The heart consists of a left side and right side. The function of the heart is to pump oxygenated blood to all body tissues as well as exchanging deoxygenated blood in the lungs which is converted to oxygenated blood than out the aorta to service bodily needs. Failure of the valves pumping this blood as well as dilating of the myocardium (dilitative cardiomyopathy) can lead to congestive heart failure.
Congestive heart failure is seen commonly in small breeds of dogs such as: Poodles, West Highland Terriers, Pugs, Miniature Schnauzers, Yorkshire Terriers and others. Cats and large dogs that develop cardiomyopathy also can suffer from congestive heart failure.