Polyarthritis involves inflammation of multiple joints and is classified as infectious (septic arthritis) or noninfectious (erosive or nonerosive [immune-mediated]). 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 (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.