Heart disease in the Boxer dog was initially documented in the 1980s and referred to as Boxer cardiomyopathy. Recent studies have confirmed that this disease is inherited and is primarily characterized by disturbances in the cardiac electrical system, fainting episodes and sudden death. The inherited nature of the disease has led to increased interest in the development of a genetic test for the disease that could be used to diagnose affected dogs before they were used for breeding. However before investing significant time and resources into the development of a genetic test it is imperative that the familial nature of the disease be well understood. To this date, both studies suggesting a familial nature to Boxer ventricular arrhythmias have been performed in eastern regions of the United States. It is important to perform similar genetic evaluations in a unique geographical region to confirm that the familial nature and the mode of inheritance are constant. The study proposed here will provide an increased understanding of the pattern of inheritance and genetic etiology of this disease within the United States as well as to provide a bank of DNA samples from affected dogs.