Arrhythmogenic Right Ventricular Cardiomyopathy is a disease that primarily affects the Boxer. In this disease, the heart muscle is replaced with fat and scar tissue. This abnormality of the heart muscle results in arrhythmias. Dogs with this disease can be asymptomatic or dogs can have clinical signs of fainting (syncope) or even pass away suddenly. It is commonly diagnosed by an ECG, an electrocardiogram, or placement of a Holter monitor, 24 hour ECG recording, to monitor your dog’s heart rate and rhythm. ARVC treatment is focused on treating the clinical signs associated with the arrhythmia, but treatment does not reduce the risk of passing away suddenly. Common treatments for the arrhythmia includes potassium channel blockers such as sotalol and fish oil therapy. The prognosis is variable with this disease. Approximately 25% of boxers with this disease can develop weakening of the heart muscle, enlargement, and ultimately congestive heart failure or a fluid accumulation in the lungs (pulmonary edema) or body cavities such as around the lungs (pleural effusion) or in the belly (ascites). This is diagnosed by Echocardiogram or an ultrasound of the heart. The prognosis is very variable with this disease with some dogs living years after diagnosis. Poor prognosis can be associated with clinical signs, severity of the arrhythmia, and presence of congestive heart failure and dilated cardiomyopathy. This has been linked to a gene associated with striatin deficiency in the boxer.