Innocent murmurs tend to occur in puppies and resolve by 6 months of age. These are important features to distinguish innocent murmurs from congenital heart murmurs. They are best heard with the bell of the stethoscope. An audible gallop may be an early sign of heart disease, and can be present before other signs of heart failure appear. They indicate abnormalities of ventricular filling.
Gallop sounds can wax and wane with respiration.
S 3 gallops likely represent ventricular decompensation. S 4 gallops are usually associated with reduced ventricular distensibility. S 3 gallops are frequently detected in cases of severe left ventricular dysfunction. In our attempt on physical examination to distinguish mild disease from severe disease, the presence of a gallop usually reflects severe myocardial disease.