How to interpret an electrocardiogram

Abstract

Electrocardiography is the ultimate tool for diagnosing suspected cardiac arrhythmia, and the required equipment is readily available to an equine practitioner. Careful interpretation is essential to determine whether an arrhythmia is significant, either as a cause of poor performance or as a risk for collapse and sudden death. A good quality electrocardiogram recording is essential, usually an exercising electrocardiogram and a recording over 24 hours. Electrocardiographical interpretation is aided by modern electrocardiogram analysis software, and technology enables access to a second opinion when required. Vagally-mediated arrhythmias are common in horses at rest, but should be overridden by exercise. Atrial fibrillation or frequent ectopic beats during exercise warrants further cardiac evaluation.