My dog has a heart murmur. What is the cause, diagnosis and treatment?

Original Question: I am writing on behalf of my mom who is 76 years old. This past week I had her and her dog at the vets for our yearly check up. The vet mentioned that she could hear a heart murmur on the right side. She also said that could be why her tummy felt floppy. She said maybe it has fluid in it. This heart murmur has been mentioned before but nothing else was said. We were given no other information at that time. This time we were told to count her breaths when she is relaxed or sleeping for 15 seconds and times that by 4. We are to do this for 2 weeks. If the number is between 14 and 18 they will not worry at this time. Anything over 18, they would like to start a diuretic. Nothing else has been explained to us. Please note I have not noticed Ariel coughing and neither has my mom. Ariel has never been a walker or a run around and play type girl. She would rather watch. What questions should I ask my mom's vet? How serious is this? The vet did say that with small breeds any time over 12 years is bonus time. My ultimate goal is to make Ariel comfortable. I do not know what to do. Thank you for taking the time to answer my questions. - Lisa

Jan 26, 2019

Hi Lisa,

Thanks for your question. Let’s take a have look into canine heart murmurs, how serious they are, diagnostics and treatment.

What is a heart murmur in dogs?

A heart murmur is an abnormal vibration that can be detected during auscultation of the heart. If abnormal blood flow is occurring, that turbulence will create a vibration that we can detect.

How serious is a dog heart murmur?

Simply confirming the presence of a heart murmur does not mean that a serious heart condition exists. There are harmless reasons why a murmur may occur, such as stress during a pet check-up, however, if it is consistently present and repeatedly identified and progresses in severity, it is suggestive that a heart condition may be present. Heart murmurs are graded on a scale of 1 to 6. The more serious the murmur, the higher the grade.

Initiating a treatment plan based on auscultating the heart and the presence of a murmur is not considered by most veterinary professionals to be an adequate level of evidence to confirm a diagnosis and initiate treatment. There are different manifestations of heart disease and different severities that could be present. It is critically important that the condition and its severity be confirmed in order to develop a valuable and targeted treatment plan.

How is a heart murmur in dogs diagnosed? Treatment?

To evaluate this the first test I would do is called a cardiac ultrasound. It’s true that cardiologists will perform this test but there are ultrasonographers who travel around to clinics who perform this test as well. There are quite a few of them and I believe that your veterinarian would likely know one of them and could give them a call and book an appointment at your current clinic so that you don’t have to go elsewhere. A cardiac ultrasound is a very thorough test and should be able to pinpoint the source of the murmur, the type of heart disease, and whether treatment is necessary and what type of treatment that would be. It will also clearly indicate how serious this truly is.

As another thought, I would also recommend that you perform routine blood work to make sure that there are no other concerns or negative effects impairing the other organs based on a deficient cardiac system. You’ll also want to consider performing chest X-rays to evaluate if pleural effusion exists which can be a clinical symptom of heart disease.