As a veterinarian, one of the most common concerns I hear from puppy parents is about puppy heart murmurs. If your vet mentioned this during a routine check-up, I can imagine your mind racing with questions: "What does this mean for my puppy?” “Is it serious?” “Will they grow out of it?"
Don’t worry - we’ve got you covered! Let’s dive into everything you need to know about puppy heart murmurs and when you should worry.
What is a heart murmur in dogs?
A heart murmur is an unusual sound heard within your puppy’s heartbeat, typically picked up during a physical exam with a stethoscope. Instead of the familiar “lub-dub” sound that the heart makes, murmurs produce a whooshing or swishing sound caused by turbulent blood flow, in or around the heart.
Do all murmurs sound the same?
Not quite! Murmurs vary based on their cause and severity. Some are faint and barely detectable, while others are loud and pronounced. Vets classify murmurs by their timing, duration, and pitch - helping to identify whether they’re benign or something more serious.
At what age do puppies get a murmur?
Puppy heart murmurs are most often detected during their early weeks of life - usually between 6-12 weeks of age. Many are harmless and will resolve as your puppy grows. But if the murmur persists beyond 4-6 months, it might warrant further investigation.
Common causes of puppy heart murmurs
Heart murmurs in puppies can be caused by several factors. Let’s break these down:
Structural causes
These involve abnormalities within the heart itself, such as:
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Congenital defects: Problems present at birth, like patent ductus arteriosus (PDA) or a ventricular septal defect (VSD) - medical names for something that went wrong in a puppy’s development.
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Valve malformations: Improperly functioning heart valves causing turbulent blood flow.
Extracardiac causes
Sometimes, the murmur isn’t caused by the heart directly but by other conditions, such as:
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Anemia
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Infections
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High fever
Innocent vs. pathological murmurs
Murmurs in puppies can generally be divided into two categories:
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Innocent murmurs (also called functional murmurs) are common in puppies. They’re typically low-grade and disappear as your puppy matures.
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Pathological murmurs result from structural or functional heart issues that may require treatment.
Grading heart murmur stages
If your vet discovers a heart murmur in your puppy, the first thing they’ll do is give it a grade. This gives an indication of how serious the murmur might be. It’s important to mention that while generally higher grade murmurs are of more concern, this isn’t always the case. However, higher grade murmurs often require more in-depth investigations.
Heart murmurs are graded on a scale of 1 to 6, based on how loud they are when your vet listens to your puppy’s heart with a stethoscope:
Stage 1
Stage 2
Stage 3
Stage 4
Stages 5 and 6 are the loudest and may even be felt as a vibration on the chest without the need for a stethoscope.
Heart murmur symptoms in dogs
Most puppies with murmurs, especially innocent ones, show no symptoms. However, more severe cases might present signs like:
If you notice any of these symptoms, especially if your dog’s already been diagnosed with a heart murmur, then it’s important to get them checked out as soon as possible - more on that later.
How’s a heart murmur detected?
Detecting and investigating a heart murmur involves multiple steps:
Physical examination
First your vet will listen to your puppy’s heart using a stethoscope, to identify the murmur’s timing, location, and intensity. This is when a murmur’s first picked up. Remember that the presence of a murmur tells us nothing about what might be causing it, so the next step is to investigate further.
Imaging techniques
X-rays or an echocardiogram (ultrasound of the heart) can visualise the heart’s structure, and pinpoint abnormalities. This allows the veterinarian to assess the size of your puppy’s heart and how blood is flowing through it. Thickening or changes to the heart muscle or problems with the valves are some of the most common things they’ll check for.
Electrocardiography
An ECG records your puppy’s heart’s electrical activity, to detect rhythm abnormalities. This can tell the vet if there’s something wrong with your puppy’s heart tissue, and the way that it conducts the electrical impulses - that are essential for a normal functioning heart.
Treatment options for heart murmurs
Most puppy murmurs don’t require treatment, as they’re ‘innocent’ murmurs that disappear as your puppy grows and develops. However, for those murmurs that don’t disappear or that have been diagnosed as a concern - then treatment’s likely necessary. Treatment depends on the underlying cause and severity. Here are the main options:
Observation and monitoring
For innocent murmurs, regular check-ups to monitor your puppy’s growth and heart health are often sufficient.
Medications
If a structural issue or heart failure symptoms are detected, medications like diuretics or ACE inhibitors may be prescribed. Similarly, any other causes such as anaemia will be addressed.
Surgical interventions
In severe cases, such as PDA, surgery might be necessary to correct the defect. This is rare, but many puppies can go on to live a normal life following surgery.
When to seek veterinary advice
If your vet identifies a murmur, ask these key questions:
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Is the murmur innocent or pathological?
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What follow-up tests or monitoring are needed?
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What symptoms should I watch for at home?
Prognosis of heart murmurs in puppies
The prognosis depends on the cause. Innocent murmurs usually resolve by 6 months old, while structural defects may require life-long management or surgery.
Most heart murmurs in puppies are innocent, and the puppy grows out of them to go on to live a normal life. However, for those more serious cases where an underlying cause is identified, the prognosis will depend on the severity of the murmur and how it responds to treatment.
What other tests may be recommended?
In addition to the diagnostic tests mentioned previously, your vet might suggest additional diagnostics like:
Myths and misconceptions about heart murmurs
Many pet owners panic when they hear that their puppy has a heart murmur, and it’s normal to do so - you’ve just been told that your little bundle of joy is imperfect. There are unfortunately many myths about heart murmurs in puppies that contribute to that panic.
The first myth is that a heart murmur always means a heart defect. This is often not the case - many murmurs are innocent and pose no long-term risk.
Another common misconception is that all heart murmurs require surgery. The truth is that most don’t; even murmurs that have a structural cause don’t always require surgery.
A small number of heart murmurs in puppies may require surgery to fix, but these are far more rare than you might think.
Life expectancy of puppies with heart murmurs
For puppies with innocent murmurs, life expectancy is completely normal. For those with congenital heart defects, prognosis varies based on the condition’s severity and treatment.
What percentage of puppy heart murmurs are innocent?
The vast majority of heart murmurs in puppies are innocent - around 50-70%. These will often resolve on their own, so there’s no need to panic straight away,
Conclusion: Making informed decisions about your puppy’s heart health
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Take your puppy to the vet for regular check-ups to keep an eye on the severity of the murmur. If it’s getting worse, then further investigations might be needed. However, many murmurs will get quieter as your puppy develops to the point at which they disappear.
FAQs
Should I get a puppy with a heart murmur?
Buying a puppy with a murmur can be confusing as it’s hard to know if they’ll grow out of it. It’s perfectly fine to hold off taking the puppy home to see if the murmur resolves itself. If you do take them home, then be sure to get them checked by your vet asap and be aware of the worst case scenario - should it be anything other than an innocent murmur.
What if a breeder says a puppy has a heart murmur?
If a breeder says that one of their puppy’s has a heart murmur, it’s a good idea to ask them for the medical history of the parent dogs. Is there any history of heart disease in genetics? Have any of the previous litters had puppies with heart problems? These will all help you make an informed decision as to whether the murmur is likely to be innocent or not. Ask for veterinary records and consult your own vet for a second opinion.
Can a Grade 3 heart murmur in a puppy go away?
In some cases, yes - especially if the murmur’s innocent. However, follow-up checks are essential to confirm this. If the murmur isn’t getting quieter, or even getting worse, then it’s more likely to have an underlying cause that warrants investigation.
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