Postnatal growth of the dog heart.

We have found that, in the dog at birth, the right ventricle weighed significantly more than the left. At 3 days the left ventricle weighed the same as the right ventricle. No evidence for postnatal atrophy of the right ventricle was found--the right ventricle simply gained weight at a much slower rate than the left. The left ventricle weighed significantly more than the right at 7,9,11,13,15 and 17 days.