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Twenty penis from normal boars were injected with various media at known reservoir pressures and examined by radiography, dissection, maceration, clearing and sectioning. Injections into the corpus spongiosum penis (csp) produced dorsal deviation and clockwise spiral twisting. The ccp was traversed by a system of large longitudinal cavernous spaces. The csp consisted of one large vascular space, its walls joined by trabeculae which were close together ventrally and further apart dorsally. The corpus spongiosum glandis (csg) was a vascular network within the penile integument communicating with the csp by fine vascular spaces around the urethral orifice. The penile arteries and veins were supplied and drained by the internal pudendal vessels. The ccp was drained from its crura by the v profunda penis but no venous drainage of this cavernous body was demonstrated within the body of the penis. The csp was drained from its bulb by the v bulbi penis; its distal extremity was drained by two large veins which ran proximally enclosed by the tunica albuginea of the csp. The right vein was always much larger than the left vein and at the sigmoid flexure the two united to form the right tributary of the v dorsalis penis. The csg and the entire penile integument were drained by the left tributary of the v dorsalis penis; the csg was also drained by one or both of the ventral veins of the csp. Blood from the scrotum was drained by the v circumflexa perinealis and v perinealis ventralis into the v dorsalis penis and v penis. A large dorsal lymphatic vessel drained lymph from the body of the penis into the pelvic lymph nodes. No connections with the superficial inguinal lyphocentres were identified.

A new indirect radiographic technique is described for the differential diagnosis of erectile impotence in the bull. Two cases of impotence have been investigated in this way. In the first, occlusion of the dorsal longitudinal canal of the corpus cavernosum penis in an 18-month-old Hereford bull was diagnosed. In the second, distal venous drainage of the corpus cavernosum penis was demonstrated in a five-year-old Hereford bull. Post mortem examination of the reproductive tract confirmed the diagnosis in each case.

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.

Six boars were deficient in penile erection and incapable of intromission, but produced ejaculates containing spermatozoa. In five of these boars impotence was primary, but one boar had served normally for two seasons before showing secondary impotence. Sexual libido was good in two, moderate in two and poor in two of these animals. Post mortem studies on the reproductive tracts revealed no abnormalities except in the penes. In one of the boars with primary impotence, the penis showed an abnormal type of spiral deviation during simulated erection, but there was no abnormality in the venous drainage of the organ. In the other five boars, injection experiments revealed venous drainage of the corpus cavernosum penis (ccp) into the dorsolateral (left) tributary of the v dorsalis penis. In four cases, the apical cavernous spaces of the ccp communicated with the vascular spaces of the corpus spongiosum glandis. No direct communications with the corpus spongiosum penis (csp) were demonstrated but the csp was injected from the ccp indirectly, by way of the dorsal venous system. It is suggested that these abnormalities may have been the immediate cause of impotence in these five boars. This possibility is discussed in relationship to the processes of erection and ejaculation and to various clinical signs shown by these animals. The abnormalities of venous drainage were thought to be developmental in origin and the condition may be inherited.

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.

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.