Your Dog Has a Heart Murmur. Now What? The At-Home Breathing Check That Matters Most

The short answer: A heart murmur means your vet hears turbulent blood flow in your dog's heart. Some murmurs are harmless, others point to heart disease. The best at-home habit is tracking your dog's sleeping breathing rate. Most healthy dogs breathe between 11 and 20 times a minute at rest, and a rate that stays above 30 is a reason to call your vet.

What is a heart murmur in dogs, really?

A murmur is a whooshing sound between the normal "lub-dub" of the heartbeat. Vets grade it from 1 (barely audible) to 6 (loud enough to feel through the chest wall). The grade describes how loud it is. It doesn't directly tell you how sick your dog is.

In adult dogs, the most common cause is mitral valve disease, where the valve between the left chambers of the heart slowly starts to leak. Small breeds like Cavaliers, Dachshunds, Chihuahuas, and Shih Tzus are especially prone to it. Puppies can also have "innocent" murmurs that fade on their own by around six months old. If you want the full breakdown of grades and causes, this guide to heart murmur in dogs walks through each stage.

Why does your vet keep bringing up breathing?

Because breathing changes first. When a leaky valve starts to strain the heart, fluid can slowly build up in or around the lungs. Before a dog coughs, gets tired on walks, or looks unwell, their resting breathing rate often creeps up.

That's why so many vets send dog parents home with the same instruction: count your dog's breaths while they sleep. It's the earliest warning sign you can actually measure at home.

What is a normal respiratory rate for dogs?

The line most vets use is 30 breaths per minute at rest. But healthy dogs usually breathe well below that.

Maven Pet studied resting breathing in 1,376 healthy dogs using continuous at-home monitoring. The median was about 14 breaths per minute, and 80% of healthy dogs fell between 11 and 20. Only 0.5% sat above 30. Interestingly, dog size barely mattered. A healthy Chihuahua and a healthy Great Dane breathe at nearly the same rate while asleep. You can see the full breakdown of the normal respiratory rate for dogs, including how the numbers were measured.

One caveat worth knowing: "healthy" in that study means dogs whose parents reported no chronic conditions when they signed up, not dogs confirmed healthy by a vet.

Does a murmur mean breathing is already abnormal?

Usually not. In a smaller group of 36 dogs whose parents reported a heart murmur, the median resting rate was about 15 breaths per minute, barely higher than healthy dogs. The upper end of that group reached around 23, still under the 30 line.

That's a small sample, so treat it as a pattern rather than a rule. But the takeaway is reassuring and practical at the same time. Many dogs with murmurs breathe normally today. What matters is whether that number stays steady over the months ahead. And you can only spot a change if you know your dog's starting point.

How to count your dog's breathing at home

1. Wait until your dog is in deep, quiet sleep. Twitching paws and dreaming mean REM sleep, which can briefly speed breathing up.

2. Watch the chest or belly. One rise and one fall is one breath.

3. Count for 30 seconds, then multiply by two.

4. Write it down with the date and time, and try to count at a similar time each day.

The first week is easy. The third month is not. Your dog wakes up the second you tiptoe over, you forget a few nights, and you start wondering if 18 was actually 16.

When should you call your vet?

Call your vet if your dog's sleeping breathing rate stays above 30 across several readings, or if it rises steadily from their usual number. Call the same day if it stays above 40, or if you notice any of these:

• Visible effort with each breath, like belly pushing or an outstretched neck

• Pale, gray, or bluish gums

• A new cough, especially at night or after lying down

• Restless nights, trouble settling, or sleeping sitting up

Making it stick when life gets busy

This is where a wearable earns its place. Maven Pet is a small sensor that clips onto your dog's existing collar. It only measures breathing after your dog has been still for 15 minutes, so you get real resting numbers instead of post-walk panting. It spends the first week learning your dog's normal, then alerts you when their breathing climbs above it. You can also download a monthly health report to bring to your vet or cardiologist.

Accuracy matters when you're making medical decisions. A University of Florida cardiology team compared the sensor against vets counting breaths by hand across 120 side-by-side checks, and the difference averaged less than one breath per minute.

A tracker doesn't diagnose anything, and it won't replace an echocardiogram or your dog's medication. What it gives you is months of nightly data instead of a handful of rushed counts, so your vet can make timing decisions with real evidence. Plans start at $13.99 a month billed annually, with the sensor included.

FAQ

Can a dog live a normal life with a heart murmur?
Many can. Dogs with low-grade murmurs from mild valve disease often live for years without developing heart failure. Regular vet checks and home monitoring help catch changes early.

Does a heart murmur always mean heart disease?
No. Some murmurs are innocent, especially in puppies. Others are linked to dog heart disease like mitral valve disease. Your vet may recommend an echocardiogram to find the cause.

Is it normal for my dog to breathe fast while sleeping?
Brief bursts during dreaming are normal. Fast breathing that continues during deep, still sleep, especially above 30 breaths per minute, is worth reporting to your vet.

How often should I count my dog's breaths?
Ask your vet for a schedule. Many recommend daily counts for dogs with a known murmur, particularly once medication starts.