Abstract
The morphology of the cardiovascular system in 54 conjoined calves including 29 previously reported cases was investigated. All of the 21 cases of diprosopus had a single heart. Among 19 cases of dicephalus, 2 cases had two separate hearts with vascular union between great vessels, and the other 2 cases had separate hearts with no vascular union. Four cases had a compound heart with cardiac fusion at the atrial level, other 4 cases had a compound heart with fusion at both atrial and ventricular levels, and remaining 7 cases showed a single heart. In 8 cases of thoracopagus, 4 cases had separate hearts with no vascular fusion, one case had a atrial compound heart, and 3 cases had a single heart. In 5 cases of cephalothoracopagus, 2 cases had separate hearts with vascular union, 1 case had a compound heart with fusion at both atrial and ventricular levels, and 2 cases had a single heart. A case of pygopagus had separate hearts with no vascular union. Fourteen of 33 single hearts showed various congenital anomalies. Conjoined calves with separate hearts commonly had two sets of the lung and ventriculus, and the cases having a single heart showed a set of the lung and ventriculus.
