Hemothorax (Blood in the Chest) in Dogs and Cats: Symptoms, Treatment, and Prevention

1 Symptoms

Hemothorax is blood retained in the chest cavity from bleeding of the parietal pleura, chest organs, or diaphragm — also called blood in the chest. It most often follows trauma: rib fractures, penetrating chest wounds, lung angiosarcoma, lung contusion, vessel rupture during chest surgery, or bleeding from a diaphragmatic hernia involving the lung or diaphragm; splenic or liver rupture with a diaphragmatic hernia also contributes. Bleeding disorders, coumarin (rodenticide) poisoning, depressed bone-marrow function, and heartworm damage to the aorta and pulmonary arteries are other important causes.

Signs are obvious abdominal breathing, shallow and labored; severe bleeding causes hemorrhagic shock — sudden collapse, cool limbs, thin weak pulse, pale mucous membranes, dullness. Auscultation shows weak alveolar sounds and a fast weak heartbeat; the alveolar listening area shifts toward the back, and percussion gives a horizontal dull line. Fluid drawn is blood that clots and matches peripheral blood.

2 Causes and Transmission

Causes are chest trauma (rib fractures, penetrating wounds), surgical bleeding, tumors, diaphragmatic hernia, bleeding or clotting disorders, rodenticide poisoning, and heartworm disease. It is not contagious, but the underlying toxin or bleeding disorder must be corrected.

3 Diagnosis

Diagnosis is based on trauma or bleeding history, shock signs, and a horizontal dull chest; radiographs or ultrasound show chest blood. Fluid drawn by thoracocentesis is confirmed as blood. Your veterinarian will test clotting times and look for rodenticide, heartworm, or tumors.

4 Treatment

Treatment counteracts shock, stops bleeding, restores circulation, and prevents infection. This is an emergency requiring hospitalization.

The chest is drained to remove the blood, then antibiotics are instilled. Surgery ties off bleeding vessels in heavy bleeders. Corticosteroids, blood-pressure support drugs, and transfusion, fluid, and oxygen therapy stabilize the patient. Hemostatic medication and vitamin K (for rodenticide) address the clotting problem.

5 Prevention

Prevent chest trauma and keep pets away from rat poisons. Maintain heartworm prevention, and manage bleeding or clotting disorders. Any chest injury with collapse or pale gums is an emergency needing immediate care.