Hemothorax: Bleeding in the Chest in Cats

Overview of Hemothorax in Cats

Hemothorax is defined as blood within the chest cavity (thorax). The most common cause of hemothorax in cats is chest trauma, although tumors within the thorax can also result in a hemothorax if they rupture, slowly bleed, or invade into a blood vessel causing blood to accumulate within the thorax. Clotting disorders (coagulopathies) may also cause an animal to bleed into the chest cavity. Hemothorax is usually an emergency situation, requiring rapid diagnosis and treatment.

What to Watch For

• Difficulty breathing
• Increased panting
• Weakness
• Collapse
• Pale mucus membranes (the best place to check is the gums or inner lining of the lips)

Your cat may take short, shallow, rapid breaths. Look for any observable bruising under the skin or evidence of external trauma.

Diagnosis of Hemothorax in Cats

A thorough history and complete physical exam, emphasizing lung auscultation (listening with a stethoscope), is essential for prompt and accurate diagnosis. Your veterinarian may also recommend:

• Thoracic radiographs (X-rays)
• Thoracentesis – inserting a needle and syringe into the chest cavity through the skin to obtain a sample of fluid for analysis. Fluid analysis is performed on the aspirated fluid sample.
• Complete blood count (CBC)

Depending on the animal’s condition and initial test results, additional tests that may be required include:

• Biochemistry profile
• Arterial blood gas analysis
• Thoracic or cardiac ultrasound
• Clotting tests including an activated clotting time (ACT), a prothrombin time (PT), activated partial thromboplastin time (APTT), and platelet count.

Treatment of Hemothorax in Cats

The general approach to treatment varies depending on the clinical condition of the patient.

• Thoracentesis, while a diagnostic aid, is also an important treatment to remove fluid from the chest
• Chest tube placement and suctioning of chest fluid
• Intravenous fluid therapy
• Blood transfusion
• Oxygen therapy
• Analgesic medication (pain medication)
• Vitamin K therapy
• Emergency chest surgery (thoracotomy) is occasionally required if the bleeding cannot be stopped and if blood clotting tests are normal. This procedure is most commonly indicated when there are penetrating chest wounds or bleeding tumors.

Home Care

Hemothorax is usually an emergency situation. Veterinary care should be sought as soon as possible. Keep your cat calm and comfortable and minimize stress. Keep him warm, and, if a traumatic injury is suspected, be careful moving him, as fractures or spinal injury may be present.

In-Depth Information on Hemothorax in Cats

The space between the lungs and inner chest wall is called the pleural space. In health, this space is a potential space, with negative pressure holding the lungs in contact with the inner chest wall. As the chest expands, the lungs expand as well, and air flows in.

If the pleural space fills with blood, there is less room for the lungs to expand and fill with air. Breathing becomes labored, gas exchange is impaired, and less-well oxygenated blood is distributed to the body. As the volume of blood in the chest cavity increases, the ability of the cat to breathe properly decreases and rapid intervention is needed.

Rapid blood loss into the chest leads to a decrease in blood pressure and tissue perfusion. A state of hemorrhagic shock ensues. As blood loss continues, there is a fall in numbers of circulating red blood cells, causing anemia. If veterinary attention is not found quickly, rapid blood loss or respiratory failure may lead to the cat’s death. Situations in which blood is lost more slowly allows for more time for veterinary care to be sought.

Chronic (long standing) or intermittent blood loss creates a slowly insidious condition associated with more subtle clinical signs. When blood loss into the chest is slow, the body can reabsorb some of the blood. Thus, cats with chronic hemothorax may have only a small amount of blood present in the chest cavity. These cats may not present in an emergency situation, in shock and with breathing problems, but may nevertheless still have a serious underlying disease process. Recognizing the existence of hemothorax is critical in establishing an underlying cause and instituting the correct symptomatic treatment.

If a cat with hemothorax has normal clotting parameters, the bleeding into the chest will, often times, stop on its own. Blood clots stop the bleeding. Blood clots can, however, become dislodged, especially in the presence of increased movement or manipulations. If blood clots are dislodged, the bleeding may start again. In many cases of hemothorax caused by chest trauma, the bleeding will stop on its own.

Causes of Bleeding in the Chest in Cats

There are several main causes of a hemothorax – with trauma the leading factor. A lacerated blood vessel within the thorax or pleural lining may lead to rapid or slow bleeding, depending on the extent of the trauma and size of the affected vessel or vessels. Outdoor cats are at a significantly greater risk of acquiring hemothorax than indoor cats. In addition, young cats are more prone to injures that could lead to hemothorax. In young cats with a hemothorax and no history of trauma, a bleeding disorder (coagulopathy) should be suspected. Bleeding into the chest as a result of coagulopathy usually does not stop unless vitamin K or other appropriate therapy is administered. In older animals with a hemothorax and no history of trauma, a bleeding tumor within the chest cavity is often the reason for the condition. Bleeding tumors may cause a rapid or chronic/intermittent blood loss.

Specific causes of hemothorax in cats include:

• Trauma. The most common traumatic injury causing hemothorax occurs when a cat is hit an automobile. Severe chest trauma may cause death rapidly if there is extensive bleeding. Sometimes bleeding occurs more slowly and there is time to locate an emergency care facility. Fractured ribs may lacerate vessels leading to bleeding into the thorax (chest). Other causes of trauma include gunshot and knife wounds.
• Tumors. Tumors in the thorax may erode into blood vessels or rupture and cause bleeding. Tumors located on the inner surface of the chest wall, tumors of blood vessels within the chest, lungs, or heart, may rupture causing hemothorax.
• Coagulopathies. Rodenticide poisoning with products containing anticoagulants is a common cause of bleeding disorders in dogs, though this is less common in cats. Bleeding may occur exclusively into the chest or may involve other sites (e.g. under the skin). Products containing the following active ingredients may cause a hemothorax: warfarin, fumarin, chlorophacinone, diphacinone, pindone, bromadiolone, or brodaficoum.

Diagnosis In-depth

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.

• 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.
• 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.

Treatment In-depth

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.