Dilated cardiomyopathy is the second most common form of heart disease in dogs. Dilated cardiomyopathy is a disease of the heart muscle itself where the dog's heart fails to pump effectively. The contractions of the heart are weak and therefore blood is not pumped through the body efficiently. Typically, the heart stretches and enlarges, becoming overly thin, which over time further decreases its ability to pump blood around the body.
Disease of the heart muscle is more common in medium to large dogs. 1,2
If your dog is one of these breeds, there is no need to be alarmed. But you should watch for early signs of heart failure.
1. Ware WA. Cardiovascular Disease in Small Animal Medicine. London: Manson Publishing Ltd; 2011. 2. Data on file. Ingelheim Pharmaceuticals (Pty) Ltd, Animal Health Division.