A female raccoon dog (Nyctereutes procyonoides) captured September 1992 in Nara prefecture, Japan, suffering from swollen joints of all four limbs was necropsied. Radiographically, there was a shadow in the right pulmonary caudal lobe and periosteal bone formation around several joints. Microscopically, there was extensive edema, along with one large and many small pyogranulomatous nodules and purulent bronchitis in the right lobe and left caudal lobe of the lungs. There were intermingled branching filamentous bacteria in the lesion, which stained positively with Warthin-Starry, Grocott, and Gram stains, and partially with periodic acid Schiff and Ziehl-Neelsen stains. Extensive exostosis with coralloid trabeculation had developed bilaterally at the carpal, stifle and hock joints in the surrounding well vascularized loose connective tissue. Degeneration of articular cartilage and villous proliferation of synovial membranes were apparent. This is the first report of hypertrophic pulmonary osteoarthropathy in the raccoon dog.