Hemothorax: Bleeding in the Chest in Cats
Dr. Douglas Brum
Thoracic X-rays are an excellent way of evaluating fluid in the chest cavity. Although chest X-rays provide evidence of fluid within the chest, they do not differentiate the type of fluid. Chest X-rays also identify traumatic injuries, such as rib fractures or concomitant pneumothorax (air in the pleural space). Lung masses are often easily visualized on X-ray.
The order of diagnostic tests depends on the clinical condition of the cat. In an emergency situation, the cat should be stabilized prior to any significant diagnostic procedures. A rapid but thorough veterinary evaluation is critical to prioritizing appropriate diagnostic procedures.
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 For a diagnostic procedure, a small sample of fluid is withdrawn from the thoracic cavity and the fluid is submitted for microscopic analysis. The bloody fluid withdrawn should not clot, since blood in the pleural space rapidly loses its ability to clot. When a hemorrhagic (bloody) fluid is obtained that does clot, it usually means that the blood was inadvertently collected from a thoracic blood vessel.
Fluid analysis shows mainly red blood cells with some white blood cells, in quantities similar to those found in peripheral blood. The hematocrit (red blood cell count) should be similar to that of the peripheral blood.
A complete blood count (CBC) is an important test since it evaluates the type and numbers of red and white blood cells. When hemothorax is suspected, the hematocrit is used to evaluate the extent of blood loss. A CBC also provides information on whether the blood loss is acute or chronic. Red blood cell morphology (shape) changes may suggest hemangiosarcoma, or some other malignancy.
A biochemical profile is a useful test to evaluate whether any other organ systems are affected. Animals with traumatic injuries (and sometimes cancer) will often have elevated liver enzymes. Kidney function is also evaluated by this test.
Full blood clotting tests are especially important in young animals with no history of trauma. If trauma and tumors of the chest cavity are ruled out, or if the bleeding does not stop within a reasonable time, a clotting panel is indicated.
Arterial blood gas measurements are indicated in the more critical patients. This test quantifies the level of oxygen and carbon dioxide in the blood. Using blood gas measurements, oxygen therapy can be instituted and clinical progress can be assessed. Blood gas measurements require specialized equipment and are usually only available in emergency clinics or specialty hospitals.
Thoracic ultrasound (or echocardiogram) can be attempted once the patient has been stabilized. This test is used to determine if there is a tumor present within the chest cavity. It is the best diagnostic test for right atrial hemangiosarcoma. Sometimes a right atrial mass may not be visualized on thoracic ultrasound, but if it still suspected, an abdominal ultrasound may help. Abdominal ultrasound is used to look for masses (tumors) within the abdomen. If found, an abdominal mass, in the presence of hemothorax, suggests metastatic spread of the tumor to the thorax.
Your veterinarian may recommend one or more of the diagnostic tests described above. In the meantime, treatment of the patient is required, especially if the problem is severe. The following nonspecific (symptomatic) treatments may be applicable to some, but not all, cats with hemothorax. These treatments may reduce severity of symptoms and provide relief for your pet. However, nonspecific therapy is not a substitute for treatment of the underlying disease entity responsible for your cat's condition.
A hemothorax is often 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 required prior to other diagnostic tests. Removing fluid from within the chest improves respiration and allows more time for continued diagnostic work-up and further treatment of the patient. Occasionally, a chest tube has to be secured in place.
A chest tube allows rapid and continual removal of blood from the thorax. The tube must be surgically placed and secured to the cat's chest. Insertion of a chest tube usually requires sedation or anesthesia. Once in place, the tube can be intermittently suctioned or attached to a continuous suction device. Placing a chest tube is useful when there is continuous bleeding. Significant chest trauma, with additional injuries (pneumothorax), and chronic intermittent bleeding due to a thoracic tumor, are examples of when a chest tube may be needed.
Intravenous fluids should be given to combat shock if there is significant or rapid blood loss. Intravenous fluids maintain blood pressure and improve tissue perfusion. In trauma cases, cats may be in shock and may have multiple injuries. Fluid therapy is critical in these patients.
Blood transfusions may be required if there has been significant blood loss, causing anemia. Blood loss may occur only in the chest or may occur at other locations, too.
Finally, oxygen therapy may be needed in cats with a large amount of blood in the chest. Oxygen therapy is especially useful early in treatment, before or during thoracentesis. Oxygen can be administered via oxygen cage, facemask, or nasal canula.