A Contusion (bruise) is an injury of a part of body without a break in the skin. A pulmonary contusion is an injury to lung parenchyma (functional tissue of the lungs) due to a blunt trauma to the chest (thorax) which causes bleeding (hemorrhaging) and/or fluid accumulation within the lungs. In this condition, bruising or bleeding of lung tissue occurs that may cause pain and trouble breathing. It is a common lung injury after a blunt trauma to the chest. Damage to the lungs results in breathing difficulty since lungs are responsible for oxygen supply to the body.
Common symptoms associated with pulmonary contusion include direct effects of physical trauma such as chest pain and coughing up blood as well as signs that body is not receiving adequate oxygen supply, such as cyanosis (bluish discoloration of skin). The dog will manifest respiratory distress or abnormal respiratory effort (tachypnea).