Cardiomyopathy and juvenile mortality is an inherited cause of early mortality in dogs. Puppies present as early as 6 weeks of age with variable clinical signs that may include tremors, gastrointestinal issues or difficulty breathing. A veterinarian may observe an enlarged heart and/or narrow trachea via an X-ray exam. Affected dogs have degenerative changes to the heart muscle likely from abnormal metabolism in the cells. Puppies with this condition die within 8 weeks of age from heart failure.