❤️ Vet Guide 2025: Pulmonic Stenosis in Dogs and Cats – Causes, Symptoms & Treatment Options 🐶🐱

By Dr Duncan Houston, BVSc

🫀 What Is Pulmonic Stenosis?

Pulmonic stenosis (PS) is a congenital condition where the pulmonary valve—which controls blood flow from the heart to the lungs—is too narrow or stiff, restricting proper blood flow. The heart must work harder to push blood through the narrowed valve, leading to right-sided heart muscle thickening and potential complications.

📊 How Common Is It?

Pulmonic stenosis is the third most common congenital heart disease in dogs. It occasionally occurs in cats but is far more common in certain dog breeds.

🐾 Breeds Prone to PS:

• Labrador Retrievers
• Terriers
• Miniature Schnauzers
• Samoyeds
• Bulldogs
• Boxers
• Beagles
• Basset Hounds
• Cocker Spaniels
• Mastiffs

🩺 Understanding the Heart's Role

The heart has two sides:

• ❤️ Left side: Pumps oxygen-rich blood to the body
• 💙 Right side: Pumps oxygen-poor blood to the lungs

In PS, blood leaving the right ventricle struggles to pass through the malformed pulmonary valve. This causes the right side of the heart to work harder, potentially leading to muscle thickening, heart rhythm disturbances, and heart failure if untreated.

🔍 Types of Pulmonic Stenosis

• 🌀 Valvular – Narrowing at the valve (most common)
• 🪟 Subvalvular – Narrowing just below the valve
• 🌊 Supravalvular – Narrowing just above the valve

⚠️ Symptoms of Pulmonic Stenosis

Many cases are mild and go unnoticed, but severe cases may show:

• 🐾 Fatigue or exercise intolerance
• 😵 Fainting spells
• 💧 Fluid accumulation in the abdomen
• 💙 Cyanotic gums (especially during exertion)

📊 About 30% of dogs with severe PS may experience sudden death without treatment.

🧪 Diagnosing Pulmonic Stenosis

Vets often detect a heart murmur during early exams. If PS is suspected, the following tests are used:

• 🩻 Chest X-rays – show heart enlargement or post-stenotic dilation
• 🫀 Echocardiogram – visualizes valve structure and measures heart muscle thickness
• 📈 Continuous-wave Doppler – calculates pressure gradient across the valve

Pressure gradient severity guide:

• <40 mmHg – Mild, usually no treatment needed
• 40–80 mmHg – Moderate, individual decisions needed
• >80 mmHg – Severe, needs treatment

🎈 Balloon Valvuloplasty: First-Line Treatment

This minimally invasive procedure involves inserting a balloon catheter into the narrowed valve and inflating it to widen the passage. It’s highly effective in appropriate cases and:

• ⬇️ Reduces pressure gradient by 53%
• 💪 Improves quality of life
• 🛡️ Lowers risk of sudden death

Not all dogs are candidates. If there's a coronary artery anomaly (R2A) or complex valve deformity, balloon valvuloplasty may be contraindicated due to risk of artery rupture.

⚠️ Valvuloplasty Risks

• 💥 Heart arrhythmias
• 🧱 Valve rupture or "suicide right ventricle" (a rare complication from stiff heart muscle)
• 🩺 Heart puncture (rare)

Most pets go home the same day, and medication is continued for 3–6 months to support healing.

🔧 Surgical Options

If the stenosis is subvalvular, surgery may be more effective. Techniques vary and include valve widening or bypass. These surgeries carry higher risks and are reserved for specialized cases.

💊 Medication Management

Medication isn’t curative but may help control signs of right-sided heart failure or heart arrhythmias. Beta blockers may help reduce heart muscle strain and slow heart rate.

🧬 Common Complications

R2A Anomaly (Coronary Artery Compression)

In breeds like bulldogs and boxers, the coronary artery may wrap around the pulmonary artery. Attempting balloon valvuloplasty in these dogs risks fatal tearing of the artery.

Tricuspid Valve Dysplasia

If the tricuspid valve leaks while the pulmonary valve is too tight, the heart struggles to pump forward and backward simultaneously—rapidly leading to right heart failure.

Patent Foramen Ovale

A persistent opening between the heart chambers allows unoxygenated blood to bypass the lungs. Though often mild, it can contribute to oxygen deficiency and fatigue.

📈 Prognosis

Pets with mild PS live normal lives. Those with severe cases require careful monitoring and treatment. With successful valvuloplasty or surgical correction, prognosis significantly improves.

🩺 Final Thoughts from Dr Duncan Houston

Pulmonic stenosis, though common in certain breeds, is highly manageable with early diagnosis. Don’t dismiss fainting or fatigue as simple aging—these can be signs of hidden heart disease.

Advanced imaging and referral to a veterinary cardiologist can make all the difference in quality and length of life. 🎯

📲 Concerned About a Heart Murmur? Ask A Vet Today!

If your dog has a known murmur, fainting episodes, or breed predisposition to PS, get expert guidance from the Ask A Vet app. Chat 24/7 with professionals like Dr Duncan Houston for support with diagnostics, treatment options, and specialist referrals. 🐶❤️🩺