Suppuratives bronchopneumonia was found in a 3-month old domestic muskrat (Ondatra zibethicus). Dead muskrat showed hemorrhagic nasal discharge, severe hemorrhage and consolidation were observed in the lungs in necropsy. Histologically, severe polymorphic neutrophils and alveolar macrophages were infiltrated in the bronchus, bronchioles, alveoli. P. multocida and B. bronchiseptica were identified from the lungs, Klebsiella was isolated from the cecum. We demonstrated those organisms by biochemical test and confirmed P. multocida capsular type A by means of polymerase chain reaction (PCR).