Polyarthritis involves inflammation of multiple joints and is classified as infectious (septic arthritis Septic Arthritis in Dogs and Cats Infectious arthritis is most frequently associated with bacterial agents such as staphylococci, streptococci, and coliforms. Causes include hematogenous spread or penetrating trauma, including... read more ) or noninfectious (erosive or nonerosive [ immune-mediated Immune-mediated Arthritis in Dogs and Cats Inflammatory polyarthritis secondary to deposition of immune complexes can produce erosive (destruction of articular cartilage and subchondral bone) or nonerosive (periarticular inflammation)... read more ]). Nonerosive can be idiopathic or breed (Akita) associated, while erosive is characteristic of feline progressive arthritis and rheumatoid arthritis.
Clinical signs of a polyarthritis include fever, lameness, swollen joints, lethargy, and inappetence.
Diagnosis is by 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 
(joint effusion, possible erosive bone destruction) and abnormal (increased cell counts) joint fluid analyses.
Treatments involve longterm glucocorticoid therapy or other immunosuppressive medications such as azathioprine or cyclophosphamide.
Prognosis in most cases is guarded or poor, with relapses common.
