Impotence in the bull: (3) Rupture of the corpus cavernosum penis proximal to the sigmoid flexure.

Penile haematomas, lying outside the tunica albuginea, were found in six bulls of various breeds, aged one-and-a-half to nine-and-three-quarter years. In five cases the haematomas definitely arose from rupture of the dorsal or crural canal and tunica albuginea of the corpus cavernosum penis (ccp) within the proximal 12 cm of the penile body. In the sixth bull, lesions of the tunica albuginea and distortion of the penis just proximal to the proximal bend of the sigmoid flexure may have represented the site of rupture. There was no evidence of rupture at the distal bend of the sigmoid flexure or of rupture of the dorsal penile vessels in any of these specimens. In all six specimens, the dorsal canals of the ccp were occluded by translucent fibrous tissue distal to the sites of rupture; this was considered to be the factor immediately predisposing to proximal rupture of the ccp. Clinically, a small haematoma in the perineal region is difficult or impossible to palpate externally. However, when the haematoma of proximal origin is large, differentiation from rupture at the distal bend of the sigmoid flexure may be based tentatively on a careful clinical examination. In cases of proximal rupture the haematoma lies caudal and dorsal to the scrotum and no abnormality of the distal bend may be palpable. In cases of distal rupture, the haematoma usually lies cranial to the scrotum and involves the distal bend of the flexure. Severe disruption of the vascular structure is found in cases of proximal rupture of the ccp; therefore the prognosis is grave.