Angiography has been used to identify congenital heart lesions and acquired conditions in foals and small (<300kg) adults. Expensive equipment is required, including a wide field-of-view image intensifier, a rapid film changer, cineor video recording, a high output X-ray generator and a pressure injector capable of injecting up to 150 ml of contrast in under 4 seconds. Angiography has largely been replaced by 2DE and DE as the diagnostic method of choice for congenital heart disease in all species and is unlikely to be used in future clinical investigations. Selective echocardiographic contrast studies can also be performed and are more practicable than angiography. However, these studies are seldom required in order to reach a diagnosis.