Heart (Aortic) Blood Clot in Dogs

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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.

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