Boxer arrhythmogenic right ventricular cardiomyopathy (ARVC) is an adult onset genetic disease that results in fat accumulation in the heart muscle and development of ventricular arrhythmias (abnormal heart beats originating from the lower heart chamber). Single abnormal beats rarely cause any clinical problems. However, if the beats are continuous and occur at fast rates then the heart does not have sufficient time to fill with blood or pump enough blood to the vital organs. This leads to signs of syncope (collapse), muscle weakness, exercise intolerance, and even sudden death. Syncopal episodes often occur during exercise but can also occur during rest. In some cases, dogs can develop signs of right-sided heart failure (abdominal distension from fluid build-up) or left-sided heart failure (coughing, increased respiratory rate and effort, or difficulty breathing).

Boxer ARVC cannot be diagnosed by physical examination alone and definitive diagnosis requires diagnostics such as blood pressure measurement, electrocardiography (ECG), radiographs (x-rays), and an echocardiogram (ultrasound of the heart). In addition, a 24-hour Holter monitor is used to determine the frequency and severity of the arrhythmias as well as monitor the response to treatment.

The cornerstone of treatment for ARVC is anti-arrhythmic therapy. Some boxers require intravenous anti-arrhythmic therapy in hospital for immediate control of the arrhythmias while others can be started on oral medications as their initial treatment. In either situation, the goal of therapy is to decrease the frequency and severity of the arrhythmias. Multiple drugs can be used depending on your pet’s needs and most of the drugs will need to be continued throughout his/her life. Routine reevaluation of your pet is needed in order to provide optimal care.

ARVC is a lifelong disease but life expectancies are extremely variable. Many dogs enjoy years of quality life with medication and monitoring; however, the disease can also be so severe that sudden death occurs even with treatment. If your boxer has been diagnosed with ARVC then it is important to monitor for evidence of worsening arrhythmias or congestive heart failure. These signs include weakness, syncope, distension of the abdomen, difficulty breathing (increased rate or effort), and a decrease in appetite. In addition, it is recommended to limit your dog’s activity level as exercise and excitement can exacerbate the arrhythmias.