Hemothorax, the accumulation of blood in the pleural (chest) cavity, is usually caused by trauma to the chest, blood clotting disorders, or tumors in the chest. Hydrothorax, the accumulation of clear fluid in the pleural cavity, is usually due to interference with blood flow or lymph drainage. Chylothorax, the accumulation of a high-triglyceride lymphatic fluid in the pleural cavity, is relative
The respiratory system consists of the large and small airways and the lungs. When a dog breathes air in through its nose or mouth, the air travels down the trachea, which divides into the tubes known as the right and left bronchi, then into the smaller airways called bronchioles in the lungs. The bronchioles end in the small sacs called alveoli, where the barrier between the air and the blood is a thin membrane.