Heart (Aortic) Blood Clot in Dogs

By PetMD Editorial on Apr. 15, 2010

Aortic Thromboembolism in Dogs

Aortic thromboembolism, also referred to as saddle thrombus, is a common heart condition which results from a blood clot dislodging within the aorta, leading to the interruption of blood flow to tissues served by that segment of the aorta. The largest artery in the body, the aorta distributes oxygenated blood to many parts of the body, including the legs, kidneys, intestines, and brain. Therefore, complications arising in the aorta can be very serious.

Aortic thromboembolism is rare in dogs in comparison with cats.

Symptoms and Types

  • Vomiting
  • Paralysis
  • Pain (especially in the legs)
  • Abnormalities with gait and/or lameness
  • Difficult breathing (e.g., tachypnea)
  • Unusual barking or anxious temperament
  • Bluish or pale nail beds and food pads
  • Hypothermia


  • All forms of cardiomyopathy (i.e., dilated, hypertrophic, etc.)
  • Infection of the bloodstream (e.g., septicemia)
  • Hyperadrenocorticism (dogs)
  • Protein-losing nephropathy (dogs)
  • Sepsis (dogs)


You will need to give the veterinarian a thorough history of your dog’s health, including the onset and nature of the symptoms. He or she will then perform a complete physical examination, urinalysis, and biochemistry profile -- which may show abnormally high creatine kinase enzyme level due to muscle damage. Moreover, the levels of aspartate aminotransferase and alanine aminotransferase are typically found in dogs with aortic thromboembolism due to muscle and liver damage.

Dogs under stress may have abnormally high level of glucose in the blood. Mild increase in blood urea nitrogen and creatinine may also be present due to low cardiac output and possibly due to presence of blood clot in a kidney. In some dogs, electrolytes imbalances as well as low levels of calcium and sodium and high levels of phosphate and potassium may be present.

Chest X-rays, meanwhile, commonly show an abnormal enlargement of the heart and a collection of fluid within the lungs and in the pleural cavity. In rare cases, the X-rays may reveal a tumor in the lungs. Abdominal ultrasounds may help your veterinarian identify the exact location of the blood clot, and echocardiography will confirm an abnormal enlarging of the heart, which is a common cause for aortic thromboembolism.


Most dogs with this condition require immediate intensive care and hospitalization to prevent complete heart failure. Hospitalization is also necessary to minimize the stress and pain associated with this disease. Dogs with breathing problems require oxygen therapy to reduce the stress of rapid breathing and to allow achieving required levels of oxygen in the blood.

Thrombolytics medications, which are used to dissolve the blood, are essential for treatment. Dogs that do not respond to conventional treatment, however, will require surgery to remove the blood clot. Your veterinarian will also give pain killers to reduce the severe pain associated with this disease.

Living and Management

Unfortunately, the prognosis for most dogs with aortic thromboembolism is not good. Even with treatment, clots can again develop and block the aorta. If blood supply to the legs are not restored quickly, permanent muscular abnormalities may develop in the affected limb.

Dogs recovering from aortic thromboembolism should not be allowed to move and should be placed in a stress-free environment, away from other pets and active children. Severe pain is a common symptom associated with this disease and many dogs find it difficult to urinate due to problems with their posture. You may need to gently press your dog's bladder to assist in urination. In addition, most affected dogs find it difficult to eat and may require new foods to tempt the palate. This lack of appetite (anorexia) may lead to further complications. Seek your veterinarian's advice for dietary changes.

Lastly, closely monitor your dog and watch for bleeding, which may occur due to the type of medications frequently used in the treatment of this disease. If you observe any sort of bleeding, immediately call your veterinarian.

To monitor the progress of treatment, frequent checkups and laboratory tests will be required. If the dog does not respond to treatment, your veterinarian may recommend euthanizing the animal due to the severe complications.

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