Dogs affected by this disorder have an enlarged heart and thin heart muscle. The clinical signs of cardiac failure are exercise intolerance, persistent cough, breathing difficulties, and swelling of the abdomen (ascites). DCM is also characterized by arrhythmias which can cause sudden cardiac death without any previous clinical signs. Diagnosis is based on a cardiac ultrasound examination. ECG and thoracic X-rays may also be performed. Arrhythmias may be the first sign of the disease.

If the dog has been diagnosed as possessing a higher risk of developing dilated cardiomyopathy, the dog should be examined once a year by a veterinarian, preferably a cardiologist. Holter examinations may be used in asymptomatic dogs since arrhythmias may be the first clinical signs of the disease. There is no curative treatment for the disease. Affected dogs are treated symptomatically with antiarrhythmic medications and medications treating cardiac failure. Stress must be avoided.

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to develop. A carrier dog with one copy of the DCM mutation can be safely bred with a clear dog with no copies of the DCM mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the DCM mutation. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the DCM mutation could develop due to a different genetic or clinical cause.