Hemothorax: Bleeding in the Chest in Dogs
Dr. Douglas Brum
The order of diagnostic tests depends on the clinical condition of the pet. In an emergency situation, the pet would be stabilized prior to significant diagnostic procedures. A rapid but thorough veterinary evaluation is critical to prioritizing appropriate diagnostic procedures.
Thoracic radiographs are an excellent test for evaluating fluid in the chest cavity (pleural fluid). Although they are a good initial diagnostic, they cannot differentiate the fluid type. Chest radiographs also may identify traumatic injuries such as rib fractures or a pneumothorax (air in the pleural space). Lung masses are usually easily visualized radiographically. Occasionally, a right atrial mass (usually hemangiosarcoma) will be seen.
Thoracentesis is both a diagnostic and therapeutic procedure. For a diagnostic procedure, a small sample of fluid is withdrawn from the thoracic cavity and the fluid submitted for microscopic analysis. The bloody fluid withdrawn should not clot, since blood in the pleural space rapidly becomes defibrinated (loses it's ability to form a clot). When a hemorrhagic (bloody) fluid is obtained that does clot, it usually means that a blood vessel was inadvertently aspirated.
The fluid analysis will show mainly red blood cells with some white blood cells, in quantities similar to peripheral blood. The hematocrit (red blood cell count) should be similar to that of the peripheral blood.
The complete blood count (CBC) is an important test since it evaluates the red and white blood cell lines. When a hemothorax is suspected, a hematocrit is used to evaluate the degree of blood loss. The CBC also provides information on if the bleeding was acute or chronic. Red blood cell morphology (shape) changes may suggest that hemangiosarcoma or other malignancy is present.
The biochemical profile is a useful test to evaluate if any other organ systems are affected. Animals with traumatic injuries (and sometimes, neoplastic disease) will often have elevated liver enzymes. Kidney function is also evaluated.
Full clotting tests are especially important in young animals with no trauma history. If trauma and intrathoracic (within the chest cavity) tumors are ruled out, or if the bleeding is not stopping, a clotting panel is indicated.
Arterial blood gas measurements may be indicated in the more critical patients. This test helps determine the degree to which oxygen is getting to the tissues. Using the blood gas measurements, oxygen therapy can be instituted and the clinical progress of the most critical patients assessed. Blood gas measurements require specialized equipment and usually are only available at emergency or specialty hospitals.
Thoracic ultrasound (or echocardiogram) can be attempted once the patient is stabilized. This test is used to determine if there is an intrathoracic tumor present. It is the best diagnostic test for right atrial hemangiosarcoma. Sometimes a right atrial mass may not be visualized on thoracic ultrasound, and if it is still a high suspicion, an abdominal ultrasound may be considered. The abdominal ultrasound is used to look for masses (tumors) in the abdomen. If found, it suggests that a metastatic spread of the tumor (small enough that it is not visualized on thoracic ultrasound) is the cause of the hemothorax.
One or more of the diagnostic tests described above may be recommended by your veterinarian. In the meantime, treatment of the symptoms might be needed, especially if the problem is severe. The following nonspecific (symptomatic) treatments may be applicable to some, but not all pets with hemothorax. These treatments may reduce severity of symptoms or provide relief for your pet. However, nonspecific therapy is not a substitute for treatment of the underlying disease responsible for your pet's condition. If possible immediate veterinary care should be sought. A hemothorax may be a life threatening condition requiring immediate intervention. If your veterinarian makes this assessment, time is critical, and immediate thoracentesis may be life saving. Many times, thoracentesis is needed prior to any other diagnostics. Removing the fluid in the chest to improve respiration allows time for the continued diagnostic work up and continued treatment of the patient. Occasionally a chest tube may need to be placed.
A chest tube allows for a more rapid removal of blood from the thorax. The tube needs to be surgically placed and is bandaged around the animals chest. It usually requires sedation or anesthesia. Once in place, the tube can be intermittently suctioned or continuous suction devises may be used. Placing this tube is useful if there is continuous bleeding. Significant amount of chest trauma with additional injuries (pneumothorax), or chronic intermittent bleeding due to a thoracic tumor are instances when chest tube may be needed.
Intravenous fluids are given if there is significant or rapid blood loss. Intravenous fluids maintain blood pressure and improve tissue perfusion. In trauma cases animals are commonly in shock, and have multiple injuries. Fluid therapy is critical in these patients.
Blood transfusions may also be required if there is a significant amount of blood loss causing anemia. Blood loss may be only intrathoracic, or be present elsewhere in the body.
Finally, oxygen therapy may be needed in animals with a large amount of blood in the chest. It is especially useful early in treatment, before or during thoracentesis. Oxygen is administered via oxygen cage, mask or nasal oxygen canula.