Medically reviewed by Dr. Sara Ochoa, July 22, 2022
It’s scary when your dog gets a diagnosis of a heart murmur. You want to know what it means, how it’s treated, and what kind of life expectancy you can expect for your dog.
Essentially, a heart murmur is an abnormal heart sound. It’s detected when a veterinarian listens to the heart using a stethoscope.
The abnormal sound is caused by turbulence in the blood being pumped through your dog’s heart. At this stage, the veterinarian will want to determine what is causing the heart murmur.
A good way to understand a heart murmur is to picture a hose with a kink in the line. The hissing-sound of the water flowing past the kink is similar to a heart murmur.
There’s Hope
This dog heart murmur life expectancy guide is designed to give you hope and a better understanding of the diagnosis. Ultimately, the prognosis for a dog with a heart murmur has a lot to do with the severity.
The veterinarian will also take into consideration whether the heart murmur is caused by:
- structural heart disease
- extracardiac problems
Rest assured, dogs with heart murmurs often live long and healthy lives.
Once a diagnosis is made, it’s important to understand that your dog’s life expectancy isn’t necessarily related to the heart murmur.
It’s Common
Heart murmurs are a common diagnosis in veterinary medicine.
While we tend to associate heart problems with older dogs, puppies and young dogs can develop these murmurs as they grow.
The abnormal sound is caused by turbulence in the blood being pumped through your dog’s heart. At this stage, the veterinarian will want to determine what is causing the heart murmur.
TIP: A good way to understand a heart murmur is to picture a hose with a kink in the line. The hissing-sound of the water flowing past the kink is similar to a heart murmur.
What is a Heart Murmur?
A murmur is an audible noise that can be heard through a stethoscope. It’s caused when there is a disturbance in the blood flow. Veterinarians break heart murmurs into different classifications.
What Causes Heart Murmurs in Dogs?
Unfortunately, determining the cause of the murmur can be difficult. There are many kinds of heart disease and heart defects that can lead to heart murmurs in dogs.
Generally speaking, a veterinarian will try to identify the cause based on different categories of blood flow disturbances including:
- Abnormal valves or vibrations
- Obstruction, diseased valves, or dilated blood vessels
- Regurgitant flow disturbance
Different Types of Heart Murmurs
There are three types of heart murmurs in dogs:
Systolic Murmurs
The most common cause of systolic murmurs is due to a narrowing of the blood vessel that causes obstruction of blood flow.
This type of murmur the most commonly diagnosed in dogs. The most common reason for systolic murmurs in dogs is related to the narrowing of the blood vessels which causes an obstruction of blood flow.
Other underlying conditions that could cause a systolic murmur include:
- Anemia
- Heartworm disease
- Hyperthyroidism
- Cardiomyopathy
- Aortic valve insufficiency
- Mitral and tricuspid heart failure
- Systolic anterior mitral motion
- Endocarditis of the mitral and tricuspid valve
READ: Life Expectancy of a Dog With Artery Inflammation
Diastolic Murmurs
This type of murmur is very rare in dogs. When it happens, however, it is usually associated with aortic insufficiency. Aortic insufficiency occurs when the aortic valve does not close tightly.
Continuous Murmurs
Continuous heart murmurs in dogs are most commonly caused by patent ductus arteriosus (PDA).
This is a heart defect that happens when the ductus arteriosus (a blood vessel in the developing fetus) fails to constrict. This leaves a passageway for blood flow. Eventually, it leads to left-sided heart disease or generalized heart failure.
The ductus arteriosus is supposed to close at birth. When it doesn’t, it causes a continuous murmur.
Dog breeds that may be more predisposed to PDA include:
- German Shepherd
- Newfoundland
- Maltese
- Chihuahua
- Poodle
- Pomeranian
- Yorkshire Terrier
- Doberman
Innocent (Physiological) Murmurs
These so-called “innocent” murmurs usually appear around 6 weeks of age. Sometimes they come and go, and your vet may hear a murmur on one visit but not the next.
These murmurs are caused by changes in the heart as the puppy rapidly grows but have no lasting impact on your dog’s health. Puppies tend to outgrow this type of murmur.
A puppy or young dog with an innocent heart murmur has the same life expectancy as a dog with no heart murmur.
Congenital Heart Murmurs
Not all murmurs in puppies are innocent murmurs.
If your puppy has an intense murmur or one that does not improve as they grow your vet may start to suspect they have congenital heart disease.
Congenital heart defects are structural defects in the heart that your dog is born with. They may be mild or severe, and are fairly common in some breeds of small dogs.
Some congenital heart defects are surgically-repairable but many are not.
Unfortunately, congenital defects may dramatically reduce the life expectancy of your dog if they can’t be corrected through surgery.
Heart Murmur Qualities or Configurations
Once the kind of heart murmur is diagnosed, the veterinarian will be able to identify the quality of the murmur. It can be confusing for dog owners to understand all of this information which is why we always suggest asking a veterinarian for clarification.
The 4 main types of configurations include:
Plateau Murmurs in Dogs
These have a uniform loudness. Instead of getting louder and quieter, the noise level remains the same. This is usually associated with aortic valve insufficiency (a disease of the heart valves where the aortic valve doesn’t function properly).
Crescendo-Decrescendo Murmurs
These murmurs get louder and then quieter. They are associated with aortic and pulmonic stenosis. An aortic stenosis (or aortic valve stenosis) occurs when the valve narrows. When this happens, blood flow is blocked and cannot easily flow from the heart to the main artery.
Decrescendo Murmurs
These murmurs start loud and then get quiet. They are usually seen with either an aortic valve insufficiency or a ventricular septal defect.
Machinery Murmurs
Machinery quality, or continuous murmurs, are associated with congenital heart defects in dogs.
6 Signs of Heart Murmurs in Dogs
If your dog starts to display any of the following symptoms, have them evaluated by a vet as soon as possible.
Coughing Dog
Dogs cough for a variety of reasons and that one sign doesn’t necessarily point to a heart murmur or heart disease.
For example, heartworms, parvo, and kennel cough can all cause a dog to cough. It’s important to know that sound and severity of the cough isn’t directly related to heart murmurs in dogs.
Dogs with a heart murmur tend to have an enlarged heart. When the heart is enlarged, it loses the ability to pump blood efficiently through the lungs and to the rest of the body.
It’s normal for a dog to cough sometimes, but if you notice it happens more often than it should, and is accompanied by other signs (like those below), seek the advice of a licensed veterinarian.
In fact, anytime your intuition tells you there’s something not right, make an appointment for your dog to see a veterinarian.
Dog Has Difficulty Breathing (Dyspnea)
Rapid breathing isn’t the same as panting on a hot day or after exertion.
When a dog is having trouble breathing, you’ll notice other problems like anxiety and an unusual stance.
Your dog might sit or stand with legs wide. The dog’s mouth may remain open as he tries to get more air into his lungs.
Difficulty breathing is one sign of heart disease in dogs. Take note of when it happens and how long it lasts.
This is important information for the veterinarian to know. Is your dog having trouble breathing during or after exercise? Does it happen when your dog is at rest?
Congestion or “Noisy” Breathing
Brachycephalic dogs (dogs with flat faces and very short noses) are known for noisy breathing.
You might heart “snorting”, “snoring sounds”, or a high-pitched sound known as stridor.
You know what sounds normal for your dog and what doesn’t.
If you suspect any kind of unusual breathing patterns, it’s time to take your dog to the veterinarian for an assessment. It could be a sign of heart disease in dogs.
Exercise Intolerance
Recognizing an exercise intolerance in dogs can be tricky.
It’s easy to blame old age, a shift in weather, sore joints, or any number of things on a dog’s reluctance to exercise.
Most dogs, however, are happy to get out for a regular walk.
If your dog is showing signs of distress and suddenly refuses to move, he/she could be showing signs of a heart murmur.
Weakness or Fatigue
The heart muscle moves vital oxygen through the body to all of the organs. Without enough oxygen, the vital organs become starved.
If your dog’s heart is working too hard (high heart rate) or not hard enough (heart failure) he/she is going to be exhausted.
Fainting Episodes
Fainting in dogs (syncope) occurs when a sudden shift in heart rhythm (could be very fast or very slow) halts adequate blood flow to the brain.
Fainting on it’s own isn’t particularly dangerous. However, the underlying cause could be.
Gray or Blue Gums
Gray or blue gums are caused by lack of oxygenated blood flow through the body.
If your dog’s heart is not properly pumping blood, he/she may have gray or blue-tinged gums.
Sometimes, discolored gums are a sign of dehydration unrelated to heart conditions.
Abdominal Distention (Pot Belly)
The sudden appearance of a pot-belly on a dog coud be related to heart disease.
When the heart cannot pump blood adequately through the body, fluid build-up can occur in the tummy.
Collapse
In severe causes of heart disease, the body simply cannot generate enough energy.
How Is a Heart Murmur Diagnosed in a Dog?
Most of the time, a heart murmur is diagnosed at a routine vet visit. Many murmurs are so subtle that they can only be detected by listening to the heart with a stethoscope.
Even then, low-grade murmurs can be easy to miss.
Read: Symptoms of Heart Disease in Dogs
Physical Exam
The veterinarian will perform a physical exam to check respiratory rate and blood pressure. He/she will use a stethoscope to listen to the heart sounds.
Chest X-Rays
Chest x-rays are useful as a way to check for any physical abnormalities.
If your vet hears a heart murmur the first thing they will do is determine the grade of the heart murmur.
Heart murmurs are graded 1 through 6 based on how loud or intense they are.
A level 1 murmur is a subtle sound, while a 6 is so loud you can actually feel the murmur with your bare hand.
Click here to read about Von Willebrand Disease in Dogs
Grading Scale for Heart Murmurs in Dogs
Grade 1– barely audible.
Grade 2– soft, but easily heard with a stethoscope.
Grade 3 -intermediate loudness.
Grade 4– loud murmur that radiates widely, often including opposite side of chest
Grade 5– very loud, audible with stethoscope barely touching the chest; the vibration is also strong enough to be felt through the animal’s chest wall.
Grade 6– very loud, audible with stethoscope barely touching the chest.
The vibration is also strong enough to be felt through the animal’s chest wall.
Once your vet has graded the murmur they will also classify it based on several other characteristics.
They will consider the location of the murmur (right or left side of the heart) and whether the murmur is heard during the heart’s contraction or while it is relaxed (systolic vs diastolic).
Senior Dog Heart Murmur Life Expectancy
A heart murmur diagnosis in an older dog may or may not affect their life expectancy
It depends on what is causing the murmur. Many vets do not treat an acquired heart murmur as long as the dog isn’t showing any symptoms of heart disease.
READ NEXT: The Ultimate Dog Seizure Bible
Early Diagnosis is Key
If your dog has a congenital heart defect, it is important to get an early diagnosis and have a cardiologist involved.
While medications can often reduce the impact of a congenital heart defect, without surgery most dog with a defect like this will go into heart failure at a young age.
When Is a Murmur a Problem?
So when do you need to be worried about a heart murmur?
Generally, if your dog has a low-grade murmur ( grade 1 or 2) and has no other symptoms of heart disease your vet may recommend a wait-and-watch approach.
They may have you come in more frequently for exams, or have you monitor your dog’s breathing at home.
Heart murmurs can be a serious sign of other medical problems, however. If your dog is sick or showing signs of heart disease then your vet will likely want you to consult with a specialist.
Should You See a Specialist?
Having a dog with a heart murmur evaluated by a cardiologist is never a bad idea if you can afford the expense.
Many cardiologists are covered under pet insurance plans too.
A cardiologist will be able to view your dog’s heart using a special kind of ultrasound called an echocardiogram.
This will allow them to view the chambers, valves and arteries and check the thickness of the heart wall.
You will get a specific diagnosis and treatment plan from your cardiologist and you will have the benefit of knowing exactly what your dog faces.
The only true way to know how a heart murmur will impact your dog’s life expectancy is to seek specialty care.
A dog can have a heart murmur for years before they develop signs of heart disease. If you know what to watch for, you can get your dog into a vet before they go into a crisis.
What Causes Heart Murmurs in Dogs?
Causes of heart murmurs are generally due to blood flow disturbances.
These can be:
- Abnormal valves or vibrations
- Obstruction, diseased valves, or dilated vessels
- Disturbances caused by regurgitant flow
- Mitral valve regurgitation
In some cases, underlying disease may be the cause.
Heart Murmurs Are Hard to Predict
As you can see, heart murmurs are difficult to predict. The life expectancy of a dog with a murmur will vary a lot and will depend on what is causing the murmur.
Many dogs have murmurs for years and never develop any signs of heart disease, while others slip into CHF rapidly. Some breeds are more prone to developing heart disease.
These include:
- Cavalier King Charles Spaniel
- Doberman Pinschers
- Pugs
- Chihuahuas
- Boxers
- Cocker Spaniels
The good news is that many dogs with murmurs never develop active heart disease, and even those that do often do well with treatment. I have seen dogs survive with CHF for several years with diligent care and medication.
A heart murmur is not necessarily a dangerous diagnosis, even though it sounds scary.
There are also many great treatment options for dogs with early-stage heart disease. When in doubt, talk to your vet or seek out a cardiologist for advice.
Congestive Heart Failure in Dogs
Congestive heart failure occurs when the heart cannot pump an adequate amount of blood to the body.
This causes an increase in pressure and fluid. Eventually, that fluid leaks into the lungs.
When fluid gets into a dog’s lungs, the dog cannot breath normally. The lungs are unable to expand enough to take in sufficient oxygen. CHF doesn’t always happen quickly. It can be slow-onset over time.
Causes of Heart Failure in Dogs
Not all dogs with a heart murmur will develop Congestive Heart Failure.
The severity of the heart murmur, the age of the dog, and the combination of underlying disease (secondary disease) may impact the outcome.
Progression to Heart Failure
Once fluid begins to back into the heart chambers or extend into the lungs, the heart chambers become damaged.
This is due to preload and stretching of the heart chambers.
This fluid increase also causes something called hydrostatic pressure in vessels that supply the left and right atria.
Underlying Disease Leading to CHF
There are different heart conditions that can lead to CHF in dogs. Some of these conditions include the following:
- Degenerative Mitral Valve Disease – most common acquired heart disease in dogs. Sometimes a heart murmur is a sign of DMVD.
- Dilated Cardiomyopathy – disease of the heart muscle that may have no symptoms for up to 2 years
At Home Monitoring of Heart Disease in Dogs
Veterinarians may suggest that you become as educated as possible about the clinical signs of heart disease in dogs. In addition, you may be asked to record resting or sleeping breath rates at home.
Other suggestions for monitoring your dog’s health include:
Avoid High-Salt Foods
Talk to your veterinarian about the best food for your dog. Dogs with heart disease require more than just a low-salt diet. It’s also important to watch phosphorus and potassium levels in dog food.
Monitor Activity Level
Strenuous exercise may be dangerous to a dog with heart disease. Talk to the veterinarian about the most appropriate exercise level for your dog.
An easy way to monitor the precise activity level your dog is getting on a daily basis is through the FitBark Inc. monitor system.
Note: Always check with a veterinarian before changing your dog’s activity levels, especially if your dog has been diagnosed with a heart condition.
Success is often measured in the quality of the dog’s life in addition to life span after diagnosis.
When the dog’s health is managed properly, dogs can enjoy a good quality of life and extended survival times.
Frequently Asked Questions about Heart Murmurs in Dogs
How Long Can A Dog Live With a Heart Murmur?
Dogs can live a long life after being diagnosed with a heart murmur. The best place to get the most accurate prognosis is from the veterinarian.
He/she knows your dog and can make an assessment based on the severity of the heart murmur, your dog’s age, and whether underlying conditions are present.
How Serious Are Heart Murmurs in Dogs?
Although they sound scary, heart murmurs are not always a cause for concern. Depending on what’s causing the heart murmur, they can often be treated. Sometimes they will even resolve on their own.
Should I Walk My Dog With a Heart Murmur?
Dogs with heart murmurs tend to be less tolerant of hot and humid days. Short walks with less exertion may be advisable.
Always speak to a veterinarian about your dog’s exercise needs and limitations.
What Happens to a Dog with a Heart Murmur?
A heart murmur prevents the heart from effectively pumping blood throughout the body. As a result, your dog may be weak and not in the mood to exercise much. Dogs can develop extreme weakness and fatigue.
Although there is no direct treatment for heart murmurs themselves, the veterinarian can likely form a treatment plan for whatever is causing the murmur.
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Thank you
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If you have any comments or questions, please contact me directly at latheriault@hugspetproducts.com. And please…take a second to share! Thank you.
Kevin Dever
Monday 5th of June 2023
My Dog Chihuahua had a murmur sine he was an infant. Vet says its a minor murmur but he could hear in each we brought him in for an exam. Now he became 13 years old but seemed to be active loved going for walks and playing with his toys. One bad thing he sat on the couch headrest looking out the window and would bark sometimes vigorously especially with large muscular dogs he would go crazy with anger (hair Sticking up. I was worried when her would get so angry I thought he would fall out the window one day. This event happened daily. Then one day he did not eat his breakfast and by early afternoon he vomited and we could be pieces of last nights dinner. Afterward he kept vomiting but it was a bile a clear liquid he threw out. We made an urgent care appointment to see the vet. Xray showed no blockages in stomach or intestines. Blood draw showed no signs if poison. Exam he heard the murmur again but felt that it was minor. Stool came out during the visit and it was clear with blood color in the stool. The doctor gave us 3 vaccinations the third one was a Antibiotic and he was also prescribed for the next day to be taken until finished. The vat said don't worry he will be fine by tomorrow. We agreed as with the medicine starting he will be better. We took him home. He did not want food tool some water but could not get comfortable moving from the couch to the floor to the ottoman to six different places. We still figured he needed time for the medicine to work. He died in my arms stretched across my chest in a recliner chair. We was whimpering a little and he made some grunting noises mixed in with the whimpering. He was breathing hard, seems like I felt some contractions around stomach now and then. 15 minutes later he made three deep breaths and he died in my Ares. Once he passed he went completely limp and blood came from his nose. We lost me. He seemed to be in good health prior and this happened all of the sudden. The doctor/vet was shocked when I called him the next day. He said nothing in his evaluation let him believe that he would pass. We are all confused. Any thoughts?
Thank You
Kevin
Lisa Theriault
Monday 5th of June 2023
I'm so sorry for your loss! It's heartbreaking when we lose a pet. They're part of the family! I'm not a veterinarian, so anything I say is not to be taken as medical advice. My personal opinion (not a medical opinion in any way) is that he may have an internal rupture of some kind. I recently had to have my dogs humanely euthanized for various medical reasons. But one of my dogs had an enlarged spleen that was ready to rupture. It's possible that's what happened to your dog, but - again - I'm not a veterinarian.
You may want to look up information on enlarged spleens in dogs for more information. It could have been any number of things, however. Again, I'm so sorry for your loss. I am still deeply grieving the loss of my own two senior dogs and I understand how painful the process is.