A 2 yr old female English setter dog was admitted for acute dyspnea. The dog underwent treatment of a T9T10 thoracic vertebral fracture subluxation at the authors' institution 15 mo earlier. Upon admission, a chest X-ray revealed a pneumothorax and a metallic foreign body in the left hemithorax. An emergency video-assisted thoracoscopic surgery was successfully performed to remove a 4.6-mm long Kirschner wire that migrated from the thoracic vertebral column to the thoracic cavity. The operating time was 27 min. The dog made an uneventful recovery and was discharged on the third day after surgery. Pneumothorax should be considered in patients that develop acute dyspnea and have a history of wire fixation in the thoracic vertebral column. Video-assisted thoracoscopic surgery is a safe and effective treatment of this condition.