Electrocardiographic anomalies in the racehorse

Abstract

Extract

The veterinarian is often asked to examine the heart of the horse when its performance is below the standard that its owner knows — or hopes — that it should be. The usual complaint is that the horse has become deficient in stamina — it races well up to a point in the race, but when the gap comes and the jockey or driver tries to urge the horse through it, he finds that the gap is going faster than the horse and by the time he gets to the post there is nothing behind him but the ambulance. The clinician is usually under some pressure to provide a diagnosis and it is tempting to point to a prolonged PR interval or dropped beat. Of the 20 years I spent in practice, a good deal of my time was devoted to investigating horses with reduced exercise capacity and I must admit that the heart was only rarely involved. Perhaps this is not surprising since racehorses are not exposed to factors that cause heart disease in other species — e.g., high cholesterol-producing diets, persistent emotional tension, high circulating androgen levels, degenerative aging changes, genetic predisposition — horses are selected to eliminate this — and insufficient exercise.