Heart murmur in dogs and cats

Literally not an hour goes by in practice that I do not encounter a heart murmur in a canine or feline patient whether it is newly diagnosed heart murmur or it is follow up with a patient that has been living with a heart murmur.  Heart murmurs are equally as common in cats as they are dogs.  Mild heart murmurs are generally innocent at first but have the ability to progress and cause serious disease.  Thus, in addition to optimal nutritional management of pets living with heart murmur, regular vigilance – twice yearly physical examination to begin with, yearly to semi yearly chest x-rays, ECG, and cardiac ultrasound as murmurs progress – is of the utmost importance to maintain quality of life and facilitate longevity.

First, I would like to explain what a heart murmur is and why chronic changes they can cause over time makes it extremely important to monitor the pet carefully throughout his or her lifetime.  A heart murmur is an unusual sound associated with the heartbeat that is audible to the veterinarian using a stethoscope.  Murmurs often cause a “swooshing” or “whooshing” sound that signifies abnormal blood flow through the heart.  The abnormal flow can vary from thickened or abnormal heart valves that allow some back flow when the heart pumps.  In other cases, heart murmurs can signify defects of the heart septum or heart muscle itself causing more widespread disruption of proper blood flow through the heart and ultimately compromising blood circulation to the rest of the body.

While severe cases of cardiac disease associated with murmurs will commonly require various medications to slow the progression of disease and maintain quality of life and longevity, nutrition can play a huge role as well in the treatment process.  Using some of the nutritional support guidelines below can significantly facilitate a reduction in the rate of progression of cardiac disease.

Sodium Restriction

Sodium is an essential electrolyte necessary for life.  However, in normal to excess amounts it can contribute to high blood pressure, aka, hypertension, in dogs and cats with compromised cardiovascular systems.  Thus, it is essential for heart murmur patients to toe the line between consuming adequate amounts of sodium to sustain metabolic homeostasis but restricting it to the extent that is does not contribute to rising blood pressure.

Hypertension increases the pre and after load of the heart, essentially requiring the heart to have to pump harder and faster to move normal amounts of blood to enable effective full body perfusion .  The subsequent cardiac muscle enlargement that follows will worsen the defects that cause the heart murmur, lessen the efficiency of the heart, and make the cardiac patient more clot prone.


Taurine is an amino acid which, if deficient, can cause a specific heart disease in dogs and cats that is rising in incidence. Complete and balanced commercial cat foods generally have enough taurine added to them but diets that are not complete and balanced, vegetarian diets or homemade diets can be too low in this nutrient. If your cat is diagnosed with the specific heart disease, Dilated Cardiomyopathy (DCM), the veterinarian will usually test their blood taurine level to see if they are deficient and prescribe supplements to help treat the disease.

Dogs, unlike cats, are not thought to require taurine in the diet as an essential dietary amino acid. However, certain breeds (Cocker spaniels, Newfoundlands, St. Bernards, English setters, Labrador and Golden retrievers) may require some in the diet to avoid a deficiency. Lamb and rice diets, grain free, high fiber, and low protein diets in these predisposed breeds may make it more likely for them to develop a taurine deficiency and predispose them to heart disease. Dogs of these predisposed breeds that develop DCM may have their blood tested for taurine levels as well.

Omega-3 Fatty Acids (Fish Oil)

Certain types of fatty acids present in fish oil (called omega-3 fatty acids) have been shown have a positive effect in dogs and cats with heart disease. Omega-3 fatty acids do not help to prevent heart disease as they do in people. This is because in people, omega-3 fatty acids have a beneficial effect in coronary artery disease, which does not occur in dogs and cats. In pets with heart disease, fish oil is recommended for dogs and cats who have reduced or altered appetite or any muscle loss; and to reduce inflammation within the heart generated by abnormal blood flow to reduce scarring of the heart chambers and prevent clot formation. Omega-3 supplements can also be used as adjunctive therapy in the treatment of dogs with abnormal heart rhythms known arrhythmias.

Fish oil may be purchased over-the-counter at almost all human pharmacies but the dose and quality of the products vary widely. I generally recommend a one gram fish oil capsule that contains 180 mg of eicosapentaenoic acid (EPA) and 120 mg of docosahexaenoic acid (DHA). The quality control of the individual product should be checked to ensure your pet is getting the right amount and is not getting unwanted nutrients or contaminants. The nutritional supplement industry is not FDA regulated and subsequently bogus product is rampant.  You veterinarian is your best source to recommend reputable, high quality products.

With capsules of this size most dogs and cats can be given one capsule per 10 pounds of body weight per day. Fish oil is safe but if your pet has a bleeding disorder or is already eating a diet high in omega-3 fatty acids, supplementation should be carefully considered with your veterinarian. Fish oil supplements should contain vitamin E as an antioxidant, but other nutrients should not be included. Cod liver oil and flax seed oil should not be used as sources of omega-3 fatty acids in dogs and cats.

Prescription Heart Diets

Rather than having an arsenal of supplements and having to watch pet food labels for sodium content, the easiest method to feed a well balanced, heart friendly diet to pets living with heart disease is to feed a prescription heart support diet.  Disease specific nutrition has become one of the cornerstones of disease management in veterinary medicine and new innovations through ongoing research occur on a constant basis.  Chronic heart disease is no exception.

Thus, I will usually urge clients with pets living with heart murmurs and cardiac disease to make their life easy and simply feed one of the prescription diet options that have the exact balance of nutrients necessary to facilitate optimal heart health.

Be Integrative

While nutritional support for cardiac disease in pets is crucial, it is not the end all be all of management of heart disease.  Regular examinations and diagnostics are crucial to determining when it is necessary to integrate cardiac medication therapy to the nutritional regimen to sustain life and quality.

Dr. Roger Welton is a practicing veterinarian and highly regarded media personality through a number of topics and platforms.  In addition to being passionate about integrative veterinary medicine for which he is a nationally renowned expert, Dr. Welton was also an accomplished college lacrosse player and remains to this day very involved in the sport.  He is president of Maybeck Animal Hospital , runs the successful veterinary/animal health  blogs Web-DVM and Dr. Roger’s Holistic Veterinary Care, and fulfills his passion for lacrosse through his lacrosse and sport blog, The Creator’s Game.

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