Canine rheumatoid arthritis.

A miniature poodle was presented with a history of a chronic, insidious hind limb lameness. As part of the clinical approach to the case, a serum electrophoresis was done which revealed a polyclonal hypergammaglobulinemia. Analysis of stife and carpal joint fluid revealed an elevated white cell count, that consisted of about 75% neutrophils and 25% monocytes. The joint fluid was sterile on bacteriological culture. Radiographs of the carpal joints indicated some narrowing of joint spaces and subchondral lucencies. Rheumatoid factor was identified on serological testing. Histopathology of carpal joint biopsies indicated a nonsuppurative synovitis. These findings are consistent with a diagnosis of rheumatoid arthritis. The dog was treated with prednisone on a long term basis. Response to treatment has been good.