Objectives: The purpose of this study was to investigate a family of Great Danes with known dilated cardiomyopathy (DCM) using serial echocardiographic evaluation. Animals, Materials, and Methods: Twenty-two dogs were included in this study. They were split into two groups, clinically normal and those with DCM. The dogs were scanned using 2D and M-mode echocardiography every thirty to sixty days beginning at approximately14-20 days of age. Data were collected and analyzed using generalized additive mixed regression, linear regression, and non-linear regression. Results: All dogs demonstrated progressive echocardiographic changes. The Great Danes with DCM showed several echocardiographic differences when compared to the normal dogs. They included differences in left ventricular diameter, left atrial diameter, interventricular septal thickness, ejection fraction, and fractional shortening. Conclusions: The present study shows that progressive echocardiographic changes occur in both clinically normal Great Danes and those with DCM as they mature. Additionally, the two groups differed with regards to left ventricular diameter, left atrial diameter, interventricular septal thickness, ejection fraction, and fractional shortening.