Heart Murmurs in Dogs and Cats

Heart Murmurs in Dogs and Cats

 

What is a heart murmur?

 

When your veterinarian listens to your pet’s heart during their physical exam, the heart sounds are very similar to human heart sounds, described as “lub dub...lub dub...lub dub”.  A heart murmur is an abnormal heart sound that is caused by turbulent blood flow.  If your pet has a heart murmur, rather than these regular sounds, the heart beats may sound like “lub swoosh...lub swoosh...lub swoosh”.  The swooshing sound is caused by a disruption in smooth and regular blood flow through the heart.

 

What kinds of disease can cause a heart murmur?

 

A heart murmur is a clinical sign of heart disease, but it is not specific for the cause or the severity of your pet’s underlying heart disease. 

•  In cats, heart murmurs are often caused by abnormal thickening of the heart walls, causing the heart walls to become stiff and rigid.  In turn, this reduces the amount of filling and pumping the heart can do.  The most common cat breeds affected are Maine Coon and Ragdoll.
• In small dogs, heart murmurs are often caused by degeneration of the valves that keep blood flowing in a forward direction.  Specifically, the mitral valve, which forms a tight seal from the left atrium to the left ventricle, and can degenerate over time and allow blood to leak backwards into the atrium every time the heart pumps.  Other valves can also become degenerative over time, but the mitral valve is the most common.  The most common breeds affected are Cavalier King Charles Spaniels, Miniature Poodles, Cocker Spaniels, Miniature Schnauzers, and Dachshunds. 
• In puppies and kittens, a murmur detected on physical exam may be a sign of a congenital abnormality that may require early and aggressive treatment, or may go away within a few weeks of birth.  Fortunately, these murmurs are rare.
   
  How do I know if my pet has a heart murmur?
   
  You cannot tell your pet has a heart murmur just by looking at them.  Heart murmurs are detected on physical exam when your veterinarian listens to your pet’s heart sounds with a stethoscope.  If a heart murmur is detected for the first time during an exam, your veterinarian may recommend to re-check the murmur in a few weeks to see if it is still present or has changed.  Murmurs are graded on a scale from 1-6 and allow veterinarians to monitor for progression of the murmur over time.  Other signs of heart disease that you can watch for at home are coughing, exercise intolerance, lethargy, or increased respiratory (breathing) rate.
   
   
  My pet has just been diagnosed with a heart murmur, what do I do next?
   
  If your pet has just been diagnosed with a heart murmur, there is no need to panic.  Many dogs and cats have murmurs that do not progress to heart failure; they live a long full life that does not require treatment of their heart disease.  However, additional diagnostic tests may be necessary to determine the specific type of heart disease and how advanced it may be.  These tests help you and your veterinarian to determine if treatment is necessary.

•  Chest x-rays may be recommended by your veterinarian to monitor for evidence of heart enlargement. 
• An echocardiogram is an ultrasound exam of the heart; this test is useful to determine the exact cause of your pet’s heart disease and also determine how well your pet’s heart is functioning. 
• Other tests such as an ECG (electrocardiogram) to evaluate the heart’s electrical activity, blood pressure, or blood tests may also be recommended.
• In some cases, referral to a veterinary cardiologist may be recommended.

                            

                                     Here is a radiograph of the heart and lungs

 

How do you treat a heart murmur?

 

There is no specific treatment for a heart murmur, but depending on the specific case, medications may be indicated.  Some heart disease medications work to decrease the work load on the heart by lowering blood pressure or decreasing blood volume.  Other medications are used to improve amount of blood the heart pumps out by strengthening the heart muscle contractions or slowing the heart rate to make the heart a more effective pump.  If your pet is diagnosed with a heart murmur, discuss the appropriate treatment options that are available to you and your pet.

                               

                             

                          Here Dr. Helgen is pictured performing an echocardiogram

                  (ultrasound of the heart) to evaluate a patient with a heart murmur.

 

An annual physical exam with your veterinarian is vital to detect heart murmurs, which are often the earliest and most subtle signs of underlying heart disease.  If your pet has a newly discovered heart murmur, talk to your veterinarian about what diagnostic tests are available, treatment options, and what you can be watching for at home. 

•  For additional information, please visit these sites:
   
  http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=2488
   
  Dogs:  http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=2515
   
  Cats:  http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=2507
   
   
• Dr. Colleen Helgen   Capitol Illini Veterinary Services    Springfield, IL    January 2014