Hemothorax: Bleeding in the Chest in Dogs

Overview of Hemothorax: Bleeding in the Chest in Dogs

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

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 dog may take short, shallow, rapid breaths. Look for any observable subcutaneous (under the skin) bruising or evidence of external trauma.

Diagnosis of Hemothorax in Dogs

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 definitive diagnosis. Fluid analysis is performed on the aspirated fluid sample.
• Complete blood count (CBC)

The above tests are generally the minimum required diagnostic tests needed to obtain a diagnosis. Depending on the animal’s condition, and initial test results, additional tests that may be required include:

• Biochemical profile
• Arterial blood gas analysis
• Thoracic or cardiac ultrasound
• Clotting tests including an activated clotting time (ACT), a prothombin time (PT), activated partial thromboplastin time (APTT), platelet count, and possible a von Willebrands (VWF) test

Treatment of Hemothorax in Dogs

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

• Thoracentesis, while a diagnostic aid, is also an important treatment as fluid in the chest is slowly removed
• Chest tube placement and period or constant suctioning of chest fluid
• Intravenous fluid therapy
• Blood transfusions
• Oxygen therapy
• Analgesic medication (pain medications)
• Vitamin K therapy
• Emergency thoracotomy (chest surgery) is occasionally required if the bleeding cannot be stopped and the clotting tests are normal. This is most commonly needed with penetrating chest wounds or bleeding tumors.

Home Care

A hemothorax is generally an emergency situation. Veterinary care should be given as soon as possible. Keep your pet calm and comfortable and minimize stress. Keep your pet warm, and if a traumatic injury is suspected, be careful moving your pet, as fractures may be present.

In-depth Information on Hemothorax

A hemothorax is a potentially life threatening situation. In a normal animal the space between the lungs and the inner chest wall is called the pleural space. This space is more of a potential space, since a vacuum is present and the lungs are always in close contact with the pleural (inner lining) surface of the chest. Thus, as the chest or diaphragm expand, the lungs expand passively as well. If the pleural space becomes filled with blood, there is less room for the lungs to expand and fill with air. Breathing becomes more labored, and less oxygenated blood is distributed to the body. As the volume of blood increases, the ability to breath decreases and rapid intervention is needed.

Rapid blood loss into the chest can also lead to a decrease in blood pressure and tissue perfusion. This may lead to shock. As continued blood is lost, a decrease in circulating red blood cells may lead to acute (sudden) anemia. If veterinary care is not immediately available, rapid blood loss may lead to death. A slower blood loss is more common and will allow for more time to seek veterinary care.

Chronic (long standing) or intermittent blood loss generally occurs more slowly, and more subtle clinical signs might be present. If the blood loss is slow, the body can reabsorb the free blood in the chest. Thus, animals may only have a small amount of blood present in the chest cavity. These animals may not present as an emergency with breathing problems, but they still may have a serious underling disease process. Making the diagnosis of a hemothorax is critical in establishing an underling cause.

If the animal has normal clotting parameters the bleeding into the chest will, many times, stop on it’s own. Blood clots form that stop the bleeding. Blood clots can, however, be dislodged especially with increased movement or manipulations. If blood clots are dislodged, the bleeding may start again. In many cases of hemothorax due to chest trauma, the bleeding will stop on it’s own.

Causes of Blood in the Chest in Dogs

There are several main causes of a hemothorax. Trauma is the most common cause. A lacerated blood vessel within the thorax or pleural lining may lead to rapid or slow bleeding depending on the amount of trauma and the size of the affected vessel or vessels. Outdoor animals are at significantly greater risk then indoor animals. Younger animals are more likely to be injured as well. In young animals with a hemothorax and no history of trauma, a coagulopathy (bleeding disorder) should be suspected. Bleeding into the chest usually does not stop on it’s own, 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 cause. Bleeding tumors may cause a rapid blood loss or be chronic, having intermittent smaller bleeding events. Specific causes of hemothorax include:

• Trauma. The most common traumatic injury causing a hemothorax occurs when a car has hit an animal. Severe chest trauma may cause a very rapid death if the bleeding is significant. Sometimes the bleeding occurs more slowly and there is time to seek emergency care. Fractured ribs may lacerate vessels leading to bleeding into the thorax (chest). Other cause of trauma include gun and knife wounds.
• Tumors. Tumors in the thorax may erode a blood vessel or rupture and cause an acute bleed. Tumors located on the pleural surface of the chest, blood vessels within the chest, lungs or heart may all cause a hemothorax. The most common tumor to cause a bleed is hemangiosarcoma (a malignant tumor of blood vessels). These tumors are commonly found on the right atrium of the heart. Golden retrievers and German shepherd dogs are two breeds at increased risk of getting this tumor.
• Coagulopathies. Rodenticide poisoning with products containing anticoagulants is a very common cause of bleeding disorders in animals. The bleeding may be exclusively in the chest, or may more commonly 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 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.

Treatment In-depth

One or more of the diagnostic tests described above may be recommended for your dog 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.