What is Cardiomyopathy?

Cardiomyopathy is the term used for diseases that directly affect the heart muscle (myocardium), compromising its ability to pump blood efficiently. The most relevant forms in pets are dilated cardiomyopathy, in which the heart's chambers enlarge and contraction strength decreases (most common in large-breed dogs, such as Doberman Pinschers and Boxers, and in some cases associated with certain diets), and hypertrophic cardiomyopathy, in which the heart's walls thicken and impair proper filling of the chambers (the most common form in cats, with a predisposition in breeds such as Maine Coons and Ragdolls).

Symptoms vary depending on severity and can take time to appear: easy tiring, labored or rapid breathing even at rest, coughing (more common in dogs), fainting, exercise intolerance, and, in advanced cases, fluid buildup in the chest or abdomen (a sign of heart failure). In cats, a serious, emergency sign is sudden hind-limb paralysis, caused by a blood clot (thromboembolism) that forms as a complication of cardiomyopathy.

Diagnosis is made through a physical exam (heart auscultation), chest X-rays, echocardiogram, and sometimes an electrocardiogram. There is no cure in most cases, but specific medications help control symptoms and can significantly prolong survival with a good quality of life. See a veterinarian urgently if a pet has labored breathing at rest, easy tiring, fainting, or, in cats, sudden hind-limb paralysis.