Atrioventricular Block in Horses Is Not Always that Innocent: Three Case Reports

Introduction : Second degree atrioventricular block (AVB) is the most common physiological arrhythmia in horses associated with high vagal tone. On rare occasions atrioventricular (AV) conduction remains disturbed even at higher sympathetic tone, leading to exercise intolerance, or may evolve to third degree AVB with syncope [1]. A variety of causes including electrolyte imbalances, intoxication, AV node inflammation and infection can lead to impaired conduction, making treatment sometimes challenging. History Two horses were presented at the clinic with a history of decreased performance. Horse 1 had received an intramuscular injection with iron dextran one day before admission and horse 2 had shown epistaxis during exercise. Horse 3 suffered from recurrent syncope. […]