So. Following Alfie's second pneumothorax, he had major surgery to remove parts of both lungs. His remaining lungs are still covered in small blisters called bullae which can burst and release air into his chest cavity which will cause further pneumothorax. We are convinced that his previous pneumothorax were caused by bullae bursts due to him exercising more than he usually does so now our four year old lab who loves to play, chase, explore etc will have to take things easy from now on.