- A heart murmur is detected when your veterinarian hears an abnormal sound while listening to your pet’s heart with a stethoscope
- The cause of heart murmurs varies, and thus does the range of treatment and prognosis
- Additional tests such as radiographs, electrocardiography (ECG) and echocardiography (cardiac ultrasound) are required to diagnose the cause of the murmur and guide the treatment
- A heart murmur is not always an indication of cardiac disease
- Some animals with murmurs do not show any outward signs of disease, while other animals may show signs of significant cardiac disease
- Signs of cardiac disease include difficulty breathing, cough, abdominal distention, exercise intolerance, weakness, and collapse
Understanding Heart Murmurs
Learning that your dog or cat has a heart murmur can be frightening but understanding what a heart murmur is—and isn’t–can help you as a pet parent understand what your veterinarian means should you ever hear these words.
A heart murmur is an abnormal sound that a veterinarian hears when listening to the pet’s heart through a stethoscope during a physical exam. Normally, your pet’s veterinarian hears two distinct normal heart sounds when we listen to the heart: lub-dub…lub-dub…lub-dub. When we hear an additional “whooshing” sound in between normal heart sounds, this is a heart murmur.
If your pet’s veterinarian hears a heart murmur, it’s not time for panic mode but it is time to gather some more information. Some heart murmurs can be benign and may resolve on their own, especially in puppies and kittens. The only way to know for certain is to work with your veterinarian or veterinary medical cardiologist to determine the cause of the murmur and severity of the heart disease. Additional diagnostic tests such as cardiac radiographs (x-rays), an electrocardiography (ECG) or an echocardiography (cardiac ultrasound) may be needed.
Anything that alters the blood flow through the heart can cause a murmur to be heard. Some of the common causes of heart murmurs in dogs and cats include:
- Heart valve deficiencies
- Defects in the heart walls
- Infection of the heart valves
Congenital cardiac defects
- patent ductus arteriosus (extra vessel connecting great arteries)
- ventricular septal defect (defects in the heart muscle walls)
- pulmonic stenosis (obstructive lesion of the pulmonary valve)
- subaorti stenosis (obstructive lesion below the aortic valve)
- mitral/tricuspid valve dysplasia (defective mitral/tricuspid valve)
Acquired cardiac diseases
- myxomatous mitral/tricuspid valve degeneration (thickening of the heart valves)
- infective endocarditis (infection of the heart valves)
- cardiomyopathies (weakening or thickening of the heart muscle)
- dynamic obstruction of the right ventricle (benign condition in the cat)
Signs of Cardiac Disease
Not all dogs and cats diagnosed with a heart murmur will suffer from cardiac disease; alternatively, not all dogs and cats that suffer from cardiac disease will have a detectable murmur. This is part of the reason why your local veterinarian or veterinary medical cardiologist will weigh all your pet’s physical exam findings and history in deciding when and which additional diagnostic tests are needed.
If your dog or cat does exhibit symptoms of cardiac disease, a cardiac work-up will give you much needed information. Symptoms of cardiac disease in dogs and cats can include: difficulty breathing, rapid shallow breathing, cough, abdominal distention, exercise intolerance, weakness, grey or blue gums, and collapse. If your pet is diagnosed with a heart murmur it is important to always watch for these signs. If your pet exhibits one more of these symptoms, contact your veterinarian or veterinary medical cardiologist. Emergency symptoms that warrant immediate veterinary intervention include blue or grey gums, collapse, ,cough, and open mouth breathing and/or limb paralysis in cats.
Treatment and Prognosis
Treatment is targeted at the alleviation of clinical symptoms secondary to heart disease with the heart murmur. Most asymptomatic dogs and cats with a heart murmur may live normal lives and never require treatment; others with clinical symptoms will benefit significantly from treatment, which can range from administration of oral medications to surgery.
A veterinary medical cardiologist will tailor a treatment plan to enhance your pet’s quality of life, as well as extend the time your have together. The good news is that a heart murmur is a clinical finding, not a disease diagnosis, and certainly not a prognosis.
Did you know? Depending on the cause of the heart murmur, treatment may sometimes “cure” the murmur. For instance, if your dog is diagnosed with a patent ductus arteriosus with a heart murmur, successful treatment of the patent ductus arteriosus will resolve the heart murmur entirely, and a normal life-expectancy is anticipated. This is one example of how crucial it can be to investigate the cause of the heart murmur with further diagnostic testing with a veterinary medical cardiologist.
Article written by Laci Schaible, DVM, CVJ.