How to care for a dog with a heart murmur

Disclaimer: This article, its content, and its related references do not constitute veterinary advice and should not be considered a substitute for veterinary care. If your pet is showing any symptoms that could indicate a medical emergency, please seek immediate emergency care.

A heart murmur is an extra, abnormal sound caused by turbulent blood flow within the heart. Heart murmurs are common in dogs and can be caused by a variety of heart conditions and other health issues. While not all murmurs require treatment, dog owners need to know what to watch for and how to care for their pet when they have a murmur. If your dog has been diagnosed with a heart murmur, read on to learn:

• What causes the heart murmur sound
• How to help dogs who have heart murmurs
• Common conditions that can cause heart murmurs
• How murmurs are diagnosed and treated

It’s important to have a dog’s heart murmur evaluated by a veterinarian and to follow the vet’s plan for monitoring and treatment. Treatment varies depending on the underlying cause and presenting clinical signs. Owners can help their dogs by following their vet’s recommendations, such as monitoring their dog’s respiratory rate, minimizing stress on the heart, and bringing their dog in for appointments as recommended. Common conditions associated with heart murmurs in dogs include congestive heart failure, mitral valve disease, and congenital heart defects. Some dogs with murmurs have no other symptoms, while others may show exercise intolerance, lethargy, coughing, and other signs of illness.

A heart murmur is an abnormal sound heard when listening to a dog’s heartbeat. It’s caused by abnormal, turbulent blood flow through the heart. Instead of hearing two distinct “lub-dub” heartbeat noises, a murmur may sound like a “whoosh” or a fluttering vibration between or in addition to the sounds of a normal heartbeat.

“Normally, blood flows smoothly in one direction between the four heart chambers,” explains Dr. Jo Myers, a veterinarian on the Vetster platform. “The normal ‘lub-dub’ sound of a heartbeat is caused by the heart valves closing as the heart beats. Anything that interferes with the normal flow of blood through the heart and major blood vessels can cause turbulence and an abnormal sound.” This includes:

• Leaky valves
• Defects in the walls of the heart
• Abnormalities in the path blood takes to, from, and within the heart

Heart murmurs are common in dogs and can occur for a wide variety of reasons ranging from benign to life-threatening. Murmurs are graded on a scale of I–VI. The lower the grade, the quieter the murmur is. Most canine heart murmurs are incidental findings during wellness exams on dogs who are acting perfectly healthy. Affected dogs may have no other signs or symptoms of heart disease.

Types of heart murmurs in dogs

Heart murmurs can be congenital or acquired. Congenital murmurs are present from birth and are usually caused by a congenital heart defect. Acquired murmurs develop later in life due to an underlying medical condition affecting the circulatory system. Puppies under six months of age may have a benign physiologic murmur, also known as an innocent murmur. These are not harmful, and puppies usually outgrow them by about six months of age.

There are various ways pet parents can care for their dogs with heart murmurs. It’s important to have a dog’s murmur evaluated by a veterinarian and follow the vet’s plan for monitoring and treatment. Common recommendations for dogs with murmurs include:

• Monitoring breathing rate and effort
• Minimizing stress on the heart
• Routine follow-ups with a vet to have the murmur rechecked

Monitoring respiratory rate and effort

Heart disease often causes an increase in a dog’s breathing rate and effort. It’s important for owners of dogs with heart murmurs to regularly monitor their breathing rates. An increased rate or effort may indicate the underlying condition is getting worse. To count a dog’s respiratory rate:

• Observe your dog sleeping or resting where they are comfortable
• Count the number of complete breaths — a full inhale and exhale counts as one
• Keep count for 15 seconds and multiply by four to get their respirations per minute (RPM)

A healthy dog’s respiration rate is usually between 18 and 35 RPM, though this varies between individuals. Contact a veterinarian if your dog’s RPM is regularly over 35, and seek emergency care if their breathing is labored.

Minimize stress on the heart

Murmurs are caused by turbulent blood flow, and since turbulent blood flow is less efficient than normal blood flow, the presence of a murmur means the circulatory system isn’t working as well as it should. Added stress on the heart can make this worse and exacerbate the underlying heart condition. Common stressors include:

• Exercise
• Environmental stressors
• Obesity

Some affected dogs may be able to continue to exercise normally after diagnosis, but others may need to avoid strenuous exercise to prevent extra stress on the heart. Hot weather and high elevation put added stress on the canine cardiovascular system. A vet may recommend leash walks only, or avoiding or spending minimal time in hot weather or at high altitudes.

Obesity puts a large burden on the heart by making it more difficult for dogs to breathe normally. Maintaining a healthy weight can help relieve this added stress. A veterinarian may recommend a special diet for a dog with a heart murmur to encourage weight loss and to support heart health. There are specialized diets to support dogs with heart conditions containing more protein and less sodium that may help some dogs. Talk to a veterinarian to discuss the best weight management and nutrition plan for your dog.

Regular checkups with a veterinarian

Your vet may recommend more frequent checkups after diagnosing a heart murmur in your dog. Wellness checks involve checking heart and lung sounds, and running blood tests to check heart stress and function. These checks will help a vet adjust treatment, monitoring, or preventative measures according to the underlying issue. Visiting a vet as recommended will aid in monitoring your dog’s murmur and help catch any changes before clinical signs become apparent.

There are many health conditions that affect the heart and potentially lead to heart murmurs. These include:

• Dilated cardiomyopathy
• Congestive heart failure
• Congenital heart defects
• Degenerative mitral valve disease
• Endocarditis
• Heartworm disease
• Anemia from disease or blood loss

Some diets, including grain-free diets, have been associated with the development of dilated cardiomyopathy in dogs. Research is still underway, and the exact association has not yet been determined. These diets commonly include ingredients such as peas, lentils, chickpeas, dry beans, potatoes, or sweet potatoes. Not all dogs who eat these diets develop heart disease, and not all dogs with acquired cardiomyopathy eat diets containing these ingredients. The association between various diets and heart disease in dogs is very complex and is still being investigated. If you’re concerned about your dog’s food, talk to a veterinarian to learn more about diet-associated dilated cardiomyopathy.

Clinical signs of heart disease in dogs

Dogs with various types of cardiac disease associated with murmurs often show other symptoms, such as:

• Faster resting breathing rate
• Exercise intolerance
• Coughing
• Lethargy
• Bloated abdomen

Emergency symptoms of heart disease can also occur, such as:

• Difficulty breathing
• Collapse or loss of consciousness
• Blue gums

It’s important for owners to seek veterinary care when they notice changes in their dog’s health, even if those changes seem minor. Early symptoms of heart disease in dogs are often subtle, such as not exercising as frequently or breathing faster than normal while sleeping.

Veterinarians can hear heart murmurs when they listen to a dog’s heartbeat with a stethoscope during a physical exam. The murmur itself is not usually treated. Instead, the underlying cause needs to be definitively diagnosed and properly treated. To determine what’s causing the murmur, a vet may recommend diagnostic testing, such as:

• Bloodwork
• Diagnostic imaging, including chest X-rays and ultrasounds (echocardiogram)
• Electrocardiogram (ECG)

Treatment isn’t always necessary. When it is, treatment options vary depending on what’s causing the murmur. Treating the heart murmur or reducing its impact on circulation may involve:

• Heart medications
• Surgery to correct defects
• Diet change

The prognosis depends on the underlying condition and how the dog responds to treatment. Some situations, such as innocent heart murmurs, are benign, while other heart conditions, such as congestive heart failure, have a poor prognosis. With early diagnosis and proper management, many dogs with heart murmurs can have a good quality of life.

If you would like veterinary help managing your dog’s weight and diet to help their heart murmur or have concerns about your dog’s symptoms, online vets are available 24/7 through the Vetster platform.

Should dogs with heart murmurs be on medication?

Not all heart murmurs in dogs require treatment. Some puppies may have innocent heart murmurs that are fully benign and go away as they get older. Other murmurs are caused by health conditions that your vet may regularly monitor instead of suggesting your dog immediately start heart medications. Talk with your vet about the cause of your dog’s murmur and the best course of action for treatment.

How do you monitor a dog’s heart murmur at home?

The best way to monitor your dog’s heart murmur at home is to follow your veterinarian’s instructions. They may suggest regularly checking their resting breathing rate. You can do this by counting the number of full breaths they take while resting or sleeping for 15 seconds, then multiplying the number by four. This gives you their breaths (respirations) per minute (RPM). Talk to a vet if your dog’s RPM is consistently over 35.

When should I worry about a heart murmur in my dog?

Follow your veterinarian’s instructions about monitoring your dog at home and any treatment that may be needed. Seek veterinary attention if your dog’s resting breathing rate is over 35 breaths per minute, their breathing is labored, they begin coughing, they appear lethargic, or their gums appear bluish in color.