Pulmonic stenosis is the second-most common congenital heart defect in dogs, and it's caught most often as an incidental loud heart murmur at a puppy's first wellness visit. Bulldogs, Boxers, Beagles, and Chihuahuas are over-represented. Severe cases (peak gradient over 80 mmHg) benefit dramatically from balloon valvuloplasty, which extends median survival from roughly 1 year to 8 years in selected dogs (Bussadori et al., 2017, J Vet Cardiology). The murmur on a puppy exam is the single most important early sign.
Last reviewed: June 2026
What Pulmonic Stenosis Is
Pulmonic stenosis (PS) is congenital narrowing of the pulmonic valve, the valve between the right ventricle and the pulmonary artery. The right ventricle must generate much higher pressures to push blood through the narrow valve, which leads to right ventricular hypertrophy. Severity is classified by Doppler-measured peak gradient: mild (less than 40 mmHg), moderate (40 to 80 mmHg), severe (over 80 mmHg). Most mild cases are clinically silent for life. Severe cases progress to right-sided heart failure, exercise intolerance, syncope, and sudden death.
Signs Owners First Notice
In mild-to-moderate PS, most owners notice nothing — the diagnosis is incidental at puppy vaccines when the vet hears a loud left-sided heart murmur. Moderate-to-severe disease produces exercise intolerance, fainting (syncope) during play or excitement, blue-tinged gums during exertion, abdominal distension from ascites in advanced right-sided failure, and stunted growth in young dogs. A high-pitched ejection murmur audible best over the left heart base is the cardinal physical finding.
How It's Diagnosed
Echocardiography with color Doppler is the definitive test. The peak transvalvular gradient classifies severity and the morphology of the valve (type A: mostly fused commissures, type B: hypoplastic annulus) guides intervention planning. Chest radiographs may show right ventricular enlargement and a post-stenotic dilation bulge in the main pulmonary artery. ECG findings of right axis deviation support the diagnosis. As detailed in Côté's Clinical Veterinary Advisor, severity-based gradient cutoffs guide both prognosis and the decision to intervene.
Treatment
Severe PS is best treated with balloon valvuloplasty by a board-certified veterinary cardiologist. The procedure passes a deflated balloon through the femoral vein into the stenotic valve and inflates it to tear the fused commissures. Reported success in reducing gradient below 50 mmHg is achieved in 60 to 80 percent of selected cases, with median post-procedure survival of 8 years versus 1 to 2 years for untreated severe PS (Bussadori et al., 2017, J Vet Cardiology). Beta-blockers (atenolol) may improve symptoms and reduce arrhythmia in dogs awaiting or unsuitable for valvuloplasty. As reviewed in Bonagura's Kirk's Current Veterinary Therapy, mild cases are monitored with annual echo without intervention.
When to See a Vet
Call your vet today if:
- A loud heart murmur was heard at a puppy visit and not yet worked up
- A young dog is fainting during play or excitement
- Blue or grey tinge to gums during exertion
- Exercise intolerance worse than expected for age
- Abdominal distension or fluid wave in a known heart-affected dog
Go to the ER immediately if:
- Collapse with loss of consciousness for more than a few seconds
- Severe respiratory distress, blue or purple gums at rest
- A dog with known severe PS collapses or has a witnessed seizure
- Sudden inability to stand
- Markedly distended belly with labored breathing
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Frequently Asked Questions
How serious is "mild" pulmonic stenosis?
Mild PS (gradient under 40 mmHg) generally does not shorten lifespan and is monitored without treatment. Annual echocardiography in the first 2 to 3 years of life confirms the gradient is stable, after which monitoring frequency can decrease. Most mild PS dogs live a normal full life.
How much does diagnosis and treatment cost?
Initial vet exam typically runs $50 to $150 in the US. A complete echocardiogram with a cardiologist costs $400 to $800. Chest radiographs add $150 to $400. Balloon valvuloplasty at a specialty hospital is typically $4,500 to $8,000 including anesthesia and overnight stay. Annual recheck echos are $300 to $600. Beta-blocker therapy is inexpensive at $20 to $60 per month. Catching severe PS as a young puppy and intervening with valvuloplasty is dramatically more effective than waiting for heart failure to develop.
Can a dog with PS be bred?
Most cardiologists recommend against breeding affected dogs because the trait is heritable in several breeds, including Boxers, Bulldogs, and Beagles. Cardiac screening before breeding is standard in many show-line programs.
Will my dog need lifelong medication?
Dogs after successful valvuloplasty often do not need cardiac medications and live normally with annual rechecks. Dogs with residual moderate-to-severe disease are commonly maintained on atenolol. Dogs in right-sided heart failure require furosemide, pimobendan, and an ACE inhibitor.
Still Not Sure if Your Dog Needs a Vet?
When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share a video of any fainting episodes and your dog's exertion tolerance, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.