Heart Murmurs in Puppies
The heart operates with a pump like action.
Divided into four chambers the heart has four valves that work to
keep blood flowing in one direction. The valves open and close,
letting blood in and then pumping it out. That sounds is created
from the movement of the valves and the flowing of the blood.
The sound a murmur makes depends on when it occurs in the
cardiac cycle.

Correct auscultation of a puppy's heart at less than 8 weeks of age
may reveal a heart murmur. This does not necessarily mean that
there is a disease process occurring; however, it may.

Heart murmurs are graded by intensity of sound, on a scale of
1 to 6. It is not infrequent that one may hear a grade 1 or 2 heart
murmur in a 6-10 week old puppy. Often these murmurs disappear
by the time the puppy is 12-18 weeks old, and are therefore termed
innocent murmurs.
However, murmurs with a greater intensity may mean that there is
a congenital heart defect. Most grade 2 or lower will disappear by
18 weeks and the puppy will be fine with no long term or damaging
effects. The puppy would be considered healthy and normal by 18
weeks. However, grade 3 usually or higher may be a serious
problem and may need and Echo Cardiogram.
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