Inflammatory polyarthritis secondary to deposition of immune complexes can produce erosive (destruction of articular cartilage and subchondral bone) or nonerosive (periarticular inflammation) joint disease. Rheumatoid arthritis, Greyhound polyarthritis, and feline progressive polyarthritis are examples of erosive arthritides. Systemic lupus erythematosus is the most common cause of nonerosive arthritis.
Clinical signs are lameness, multiple joint pain, joint swelling, fever, malaise, and anorexia. Clinical signs commonly wax and wane.
Diagnosis is aided by radiography, biopsy, arthrocentesis, and serologic testing. Radiography Radiography of Animals Radiography (generation of transmission planar images) is one of the most commonly used diagnostic tools in veterinary practice even though other imaging modalities such as ultrasonography,... read more reveals periarticular swelling, effusion, and joint collapse plus subchondral bone destruction in erosive conditions. Joint fluid analysis will reveal elevated cell counts exceeding 3,000/mcL, composed primarily of normal polymorphonuclear cells. Biopsy of synovial tissue reveals mild to severe inflammation and cellular infiltrates. Serologic testing is performed for rheumatoid factor and antinuclear antibodies.
Treatment involves anti-inflammatory medications (eg, corticosteroids Corticosteroids in Animals Two classes of steroid hormones, mineralocorticoids and glucocorticoids, are naturally synthesized in the adrenal cortex from cholesterol. (Also see The Adrenal Glands.) Mineralocorticoids ... read more ) and chemotherapeutic agents (eg, cyclophosphamide, azathioprine, or methotrexate). Prognosis is guarded because of relapses and inability to determine the inciting cause of the autoimmune reactions.
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Also see pet health content regarding immune-mediated arthritis in dogs Immune-mediated Arthritis Some joint diseases, such as arthritis, affect the joint membranes themselves. Other types of joint conditions affect the tendons, cartilage, bursae, and fluid within the joint. Joint disorders... read more and cats Immune-mediated Arthritis Some joint diseases, such as arthritis, affect the joint membranes themselves. Other types of joint conditions affect the tendons, cartilage, bursae, and fluid within the joint. Joint disorders... read more .