taken to prevent the occurrence of immune-mediated joint disease. Knowledge of what breeds may be at risk and the associated clinical signs may allow for earlier diagnosis.

If your pet has had immune-mediated disease, future vaccinations should be used with caution. An appropriate vaccination schedule should be discussed with your veterinarian.

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