The normal heartbeat makes a sound that corresponds to the closing of heart valves during the heart cycle.  A heart murmur, caused by turbulent blood flow within the heart or large vessels that arise from it, sounds like an abnormal whooshing or swishing sound during the heart beat cycle. This can be heard with a stethoscope and, if loud enough, can be felt as a buzzing or vibration over the heart. Careful listening with a stethoscope to your dog’s heart by your family veterinarian is an important part of any physical examination.

What are Possible Causes of Heart Murmurs in Dogs?

Most heart murmurs in dogs indicate underlying heart disease; however, the severity of that heart disease can vary significantly from dog to dog.  The grade (loudness scale) of the heart murmur does not necessarily correlate with the severity of the underlying heart disease. For example, dogs with significant heart muscle disease that causes poor pumping function and secondary valve leakage typically have soft or low-grade murmurs. Occasionally, dogs can have what are known as flow or innocent heart murmurs, meaning that no structural heart disease is present. These examples illustrate why additional diagnostic testing is so crucial to determine the underlying cause of a murmur in an individual dog.

The most common structural heart diseases in dogs are degenerative valve disease in aging small breed dogs, dilated cardiomyopathy (a heart muscle disease) in larger breed dogs, and congenital heart defects (present since birth), the most common of which vary breed by breed. It is important to determine which disease an individual dog has and how severe it is in order to best tailor treatment for that particular patient.

What can be Done to Diagnose the Cause of My Dog’s Heart Murmur?

The gold standard for diagnosing the cause of a dog’s heart murmur is a complete echocardiogram by a board certified veterinary cardiologist. The echocardiogram is an ultrasound of the heart that allows the cardiologist to examine the two-dimensional structure, pumping and relaxation function of the heart, and blood flow through the heart valves and great vessels. This is a completely non-invasive procedure, without pain, and completed without sedation in almost all patients.  The complete echocardiogram allows the cardiologist to determine the cause and severity of your dog’s heart murmur and also to guide treatment.

Other diagnostic tests that may be indicated on a patient-by-patient basis include chest radiographs (X-rays), blood pressure measurement, ECG (for analysis of heart rhythm), and blood tests. These tests are complementary to but do not replace the echocardiogram. For owners who are not able to pursue an echocardiogram, your family veterinarian can gain information about your dog’s overall heart size and the presence of absence of congestive heart failure through a physical examination and chest radiographs (X-rays). This approach will not provide the detailed heart information that an echocardiogram does, but can be used to generally guide therapy.

What Treatment Options are Available for Dogs with Heart Murmurs?

The treatment course depends on the underlying heart disease and its severity, as determined by the testing outlined above. Some dogs have mild or no structural heart disease and require no treatment at the time of diagnosis.  Other dogs have severe heart disease and will have a treatment regimen recommended that is tailored to their particular condition. Some dogs, for example, have significant heart disease and underlying kidney disease, which requires the cardiologist to achieve a careful balance between these two systems. All treatment protocols will be discussed at length with you, so that you are comfortable with your dog’s care.  You serve as a vital part of the team that strives to optimize your dog’s quality and length of life.

Our cardiology specialists work with your family veterinarian

A board certified veterinary cardiologist has 4 years of specialized training beyond veterinary school and has passed a series of exams to achieve board certification. MedVet’s veterinary cardiologists work carefully with your family veterinarian for the best care of your dog.  They form a team, along with you the owner, to best care for your pet.  Much of the follow-up testing can be performed at your family veterinarian’s office, with periodic follow up with your dog’s veterinary cardiologist. Our goal is to prevent or delay significant complications in dogs with heart disease such as congestive heart failure, and avoid stressful and more expensive emergency room visits.