Abstract
A three-year-old male Chihuahua was presented with difficulty in walking. The owner reported that the dog had shown progressive lameness for about one year. Radiographic examination revealed symmetrical erosive arthritis in the carpal and tarsal joints. Besides the joint lesions, mitral insufficiency (MI) was observed by two-dimensional echocardiography. Although there was no rheumatoid factor detected using denatured rabbit lgG, and an incision biopsy of the joint capsule did not provide sufficient histological evidence for rheumatoid arthritis (RA), a tentative clinical diagnosis of RA associated with rheumatic mitral valvular disease was made on the basis of radiographic and echocardiographic findings. The dog was treated with prednisolone, azathioprine, ACE inhibitor, digoxin, and furosemide, but the signs of RA and MI worsened gradually, and it died of severe pulmonary edema six months after admission. Postmortem examination confirmed rheumatoid arthritis and rheumatic heart disease in this case.
