Abstract
A race horse 3 years and a half old suddenly died. It was found to have been suffering from coronary aneurysm accompanied by rupture, and was studied formal-pathogenetically. The aneurysm was shown in the right coronary artery at a portion transitional to its descending branch. The results of this investigation essentially lend support to the neurogenic theory which has been asserted by one of the authors, SATOH, and his associates from their studies on so-called idiopathic rupture of the aorta in an aged stallion. The histopathologic findings in the wall of the affected portion of the coronary artery were represented by an extensive hydropic medial degeneration. This change was regarted as a result of the primary continuous edmatous process (disturbance of water metabolism), which had been caused by "microvascular alteration" (edematous loosening and swelling of the wall) of the vasa vasorum of the artery. In conclusion, it seems that the "microvascular alterations" were caused by neurogenic changes : there were organic nervous disturbances in the adventitia of the aneurysm-affected portion of the coronary artery. Formal-pathogenetically, it was understood that extensive hydropic medial degeneration was a factor necessary for the occurrence of aneurysm and rupture. The wall of the coronary artery became thin and rarefied as a result of medial degeneration. Accordingly, this change would bring about the dilation and the rupture, which might be accelerated by blood pressure or the partial.
