Canine Heart Murmurs

a dog having it heart checked by a vet

Any dog, regardless of age, sex, size, or breed, can develop a cardiac murmur. While cardiac murmurs are not always a concern, they can be an indication of other major health issues and may signal the presence of heart disease. Veterinarians notice heart murmurs as aberrant noises during exams. There are a number of reasons why your doctor could hear this sound while listening to your dog's heart using a stethoscope. The most prevalent causes include structural abnormalities and extracardiac diseases, including "innocent" heart murmurs that do not require treatment and can go away on their own. Large-breed puppies are more likely to develop innocent heart murmurs, whereas small-breed puppies are more likely to develop acquired heart murmurs.

Heart illness can cause major health problems if left untreated, thus heart murmurs should be investigated by a veterinarian to see if there are any other disorders present. Even if no symptoms are apparent, your veterinarian may discover an accidental murmur in your dog's heart during a normal health examination. Because cardiac murmurs can go unnoticed without regular visits to the veterinarian, dog owners should arrange yearly check-ups for their pets.

What Is a Heart Murmur?

A heart murmur is an abnormal heart sound that develops when blood flow in the heart is turbulent, and it sounds like a whooshing noise when heard with a stethoscope. A heart murmur, while not an illness in and of itself, may suggest cardiac disease or another condition in the body.

Any disturbance in the heart's normal blood flow can generate turbulence, which can be heard with a stethoscope. The right atrium, right ventricle, left atrium, and left ventricle are the four chambers of the heart. Oxygen-depleted blood from the veins enters the right atrium and is pushed into the right ventricle in a healthy heart. The blood reaches the left ventricle after passing via the pulmonary artery and becoming oxygen-saturated. This oxygenated blood is pushed via the left atrium and then out through the arteries to the rest of the body. Blood is kept going in the right direction via valves between each chamber and the blood arteries.

The severity of heart murmurs is usually assessed on a scale of one to six (I-VI). The mildest cardiac murmurs are grade I, and they might be difficult to detect. These whispers are subtle and might happen at any time. Murmurs of grade VI are the most serious. When listening with a stethoscope, they are quite loud and can typically be felt by laying your hands on the dog's chest. The greater the blood flow turbulence in the heart, the higher the grade of a heart murmur.

Symptoms of Heart Murmurs in Dogs

Heart murmurs in dogs may or may not be accompanied by clinical indications of disease. Because a heart murmur is a symptom of a potential cardiac issue rather than an illness, the occurrence of other symptoms is dependent on the severity of any underlying condition. If your dog has a history of heart murmurs, keep a look out for indicators of serious issues, such as heart failure, or mild symptoms that indicate other diseases that need to be tested further. A heart murmur can signal the following symptoms in dogs with heart disease:


  • Coughing
  • Lethargy, exercise intolerance, or weakness
  • Panting or abnormal breathing
  • Pale gums
  • Distended abdomen (bloated appearance of belly)
  • Episodes of collapse


Heart swelling can put pressure on the lungs, causing coughing in dogs with heart disease. Coughing can indicate a variety of heart conditions, since many cardiovascular disorders can all cause your dog's heart to grow.

Lethargy, Exercise Intolerance, or Weakness

Another prevalent symptom of cardiovascular illness in dogs is exercise intolerance. Due to inadequate cardiac function, your dog may grow fatigued fast after being active, seem frail, or act sluggish at home.

Panting or Abnormal Breathing

Your dog may pant often or have irregular respiratory patterns. Breathing problems in dogs with heart disease are more common at night when they sleep or when they get up from laying down.

Pale Gums

In dogs, pale gums are linked to more advanced stages of heart disease. If your dog's gums are any color other than pink, this might be an indication of dental problems. Make an appointment with your veterinarian to discover the cause.

Distended Abdomen

Dogs with heart disease may appear bloated in their bellies. This is caused by fluids pooling in the abdomen and may also be referred to as ascites.

Episodes of Collapse

If your dog collapses, get medical treatment immediately. These episodes occur in dogs with heart disease when the ailment produces a shortage of blood supply to the brain (and ultimately, makes the dog lose consciousness).

Causes of Heart Murmurs

A cardiac murmur can arise for a variety of causes and is not always indicative of other illnesses. In order to find an actual reason, more tests are usually required, especially with higher-grade murmurs.

Heart Structure Abnormalities

Improper blood flow can be caused by structural issues such as leaky valves or holes in the heart chamber. Turbulence is created, which is audible as a cardiac murmur. Some structural defects are apparent at birth, while others emerge later. The following are common cardiac structural abnormalities:

  • Mitral valve disease (also known as mitral insufficiency, and more common in small breeds)
  • Tricuspid valve disease
  • Subaortic or pulmonic stenosis (narrowing of valves)
  • Patent ductus arteriosus (extra vessel present at birth)
  • Endocarditis (inflammation in the heart; sometimes caused by an infection)

Extracardiac Conditions

Certain problems in the body can affect the flow of blood through the heart, even if the heart itself is functioning normally.

Innocent Heart Murmurs

Heart murmurs that are "innocent" or "physiological" are benign, meaning they are not produced by a disease process. These murmurs are usually mild to moderate in intensity (grade I-II). Heart murmurs in puppies are common and usually fade away as they develop.

If your veterinarian discovers a mild to moderate heart murmur in the absence of additional symptoms, he or she may prefer to just revisit your dog on a regular basis to monitor the murmur rather than ordering further testing straight immediately.

Diagnosing Heart Murmurs in Dogs

Heart murmurs are identified when your veterinarian listens to your dog's heart using a stethoscope and detects an odd whooshing sound. If no other symptoms are present, mild or moderate murmurs are commonly discovered during regular veterinarian visits, while severe murmurs are frequently accompanied by indicators of more serious disorders. Murmurs in dogs that are caused by extracardiac disease or structural heart problems usually have accompanying symptoms that might assist your veterinarian figure out what's wrong.

Your veterinarian will do a complete physical examination after gathering a detailed medical history about your dog from you. If a cardiac murmur is detected, it will be given an intensity rating (from I to VI).

The presence of another disease will be determined by your veterinarian. To examine heart function and total body health, several diagnostic tests are required. To examine organ health and cell counts, blood chemistry, a complete blood count, and a urinalysis will be conducted. To examine the heart size and features of the heart and lungs, radiographs (X-rays) of the chest will be required.

To gain a better look at the heart, specialized cardiac tests may be required. This testing may be referred to a veterinary cardiologist by your general physician. An electrocardiogram (ECG or EKG) displays waveforms that may be studied to check for anomalies in the heart's electrical activity. An echocardiogram is a type of cardiac ultrasound that displays the heart beating and blood flow through it. The sonographer can examine the heart's chambers and valves, as well as aberrant blood flow patterns.

Treatment & Prevention

Because a cardiac murmur is an indication of possible disease rather than a disease, the therapy will be determined by the underlying cause, if any. A dog with a slight cardiac murmur that is asymptomatic may not require therapy. A moderate to severe murmur, on the other hand, necessitates additional investigation, especially if clinical indications are present.

Treatment options might be addressed once a diagnosis has been determined. Some cardiac problems will require surgery to correct. In addition to supportive care from the owner, other illnesses may be addressed with specific diets or drugs. Dogs with heart disease will need to see their main veterinarian and/or a cardiologist on a regular basis to monitor their reaction to therapy and assess the illness's development.

Prognosis for Dogs With Heart Murmurs

Some heart murmurs fade away with time. Many harmless murmurs in pups will go away as the dog grows older, but certain serious diseases, like as dilated cardiomyopathy, can be deadly. Congenital heart problems offer a wide range of prognoses: some may be treated with surgery, while others may require long-term care or be more severe. The reason of your dog's cardiac murmur, which your veterinarian can identify to establish the correct treatment approach, will influence your dog's individual prognosis.

How to Prevent Heart Murmurs

Although not all cardiac murmurs may be avoided, early discovery allows your veterinarian to address an underlying condition before it becomes problematic. Always follow your veterinarian's treatment and follow-up suggestions. If you're having problems following the suggestions, speak with your veterinarian, since consistency in treatment might be critical to your dog's life. While certain heart murmurs produced by extracardiac illness cannot be avoided, those generated by harmless murmurs and those caused by structural abnormalities may.

Regular Dental Cleanings

Maintaining your dog's oral health is important for preventing cardiac disorders such as endocarditis. Maintain regular at your veterinarian's office, as well as crucial at-home care such as brushing your dog's teeth. Dental chews are also good, but treats should be limited in order to keep your dog at a healthy weight.

Diet and Nutrition

Putting on too much weight puts your dog at risk for heart disease and other major health problems. Because this is the most prevalent preventive canine condition, it is also one approach for owners to assist their pets avoid cardiac issues. Consult your veterinarian to establish suitable portion amounts depending on your dog's individual needs. Feed your dog a diet.


Exercising with your dog on a regular basis throughout its life can assist to maintain heart health. A veterinarian should manage the exercise regimen of dogs with underlying illnesses to ensure that their hearts and lungs can support their activity level.


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