Heart (Aortic) Blood Clot in Cats

By PetMD Editorial on Apr. 15, 2010

Aortic Thromboembolism in Cats

Aortic thromboembolismis 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. Therefore, complications arising in the aorta can be very serious.

Aortic thromboembolism, also referred to as saddle thrombus, is more common in cats in comparison to dogs, and it is believe to be hereditary in nature. And although mixed breed cats are most commonly affected with this condition, the Abyssinian, Birman, and ragdoll are all known to also suffer from aortic thromboembolism. In addition, male cats are twice as likely to suffer from this heart condition than females.

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


In addition to various forms of cardiomyopathy (i.e., dilated, hypertrophic, restrictive, etc.), infections of the bloodstream (e.g., septicemia) are common causes for aortic thromboembolism.


You will need to give the veterinarian a thorough history of your cat’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 cats with aortic thromboembolism due to muscle and liver damage.

Cats 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 cats, 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 cats 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. Cats 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. Cats 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 cats 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.

Cats 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 cats find it difficult to urinate due to problems with their posture. You may need to gently press your cat's bladder to assist in urination. In addition, most affected cats 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 cat 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 cat does not respond to treatment, your veterinarian may recommend euthanizing the animal due to the severe complications.

Image: Timolina via Shutterstock

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