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Aortic Thromboembolism in Dogs

What is aortic thromboembolism?

aortic-thromboembolism-in-dogsAortic thromboembolism is a devastating condition. The aorta is the main artery of the body and carries oxygenated blood from the heart out to the rest of the body. The word “thromboembolism” combines the words “thrombus” and “embolism.”  A thrombus is a blood clot that occurs inside a blood vessel, and the word embolism describes that the clot has traveled through a blood vessel to a location distant from where it formed.

An aortic thromboembolism results from a blood clot that is dislodged and travels within the aorta, becoming lodged in a distant location. This causes severely reduced blood flow to the tissues receiving blood from that particular part of the aorta, leading to decreased oxygen in the tissues.

 

How does this happen?

Aortic thromboembolism is a rare occurrence in dogs. Although it is not commonly thought of as an inherited disease, it can be associated with an inherited abnormality of the heart muscle.

Aortic thromboembolism can also be associated with other problems, such as: cancer; a body-wide generalized infection called “sepsis”; increased levels of the steroid hormones produced by the adrenal glands during Cushing’s Disease (also known as hyperadrenocorticism); and with increased protein-loss through diseased kidneys.

 

What are the signs of aortic thromboembolism?

Sudden paralysis and pain, usually in the rear legs, are the most common clinical signs of aortic thromboembolism, although weakness and lameness may be seen. If the rear limbs are affected, there may be decreased or absent pulses in the femoral arteries of the rear legs. Sometimes a front leg is involved. Rapid breathing or difficulty breathing may be seen. The dog may vocalize from pain, and may act anxious.  Occasionally the dog will vomit. The dog may also experience a lower-than-normal body temperature.  Sometimes the heart will sound abnormal (a murmur or irregular heartbeat) through a stethoscope.

 

Is there any treatment for dogs with aortic thromboembolism?

Initially, dogs may need to be treated as inpatients, because they may have serious co-existent disease like congestive heart failure (CHF) as well as considerable pain and distress. Supplemental oxygen therapy may be beneficial. Initially, affected legs should be handled minimally. As blood flow returns, physical therapy (passive extension and flexion of the legs) may speed full recovery. It is best to restrict activity as treatment starts.

Surgical removal of the aortic thromboembolism is typically not recommended as these are high-risk patients from their severe heart disease.

Aspirin is theoretically beneficial during and after an episode of aortic thromboembolism, but should be used only under the direct supervision of your veterinarian.  Aspirin prevents platelets – blood cells that assist with blood clotting – from activating to clump together to form a clot while flowing through the blood vessels.

Finally, the dog’s heart disease should be treated as is appropriate for the type and severity of the disease.

 

Is there any monitoring that should be done?  What is the expected outlook?

There is a high rate of recurrence with blood clot formation.

Blood work should be monitored in order to improve the management of heart disease. The legs may be evaluated to assess the clinical response to therapy. 

There may be permanent nervous system damage, or the hind leg muscles may be adversely affected. There may be sudden death, usually associated with irregular heartbeats secondary to increased levels of potassium in the blood.

The expected course of this disorder is days to weeks for full recovery of function to the legs, but the prognosis in general is very poor. Long-term prognosis varies between 2 months to several years with, the average being approximately a few months with treatment.

 

Robin Downing, DVM, DAAPM, DACVSMR, CVPP, CRPP
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