Pulmonic Stenosis (PS) in Dogs

11 Apr Pulmonic Stenosis (PS) in Dogs

If your dog has been diagnosed with a heart murmur or is showing signs like fatigue, fainting, or trouble during exercise, pulmonic stenosis could be the underlying cause. This congenital heart condition is one of the most common in dogs—and while it can be mild and manageable, it can also be serious or even life-threatening if left untreated. 

Understanding what pulmonic stenosis is, how it affects the heart, and what treatment options are available can help you make informed decisions for your pup’s health. In this guide, we’ll break down everything you need to know about pulmonic stenosis—from how it develops to what breeds are most at risk and how veterinarians diagnose and treat it.

What is Pulmonic Stenosis?

Pulmonic stenosis (PS) is one of the three most common congenital heart defects in dogs. It occurs when the pulmonic valve or right ventricular outflow tract (RVOT) is abnormally narrowed, obstructing blood flow from the right ventricle to the lungs.

The severity of PS can range from mild and incidental to severe and life-threatening, and it can sometimes be complicated by concurrent congenital heart defects.

Understanding the Right Ventricular Outflow Tract (RVOT)

The RVOT includes:

• The right ventricle’s exit
• The pulmonic valve (which normally ensures one-way blood flow to the lungs)
• The main pulmonary artery

Types of Pulmonic Stenosis

Pulmonic stenosis can occur at different locations within the RVOT:

• Valvular Pulmonic Stenosis (Most Common Type) – The pulmonic valve is thickened, malformed, or has fused cusps, restricting blood flow.
• Subvalvular (Infundibular) Stenosis – The narrowing occurs just below the pulmonic valve within the right ventricle.
• Supravalvular Stenosis – The narrowing occurs just beyond the pulmonic valve in the pulmonary artery.

How PS Affects the Heart

When blood flow is restricted at the pulmonic valve:

• The right ventricle must contract harder to push blood through the narrowed area.
• The right ventricular muscle thickens (hypertrophy) due to the increased workload.
• A post-stenotic dilation (bulging of the pulmonary artery) develops beyond the stenosis, caused by high-pressure blood flow.
• Abnormal heart rhythms (arrhythmias) may develop due to electrical disturbances in the thickened heart muscle.

Breeds at Higher Risk for PS

Pulmonic stenosis is hereditary and most common in certain breeds, including:

Bulldogs (English and French)

Boxers

Labrador Retrievers

Terriers (West Highland White, Jack Russell, etc.)

Miniature Schnauzers

Samoyeds

Beagles

Cocker Spaniels

Basset Hounds

Mastiffs

Chow Chows

Some breeds, particularly Bulldogs and Boxers, can have an R2A coronary artery anomaly, which complicates treatment (explained later).

Clinical Signs of Pulmonic Stenosis

The severity of PS dictates the clinical signs:

• Mild PS – No symptoms; dogs may live normal lives without intervention.
• Moderate PS – May cause mild exercise intolerance or fatigue.
• Severe PS – Can lead to serious complications, including:
  • Fainting (syncope), especially during exercise (due to inadequate blood flow to the lungs and brain).
  • Abdominal fluid accumulation (ascites) from right-sided heart failure.
  • Cyanosis (blue-tinged gums), particularly with exertion (a sign of oxygen deficiency).
  • Sudden death (in cases of extreme obstruction or lethal arrhythmias).
  • Approximately 35% of dogs with severe PS develop clinical signs.

Diagnosing Pulmonic Stenosis

• Auscultation (Listening to the Heart) – Identifies a murmur caused by turbulent blood flow.
• Chest X-rays – May show right heart enlargement and post-stenotic pulmonary artery dilation.
• Echocardiography with Doppler Studies (Gold Standard) – Confirms the diagnosis and measures severity based on the pressure gradient across the pulmonic valve:
  • Mild PS → Pressure gradient < 50 mmHg – often no treatment needed.
  • Moderate PS → Pressure gradient 50-80 mmHg – treatment considered in symptomatic cases.
  • Severe PS → Pressure gradient > 80 mmHg – requires intervention to prevent heart failure and sudden death.

Treatment Options for Pulmonic Stenosis

1. Balloon Valvuloplasty (Minimally Invasive Procedure)

• Procedure: A catheter with an inflatable balloon is inserted into the pulmonic valve and inflated to break open fused or thickened valve leaflets.
• Ideal for: Dogs with valvular PS and pressure gradients > 80 mmHg.
• Effectiveness: Reduces obstruction and improves blood flow, heart function, and lifespan.
• Limitations:
  • May not fully correct the condition, requiring follow-up treatments.
  • Not effective for dogs with R2A coronary artery anomaly.

2. Beta Blockers (Medication Therapy)

• How they help: Relax heart muscle, lower heart rate, and reduce arrhythmia risk.
• Best for: Mild or inoperable cases.
• Limitations: Does not fix the stenosis, only manages symptoms.

3. Surgery (For Select Cases)

• Procedure: Open-heart surgery to bypass or reconstruct the pulmonary valve.
• High-risk and rarely performed due to its complexity.
• Best for: Supravalvular or subvalvular stenosis that is not amenable to balloon valvuloplasty.

Special Considerations in PS

R2A Coronary Artery Anomaly (Seen in Bulldogs and Boxers)

Some dogs with pulmonic stenosis have a coronary artery that wraps around the pulmonary artery, compressing it externally. This is called an R2A anomaly, and it is very dangerous because:

• Balloon valvuloplasty is NOT recommended – The balloon can rupture the coronary artery, leading to fatal hemorrhage.
• No definitive treatment exists – Prognosis depends on severity.

Pulmonic Stenosis + Tricuspid Valve Dysplasia (A Deadly Combination)

In some dogs, tricuspid valve dysplasia (TVD) occurs alongside PS, making the condition significantly worse.

• The tricuspid valve becomes leaky, allowing blood to flow backward into the right atrium.
• The right ventricle enlarges dramatically to compensate for both conditions.
• Right-sided heart failure develops quickly, with fluid accumulation in the abdomen (ascites).
• For these cases, valvuloplasty is still beneficial, as reducing the pulmonic stenosis decreases right heart strain.

Prognosis After Treatment

• Mild PS – Normal lifespan, no intervention required.
• Moderate PS – Good prognosis with monitoring or beta-blockers.
• Severe PS with balloon valvuloplasty – Significant symptom relief, but some may still develop heart failure over time.
• R2A anomaly or untreated severe PS – Poor prognosis, with high risk of sudden death.

Key Takeaways

• Pulmonic stenosis is a common congenital heart defect in dogs, most often affecting the pulmonic valve.
• Balloon valvuloplasty is the best treatment for severe PS (>80 mmHg), but some dogs are not candidates.
• Certain breeds, like Bulldogs and Boxers, may have a dangerous R2A anomaly that makes treatment riskier.
• Tricuspid valve dysplasia alongside PS worsens prognosis but may still benefit from intervention.
• With early diagnosis and appropriate treatment, many dogs with PS can live longer, healthier lives.

Pulmonic Stenosis Treatment in Nevada

Pulmonic stenosis may sound intimidating, but with the right knowledge and veterinary care, many dogs diagnosed with this condition can enjoy long, active lives. Whether your pup has a mild form that requires monitoring or a more severe case that calls for intervention, early detection and proper treatment can make all the difference. 

Be sure to stay informed about your dog’s specific needs—especially if they belong to a breed that’s prone to this heart defect. And remember, even in complex cases involving coronary anomalies or valve dysplasia, there are often ways to reduce symptoms and improve quality of life. Contact us at Animal Cardiology Specialists of Nevada today to schedule an appointment. Your dog’s heart deserves just as much attention as their wagging tail!

 

Images used under creative commons license – commercial use (04/11/2025) Photo by Amber Turner on Unsplash