Causes
Turbulence in the blood flow through the heart. Causes: valve disease, cardiomyopathies, congenital defects, anaemia. Some murmurs in puppies are "innocent" and disappear as they grow.
Diagnosis
Auscultation (detection) plus echocardiography to find out the cause and severity.
Treatment
The murmur itself is not treated: its underlying cause is treated, if there is one. Some murmurs need nothing more than monitoring.
Prevention
Not preventable. Regular check-ups allow murmurs to be detected early.

