Castration may not affect the penile erection ability in terms of peripheral neurocavernous mechanism in dogs

The penile erection ability (PEA) was assessed in 27 dogs with intact orchids (Group I), seven dogs with bilateral orchidectomy for one month (Group II) and four dogs with bilateral orchidectomy for three months (Group III). PEA was indicated by the increase of the intracorporeal pressure (ICP) upon electrical stimulation of the cavernous nerves. PEA was significantly decreased in both orchidectomized groups. However, when reduction in the blood pressure was considered, the difference in PEA between Group I and the orchidectomized group was no longer significant. Before the orchidectomy, plasma testosterone level of 22 adult male dogs varied widely from 105 to 6302 pg./ml. At one or three months after the orchidectomy in 11 dogs, it decreased to a level below 100 pg./ml. There was no significant change in the body weight in the post orchidectomy period. These findings indicate that the castration and/or the resulting low plasma testosterone level does not directly affect PEA through the peripheral neural and cavernosal mechanism.