Cardiomyopathy describes an abnormality of the heart muscle; dilated refers to abnormal thinning of the heart muscle. The thin heart muscle causes weakness-blood cannot pump from the heart to the rest of the body efficiently. As the disease progresses, the heart begins to fail; the blood flows backward and pools in the lungs and other organs. The cause of Dilated Cardiomyopathy (DCM) is unknown; however, there is a genetic predisposition to this disease in certain breeds: Dobermans, Boxers, Great Danes, and Cocker Spaniels. Dogs with DCM may not show any signs of a problem until the disease has become advanced. Symptoms of DCM include: collapse, cough, lethargy, exercise intolerance, and acute death. Diagnosis of DCM begins with a physical examination focusing on the heart. A murmur may not be heard, however, an abnormal rhythm may be detected. Definitive diagnosis requires x-rays of your dog’s chest and an ultrasound of the heart. Treatment of DCM requires medications to help the weakened heart muscle pump blood to the body more efficiently. Prognosis for pets with this condition has improved over time with the advent of new heart drugs; however, the long term prognosis is poor once signs of heart failure occur.