Heart Murmur Treatment in Dogs: Medications and Care

Name: Heart Murmur Treatment in Dogs: Medications and Care
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-02

Not every heart murmur in dogs treatment plan includes medication. Some murmurs are harmless and need only monitoring, while others signal heart disease that benefits from drugs like pimobendan or an ACE inhibitor such as benazepril. The right plan depends on what is causing the murmur and how advanced the disease is.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

A murmur is a sound, not a diagnosis. It tells your vet blood is flowing abnormally, and the cause decides the treatment.
Innocent murmurs in puppies often disappear as the dog grows, while most murmurs in adult dogs point to real heart disease [1].
Pimobendan is the main drug used in a specific preclinical stage of mitral valve disease once the heart is enlarged, and it is also used once congestive heart failure begins [2][3].
ACE inhibitors like benazepril are commonly used to manage heart failure and control fluid buildup, often alongside other drugs [4].
Dogs with heart disease usually need low-sodium food, regular rechecks, and careful monitoring at home [4].

What a Heart Murmur Actually Means in Dogs

A heart murmur is an extra sound your veterinarian hears through a stethoscope when blood moves through the heart in a turbulent way. The heart normally makes two clean sounds, but a murmur adds a whoosh or swish between or around them. The murmur itself does not damage the heart. It is a clue that something is changing the way blood flows.

Heart disease in dogs covers a wide range of problems, including congenital defects present at birth and acquired conditions that develop later [5]. Some are structural, like a leaky valve or a hole between chambers. Others involve the heart muscle or the electrical system that controls rhythm [5]. More than 10% of animals examined by a veterinarian have some form of cardiovascular disease [5].

That number sounds alarming, but it includes mild cases that never cause symptoms. The murmur grade, its location, and your dog's age and breed all help your vet figure out what is going on.

Signs Owners Notice at Home

Many dogs with a murmur have no signs at all, especially early on. A heart with reduced pumping ability can still be "failing" in a technical sense while the body compensates and the dog acts completely normal [6]. That is why a murmur is often found during a routine exam instead of because you noticed something wrong.

When signs do appear, they usually reflect fluid buildup or reduced circulation. Watch for:

A new cough, especially at night or after resting
Faster or harder breathing at rest
Tiring sooner on walks or lagging behind
Fainting or brief collapse
Reduced appetite or weight loss
A swollen belly or puffiness in the legs
Restlessness or trouble getting comfortable at night

Some of these signs overlap with other problems. Reverse sneezing, for example, can look alarming but is usually unrelated to the heart. If you are trying to sort out what you are seeing, this guide on dog reverse sneezing and heart murmur can help you tell the difference.

Causes and Risk Factors

The cause of the murmur drives everything that follows. Common categories include:

Degenerative valve disease. This is the most common heart disease in dogs [7]. The mitral valve thickens and stops sealing properly, so blood leaks backward. Small and medium breeds are often affected, and it becomes more common with age.

Congenital defects. These are present at birth. Patent ductus arteriosus is one example, where a vessel that should close after birth stays open and lets blood shunt between the aorta and pulmonary artery [8]. Puppies with loud murmurs need prompt evaluation because early repair can change the outcome [1].

Heart muscle disease. Some dogs develop a weakened or thickened heart muscle that reduces pumping ability [6].

Other causes. Rare problems exist, including unusual growths on valves. One report described a cyst attached to the aortic valve in a dog that stayed asymptomatic with only mild heart enlargement [9]. This shows why imaging matters, since the treatment for an unusual lesion may be very different from the treatment for a common one.

Risk factors include age, breed, body size, and family history. Your vet will weigh all of these when deciding how closely to watch a murmur.

How Veterinarians Diagnose and Stage a Murmur

Diagnosis starts with listening. Your vet notes how loud the murmur is, where it is loudest, and when in the heartbeat it occurs. A loud murmur during a puppy's first health check should prompt further testing, since normal growth and the absence of signs do not rule out serious congenital disease [1].

The next step is usually an echocardiogram, which is an ultrasound of the heart. This shows the valves, chamber sizes, and how well the heart is pumping. Staging matters because it decides whether drugs are needed now or later. In mitral valve disease, the preclinical stage with heart enlargement is the point where pimobendan is typically started [2].

When echocardiography is not available or an owner declines it, vets can use other tools. These include murmur intensity, heart size on chest X-rays, and blood markers such as NT-proBNP to identify dogs at higher risk of heart failure who may need early pimobendan [7].

A first visit for a murmur often includes a physical exam, bloodwork, chest X-rays, and sometimes an ECG. If you want to know what to expect, this walkthrough of what happens at your dog's vet visit for a heart murmur covers the steps.

Heart Murmur in Dogs Treatment: Medications and When They Start

Treatment is specific to the type of disease, and some defects can be corrected with surgery while others are managed with one or a combination of drugs [4]. The broad goals are to limit damage to the heart muscle, control fluid in the lungs, improve circulation, regulate rate and rhythm, support oxygen levels, and reduce the risk of clots [4].

Pimobendan (Vetmedin)

Pimobendan is one of the most studied heart medications in dogs. In stage B2 mitral valve disease, where the valve is leaking and the heart is enlarged but the dog has no heart failure signs, pimobendan reduced a key measure of heart size over time in treated dogs compared with untreated controls [2]. That same report advised caution about prescribing pimobendan based only on hearing a murmur, since echocardiographic staging gives a clearer picture [2].

Pimobendan also has a role once congestive heart failure begins. One multicenter study compared survival from the onset of heart failure in dogs that had received pimobendan before failure versus dogs that had not. Median time to death from any cause was 168 days in the group that had received preclinical pimobendan and 359 days in the group that had not [3]. This is a striking finding, and it is one reason your vet may adjust the plan once failure starts instead of simply continuing the same protocol.

ACE Inhibitors (Benazepril and Similar Drugs)

Benazepril belongs to a drug class called ACE inhibitors. These medications are used to manage heart failure and help control fluid accumulation, often as part of a multi-drug plan [4]. They are not a cure, and they work best when given exactly as prescribed. Your vet calculates the dose from your dog's weight and current health, and the dose may change over time as kidney values and other lab results shift.

Other Drugs Your Vet May Add

Depending on the stage and the specific problem, your vet may add a diuretic to pull fluid out of the lungs, a drug to slow the heart rate, or medication to support blood pressure. Each drug has a job, and the combination is tailored to your dog. Giving medications exactly as prescribed matters, because the wrong timing or a missed dose can reduce effectiveness and may even cause serious complications [4].

What About Surgery?

Some congenital defects can be repaired or corrected surgically [4]. This is most realistic for certain defects found early, which is why a loud murmur in a young puppy deserves prompt attention [1]. For degenerative valve disease, surgery is not the standard path in most general practices, so medical management and monitoring carry the load.

Comparing Common Treatment Approaches

Situation	Typical Approach	Why
Innocent puppy murmur	Monitor and recheck	Many fade as the dog grows [1]
Congenital defect, loud murmur	Prompt imaging, possible surgery	Early repair can improve outcome [4][1]
Preclinical mitral disease with heart enlargement	Pimobendan	Reduces heart size and delays heart failure [2]
Congestive heart failure	Pimobendan plus diuretic and ACE inhibitor	Controls fluid and supports circulation [4]
No echocardiography available	Murmur grade, X-ray heart size, NT-proBNP	Helps identify dogs needing early treatment [7]

Recovery, Outlook, and Long-Term Management

Heart disease in dogs generally does not go away. It usually becomes more serious over time and may lead to death [5]. That sounds blunt, but it does not mean your dog cannot live well for a long time. Many dogs stay comfortable for months or years with the right plan.

Treatment is considered successful when signs resolve, breathing and heart rates are normal at rest, and your dog has a good quality of life [4]. Those are the benchmarks your vet will track at each recheck.

Home Care Basics

Food. A low-sodium diet may be recommended to help the body eliminate excess fluid [4]. Do not switch foods on your own, since some prescription diets interact with the rest of the plan. Ask your vet which diet fits your dog's stage.

Medication timing. Give every dose on schedule. If you miss one, call your vet instead of doubling up.

Resting breathing rate. Count breaths while your dog sleeps. A rising rate is often the first sign fluid is building up. Keep a log and bring it to visits.

Weight and appetite. Track both. Unexplained weight loss or a sudden drop in appetite needs a call.

Exercise. Moderate, consistent activity is usually fine. Let your dog set the pace and avoid extreme heat.

Stress and travel. Keep routines calm and plan ahead for refills. Running out of heart medication is a real risk on trips.

Monitoring Tools at Home

Some owners learn to listen to their dog's heart and lungs at home. A stethoscope designed for cardiac listening makes this more practical, and this guide on veterinary stethoscopes for pet owners explains bell versus diaphragm and how to monitor a murmur over time. Home listening does not replace exams, but it can help you notice changes between visits.

For a deeper look at how mitral valve disease progresses and how treatment shifts at each stage, see this article on congestive heart failure in dogs and mitral valve disease progression.

Prevention

You cannot prevent most heart disease in dogs, but you can catch it earlier. Routine exams let your vet hear a murmur before symptoms start, and early staging is what allows treatment to begin at the right moment [2][7].

Other steps that help:

Keep regular wellness visits, especially as your dog ages
Ask your vet to listen carefully at every visit, not just annual ones
Tell your vet about any new cough, fainting, or exercise intolerance
Keep your dog at a healthy weight
Follow heartworm prevention, since heartworm disease damages the heart and lungs [4]
If you breed dogs, discuss screening for inherited heart conditions with your vet

Limitations and When to Contact a Veterinarian

No article can tell you what your individual dog needs. Murmur grade, stage, breed, and lab results all change the plan, and only your veterinarian can examine your dog and decide.

Call your vet the same day if you notice:

A new or worsening cough
Resting breathing rate clearly higher than your dog's normal
Reduced appetite lasting more than a day
Weakness or reluctance to walk
Any missed doses of heart medication

Go to an emergency clinic now if you see:

Collapse or fainting that does not fully resolve
Labored breathing, especially with the elbows out and belly moving hard
Blue or gray gums
A distended, tight belly with rapid breathing
Sudden hind leg paralysis, which can signal a clot

Schedule a routine visit if:

Your dog was just diagnosed with a murmur and has no signs
You need a medication refill or dose review
It has been several months since the last recheck

Frequently Asked Questions

Does every dog with a heart murmur need medication?

No. Innocent murmurs in puppies often need only monitoring, and many fade with growth [1]. Medication is reserved for murmurs tied to heart disease at a stage where drugs have proven benefit, such as preclinical mitral disease with heart enlargement [2].

Is pimobendan safe to start based only on hearing a murmur?

Staging with an echocardiogram is preferred before starting pimobendan, and caution is advised when prescribing based only on murmur detection [2]. When imaging is not possible, your vet may combine murmur intensity, X-ray heart size, and blood markers to guide the decision [7].

Can heart disease in dogs be cured?

Most cardiovascular diseases in dogs do not go away and tend to become more serious over time [5]. Some congenital defects can be repaired or corrected with surgery, which can be curative for certain cases [4]. For degenerative valve disease, the goal is management and quality of life, not a cure.

How long can a dog live after starting heart failure treatment?

It varies widely by dog and by stage. In one study, median time to death from any cause after heart failure began was 168 days in dogs that had received pimobendan before failure and 359 days in dogs that had not [3]. Your vet can give you a more personal estimate based on your dog's exam and lab work.

Should I change my dog's food after a murmur diagnosis?

Only if your vet recommends it. A low-sodium diet may be suggested to help eliminate excess fluid in dogs with congestive heart failure [4]. Diet changes should match the stage of disease and the rest of the treatment plan, so ask before switching.

References

Self-Reported Management of Incidentally Detected Heart Murmurs in Puppies: A Survey among Veterinarians. Animals : an open access journal from MDPI, 2024.
Echocardiographic Changes in Dogs with Stage B2 Myxomatous Mitral Valve Disease Treated with Pimobendan Monotherapy. Veterinary sciences, 2024.
Survival of dogs with myxomatous mitral valve disease administered preclinical pimobendan in comparison to pimobendan-naïve dogs from the onset of congestive heart failure. Journal of veterinary cardiology : the official journal of the European Society of Veterinary Cardiology, 2026.
Treatment of Cardiovascular Disease in Dogs - Dog Owners. Merck Veterinary Manual.
Heart Disease in Dogs - Dog Owners. Merck Veterinary Manual.
Heart Failure in Dogs - Dog Owners. Merck Veterinary Manual.
Diagnosis and management of a more advanced stage of preclinical myxomatous mitral valve disease in dogs without echocardiography. Schweizer Archiv fur Tierheilkunde, 2024.
Echocardiographic description of shunt volume in dogs with patent ductus arteriosus. Journal of veterinary cardiology : the official journal of the European Society of Veterinary Cardiology, 2025.
Echocardiographic findings of a valvular aortic cyst in a dog. Journal of veterinary cardiology : the official journal of the European Society of Veterinary Cardiology, 2025.