Pulmonic Stenosis in Dogs and Cats

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Pulmonic Stenosis in Dogs and Cats

Pulmonic stenosis is a congenital heart defect that is commonly diagnosed in dogs but is rare in cats. The condition is characterized by the narrowing of the pulmonary valve in the heart which severely affects the flow of blood from the heart to the lungs. Pulmonic stenosis (PS) is the third most common congenital heart disease in dogs. Keep reading to learn about the causes, symptoms, and treatment options for pets with pulmonic stenosis.

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Can pulmonic stenosis affect all dogs and cats?

Yes, the disease can affect any dog or cat regardless of age or gender. Pulmonic stenosis is often seen in English Bulldogs, terriers (West Highland White, Scottish, Wire-Haired Fox, Yorkshire), Miniature Schnauzers, Chihuahuas, Samoyeds, Beagles, Keeshonds, and Bullmastiffs. Pulmonic stenosis is occasionally seen in other breeds, including German Shepherds, Spaniels, and Retrievers.

However, in some cases of pulmonic stenosis, the condition is not inherited but acquired later in life. This is especially true in West Highland White Terriers, Labrador Retrievers, and Newfoundlands.

Causes of Pulmonic Stenosis in Dogs and Cats

The pulmonary valve connects the heart’s right ventricle to the pulmonary artery, the blood vessel that carries blood from the heart to the lungs. With a narrow pulmonic valve, the heart’s right ventricle must work doubly hard to propel blood from the heart to the lungs. This can lead to the build-up of pressure behind the narrow pulmonic valve, resulting in the accumulation of fluid in the abdomen or chest that can lead to congestive heart failure (CHF).

When the heart is overworked, abnormal heart sounds (heart murmur) and irregular heart rhythm (arrhythmia) can also be present.

Symptoms of Pulmonic Stenosis in Dogs and Cats

Most pets with pulmonic stenosis don’t exhibit any symptoms while they’re still young. The problem is usually discovered during a routine check-up when a heart murmur is detected. This finding will require further investigation to determine the underlying cause.

Dogs and cats with moderate or severe pulmonic stenosis may show the following symptoms which are indicative of congestive heart failure:

  • Respiratory issues - shortness of breath or difficulty breathing
  • Weakness
  • Poor tolerance to exercise or any form of physical activity
  • Collapse

The symptoms displayed by affected pets range from mild to severe. In some cases, it may not be obvious that something is wrong, or there is only a heart murmur that doesn’t have a significant effect on the animal. There are cases, however, in which the pulmonic valve’s narrowing may have serious consequences to the health and well-being of a dog or cat, such as congestive heart failure or sudden death.

How Pulmonic Stenosis is Diagnosed in Dogs and Cats

If a heart defect is suspected, your pet will undergo a complete physical exam. Specific diagnostic procedures, such as chest x-rays and echocardiograms, will also be performed.

An echocardiogram is a non-invasive ultrasound for the heart. It’s the only test that can diagnose the presence of pulmonic stenosis. During an echocardiogram, your vet will be able to see the activity of the heart in real-time, and how severe the defect is. It is also during an echocardiogram that other heart abnormalities may be detected.

Angiocardiography is a type of radiography where contrast (dye) is injected into the vasculature to see the stenosis. This is most often done at the time of treatment using balloon valvuloplasty.

Treatment for Pulmonic Stenosis in Dogs and Cats

The severity of the defect is a primary factor that will be considered when making a treatment protocol for pulmonic stenosis in dogs and cats.

In mild cases, pets generally live normally without requiring medical intervention.

Balloon Valvuloplasty

Moderate to severe defects, however, will require balloon valvuloplasty. It’s a minimally invasive procedure involving a catheter to guide a balloon through the stenosis (narrowed part of the valve) before inflating. Once it’s inflated, it causes the valve to stretch thereby improving blood flow from the heart to the lungs. This catheterization procedure lessens the workload on the right side of the heart, helps alleviate symptoms in many cases, and prolongs the lives of many pets diagnosed with the disorder.

If there’s existing congestive heart failure, your pet needs to be stabilized before balloon valvuloplasty can be performed.

Is balloon valvuloplasty indicated for all pets with pulmonic stenosis?

In Bulldogs and other brachycephalic (short-nosed) breeds, pulmonic stenosis can be a result of abnormal anatomy of the coronary arteries. Instead of originating from the aorta, the left coronary artery originates off the right coronary artery instead. Because of this anatomical defect, the left coronary artery has a different route to the left ventricle. This phenomenon is called the “R2A coronary anomaly”.

Patients with “R2A coronary anomaly” are not good candidates for balloon valvuloplasty because of the high risk of the left coronary artery being torn off during the procedure that may eventually lead to hemorrhage and death of the patient.

In cases of pulmonic stenosis in pets in which valvuloplasty is not possible or the procedure was not successful, medications may be prescribed by your vet to reduce symptoms.

Potential Complications in Dogs and Cats with Pulmonic Stenosis

There are potentially serious complications that can develop in dogs and cats with severe pulmonic stenosis. These include the following:

Diastolic dysfunction - This is caused by the hypertrophy of the right ventricle. The walls of the overworked right ventricle will become stiff, which can lead to impairment of the blood filling of the heart chambers. When this happens, it can increase a pet’s risk of developing right-sided congestive heart failure (CHF). This is especially true when a severe form of PS is present.

Ascites - The condition is characterized by the accumulation of fluid in the abdominal cavity and sometimes within the chest cavity.

Cardiac arrhythmia - Also known as the irregular beating of the heart, arrhythmias can occur in patients with severe disease as a result of a thickened right ventricle.

Sudden death - Dogs and cats with pulmonic stenosis-associated ventricular arrhythmias may die suddenly.

Prognosis for Pets with Pulmonic Stenosis

The severity of the narrowing of the pulmonary valve is an important factor in the establishment of the prognosis. Dogs and cats with severe pulmonic stenosis generally have a guarded long-term prognosis because of the potential risks of serious complications.

After a balloon valvuloplasty, examination of the patient is usually done 3 months later and then annually. Monitoring frequency and intensity depend on the patient’s condition, the severity of the problem, treatment response, and status of any preexisting problems affecting other systems of the body.

Read more:

Dilated Cardiomyopathy in Dogs

Is diet important for my dog’s heart health?

Your Pet’s Heart: A Guide to Understanding Heart Health in Dogs and Cats

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Published: 12/6/2021

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