Dilated cardiomyopathy is an inherited disorder of the heart affecting several breeds of dog. This disease shows incomplete penetrance, meaning that not all dogs at risk (those with one or two copies of the mutation) will develop the disease. In affected dogs, the heart muscle is weak and the chambers become dilated with thin walls. These enlarged hearts have poor contractility and are prone to arrhythmias. Affected dogs present with clinical signs of poor heart function between 1 to 8 years of age. Affected dogs develop clinical signs as they age ranging from mild exercise intolerance to sudden death or congestive heart failure. Signs of heart disease include exercise intolerance, fatigue, coughing, difficulty breathing, rapid breathing, fainting and sudden death. Affected dogs that don’t die suddenly from arrhythmias usually die from congestive heart failure around 7 years of age. Different disease genes and environmental factors play a role the development of dilated cardiomyopathy in dogs. Therefore, not all dogs with this disease will have the same genetic mutation.
*NOTE: The PDK4 gene mutation was originally identified in the Doberman pinscher and has only been associated with dilated cardiomyopathy in this breed. Though this mutation has been identified in several other breeds, including those known to develop dilated cardiomyopathy, a correlation between this mutation and dilated cardiomyopathy has not been established for these breeds. For this reason, the most cautious medical approach for any dog inheriting the PDK4 gene mutation would be to make all health and breeding decisions based upon cardiac exam results and recommendations from a board certified veterinary cardiologist. Dogs from breeds other than the Doberman pinscher that have been found to have inherited this mutation should not be removed from breeding programs based upon the results of this genetic test alone.