Genetic basis of ARVC - is a hereditary myocardial disease primarily affecting the Boxer dog, also reported in related breeds such as English Bulldogs, American Staffordshire Terriers, and occasionally other breeds. It is caused by a mutation in the striatin gene, which encodes a desmosomal protein important for intercellular adhesion in cardiac muscle. This mutation leads to structural and electrical instability in the heart muscle. The disease is inherited in an autosomal dominant or incomplete pattern, with variable expression; homozygosity for the mutation increases risk of developing more severe forms such as dilated cardiomyopathy.
Pathophysiology - ARVC causes progressive replacement of right ventricular myocardium with fatty or fibrofatty tissue. This structural change leads to electrical instability and the development of ventricular arrhythmias, particularly ventricular premature complexes (VPCs) and ventricular tachycardia. In advanced cases, the disease can affect the left ventricle, resembling dilated cardiomyopathy (DCM), potentially leading to heart failure. The arrhythmias can cause reduced blood flow to the brain, leading to syncope (fainting) or sudden cardiac death if sustained.
Complications - Frequent and severe ventricular arrhythmias can cause episodes of syncope or collapse. Sudden cardiac death may occur due to sustained ventricular tachycardia or ventricular fibrillation. Some dogs develop dilated cardiomyopathy with systolic dysfunction and congestive heart failure. Diagnosis can be challenging as the heart may appear normal on thoracic radiographs and echocardiograms in early or moderate disease. Affected dogs are at risk for progressive heart disease with serious clinical consequences.
Why This Matters to Breeders and Vets - Breeders benefit from genetic testing to identify carriers and avoid producing affected dogs or those at risk of severe disease. Early diagnosis by veterinarians through Holter monitoring (detecting >100-300 VPCs in 24 hours is diagnostic) allows appropriate treatment and management. Treatment focuses on controlling arrhythmias using medications such as sotalol or mexiletine combined with atenolol. Vets should monitor for signs such as syncope, exercise intolerance, or sudden death risk and provide genetic counseling. Understanding the disease helps in preventing its spread and improving clinical outcomes.
Summary - Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is a serious inherited cardiac disease in dogs, especially Boxers. It results from a striatin gene mutation causing replacement of heart muscle with fatty/fibrous tissue and life-threatening ventricular arrhythmias. Clinically, affected dogs often present with syncope, arrhythmias, or sudden death. Genetic testing, early diagnosis, and antiarrhythmic therapy improve prognosis. Responsible breeding practices informed by genetic testing can reduce disease prevalence and protect breed health.