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Heart (Aortic) Blood Clot in Dogs

Aortic Stenosis in Dogs

Aortic stenosis denotes the narrowing of the aortic valve, which regulates blood flow from the left ventricle (one of the dog’s four heart chambers) to the aortic ventricular outflow tract. This constriction places undue strain on the heart, prompting heart muscle cells to enlarge to sustain forward blood flow and resulting in thickening of the heart wall.

Aortic stenosis is congenital (present at birth) and is frequently observed in large breeds like the Newfoundland, German shepherd, golden retriever, rottweiler, and boxer. It stands as the second most prevalent congenital heart anomaly in dogs.

Symptoms and Types

There are three types of aortic stenosis: valvular (located at the valve), subvalvular (below the valve), or supravalvular (above the valve). The condition typically manifests within the first few weeks to months of life; however, symptoms can emerge at any age, depending on the severity of the obstruction. Some common symptoms include:

  • Congestive heart failure
  • Sudden loss of consciousness (syncope)
  • Difficulty breathing (dyspnea)
  • Rapid breathing (tachypnea)
  • Abnormal lung sounds


In most instances, dogs are born with this heart defect. Nonetheless, some dogs develop aortic obstruction due to bacterial endocarditis.


To diagnose aortic stenosis in your dog, it’s important to provide the veterinarian with a detailed history of your dog’s health, including when the symptoms began and their nature. The veterinarian will then conduct a thorough physical examination, which may reveal abnormal heart sounds (murmurs) indicating irregular heart valve function. However, murmurs are not always indicative of disease, particularly in young animals, as they can occur due to factors like pain, fever, or excitement. Your veterinarian will assess the findings alongside other symptoms to determine the significance of the murmur.

Additionally, the veterinarian may perform various laboratory tests such as a complete blood count, biochemistry profile, and urinalysis, although the results are typically within normal ranges. Chest X-rays may show an enlarged heart, particularly on the left side, while dogs with congestive heart failure may exhibit lung abnormalities.

For a more detailed assessment of the heart and related structures, echocardiography may be used, which can reveal thickening of the left ventricle wall and aortic valve. In some cases, echocardiography may also detect a dilated aorta resulting from stenosis, leading to abnormal blood flow.

To measure blood flow pressure more accurately, advanced tests like cardiac catheterization may be necessary. This procedure involves inserting a catheter into the dog’s heart chamber or vessel.


Treatment and management approaches for aortic stenosis are subject to debate and can vary among experts. Nevertheless, most agree that the goal of therapy is to address the complications associated with the defect. While open heart surgery, such as valvuloplasty to repair or replace the valve, is the only potential cure, it’s rarely pursued due to the unfavorable prognosis for dogs undergoing surgery.

Catheterization might be utilized to widen narrowed vessels, but the procedure doesn’t offer survival benefits for dogs with severe forms of the disease. Typically, dogs with aortic stenosis are prescribed broad-spectrum antibiotics to mitigate the increased risk of bacterial infections in the heart.

Living and Management

The primary objective for both you and the veterinarian is to alleviate the dog’s symptoms, prevent complications, and enhance its quality of life. Immediate restriction of activity is necessary to prevent complications, some of which can be fatal, resulting from overexertion. Dogs with congestive heart failure may benefit from low sodium diets.

Affected animals should not be bred and preferably neutered. It’s important to closely monitor your dog at home for any abnormal signs and promptly inform the veterinarian if they arise. Dogs with mild forms of aortic stenosis can live a relatively “normal” lifespan without treatment. However, those with severe forms of the defect typically have a poor prognosis, even with treatment. Regardless of the severity, many veterinarians advise against breeding animals with this heart defect.

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