One year old, male beagle dog was presented with acute onset of severe dyspnea, cyanosis, and anorexia. He had no trauma history. Five days earlier, the dog had been diagnosed as bacterial pneumonia caused by Pseudomonas aeruginora and E. coli. He exhibited a restrictive respiratory pattern and at admission, immediately oxygen supplementation given. On a ventrodorsal(VD) radiographic view, right lung was collapsed and contrasted with the air-filled pleural space. The mediastinum, heart, and great vessels were shifted to the left. On a right-lateral radioraphic view, the heart appeared to be elevated from the sternum. The dog was diagnosed as secondary spontaneous pneumothorax resulting from bacterial pneumonia. The chest tubes were placed on the right and left pleural cavity under general anesthesia. At 3 days after treatment, on a VD radiograph, air of right pleural cavity disappeared while left pleural cavity showed radiolucent area filled with air, and the heart was shift to the right. Therefore, the left tube thoracostomy was performed too. The right chest tube was maintained for 5 days and the left chest tube was maintained for 45 days. During the period, antibiotics and vitamin I were used for managing of bacterial pneumothorax and preventing of retroinfection through the tubes. As the result, bacterial pneumonia was well managed by medicines and secondary SP was completely treated that air in bilateral pleural cavity disappeared on radiographs. During the follow-up for 2 years, patient showed normal condition without recurrence.