Pulmonic Stenosis

What is Pulmonic Stenosis?
Pulmonic stenosis is a condition present at birth in which the outflow of blood from the heart is constricted. Normally, the right ventricle of the heart pumps blood through the pulmonic valve to the pulmonary artery and then to the lungs, where the blood receives oxygen before going back to the left side of the heart and then, the rest of the body. In dogs with pulmonic stenosis, the pulmonic valve (or the area just above or below it) is partially obstructed, forcing the heart to work harder to pump blood through the smaller opening. If the obstruction is small, it may go undetected, but if the obstruction is large, the heart may become overtaxed, and congestive heart failure may occur.

How does my dog get Pulmonic Stenosis?
Pulmonic stenosis is present at birth, although its effects are not usually noticeable until later. It is believed to be hereditary.

How do I know if my dog has Pulmonic Stenosis?
If your dog has a very mild case, you may never know it unless he has a cardiac examination. With greater degrees of obstruction, your dog may become easily tired with exercise, and as the disease progresses, may experience fainting, coughing, or abdominal enlargement. Your veterinarian will listen to his heart, which will usually have a murmur. However, heart murmurs can result from a number of other heart problems, so additional tests will be needed. An electrocardiogram can detect abnormal heart rhythms, which may again also be associated with other heart conditions. A radiograph of the heart may show that the right side of the heart is enlarged. The most definitive diagnosis is with Doppler echocardiography (a type of ultrasound), which can detect the narrowed area in the valve and measure the flow of blood. Your veterinarian will probably refer you to a veterinarian cardiologist for this test, which is done with your dog awake.

What can I do about Pulmonic Stenosis?
Unless your dog is already in respiratory distress, medications may be prescribed if your dog has signs of congestive heart failure or abnormal rhythm.   The veterinarian may also send you home with instructions to feed a low-sodium diet. This decreases blood pressure, in turn decreasing fluid back-up that causes congestion in the lungs. Avoid strenuous exercise, which also adds a burden to the heart.  In some cases, a veterinary specialist may perform balloon catheter dilation to open up the constricted area.

Is there anything I can do to prevent my dog from getting Pulmonic Stenosis?
Do not breed affected dogs, and when possible, choose a puppy from parents that have had a clear cardiac examination from a veterinary cardiologist. Even so, puppies with pulmonic stenosis can be born from clear parents. Pulmonic stenosis is one of the more common heart defects in dogs.

Are there certain breeds that get Pulmonic Stenosis more often?
Many breeds are affected, but Beagles, Chihuahuas, Cocker Spaniels, Miniature Schnauzers, Samoyeds,  Mastiffs and Bulldogs appear to be overrepresented.