dog heart murmur? read this. it could be the difference between 3 more years and a much shorter one.

Dog Heart Murmur? Read this. It could be the difference between 3 more years and a much shorter one.

Your dog's murmur is progressing quietly while you're just "monitoring." Here's what you can do today—before that next vet visit becomes a conversation you're not ready for.

Your dog's murmur is progressing quietly while you're just "monitoring." Here's what you can do today—before that next vet visit becomes a conversation you're not ready for.

  • Reviewed by Dr. Serena Gannon - DVM

Updated on 14/8/2026

If you're reading this, your dog has probably been diagnosed with a heart murmur. Or you're dreading one, because their breed is predisposed.
 

You've probably been doing everything right. Good food. Regular exercise. Vet visits kept. Maybe supplements already.
 

That's what makes the way it usually happens so strange.
 

For most owners, there's no dramatic moment. No collapse, no cough, no obvious decline.

Just a routine checkup, a vaccine, a limp, or a dental, and the vet pauses with the stethoscope a second longer than usual.

 

And then: your dog is diagnosed with heart disease—a heart murmur.
 

Some owners who found out a bit late say they'd noticed something first: a cough that wouldn't quite go away, a strange snort that sounds like a pig when he breathes, out of breath after a walk, or just a general drop in energy. Others noticed nothing at all.
 

Either way, the appointment ends the same: "Let's monitor it for now"
 

Your vet isn't wrong. 'Monitor it' is the by-the-book answer, but it's the wrong answer for your dog's quality of life. We'll get into the real reason why later in this article.
 

This article is for you if:
✔ Your dog has been diagnosed with a heart murmur, or you're dreading one
✔ You've noticed changes you can't quite name. (heavier panting, less energy, restlessness at night, an occasional cough)
✔ You can't shake the feeling that waiting is the wrong answer

What Is a Heart Murmur?

A normal heartbeat makes two clean sounds. Lub-dub. That's it.
 

A murmur is an extra sound in between. A whoosh, a swish, a sound where there shouldn't be one.
 

That sound is turbulence. Blood moving in a way it isn't supposed to.

A heart murmur isn't the disease. It's a symptom, a sign that something underneath it needs attention. 

Which is why nothing about treating a murmur is really about the murmur itself, it's about whatever's causing it.

What Causes a Heart Murmur?

The heart has valves that work like one-way doors. Blood goes through, the door snaps shut behind it, and the blood keeps moving forward.
 

In most dogs with a murmur, one of those doors has stopped closing all the way. Usually it's the mitral valve, on the left side of the heart. Instead of sealing shut, it leaks a little. Some blood slips backward through the gap.
 

That backward leak is the whoosh your vet heard.
 

The valve doesn't wear out overnight. It thickens and stiffens slowly, over years, like an old door that doesn't quite fit the frame anymore. This is why murmurs show up more often in older dogs, and why they tend to be found by accident during a routine visit rather than because something obvious went wrong.

Murmur Grade Doesn't Tell You How Serious It Is

When your vet hears a murmur, they grade how loud it is on a scale of 1 to 6. 

Grade 1 is so quiet a vet has to listen carefully in a silent room. 
Grade 6 can be felt through the chest wall with a hand.
 

Here's the part most owners aren't told clearly: loudness is not the same as severity.
 

A grade 5 murmur does not automatically mean a dog is sicker than a grade 3. Loudness mostly reflects how much turbulence the leak is creating, not how much the heart has changed because of it. 

A loud murmur can sit stable for years. A quieter one can be doing real damage.
 

So a grade tells you a murmur exists and roughly how strong the leak sounds. It does not tell you what stage the disease is at, or what happens next.

The Real Measure Of Severity 

To answer where your dog stands, your vet will refer you to a veterinary cardiologist for a full cardiac workup: an echocardiogram, chest X-rays, and often a blood test. This is what determines your dog's actual stage, not just that a murmur exists.

The stages that actually matter:

Cardiologists use a staging system built by the American College of Veterinary Internal Medicine, or ACVIM.
 

Stage A. An at-risk breed, no murmur yet, normal heart. Nothing to treat.
 

Stage B1. A murmur is there. The valve is leaking. But the echo numbers are still below the cutoffs, meaning the heart has not started enlarging yet.
 

Stage B2. Same murmur, but now the numbers have crossed the line. The heart has begun stretching to handle the extra workload.
 

Stage C. The dog has developed, or previously developed, congestive heart failure. Coughing, labored breathing, fluid backing up into the lungs.
 

Stage D. Advanced disease that no longer responds well to standard treatment.

The Trap Every Heart Murmur Owner Gets Stuck In (Before It Becomes Regret)

Your regular vet can hear the murmur. What they can't do is tell you what it means. 

Staging the disease takes imaging, and reading that imaging correctly is a specialist's job. So your vet does the responsible thing and refers you out to a specialist. 
 

Then you find out what that referral costs.
 

A cardiology consult and echocardiogram commonly runs over a thousand dollars. And cardiologists are booked out, often weeks, sometimes months. You're not being pushed to the back of a line. There simply aren't many of them.

What's worse is, your dog will only be approved for treatment once the heart has already started to enlarge, that's the threshold. It's not a flaw in the guidelines, the research genuinely doesn't support medicating earlier. But it does mean the plan is to wait until it gets worse, and only then act.
 

So the reality for most owners looks like this: 
You know something is wrong with your dog's heart. You've spent the money for the vet visit, spent more on the referral, spent weeks just waiting for the cardiology appointment to open up. 

You finally get the echo done, you sit in the waiting room while they run it, and then the cardiologist comes out and says the words meant to be reassuring: "He's still early stage. Just make sure you monitor him regularly."
 

So you go home. And you wait. Not for your dog to get better but for him to get worse. Waiting for the numbers to finally cross the line that unlocks treatment. Waiting to "successfully" progress far enough that a vet is finally allowed to give him something.
 

That's the trap. A system where the answer costs money, time and energy that most people don't have sitting ready.

Is Your Dog's Breed More at Risk?

A heart murmur is just a symptom. It doesn't tell you what's wrong, it tells you that something is. In most dogs, that something is one of two underlying conditions, MMVD or DCM. 

Left unmanaged, both follow the same path: the heart works harder, enlarges, and eventually fluid starts backing up into the lungs. That's congestive heart failure, not a new disease showing up later, just the same one, further along.
 

Small and toy breeds mostly deal with MMVD, the mitral valve wearing down. Cavalier King Charles Spaniels, Dachshunds, Chihuahuas, Maltese, Yorkshire Terriers, Miniature Schnauzers, Whippets, Toy and Miniature Poodles, Pomeranians, Cocker Spaniels, Pekingese, Shih Tzus, and Boston Terriers show up again and again in the research. If you have a Cavalier, this probably hits close to home, nearly all Cavaliers show signs of MMVD by age 10.
 

Large breeds face a different version of the same problem. Doberman Pinschers, Great Danes, Boxers, Irish Wolfhounds, Scottish Deerhounds, Newfoundlands, Saint Bernards, Portuguese Water Dogs, Standard and Giant Schnauzers, and Cocker Spaniels are more often linked to DCM, dilated cardiomyopathy, where the heart muscle itself weakens and stretches rather than a valve wearing down. 
 

Your dog's breed doesn't have to be on this list. Both conditions can affect any aging dog. 

And even for the breeds most at risk, genetics only explains who's more likely to get MMVD or DCM, not how fast it moves once it's there.

Something else decides the pace.

The Hormone That's Working Against Your Dog Right Now

Breed and genetics explain who develops a murmur. But there's one factor that influences how fast it progresses, and that's cortisol, your dog's stress hormone.
 

Cortisol is produced naturally, released whenever the body senses a threat. 

The important detail is that "threat" is decided by your dog's nervous system, not by whether the danger is real.

A knock at the door counts. So does the vacuum, thunderstorms, car rides, and being left alone. For a lot of dogs, a grooming appointment is one of the bigger ones.
 

This isn't a sign of a badly behaved or poorly cared-for dog. It's how the system is built. 

Dogs are simply more sensitive to their surroundings and to the people around them than we are. They can't put things in context the way we can. You can't explain to a dog that the vacuum is harmless, or that you'll be back in three hours. It's how the system is built.

What that does to a heart that's already weak:
 

When cortisol rises, the body prepares for fight or flight. Heart rate increases. Blood pressure increases. The heart pumps harder and faster.
 

That means more work for a heart that's already working harder than it should. Its response to sustained extra work is the same one from earlier in this article, it stretches, it enlarges. That's exactly the change a cardiologist is measuring for.
 

Breed can't be changed. Genetics can't be undone. Cortisol is the one thing that isn't fixed.
 

Cortisol doesn't only harm the heart. Chronically elevated, it's associated with weakened immune function, digestive problems, and poorer sleep quality.
 

And it compounds. A single stressful moment isn't the danger. It's the daily accumulation, day after day, that becomes the biggest factor in whether a murmur stabilizes or progresses.

Why Everything You've Tried Has Failed (And Why That's Not Your Fault)

A good vet will tell you to avoid overexertion and try not to stress him out. Fair advice, but taken too far, it isn't realistic. 

Wrapping him in bubble wrap, cancelling walks, tiptoeing around every sound, isn't the goal. It helps no one, and now your day-to-day life together is harder too.
 

So most owners do the logical thing and reach for supplements.
 

CoQ10, which supports energy production. Fish oil for inflammation. A cardiac chew, most are just overpriced treats. Each one supports the heart after the fact. Not one of them was designed to regulate the stress load putting that heart under pressure in the first place.
 

So then medication, right?

 

There's no shortcut here. These are prescription drugs for a reason. If your vet hasn't prescribed them, it's because your dog doesn't need them yet, and putting a dog on medication he doesn't need means side effects with nothing gained.

 

And if you're being told to monitor it, chances are you haven't been prescribed anything. Vetmedin typically isn't started until the heart has already begun to enlarge. Lasix comes in once fluid is backing up into the lungs. Enalapril later still, once heart failure is in the picture. 

 

They do come with their fair share of side effects. But by the time one gets prescribed, it means your dog needs it. Your dog likely can't function properly without it anymore. 

Those medications are excellent at what they do. They work on the heart's mechanics, how hard it contracts, how much pressure it pumps against, how much fluid builds up.

But none of them address the culprit (cortisol). So the daily stress load still compounds, and supporting it without addressing that pressure is like bailing water with the tap still running.

It Wasn't Your Fault. Here's What Works.

So What's Left? (The Discovery That Changed Everything)

A 7-year-old Cavalier King Charles Spaniel, Pepper, was presented with a history of cough, exercise intolerance, and nocturnal panting. 
 

Pepper was part of a 7-day study looking at something different from the usual approach.

Before starting, his heart was measured on an echocardiogram, they watched his left ventricular internal dimension (LVIDd): how wide the heart's main pumping chamber had stretched.
 

[Figure A] Day 1: The chamber was enlarged. The heart was working harder than it should, compensating for what the valve couldn't do anymore.
 

Pepper was administered one capsule daily, capsule opened and mixed into his breakfast. No diet adjustments, no activity restrictions, no new medications.

His owner also noticed something else. Pepper had always been terrified of fireworks. Day 3 happened to be the 4th of July. Normally, he'd tremble, pant, and pace for 30 minutes or more after the noises stopped. This time, he settled faster. The trembling didn't last as long. His nose stayed cool and wet.
 

[Figure B] On day 7, the same scan was run again. LVIDd had dropped by 36.47% from baseline.
 

In simpler terms, the heart wasn't stretched as wide anymore. It wasn't compensating as heavily as before, and it was starting to return to a more normal size.
 

The formulation given was VQ10.

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The Answer Is VQ10

The science is straightforward: you can't effectively support a heart while the whole nervous system is in survival mode. That is the bible VQ10 is built on. 

What is VQ10? 

VQ10 is a formulation designed specifically for dogs with heart murmur. It combines 10 ingredients, some rooted in centuries of Eastern herbal tradition, others backed by modern nutritional science, all working in a specific sequence.
 

Phase one, downregulates the stress response, and calming sympathetic nervous system activity. Phase two delivers a clinically dosed nutrient complex directly to the cardiovascular system.
 

In simpler terms: turn the tap off before you wipe the floor clean.

Ten ingredients. Here's what each one does:

Alpha-casozepine + L-tryptophan — Research has demonstrated stress-reducing effects in dogs. They work on the nervous system itself, not the heart.
Sour jujube seed — Used in traditional Chinese medicine for centuries for restlessness, anxiety, and insomnia. Modern studies show it exerts anxiolytic effects by modulating GABAergic and serotonergic neurotransmitter systems. Known as the "Sleeping Fruit of the East.
Magnesium — Supports the nervous system and helps regulate the stress response.
Ubiquinol — The pre-activated form of CoQ10. Older dogs lose the ability to convert standard CoQ10 (Ubiquinone) into its active form. VQ10 provides it ready to absorb, so their body doesn't have to do the work.
Taurine — An amino acid that heart muscle depends on directly. Essential for normal cardiac function.
Hawthorn berry — Used for heart support for over a thousand years across both Eastern and Western traditions. Research shows it exerts antioxidant, antiarrhythmic, vasodilator, and positive inotropic effects on the heart.
Astragalus — One of the most-studied herbs in traditional Chinese medicine. Research shows astragalus improves cardiac function. Canine studies specifically show astragalus saponins improve myocardial contractility and protect cardiac function.
Ginseng — An adaptogen that protects against stress and supports cardiovascular health. Ginsenosides increase resistance to stress.
Schisandra berry — A well-known adaptogen that increases the body's resistance to stress. Shown to have cardioprotective effects.
Krill — Provides omega-3 fatty acids that support overall cardiovascular health.

One capsule covers everything the cardiac system needs: the cortisol driving the damage, the fuel the heart runs on, and the deep sleep where recovery happens. Taurine's in there too, one less bottle to buy separately.

See Why Dog Owners Trust VQ10

How to Get Started

Two ways. Either works.
 

Drop the capsule whole into your dog's bowl.
 

Got a picky eater? Twist the capsule open and let the powder fall into their food. The base is hydrolyzed chicken, it smells and tastes like food, because it is food.
 

Dosage is based on your dog's size. Full details are on the VQ10 product page 'Direction For Use".

You'll Know in 7 Days—Not 3 Months

 

Healing is a process. But VQ10 is designed to work in stages, and owners consistently notice the first signs within the first week.

 

Days 1–7 — The Calm Phase

The first thing you'll notice isn't the heart. It's him. Less reactive. Sleeping more deeply. That low-level tension that became his new normal. 

 

This is the cortisol load coming down, and it matters more than it looks. Because a calmer nervous system means less pressure on a valve that's already working harder than it should.

 

 

Weeks 2–3 — The Energy Phase

With the stress load reduced, the Ubiquinol starts doing its work. Heart cells that were running on depleted energy reserves begin getting the fuel they actually need.

 

He wants to walk further. He finishes what he used to stop halfway through. Owners describe it as getting a piece of their dog back, just something quiet that had been fading, returning.

 

 

Weeks 4–8 — The Strengthening Phase

The anti-fibrotic ingredients (Astragalus, Hawthorn, Krill Omega-3) are working at a deeper level now. 

 

Supporting the heart wall. Reducing the chronic inflammation that accelerates structural decline. Slowing what the cortisol had been speeding up. This is the phase that doesn't always feel visible. But it's the most important one.

 

 

Days 60–90 — The Stability Phase

The echocardiogram. The appointment where your vet measures whether his heart has stayed stable or continued to enlarge. 

 

Owners who reach this phase with VQ10 describe that appointment differently. Not always dramatic. Just stable. Numbers that held.

 

That's the win this formula is built for.

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