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Incidental Heart Murmurs

If a heart murmur is noted during routine consultation, then a decision needs to be made what to do next. To help with the decision, it can be helpful to look at murmurs in certain patient groups.


Puppies not uncommonly have benign functional murmurs, which may disappear over time. However, congenital heart disease is best treated as early as possible before serious irreversible cardiac damage is present. This means there is a risk of waiting too long prior suggesting referral for further clarification if congenital heart disease is present and requires corrective measures.

Murmurs louder than 2/6 rarely disappear and rarely represent benign puppy murmurs. Therefore puppies with louder murmurs should be referred for cardiac investigations if possible.

Please be aware that murmurs linked to congenital heart disease are often loudest and most obvious cranial over the heart base. Careful auscultation of the more cranial part of the thorax is therefore very important in puppies.

Middle aged and older small breed dogs

The most common heart problem in middle aged and older small breed dogs is degenerative mitral valve disease, resulting in mitral valve regurgitation. For many years, no medication had been proven to influence the prognosis of dogs with asymptomatic mitral valve disease (prior onset of congestive heart failure). However, this has change decently. The results of the EPIC trial showed that a subpopulation of dogs with mitral valve regurgitation benefits from treatment with pimobendan prior onset of congestive heart failure. Those dogs are characterised by heart murmurs ≥3/6 and cardiac enlargement. Therefore, cardiac size should be evaluated in those patients. While severe cardiac enlargement can be seen on thoracic radiographs, mild enlargement is often difficult to diagnose without echocardiographic examination. Dogs with a heart murmur ≥3/6 will therefore benefit from echocardiographic assessment.

We just launched a mitral valve clinic, offering reduced cost echo to this patient group. Please click here to read our info flyer about the mitral valve clinic for more detailed information.


Heart disease is common in cats. Cats hide clinical signs for a long time and commonly the problem is only noted when the disease is very advanced. Therefore cardiac investigations should be considered if abnormalities are noted on auscultation. As general rule, gallop rhythm and arrhythmia are even more worrying findings in cats than heart murmurs with a large proportion of those patients having serious cardiac disease. But still, about one third of cats with heart murmurs do also have heart disease of varying severity. Complications in cats with heart disease can be very serious with aortic thromboembolism being one of the worst. Therefore investigations should always be recommended for cats with abnormalities noted on auscultation.

Murmur timings Original image

Location of heart murmur