Spontaneous echocardiographic contrast in the Thoroughbred: high prevalence in racehorses and a characteristic abnormality in bleeders

Abstract

Spontaneous echocardiographic contrast is the term used by ultrasonographers to describe particulate material visible in intracardiac blood by ultrasound. The purpose of the present study was to determine the prevalence of spontaneous contrast in a farm population of Thoroughbreds and in the farm's racehorses. The results showed that spontaneous echocardiographic contrast is common in Thoroughbreds, and that the prevalence of contrast is affected by age, male gender, racing and pregnancy. The amount of right-sided cardiac contrast was quantitated by videodensitometry and was increased in horses with a history of exercise-induced pulmonary haemorrhage, in comparison with racehorses without a history of bleeding. Since circulating platelet aggregates are known to produce pulmonary haemorrhage in experimental animals and their presence has been associated with echocardiographic contrast, additional studies evaluating platelet aggregates as the aetiologic agent for exercise-induced pulmonary haemorrhage are warranted.