A heart murmur is an abnormal sound that can be detected by listening to a dog’s heart with a stethoscope. This sound is caused by abnormal turbulent blood flow between the chambers of the heart. A murmur can occur when blood moves across abnormal heart structures or valves or even when blood moves rapidly across normal heart structures.
Heart murmurs can occur in dogs of any age for a variety of reasons and it is the underlying cause of the murmur that is of concern. Can dogs live normal, healthy lives with a heart murmur? Let’s examine the different scenarios in which a heart murmur will occur and how it may affect your furry friend!
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Signs Associated With Heart Murmurs in Dogs
A heart murmur is not always easily detectable in dogs. The intensity of the abnormal heart sound can vary and is graded on a scale of I (softest) to VI (loudest). A grade I heart murmur is barely audible at all while a grade VI heart murmur can be heard with a stethoscope barely touching the chest. These grades classify the murmur by the volume of the sound and don’t necessarily correlate with the severity of the murmur.
A heart murmur is not always a cause for concern. Some heart murmurs are more serious than others and many can be easily treated. Some murmurs can indicate an underlying heart condition that needs to be assessed and others may simply be “innocent murmurs” that will resolve themselves with time. Innocent murmurs most often occur in young puppies and are not associated with heart conditions. These tend to disappear by the time the puppy reaches 4 months of age. If they don’t, diagnostic testing should be performed to see if the murmur is a result of a congenital heart condition.
The most common causes of heart murmurs in dogs include heartworm disease, defects of the heart walls, tumors, valve deficiencies or blockages, endocarditis, dilated cardiomyopathy, and hyperthyroidism. There are many additional diseases or conditions that may bring on a heart murmur, so diagnostic testing by a veterinarian is often required.
Additionally, not all dogs with heart conditions show outward signs. If you know your dog has a heart murmur, crucial signs to watch for include rapid or difficult breathing, coughing, lethargy, weakness, exercise intolerance, abdominal distention (a pot-bellied appearance), congestion, fainting, and/or collapse. If your dog has a murmur and displays any of these signs, consult your veterinarian immediately! These may indicate congestive heart failure.
- Difficult or Rapid Breathing
- Congestion or Noisy Breathing
- Abdominal Distension
- Exercise Intolerance
- Fainting Spells or Collapse
History of Dogs Living With Heart Murmurs
Throughout history, plenty of dogs with heart murmurs have lived healthy lives. It is important to distinguish that a heart murmur itself is not responsible for health issues, but rather the condition or circumstances causing the murmur. In many cases, the underlying conditions causing the heart murmur can be treated or well-managed to promote health and longevity of the dog’s life.
One owner reported her Cocker Spaniel was diagnosed with a heart murmur. After detection of a murmur with a stethoscope, the dog was brought to a specialist to diagnose the underlying cause of the murmur. Using an echocardiogram and chest x-rays, the dog was diagnosed with mild mitral regurgitation as a result of degenerative valve disease.
The veterinarian that diagnosed the condition stated that based on the tests performed, the dog’s prognosis was very good. The owner monitored her dog's condition regularly with testing and he continued on to live a normal life. Another owner brought her chihuahua into the vet for skin issues that wouldn’t go away. During the visit, the vet happened to detect a heart murmur while taking the dog’s vitals.
An EKG determined that the chihuahua had degenerative valve disease causing mitral regurgitation. The owner monitored her dog on walks for fatigue, coughing, or shortness of breath and had him rechecked every year. His murmur did not affect his quality of life.
Prognosis of heart murmurs in dogs can vary from grave to excellent, so don’t panic at the first mention of the word! Talk to your veterinarian to take the appropriate diagnostic tests and consider seeing a specialist.
Science Behind Heart Murmurs in Dogs
A heart murmur is an abnormal sound that results from a disturbance of blood flow or turbulent blood flow in the heart. Murmurs can be detected with a stethoscope and are typically heard as a “swish” or “whoosh” sound.
There are 3 types of heart murmurs, classified by timing: systolic, diastolic, and continuous. Distinguishing the type of murmur is helpful in uncovering the underlying cause. Systolic murmurs take place when the heart is contracting. They are most often caused by pulmonic or subaortic stenosis, where the blood vessels narrow and obstruct blood flow.
Other causes of systolic murmurs include Heartworm disease, anemia, hyperthyroidism, aortic valve insufficiency, mitral and tricuspid heart failure, cardiomyopathy, and more. Diastolic murmurs take place in between beats when the heart is relaxed. This type of murmur is rare in dogs. Diastolic murmurs are usually caused by aortic insufficiency in which the aortic valve does not close tightly, causing leaks.
The third type is a continuous murmur, which takes place throughout the heartbeat cycle. Continuous murmurs are most often caused by Patent Ductus Arteriosus, a congenital heart disease in dogs. They can also be a result of ventricular septal defect or aortic stenosis. There are a plethora of conditions and circumstances that lead to heart murmurs, varying from mild to grave, so diagnosis by a veterinary cardiologist is recommended.
Training Your Dog to Live With a Heart Murmur
Training for a dog living with a heart murmur is primarily geared towards owners! It involves being proactive with your dog’s care to manage their heart health. Regular monitoring is important to stay informed, have peace of mind, and help your dog live their longest and best life.
It is recommended to take your dog to a board-certified veterinary cardiologist to learn as much as possible about the severity of their condition and the best management practices. An echocardiogram is an important tool in diagnosing the underlying cause of the murmur. It can differentiate between murmurs due to excitement and murmurs caused by a heart condition or disease. A proBNP blood test can provide the peace of mind that your pup has no early signs of heart disease. Chest radiographs and EKGs are also helpful tests to diagnose and monitor your pup with a heart murmur.
How else can you be proactive with the care of your dog living with a heart murmur? Most importantly, take excellent care of their overall health! Maintaining a healthy weight is hugely significant in promoting a healthy heart. Ensuring your dog has regular aerobic exercise is crucial! Feed your dog a high-quality diet balanced to meet their nutritional needs for optimal protein and amino acid levels, healthy fats, and coenzyme Q10. It is recommended that animals suffering from any type of heart pathology increase their intake of omega-3 essential fatty acids, ubiquinol, and the reduced form of coenzyme Q10.
Finally, consider brushing your dog’s teeth and/or taking them in for regular dental cleanings. Maintaining their dental health is important, as bacteria from dirty mouths in dogs have been linked to heart valve infections. By being proactive with your dog’s overall care and health, you can help them live the longest and best life possible with a heart murmur!
How to React When Your Dog is Diagnosed With a Heart Murmur
Don't panic! Many heart murmurs are treatable and can be well-managed. Be proactive with monitoring and talk to your veterinarian about the best care for your dog.
Take your dog to a specialist, like a veterinary cardiologist, to learn as much as possible about the severity of the condition and its management.
Help your dog maintain a healthy weight with regular exercise and a high-quality diet.
Safety Tips for Caring for a Dog With A Heart Murmur
Watch for any signs of rapid or difficult breathing, coughing, congestion, exercises intolerance, lethargy or weakness, abdominal distension, gray or blue gums, fainting spells, or collapse.
If any of the above symptoms are detected, consult your veterinarian immediately!