Dilated cardiomyopathy (DCM) is a primary disease of heart tissue that is characterized by cardiac enlargement, usually of one or both of the ventricles, which are two of the four chambers of the heart. Dogs with DCM have abnormal heart muscle fibers, which prevents their hearts from contracting and pumping blood properly. This, in turn, causes one or more of the chambers of the heart to stretch and enlarge, and at the same time causes the walls of those chambers to become abnormally thin. These changes further impair the heart’s ability to pump blood normally and adversely affect the overall output or amount of blood that enters circulation with each heart contraction. These abnormalities are called “reduced cardiac contractility” and “reduced cardiac output,” respectively. All organs and tissues can be adversely affected by reduced cardiac contractility and output, because of the decreased delivery of well-oxygenated blood to all parts of the body. The lungs and kidneys are especially vulnerable. DCM is often accompanied by congestive heart failure (CHF), heart rhythm abnormalities (arrhythmias), or both. In fact, DCM is one of the most common causes of congestive heart failure in large and giant breed dogs.
The causes of dilated cardiomyopathy (DCM) are not known. The medical term for this is “idiopathic”. A number of different things have been suggested as possible contributors to the disorder. These include malnutrition (dietary deficiencies in taurine [a sulfur-containing essential fatty acid] and/or carnitine [a co-enzyme of fatty acid oxydation), immune-mediated abnormalities, viral infection, protozoal infection, microvascular hyperreactivity and genetic disorders involving specific myocardial (heart muscle) structural or contractile proteins. Hypothyroidism and myocarditis have also
Many dogs with dilated cardiomyopathy (DCM) seem to be unaffected by their serious heart condition, or at least they often show no outward signs of discomfort or distress. However, when DCM becomes clinical – which means that observable signs of the condition exist – affected animals usually have respiratory difficulties which we can only assume are uncomfortable at best, and extremely painful and frightening at worst.As mentioned above, many dogs with DCM do not show
Dilated cardiomyopathy (DCM) often goes undiagnosed, even for many years. Unfortunately, it frequently is only discovered when an affected dog suddenly dies for no apparent reason. Sometimes, DCM is an incidental finding during an otherwise routine physical examination, or when a veterinarian is taking chest radiographs (X-rays) for some other reason and notices an abnormally large cardiac silhouette. The attending veterinarian may hear abnormal heart or lung sounds when listening to the chest of
All but the most severely affected dogs with dilated cardiomyopathy (DCM) usually can be treated on an outpatient basis, meaning that they rarely require hospitalization. The therapeutic goals for treating DCM are to resolve the signs of any associated congestive heart failure, alleviate any build-up of fluid in the lungs, chest and/or abdomen, improve the force of heart muscle contractions, control life-threatening irregular heart rhythms, relieve the dog’s discomfort and improve the dog’s overall quality