Heart Murmurs in Dogs and Cats
Heart murmurs are common occurrences in pets. A murmur is an abnormal sound produced by turbulent (rough) blood flow. There are many possible causes, some of little concern, but others that are associated with significant disease.
Common causes of heart murmurs include, in young animals:
"innocent" murmurs, which resolve by 4-5 months of age
congenital defects of heart, can be mild or severe
In adult animals:
degeneration of heart valves
cardiomyopathy (heart muscle diseases)
hyperthyroidism, high blood pressure
What comes next?
In patients less than 4 months old and no symptoms of heart disease, we simply wait to see if the problem resolves.
If over 4 months and no symptoms, we recommend a chest x-ray. If x-rays are normal, we can usually just monitor the situation (in cats, an ultrasound exam is recommended as well). If the x-ray is abnormal, a full assessment is warranted. This would include EKG, ultrasound, blood tests and blood pressure measurement.
For patients over 6 years, chest x-rays, blood tests, and blood pressure are warranted as initial assessment.
For any patient with signs of heart disease, a full cardiac assessment is recommended. Signs of heart disease include coughing, weakness, poor appetite, weight loss, fainting, rapid heart rate. A full assessment includes chest x-rays, ultrasound, ECG, blood tests (blood cell count, chemistry, thyroid), and blood pressure measurement.
Certain breeds of dogs (all giant breeds, cocker spaniels, boxers, and Doberman pinschers) should have a full assessment done as initial workup due to increased risk of cardiomyopathy.
Treatment of heart murmurs depends on the cause and severity of the murmur. Innocent murmurs and mild valve diseases usually require no treatment, but should be monitored. Other patients with murmurs may require aggressive treatment of heart failure, arrhythmias, secondary problems like blood clots, or management of underlying diseases.