Aortic stenosis is a heart problem that dogs are born with. It refers to a narrowing in the major artery leaving the heart known as the aorta.
The narrowed artery limits blood flow out of the heart, which puts back pressure on this organ and can cause heart failure over time.
Some dog breeds carry a higher risk than others of having aortic stenosis including:
This condition can be serious enough to cause sudden death, especially in dogs younger than 4. Those who live beyond this age are likely to develop congestive heart failure later. Even puppies born with aortic stenosis may not have a heart murmur at birth but develop one up to 1 year later.
An aortic stenosis limits blood flow from the heart to the rest of the body. The symptoms depend on how narrow the restriction is and how well the heart is coping.
Younger dogs tend to show signs such as lack of energy, tiredness and fainting. This is because the heart cannot push enough blood around the body to keep muscles supplied. At times of extra demand, such as running or play, the pet faints from a lack of oxygen.
Part of the heart’s coping mechanism is to push harder. This works well in the short term, but at a price. Over the years, as a result of constant overexertion, the heart wall thickens. Thick heart muscle lacks a good blood supply, and not enough oxygen results in an irregular heartbeat.
The heart gets more and more tired — and eventually signs of congestive heart failure set in such as a cough, heavy breathing and a lack of energy.
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Dogs with aortic stenosis are born that way, although many do not show signs until later in life.
The aorta exits the left ventricle of the heart and is the main artery through which blood flows to the rest of the body. The word “stenosis” refers to a narrowing in the artery where it joins the heart. This means the heart must push harder to overcome resistance formed by the narrowing.
The bigger the demand for oxygen, such as when the dog exercises, the harder the heart works.
Sometimes the heart just can’t match supply and demand, and lack of oxygen to the brain results in fainting.
Over the years, the heart’s coping mechanism of pumping harder backfires. This is because the heart muscle thickens, which causes new problems that can lead to an irregular heartbeat and congestive heart failure.
The first step is for the veterinarian to listen carefully to the heart sounds. The presence of a murmur in a certain location (near the left heart base), with a characteristic crescendo-decrescendo sound, will raise her suspicions.
An ultrasound scan of the heart allows a skilled ultrasonographer to actually see the narrowing where the aorta leaves the heart and the typical “post-stenotic” bulge farther downstream. In dogs who have lived with the problem for a while, the scan can also assess if the heart wall has thickened.
Radiographs and ECGs also give information about changes in the anatomy of the heart pointing toward an aortic stenosis, but the heart scan gives the most information and is the diagnostic tool of choice.
In a young pup who is otherwise healthy, specialists can perform a procedure called a balloon dilation. A fine catheter is passed into the area of the narrowing, and a balloon-like cuff is pumped up to stretch the wall. It should be noted that this procedure carries risks.
More common treatment consists of using medications to control things like heart rate to maximize the heart’s ability to pump and medical management of heart failure when it develops.
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In an ideal world, only dogs proven to be free of aortic stenosis should be bred from.
- “Congenital heart disease.” Bonagura & Darke. Textbook of Internal Veterinary Medicine. 4th edition. Ettinger. Publisher: WB Saunders.
- “CVT — Update: Canine subvalvular aortic stenosis.” Lehmkuhl & Bonagura. Current Veterinary Therapy XIIVV. Publisher: WB Saunders.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 15, 2015.