Heart Murmur in Dogs

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A dog’s heart functions in the same way as their human owner’s heart — they too can experience similar heart problems and conditions. A veterinarian can detect a heart murmur during routine checkups, and most owners are usually unaware their dog has one.

There are several types of heart murmurs, some more serious than others. Depending on the underlying conditions that result in a murmur, they may be treatable. What’s important to remember is that a heart murmur is a symptom and not a disease, and while it can be indicative of an underlying heart problem, it can also be completely innocent.

Signs and Symptoms of Heart Murmur in Dogs

A heart murmur is an extra heart vibration which results in an abnormal sound caused when there is a disturbance in the blood flow. The detectable noise is one that is distinguishable from a regular heartbeat and can be heard by a doctor with the use of a stethoscope.

If your dog has a murmur, it is not an immediate cause for panic. Talk with your vet about heart disease and what it might mean for your dog should there be something more serious going on. Many dogs diagnosed with heart murmurs never need any treatment and go on to live long and healthy lives. Symptoms include:

  • Irregular heartbeat
  • Hacking, persistent cough
  • Excessive panting even when resting
  • Tires easily
  • Lack of energy
  • Collapses or faints
  • Gums and/or tongue are bluish in color
  • Racing pulse
  • Lack of appetite
  • Severe water retention

These symptoms may also be indicative of a more serious health risk and not necessarily a heart murmur. Your veterinarian will be able to determine exactly what’s going on if your dog is exhibiting any of these signs.

Summary

A heart murmur diagnosis is not always an immediate cause for concern. If signs present themselves, talk to your veterinarian. Not all dogs with heart murmurs require treatment.

How Did My Dog Get a Heart Murmur?

The cause of a heart murmur varies. Some murmurs are determined to be “innocent” or “physiologic,” while other times, they are determined to be pathologic or caused by a disease, such as a structural problem within the heart (cardiac disease). Murmurs can also be due to a problem that is “extra-cardiac,” meaning they are not caused by heart disease.

Types of Heart Murmurs

Heart murmurs can be broken down into three types: systolic, diastolic, and continuous. They are graded on a scale of 1 to 6, with 1 being the softest and hardest to hear, and 6 being the loudest. Veterinarians go by the number scale to determine the cause of the murmur and the best course of action to take, if necessary.

  • Grade 1 – These are the least serious. They are extremely soft in sound and barely audible.
  • Grade 2 – A soft sound heard through the use of a stethoscope.
  • Grade 3 – Intermediate loudness and radiates to more than one location.
  • Grade 4 – These murmurs are moderate to intense and can be heard on each side of the chest.
  • Grade 5 – Very loud and can be heard even when the stethoscope is barely touching the chest. They can also be felt by holding a hand against the chest.
  • Grade 6 – Like a grade 5, these murmurs are very loud and can be felt by touching the chest; they are also the most severe.

What defines an “innocent” or “physiologic” heart murmur?

Not every murmur is an indication of a heart disorder. An “innocent” or “physiologic” murmur means that the murmur does not have an impact on the dog’s health. These types of murmurs are commonly seen in young puppies, especially larger breeds, as they begin to grow rather quickly. A puppy with an innocent heart murmur will most likely outgrow it by around four to five months of age.

Systolic murmur: Most heart murmurs are systolic and occur during systole, the phase of the heart cycle when the heart contracts to pump blood out. The most common cause of this murmur is a leaky mitral valve (the valve between the left upper and lower chambers of the heart). Pulmonic stenosis or subaortic stenosis, which is a narrowing of the blood vessel that obstructs the blood flow, are less common causes of systolic murmurs.

Diastolic murmur: This type of murmur is uncommon in dogs. The most common condition associated with this type of murmur is aortic insufficiency, which occurs when the aortic valve leaks as a result of the fact that it does not close tightly.

Continuous murmur: This type of murmur is most often caused by patent ductus arteriosus (PDA), which is a failure of a large blood vessel, the ductus arteriosus, to close just after birth. It is the most frequent congenital defect in dogs. The breeds most commonly affected are Maltese, Pomeranian, Poodle, Keeshond, Bichon Frise, Chihuahua, and German Shepherd.

Summary

Heart murmurs can be broken down into three categories and are graded on a scale of one to six. It’s important to note that not all murmurs impact a dog’s health negatively. Your veterinarian will be able to determine the type and severity affecting your dog with a full examination.

Diagnosing a Heart Murmur in Dogs

A veterinarian detects heart murmurs with a stethoscope by listening to the sound and how loud the murmur is and where it’s coming from. The type and grade of the murmur will help determine the cause; age, breed, and health are also taken into consideration. There are also different tests such as chest X-rays, echocardiogram, electrocardiogram, blood and urine tests to get to the underlying cause of the murmur.

Summary

The diagnostic process begins with an in-office exam to listen to the sound of the heart. Other tests may be required to determine the cause of the heart murmur. Once the root issue is uncovered, a course of treatment can be determined.

Treating a Heart Murmur in Dogs

When it comes to the treatment of a heart murmur, a veterinarian will look to treat the underlying cause and the symptoms associated with it. Medical treatment may include a change in diet, exercise restrictions, and medication. In the case of young puppies and murmurs, they may often resolve on their own.

Is there a cure for a heart murmur in dogs?

There is no specific cure for a heart murmur, as they are the result of an underlying problem. The root cause needs to be determined and addressed to treat the murmur.

Is a Heart Murmur Contagious for Humans and Other Pets?

Dogs diagnosed with heart murmurs should not be bred due to the risk of worsening their heart disease during the stress of breeding or pregnancy as well as the possibility of passing on the heart disease to their babies.

What is the cost of treating a heart murmur?

The cost of treatment varies greatly depending on the cause of the murmur and the dog’s age. Some cases will require surgery, and others may only need a modification in diet and medication. Your veterinarian will order specific tests to determine the condition accurately. Different factors such as who will perform the tests (i.e. your veterinarian or a specialist) as well as the area in which you live all can affect cost.

A breakdown of some of the tests and their expected costs:

  • Electrocardiogram – average cost is between $250 to $350
  • Ultrasound – $250 to $500
  • Chest X-rays – depending on the dog’s size, how many are needed, and whether a mild sedative is needed, can factor into the cost. Prices can range between $50 to $350.

The amounts are just an average estimate; combine them with the veterinary exam and you could be looking at upward of $1,500 to diagnose the condition.

Summary

Heart murmurs are the result of an underlying issue and to address it, your veterinarian will need to figure out the problem to prescribe proper treatment. The cost varies and is dependent on factors such as who is performing the tests and also your geographic location; costs tend to rise in the larger, more populated areas. If your dog is diagnosed with a heart murmur, it’s best not to breed and risk passing the murmur.

Recovery and Management of Heart Murmurs

A heart murmur is associated with an underlying condition. Many of those causes are treatable, and in some cases, the murmur may resolve on its own. The important thing is to catch it early and begin addressing the disease as soon as possible. Because a heart murmur is not necessarily a condition, the outlook varies based on treatment. Frequent checkups are required to monitor how well a dog is responding to treatment and ensure the murmur has not changed or gotten stronger.

Summary

Frequent visits to the veterinarian should be a part of your dog’s health care regime to manage your dog’s heart murmur. Early detection is key to addressing and treating the cause.

Preventing Heart Murmurs

A heart murmur is a clinical finding that can’t be prevented in the normal sense of the word. The underlying cause for the murmur must be determined for a resolution to be possible. The murmur itself is not preventable or treatable, it is only a sound a veterinarian detects when listening to a dog’s heart.

Is There a Vaccine for Heart Murmurs?

No vaccines are available.

Summary

Because there is no cure or vaccine to prevent a heart murmur from developing, it’s essential that you work with your veterinarian to determine if and what kind of underlying heart disease is affecting your dog.

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