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Heart murmurs do not necessarily correlate with heart disease. A heart murmur is an abnormal sound heard during while auscultation (listening to the heart with a stethoscope). In cats, heart murmurs can be from many different factors, some more concerning than others.Stress, heart disease, hypertension, hyperthyroidism, dehydration, congenital issues, innocent, being anemic, heartworm disease and many other ailments can cause murmurs in cats. Sometimes heart murmurs can be ‘innocent’, meaning we hear abnormal sounds not associated with heart disease, but the only way to know is through diagnostic testing. Although it is important to be judicious with our diagnostic tests and decision-making, the unfortunate number one sign of heart disease in every species is sudden death.
Let’s discuss the steps we take when we hear a murmur in one of our patients. First we think about the age of a patient.Young cats can have congenital issues heart issues. Generally, middle-aged cats (8-12 years) can have hypertrophic cardiomyopathy. Older cats often have hyperthyroidism that can cause heart murmurs as well. Another factor is the sound of the murmur – how loud the murmur is, when it occurs during the filling/emptying action of the heart, and the rhythm it creates. This information factors into the grading of the murmur. Murmurs are graded from 0 – VI, with 0 being not present and VI being severe. The intensity and loudness of the heart does not necessarily correlate with heart disease however it is important to keep track of how the sound changes over time.
Next we consider the patient’s demeanor. Are they very stressed during the time of the exam or are they relaxed? Are they scared and hiding or are they head booping the veterinarian? Is the heart murmur only heard when the cat is nervous?
Finally, clinical signs help us determine what actions to take. If the cat is exhibiting open mouth or abdominal breathing, lethargy or just behaviorally seems off heart disease or seems off those would be clinical signs of heart disease.
If we are concerned with a heart murmur, the gold standard is to do an echocardiogram or an ultrasound of the heart.We recommend a boarded veterinary cardiologist in concert with an exam complete these diagnostics. There is also a test called the prohormone brain natriuretic peptide test or ProBNP. This measures the concentration of this hormone that is released by the atria of the heart. The ProBNP level is elevated when the atria of the heart is stretched or damaged.If this test is run and the results are elevated, that increases our suspicion of heart disease. This is a great test to run on the day of a surgical procedure if a new heart murmur is heard to help make sure the patient likely does notis unlikely to have heart disease prior to anesthesia. We are lucky in our area to have some phenomenal cardiologists. There are different types of heart disease in cats, however with careful monitoring and appropriate medications, many cats live symptom free with a good quality of life.
Here are some additional helpful links about heart murmurs: Many heart murmurs are asymptomatic or innocent.They can be due to stress as well.Although it is important to be judicious with our diagnostic tests and decision making, to be clairvoyant, the number 1 sign of heart disease in every species is sudden death.