Subaortic stenosis is a congenital, genetic heart defect. It can affect any breed of dog, but is most commonly seen in Newfoundlands, Golden Retrievers, and Rottweilers. It is typically diagnosed in puppies 16 weeks of age or older, although more severe cases will present with a murmur at younger ages.

Patent Ductus Arteriosus (PDA) - Patent Ductus Arteriosus. CAUSE: Patent ductus arteriosus (also called PDA) is a birth defect in the heart. It is caused by incomplete changes in the heart's circulation when a dog is born. The ductus arteriosus is an important blood vessel that ensures that blood does not go to the lungs.

Cardiomyopathy - Generally speaking, the clinical signs of DCM are a loss of appetite, increased heart rate, pale gums, exercise intolerance, difficulty breathing and fainting. If the left ventricle is affected, the dog may also develop a dry cough.