A heart murmur is a noise related to abnormal blood flow in or out of the chambers of the heart. This is usually only audible with a stethoscope and can be heard in addition to, or instead of, the normal heart beat sounds. While murmurs in growing puppies are normal and often harmless (“innocent” or “puppy” murmurs), in adult dogs it usually indicates an underlying problem.
What signs might I see if my dog has a heart murmur?
This is very variable. Some dogs may show signs of a heart problem, such as lethargy, reduced ability to exercise, coughing or collapsing episodes. However, in many cases it might not be outwardly obvious that there is any issue. Quite often, a heart murmur is picked up by your vet at a routine appointment.
What causes a heart murmur?
The abnormal blood flow that results in a heart murmur can have several causes.
Valve disease
Especially in smaller breed dogs, murmurs can be caused by ‘leaky’ valves in the heart. The 4 chambers of the heart are separated by a system of one-way valves. Over time, these valves can become damaged and their parts no longer fit together perfectly to make a tight seal. This means that they are leaky. As a result, blood flows back through them into the chamber from which it has just been pumped out. This abnormal blood flow causes the sound of the murmur. This is sometimes called a murmur of regurgitation.
Narrowed vessels
The valves of the heart can also become narrowed (the veterinary term for this narrowing is “stenosis”). This means there is more resistance to blood flowing through them, resulting in abnormal blood flow.
Heart muscle disorders
Some large breed dogs (some examples of affected breeds are the Great Dane, Wolfhound, Doberman and Boxer) can develop a condition in which the heart chambers become abnormally enlarged and the heart muscle is weak and does not contract as efficiently as normal (Dilated Cardiomyopathy). This means when the heart pumps out blood, some ends up going to the lungs instead of being pumped effectively to the rest of the body. The stretching of the chambers also means that the valves can become damaged and leaky, resulting in a murmur.
Congenital heart problems
Murmurs are often audible in dogs with congenital heart defects. If there is for example an abnormal ‘hole in the heart’ this will cause abnormal patterns of blood flow and hence a murmur. However, it can be a completely normal finding for a young puppy to have a heart murmur; it does not necessarily mean a congenital heart defect is present. Some puppies have an ‘innocent’ murmur which is heard at early puppy checks but then goes away by a few months old. If your vet is concerned that a murmur may be caused by a congenital problem, then your puppy may be referred for further tests.
Changes to the blood
When dogs are unwell, for example with anaemia or a fever, the blood can become abnormally thin. In some cases, this can result in a heart murmur. This will go away once the underlying disease is resolved.
How is the cause of a heart murmur diagnosed?
To confirm what is causing the heart murmur, some diagnostic tests will often be required. Some of these may be performed at your veterinary practice or they may refer your dog to a specialist in heart disease (cardiologist) to perform some of these tests. These may include:
- X-rays of the chest – this will show fluid build-up on the lungs or an abnormally enlarged or misshapen heart.
- ECG – pads are placed on your dog’s skin to take a reading of the electrical activity from the heart. This will show up any problems with the rhythm of the heart.
- Ultrasound of the heart (echocardiography) – this scan gives an accurate picture of the size and shape of heart chambers, condition of the valves and any abnormal structures or patterns of blood flow. This will provide more detailed information than an x-ray.
What happens next?
The treatment and prognosis (predicted outcome) for a dog with a heart murmur very much depends on the condition causing it. Therefore, establishing an accurate diagnosis is crucial.
In some cases, a surgical operation may be required, for example to fix a congenital heart defect in a puppy. In many middle aged or older dogs with heart disease, treatment consists of medications given by the owner in tablet form. Your vet will also need to monitor your dog’s condition carefully with regular check-ups to listen for any changes to the heart murmur and check for any other signs developing.
As with many conditions, early diagnosis and treatment of heart problems often results in a better outcome.
Discussion
Vet told me my 11 year old chihuahua has grade 4 heart murmur. Can she go from nothing to grade 4 in 4 months? Or should they have picked it up earlier, she always has 6 month checks.
Yes, this can happen – heart disease can progress slowly, or rapidly, especially if, for example, something dramatic happens like a ruptured heartstring in the meantime.
However, I would say that what you’ve seen isn’t uncommon in smaller dogs, as the valves start to leak and suddenly a relatively loud murmur appears “out of nowhere” – the problem may well have been developing for a while, but it suddenly reached the critical point at which it produced and audible murmur.
My jack Russell terrier is three years old since birth. He has a 4 1/2 five heart murmur. I want to get him neutered the murmur has not tatties had no heart symptoms at all. Is it possible to get him neutered?
Probably, it just means that the anaesthetic will be more difficult. I’d suggest having a chat with your vet and seeing what they say; it might also be wise getting a heart scan to see WHY he has a murmur!
My four year old Whippet is said to have a heart murmur at his annual check up. He is a very nervous dog in the car and hates going inside the vet building …. could this anxiety give the impression of the heart murmur?
It is possible for a dog to develop a temporary physiological murmur due to extreme stress and a very high heart rate.
However, it’s usually fairly obvious that that’s what’s going on. And if your vets haven’t noticed it before, that does suggest that there’s an issue that wasn’t there before – either a new murmur, or a greater level of distress.
I think this does need to be taken seriously – possibly talk to your vet about re-examining him on a home visit, or even after an anxiolytic medication?
my 11 year old dog small mixed breed was seen by a vet say he has heart mumur srage 5 and i was seeing if there was any other options beside meddication because of the swelling in stomach and i was seeing if there anything else i could do or would i have put him down
It depends what has caused the heart murmur: however, in general, no: congestive heart failure due to valve leakage (what it sounds like we’re looking at here) isn’t repairable, but medication can dramatically improve quality and length of life and slow down the deterioration. There is an experimental surgery to repair damaged valves, but there are only 3 centres in the world performing it and a dog of that age probably wouldn’t be a good candidate anyway. So I think medical management, usually with pimobendan, an ace inhibitor, and a diuretic or two, is the best route forward here. Good luck!
My 1-year old dachshund puppy has been diagnosed with Stage 5/6 heart murmur, and is scheduled to be urgently seen at the Vet Hospital in Dublin (Ireland). He appears very well with no overt symptoms, but I appreciate this recent finding is serious, and am wondering if you can possibly predict what I should expect when he attends his appointment on Monday 25th July.
I’m sorry to hear that – it must have come as a great shock if he seems otherwise healthy. The first thing that the hospital (and your vets, hence the referral) will be wanting to know is what’s causing the murmur. A heart murmur isn’t strictly a disease – it’s just an abnormal sound that tells us there’s abnormal blood flow through the heart. In a puppy of that age, there are lots of different options, including holes in the heart and other congenital abnormalities, but also narrowing of certain blood vessels in the heart. So the cardiology team will want to get a really good look around – first with X-rays, and then with a series of ultrasound heart scans and ECGs, and possibly other imaging such as CT (although this is less commonly used). Once the cause is identified, the options for treatment can be discussed.
Hope it all goes well – good luck!
My one year old puppy has a heart Murmur diagnosed by our Vet. May I get a second opinion on, should we have her neutered or not? What are the Risks?
A heart murmur isn’t a diagnosis – it’s just an abnormal sound superimposed over the heart noises. It might eb completely benign and have no impact on her risk factors at all, or it might be a sign of a serious congenital heart defect meaning she is at grave risk of sudden death even without anaesthesia. If your vet is confident that it would be safe, then she probably is – but if you do want a second opinion, you’d be best getting a referralf rom your vet to a veterinary cardiologist who can determine exactly what’s going on in there, and then you’ll have all the facts you need to make an informed decision!
I’m buying a new puppy the vet has discovered a very low grade heart murmur should I go through with buying the puppy
No way to know: it depends what the murmur is! A high percentage of puppies have “puppy murmurs” or “benign murmurs” that they grow out of; however, a few do have congenital heart problems that initially sound very similar. Talk to the vet and get the advice of someone who’s actually examined the pup!
My 3 year old french bulldog has been diagnosed with a heart murmur, with the rating of 1-2. Is this something to worry about? The vet who delivered the news was very uninformative and cold. So I guess we are after a second opinion. Thanks in advance.
A heart murmur doesn’t tell us what’s happening, just that there is abnormal bloodflow through the heart. Occasionally this can be incidental, but in a 3 year old dog it’s likely to relate to some sort of heart disease. This might be leaking valves, or distended heart chambers, or narrowed vessels, or a congenital defect – the murmur doesn’t tell us what’s going on.
So, it is something to worry about? Possibly. The best way to be sure would be to get an echocardiogram (a heart ultrasound) from a vet who is an expert or a specialist in cardiology, and see what’s actually going on in there – then you’ll know what needs to be done, if anything. Good luck!
My 9 year old cavalier has been diagnosed with a grade 4-5 heart murmur . She is a bit overweight . Would it be best for her to be scanned before she loses a bit of weight or straight ?
Weight loss would make the scanning process easier, but I suspect knowing what’s going on is most important right now – have a chat with the vet who will be doing the scan (or your regular vet if it’s an external person), and see what they think.
My vets has said my dog heart murmour has got worst so they want her to have a scan but my husband doesn’t want her to have it will they say how long she has left with us is it inportant for her to have it
The scan will tell you exactly WHY your dog has a murmur – just from listening it’s impossible to be sure. It will also tell you how bad it is. Some noisy ones are actually less severe than other quieter ones. The scan won’t change what’s happening in and of itself, but it will let your vet decide what the prognosis is and what the best management options are. Otherwise, to a great extent they’re flying blind. It’s theoretically possible to fly through a mountain range using only a compass and a stopwatch, but most pilots much prefer to be able to see out the window!