Blood in the Chest in Dogs

By PetMD Editorial on Aug. 31, 2009

Hemothorax in Dogs

Hemothorax is a condition that may occur suddenly (acute) or over a long period of time (chronic), and it can occur for a variety of reasons. Hemothorax is the medical term used to identify a condition in which blood has collected in the chest cavity, or thorax. There does not appear to be a particular age, gender, or breed of dog that is more predisposed to this condition than another.

Symptoms and Types

Acute onset:

  • Symptoms of decreased blood volume usually occur before sufficient blood volume accumulates in the pleural space (lining of the chest cavity)
  • Impaired respiration/respiratory distress
  • Pale membranes
  • Weakness and collapse
  • Weak, rapid pulse
  • Breathing sounds become dull

Associated with a causative factor:


  • Trauma
  • Bleeding from any artery or vein of the thoracic wall or spine, damaged heart, lungs, thymus (a small glandular organ that is situated behind the top of the breastbone), and diaphragm
  • Rodenticide ingestion is a common cause
  • Herniated liver or spleen
  • Tumor
  • Coagulopathies (clotting disorders)
  • Clotting factor defects are more common than platelet abnormalities
  • May be congenital or acquired
  • Liver failure
  • Cholangiohepatitis (inflammation of the gallbladder and bile ducts) with concurrent small bowel disease
  • Lung lobe twisting
  • Acute thymic hemorrhage in young animals (i.e., thymus: gland at the base of the neck)


Your veterinarian will perform a complete physical exam on your dog, including a standard blood chemical profile, complete blood count, an electrolyte panel and a urinalysis so as to rule out other causes of disease. You will need to give a thorough history of your dog’s health, onset of symptoms, and possible incidents that might have preceded this condition. Clotting profiles should be performed on a blood sample to verify for delayed clotting times.

The packed cell volume, hemoglobin and platelet count will be lower than normal. The blood chemical profile may show signs of liver failure (which would cause bleeding into bodily cavities since clotting factors would not be produced).

The fluid in the chest should be sampled and analyzed at a laboratory for a comparison with peripheral blood. Platelets are often found in chest fluid samples.

X-rays are crucial for visualizing the extent of the fluid build-up in the chest, the collapse of lung lobes, and any masses that might be present in the chest cavity. An ultrasound of the chest can reveal a diseased condition with an even greater sensitivity than an x-ray image would.


Patients suffering from hemothorax should be treated on an inpatient basis. Your dog must receive fluid therapy to correct its blood loss into the chest cavity. If your dog also has air free (outside the lungs) in the chest cavity, this must be immediately corrected. If the lungs are bruised, ventilator support may be necessary. These patients often also need oxygen therapy, and will need to be kept warm to prevent shock. If your dog’s blood sample has a delayed clotting time, then a plasma or blood transfusion may be needed to restore clotting factors or to provide red blood cells for oxygen transport. Severe or recurrent thoracic hemorrhage may require surgical exploration.

Living and Management

While your dog is recovering from hemothorax, it is probably best to avoid giving it any aspirin or other over the counter medications that can lead to decreased blood clotting. Your veterinarian will schedule follow-up appointments as necessary to treat your dog’s underlying condition. If your dog shows signs of a recurrence of hemothorax, notify your veterinarian immediately; surgery may be necessary to correct recurring cases.

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