Angiography of the corpus cavernosum penis in the pony stallion during erection and quiescence

Serial arteriography was used to determine the vascular pattern and blood flow in the penis of the pony stallion. Ponies were anesthetized with pentobarbital sodium, and catheters were surgically introduced into the internal pudendal and obturator arteries. The vascular anatomy was visualized by angiography via image-intensified fluoroscopy and was recorded on 70-mm film at 3 frames/s or by direct radiography. Blood flow into the corpus cavernosum penis (CCP) was limited during quiescence because the blood was immediately shunted into the venous system. After vasodilation with mild stimulation from an electroejaculator, there was increased filling of the CCP and corpus spongiosum penis. Contrast medium injected into the internal pudendal artery entered the bulb of the penis during peak erection, but medium injected into the obturator artery could not enter the crus penis during peak erection. The contrast medium stopped in the obturator artery at the edge of the ischiocavernous muscles due to the occlusion of the deep arteries of the penis by contraction of these muscles. When contrast medium was injected directly into the CCP near the glans to outline the body of the penis, there was no evidence of venous outlets along the body.