The term "myopathy" refers to a disease of the muscle tissue. "Cardiomayopathy" is the disease of the heart muscles. Hypertrophy means enlargement of a body organ. The term "cardiomyopathy" literally means "sick heart muscle."
Hypertrophic cardiomayopathy (HCM) refers to a disease of heart in which heart muscles becomes thickend. This thickening of the heart muscles results in heart walls becoming stiffer and less compliant. It also means decreased chamber size of the heart. In this condition, walls of one or more heart chambers become thick and consequently become stiff and less flexible. The size of the chamber(s) also decrease with this condition. This leads to an inadequate amount of blood being pumped out to the body through arteries during systolic phase (pushing blood out into arteries). During diastolic phase, when the heart relaxes, an insufficient amount of blood will fill the heart. Therefore, there is every likelihood that HCM will lead to congestive heart failure.
It is a rare condition in dogs. A breed predisposition is seen in Boston Terriers, German Shepherds and Pointers.
Most dogs with HCM may remain asymptomatic. Those that do show signs, they are related to congestive heart failure (CHF). Such dogs may show exercise intolerance, breathing difficulty, panting, coughing and bluish skin. Very rarely, a dog with HCM may faint during strenous physical exercise. Clinical signs may include heart murmur and a heart gallop.