Also known as: Pulmonary Stenosis, Congenital Pulmonic Stenosis, Pulmonary Valve Stenosis, Pulmonic Valvular Stenosis
In short
Pulmonic stenosis is a common congenital heart defect in dogs where a malformed or narrowed pulmonary valve forces the right side of the heart to work dangerously hard, potentially leading to heart failure if left untreated.
TL;DR. Pulmonic stenosis is a congenital heart defect where a narrowed pulmonary valve forces the right side of the heart to work dangerously hard, potentially leading to heart failure if left untreated.
Pulmonic stenosis involves a narrowing of the valve that connects the right ventricle to the lungs.
Pulmonic stenosis is a congenital heart defect—meaning it is present at birth—characterized by a narrowing or obstruction of the right ventricular outflow tract. In a healthy canine heart, the right ventricle is responsible for pumping oxygen-depleted blood through the pulmonic valve into the pulmonary artery, which carries it to the lungs to receive oxygen. When this valve or the area surrounding it is abnormally narrow, the heart must work significantly harder to pump blood through the restricted opening.
This restriction creates a severe pressure overload within the right ventricle. To cope with this chronic strain, the muscle walls of the right ventricle thicken in a process called concentric hypertrophy. While this thickening is an adaptive response to help the heart pump against high resistance, it eventually backfires. The thickened muscle becomes stiff, inefficient, and prone to oxygen deprivation (myocardial ischemia), which can ultimately lead to right-sided congestive heart failure or dangerous heart rhythms.
Veterinary cardiologists classify pulmonic stenosis based on where the narrowing occurs. The most common form is valvular, occurring directly at the valve leaflets. However, the obstruction can also occur below the valve (subvalvular) or above the valve (supravalvular). In many cases, the severe thickening of the heart muscle below the valve creates a secondary, dynamic obstruction known as infundibular stenosis, which further restricts blood flow during each heartbeat.
Pulmonic stenosis is an inherited genetic defect in dogs. The abnormal development of the valve occurs during embryonic growth in the womb. While the exact genetic mutations responsible are still being researched, the hereditary nature of the disease is well-established in veterinary medicine.
Several breeds are highly predisposed to developing pulmonic stenosis, including:
In most breeds, the condition affects male and female dogs equally. However, a notable exception exists in English Bulldogs, where the incidence of pulmonic stenosis is significantly higher in males than in females.
Many dogs with mild to moderate pulmonic stenosis are completely asymptomatic, and the condition is only discovered during a routine physical examination. However, as the severity of the narrowing increases, clinical signs become more apparent and severe.
Exercise intolerance and labored breathing are common signs of moderate to severe pulmonic stenosis.
Diagnosing pulmonic stenosis begins with a thorough physical examination. Your vet will use a stethoscope to listen to your dog's heart. Detecting a harsh systolic murmur at the left base of the heart is the primary indicator that further cardiac testing is required.
To confirm the diagnosis and assess the severity of the disease, your vet will recommend several diagnostic tests:
"In the presence of PS, the inflow tract... and the outflow tract walls are thickened and may be hypokinetic."
"Measuring gradients under anesthesia gives pressure readings that are usually much lower than actually exist."
Echocardiography with color Doppler is the gold standard for diagnosing and grading pulmonic stenosis.
Treatment plans for pulmonic stenosis are tailored to the severity of the obstruction and the presence of clinical signs. Mild cases typically require no treatment other than routine monitoring. Moderate to severe cases require active intervention.
While there are no medications that can physically open a narrowed valve, your vet may prescribe drugs to support heart function. Beta-blockers are commonly used to reduce the heart rate, lessen the workload on the right ventricle, and minimize the risk of arrhythmias. If your dog has progressed to right-sided congestive heart failure, diuretics and other cardiac medications will be prescribed to manage fluid retention (ascites) and improve quality of life.
For dogs with severe valvular pulmonic stenosis, balloon valvuloplasty is the treatment of choice. This minimally invasive procedure is performed under general anesthesia. A specialized catheter with an inflatable balloon at its tip is threaded through a vein (usually in the neck or groin) and guided into the narrowed pulmonary valve. Once positioned, the balloon is inflated to stretch or tear the fused valve leaflets, thereby widening the opening and reducing the workload on the heart.
According to a leading veterinary internal medicine reference:
"Pulmonary valves with mild to moderate thickening and simple fusion of the leaflets are likely to be easier to effectively dilate. Dysplastic valves can be more difficult to dilate effectively, but good results are possible in some cases."
The same reference notes that a retrospective study found balloon valvuloplasty successfully reduced post-procedure pressure gradients to 50 mm Hg or less in 58% of treated dogs, representing a significant improvement in heart function.
The long-term outlook for dogs with pulmonic stenosis is highly variable and depends almost entirely on the severity of the narrowing and how early it is diagnosed.
Because pulmonic stenosis is a congenital, genetic defect, it cannot be prevented through lifestyle changes, diet, or exercise. The only effective means of prevention is responsible breeding.
Dogs diagnosed with any degree of pulmonic stenosis—even mild, asymptomatic cases—should be spayed or neutered and never used for breeding. For highly predisposed breeds, screening potential breeding pairs with an echocardiogram can help identify asymptomatic carriers of cardiac defects, preventing the transmission of these genetic anomalies to future generations.
If your dog has been diagnosed with pulmonic stenosis or a heart murmur, you should monitor them closely at home. Contact your veterinarian immediately if you notice any of the following warning signs:
These symptoms are medical emergencies indicating that the heart is struggling to meet the body's demands or that congestive heart failure is developing.
English Bulldogs require special clinical consideration. In this breed, pulmonic stenosis is more common in males. Additionally, English Bulldogs frequently present with a unique anatomical complication: an anomalous left coronary artery. As noted in surgical texts:
"In English bulldogs an anomalous left coronary artery may be seen crossing [the right ventricular outflow tract]."
If this anomalous artery is present, performing a balloon valvuloplasty can compress or rupture the coronary artery, which is fatal. Therefore, English Bulldogs must undergo thorough imaging (such as angiocardiography) prior to any balloon dilation procedure to ensure their coronary anatomy is safe for intervention.
Beagles have a well-documented, proven genetic basis for pulmonary valve dysplasia. Interestingly, despite this strong genetic link, epidemiological studies show they are not as frequently overrepresented in general clinic populations as other predisposed breeds. Nonetheless, breeding Beagles should be carefully screened.
Pulmonic stenosis is a common congenital heart defect in dogs where a malformed or narrowed pulmonary valve forces the right side of the heart to work dangerously hard, potentially leading to heart failure if left untreated.
Systolic ejection murmur、Dyspnea、Exertional fatigue、Normal to slightly diminished femoral pulses、Prominent right precordial impulse、Thrill high at the left base、asymptomatic、syncope
Echocardiography、Angiocardiography、Cardiac Catheterization、Color flow Doppler echocardiography、Electrocardiography (ECG)、Thoracic radiography
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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