Six young bulls (two Friesian, two Charolais, one polled Devon and one North Devon) that had never served successfully, showed good libido but lacked penile erection. In five of these bulls, the short flaccid organ was not protruded during attempted service. Radiography of the cavernous bodies and veins of the penis in the living animal demonstrated major venous drainage of the corpus cavernosum penis (ccp) by the dorsal venous system in all cases. This was not seen in normal bulls. Radiography and anatomical preparations of post mortem specimens showed that the ccp was drained by the dorsal venous system throughout the length of the organ. Proximally, the cavernous spaces of the ccp anastomosed with those of the corpus spongiosum penis (csp) and were drained by numerous small veins. Distally, a system of larger veins, not seen in normal bulls, drained into left and right sides of the dorsal venous system. No microscopical abnormalities of spermatozoa or of testes were found, but there was a marked lack of spermatozoa in the caudae epididymides. The evidence suggests that abnormal venous drainage of the ccp may have been the immediate cause of impotence in these bulls.

Lack of penile erection was diagnosed in nine bulls (Poll Hereford three; Aberdeen Angus two; Friesian two; horned Hereford; Sussex). Five had previously served successfully but four had proved impotent when first put to use. In each bull, the dorsal longitudinal canal of the corpus cavernosum penis (ccp) was occluded by fibrous tissue and this was considered to be the immediate cause of impotence. The ventral canals were also occluded in four bulls. In every case, the lesions were so extensive that treatment would not have been likely to succeed. In two bulls the dorsal canal and the tunica albuginea were ruptured proximal to the sigmoid flexure. Radiography of the cavernous spaces and veins during life, and anatomical injections of post mortem specimens, showed that in four bulls the ccp was drained by the dorsal venous system at or distal to the sigmoid flexure. The aetiology and the diagnosis are discussed and the possible physiological implications of occlusions of the canals are considered in terms of the functional anatomy of the ccp.

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