Arrhythmias in Boxer
Cardiomyopathy is a general term for disease of the heart muscle. Boxers are a breed with a higher chance of developing a cardiomyopathy, specifically Arrhythmogenic Right Ventricular Cardiomyopathy (previously referred to as Boxer Cardiomyopathy). ARVC is a genetic disorder but it is not apparent until adulthood (usually 4 years of age or older).
ARVC is characterized by an abnormal accumulation of fibrous (scar) tissue and fat in the heart muscle. This disturbs the electrical system of the heart and results in frequent arrhythmias. Changes in heart strength can also occur but is less common.
Symptoms vary depending on the stage of disease. It is important to remember that Boxers with ARVC are at risk for passing away suddenly even without previous symptoms. Symptoms can include:
- No outward signs but an arrhythmia is identified on physical examination or during a pre-anesthetic ECG
- Syncope (fainting) due to poor circulation
- Excessive panting at rest
- Exercise intolerance (not wanting to play, go on walks, etc)
- Signs associated with fluid retention including coughing, heavy/labored breathing, or a pot-belly appearance (often mistaken for general weight gain)
- Electrocardiogram (ECG) - An ECG is a non-invasive test that allows veterinarians to evaluate the heart rate and rhythm. Small clips (electrodes) are placed on the legs and are used to make a recording that can be printed and analyzed.
- 24-hour Holter Monitor - A 24-hour Holter monitor can be done to evaluate the heart rhythm over 24 hours. This test is more accurate for assessing the severity and frequency of arrhythmias in Boxers. In addition, it can be used as a screening test for adult Boxers.
- Echocardiogram (Ultrasound of the heart) - This is a non-invasive test that allows the cardiologist to evaluate your dog’s heart size and strength. It is used in conjunction with an ECG to determine the stage of heart disease and select treatment options.
- Genetic Testing - Genetic testing is also available for Boxers through the NC State Veterinary Genetic Lab. It is important to remember that not all genetic markers of ARVC have been identified; therefore, a negative test does not guarantee that your dog will be free of the disease. It is mostly used for breeding purposes to identify high risk dogs.
Can my Boxer be treated?
The cornerstone of treatment for ARVC is anti-arrhythmic therapy. Some boxers require intravenous anti-arrhythmic therapy 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 be continued throughout his/her life. 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 schedule regular rechecks in order to adjust medications and provide optimal care.