One of the most common causes of sudden/unexpected death in boxers, both young and old, is a condition thought to be inherited and characterized by abnormal heart rhythms involving the ventricles (the main blood pumping chambers) of the heart. This condition can cause varying degrees of disability and occasionally results in congestive heart failure. Current research has determined that the disease is the result of an electrical conduction disturbance which causes the heart to contract too early, thus producing an extra, ineffective beat, the so called Premature Ventricular Contraction (PVC). While many dog breeds may have a few of these PVC's, the boxer seems to be prone to having more of these premature beats. When large numbers of these PVC's occur together, the heart muscle cannot produce a normal, effective contraction, which results in a lack of blood flow to vital organs including the brain and the heart itself. This can cause_the animal to experience a seizure-like or fainting episode (syncope). A prolonged sequence of PVC's can lead to complete cardiac arrest unless the heart resumes a normal pattern of contractions. Less commonly, the lack of adequate contractions may cause the heart to fail and the dog's heart may dilate, causing congestive heart failure with symptoms such as shortness of breath, exercise intolerance, abdominal swelling, coughing and symptoms similar to those occurring in humans with heart failure. This is known as dilated cardiomyopathy -- a less frequent condition in the boxer than the more commonly seen electrical conduction defect. The definitive test for this disease would be a DNA test for the abnormal gene. This research is currently underway at Ohio State University, but research of this type can take a considerable amount of time and funding. Since affected dogs are often asymptomatic until a seizure or sudden death occurs, current attempts in screening for the disease are directed at the healthy appearing animal. The most sensitive tool has been determined to be a Holter Monitor examination (24-hour EKG), which records the dog's electrocardiographic activity over at least 24 hours. The monitor is strapped to the dog and electrodes are placed on the chest while the dog goes about its normal activities. The total number of beats, including the abnormal PVC's, are recorded. The electrodes must be correctly placed and the results must be interpreted by trained personnel. While current research at Ohio State University by Dr. Kate Meurs, funded by the American Boxer Charitable Foundation and the AKC Canine Health Foundation, has suggested certain thresholds of PVC's or other abnormalities for diagnosis of the condition, she has also discovered that an individual dog's numbers may vary from day to day or week to week. Her ongoing research, and that of others, will hopefully determine with greater certainty the value of this screening tool in the future until a definitive genetic test is available. While it is true that a symptomatic dog usually has thousands of beats in a 24 hour period and in severe cases may be diagnosed by simple auscultation of the heart or by a brief EKG, the Holter monitor is still probably the best screening tool for early detection, due to the often intermittant occurrance of the PVCs in the asymptomatic dog. Of recent interest to boxer cardiology researchers is a somewhat similar condition found to occur in human families, the so-called arrhythmogenic right ventricular dysplasia (ARVD), in which young and old persons, previously in good health, experience sudden death. To our knowledge, attempts to find a precise DNA marker have not been successful so far, but if this occurs, it may help veterinary cardiologists find the canine genetic defect sooner. BCM appears to be unique to boxers, so far, in the dog world, and is dissimilar in many respects to cardiomyopathy occurring in other breeds, such as the Doberman and Great Dane. Continuing research and follow-up of dogs already under study will hopefully provide better insight and understanding of this unique condition in the boxer, as well as more widespread availability of screening.