Heart murmurs can occur in any dog, regardless of age, sex, size, or breed. While heart murmurs are not always a problem, they can be a sign of other serious health issues and may indicate the presence of heart disease. A heart murmur is detected as an abnormal sound by a veterinarian during an examination. There are several reasons why your veterinarian might notice this sound while listening to your dog's heart with a stethoscope. Structural abnormalities and extracardiac conditions are common causes and often result in "harmless" heart murmurs that do not require treatment and may disappear on their own. Puppies of large breeds are more prone to harmless heart murmurs, while small breeds have a higher risk of acquired heart murmurs.
If left untreated, heart disease can lead to serious health problems, so a heart murmur needs to be noticed by a veterinarian to determine if there are other underlying conditions. Even without any symptoms, your veterinarian may detect a heart murmur in your dog during a routine checkup. Because heart murmurs can go undetected if you don't see your vet regularly, it's important for dog owners to schedule a checkup for their dog at least once a year.
What is a heart murmur?
A heart murmur is an abnormal heart sound that occurs when blood flow within the heart is turbulent; it sounds similar to a hissing sound when listened to with a stethoscope. While a heart murmur itself is not a disease, it may indicate heart disease or other health problems.
Any disturbance to the heart's natural blood flow will result in turbulence that can be heard with a stethoscope. The heart has four chambers: the right atrium, right ventricle, left atrium, and left ventricle. In a normally functioning heart, deoxygenated blood from veins enters the right atrium and is pumped into the right ventricle. Blood flows through the pulmonary artery, becomes oxygen-saturated, and then enters the left ventricle. This oxygenated blood is pumped into the left atrium and then flows through the arteries into the body. Valves between each chamber and blood vessel keep the blood flowing in the correct direction.
Heart murmurs are typically graded from 1 to 6 (I-VI) based on intensity. Grade I heart murmurs are the faintest and are difficult to detect. These murmurs are quiet and may occur intermittently. Grade VI murmurs are the most severe. They are very loud when listened to with a stethoscope and can usually be felt by placing your hand on the dog's chest. The higher the grade of the heart murmur, the greater the turbulence in blood flow within the heart.
Symptoms of a heart murmur in a dog
Dogs with a heart murmur may or may not show any clinical signs of illness. Because a heart murmur is a sign of a possible heart problem, but not an actual disease, the presence of other symptoms depends on the severity of the underlying condition (if any). If your dog has a history of heart murmurs, be alert for signs of serious problems such as heart failure, or moderate symptoms indicating other illness requiring further investigation. Dogs with heart disease often exhibit the following symptoms, which can be indicated by a heart murmur:
symptom
cough
Drowsiness, exercise intolerance, or weakness
wheezing or abnormal breathing
Pale gums
Abdominal distension (the appearance of a swollen abdomen)
The plot of the collapse
cough
A swollen heart puts pressure on the lungs, causing dogs with heart disease to cough. Coughing is a sign of many different types of heart disease, as various cardiovascular conditions can cause a dog's heart to enlarge. 3
Drowsiness, exercise intolerance, or weakness
Exercise intolerance is another common symptom of cardiovascular disease in dogs. 3. Dogs may tire quickly after activity, appear weak, or become lethargic at home due to insufficient heart function.
wheezing or abnormal breathing
Your dog may experience persistent panting or abnormal breathing. Breathing problems can be more severe in dogs with heart conditions, especially at night when sleeping or when getting up from a lying position.
Pale gums
Pale gums can be associated with a more serious stage of heart disease in dogs. While this can also be a sign of dental problems, if you notice that your dog's gums are any color other than pink, make an appointment with your veterinarian to determine the cause.
Abdominal swelling
Dogs with heart disease may experience abdominal swelling. This is caused by fluid buildup in the abdomen, also known as ascites.
The plot of the collapse
When your dog collapses, it's crucial to get it to your veterinarian's attention. These symptoms can occur in dogs with heart conditions when the disease causes insufficient blood flow to the brain (and eventually leads to unconsciousness). 3
Causes of heart murmurs
Heart murmurs can be caused by a variety of reasons and are not always a sign of other diseases. Further diagnosis is usually required to find the actual cause, especially for high-grade murmurs.
Heart structural abnormalities
Structural problems such as valvular leaks or ventricular holes can cause abnormal blood flow. This creates turbulence, which can be heard as a heart murmur. Some structural abnormalities are present at birth, while others may develop later in life. Common cardiac structural abnormalities include:
Mitral valve disease (also known as mitral regurgitation, which is more common in small dogs)
Tricuspid valve disease
Subaortic or pulmonary valve stenosis (valve narrowing)
Patent ductus arteriosus (an extra blood vessel present at birth)
Endocarditis (inflammation of the heart; sometimes caused by infection)
Extracardiac diseases
Even if the heart itself is functioning normally, certain problems in the body can affect blood flow to the heart.
anemia
Heartworm disease
Hyperthyroidism
hypoproteinemia
Infect
The noise of a pure heart
"Harmless" or physiological heart murmurs are benign, meaning they are not caused by a disease process. These murmurs are usually mild to moderate (grade I-II). Puppies may have innocent heart murmurs, which will disappear as they grow.
If your veterinarian detects a mild to moderate heart murmur without any other signs, they may simply want to re-examine your dog periodically to monitor for the murmur, rather than immediately recommending further diagnosis.
Diagnosing a dog's heart murmur
A heart murmur is detected when a veterinarian hears an unusual hissing sound while listening to a dog's heart with a stethoscope. Mild to moderate murmurs are often found during a routine veterinary appointment if there are no other symptoms, but severe murmurs usually indicate a more serious underlying condition. Dogs with murmurs associated with extracardiac diseases or structural heart problems often exhibit other symptoms that can help your veterinarian diagnose the cause.
After obtaining a detailed medical history of your dog from you, your veterinarian will perform a thorough physical examination. If a heart murmur is heard, its intensity will be graded (from I to VI).
Your veterinarian will then determine if another illness is present. Several diagnostic tests will be performed to assess heart function and overall health. Blood chemistry, a complete blood count, and a urinalysis will be conducted to assess organ health and cell counts. A chest X-ray will be necessary to see the heart size and details of the heart and lungs.
Next, specialized cardiac tests may be required to examine your heart more closely. Your primary veterinarian may refer you to a veterinary cardiologist for these tests. An electrocardiogram (ECG or EKG) measures the heart's electrical activity by displaying waveforms and analyzes these waveforms to look for abnormalities. An echocardiogram is an ultrasound examination of the heart that shows the heart beating and the blood flow through it. The sonographer can measure the ventricles and valves of the heart and look for abnormal blood flow patterns.
Treatment and prevention
Since a heart murmur itself is not a disease but rather a symptom of an underlying condition, treatment will depend on the underlying cause of the murmur, if any. Asymptomatic dogs with mild heart murmurs may not require any treatment. However, moderate to severe murmurs require further action, especially if clinical signs are observed.
Once a diagnosis is made, treatment recommendations can be discussed. Some heart abnormalities require surgical repair. In addition to supportive care from the owner, other conditions can be treated with specialized diets or medications. Dogs with heart disease require regular follow-up with their primary veterinarian and/or cardiologist to monitor treatment response and assess disease progression.
Prognosis of dogs with heart murmurs
Some heart murmurs disappear over time. Many innocent murmurs in puppies will disappear on their own as the dog grows, but some serious conditions, such as dilated cardiomyopathy, can be severe or even fatal. Congenital heart disease can have significantly different prognoses—some can be corrected surgically, but others may require long-term treatment or be more serious. Your dog's specific prognosis will depend on the cause of its heart murmur, which your veterinarian can diagnose to determine the appropriate treatment plan.
How to prevent heart murmurs
Not all heart murmurs are preventable, but early detection allows your veterinarian to treat underlying conditions before they become serious. Always follow your veterinarian's treatment and follow-up recommendations. If you are unable to follow the recommendations, consult your veterinarian, as consistency of treatment is crucial for your dog's survival. While harmless murmurs and murmurs caused by structural problems may not be preventable, the following methods can help prevent some heart murmurs caused by extracardiac conditions:
Regular teeth cleaning
Maintaining your dog's dental health is an important way to prevent heart diseases such as endocarditis. Regular dental cleanings at a veterinary office and regular brushing are essential home care practices. Teething toys may also be beneficial, but treatment should be monitored to help your dog maintain a healthy weight.
Diet and Nutrition
Excessive weight gain can increase your dog's risk of heart disease and other serious health problems. Since these are among the most common preventable canine diseases, this is also a way for owners to help prevent heart problems in their dogs. Feed your dog high-quality dog food and consult your veterinarian to determine the appropriate portion sizes based on your dog's specific needs.
exercise
Regular exercise with your dog throughout its life is an effective way to support heart health. Dogs with underlying medical conditions should engage in daily exercise under the supervision of a veterinarian to ensure their heart and lungs can support their activity levels.
