Diagnosis of penile denervation in the bull: a review

Abstract

Healthy bulls with satisfactory breeding potential are important to the beef cattle industry. Erection, mounting, intromission, and ejaculation with deposition of semen into the cow’s reproductive tract define successful mating for a breeding bull. Healthy bulls with satisfactory breeding potential are a vital part of the beef cattle industry. While injuries to the penile nerves are relatively uncommon, damage to the dorsal penile nerves is often a career ending injury for a bull. Disease processes that commonly affect the dorsal nerve of the penis include penile hematomas (via rupture of the tunica albuginea) and complex preputial injuries extending into penile tissues. Penile hematomas, cavernosal shunts, and complex preputial injuries can all cause failure of the penis to effectively achieve intromission. Evidence of failed intromission is most commonly described as continual searching of the bull’s glans penis during mounting and absence of the ejaculatory lunge. Disturbance of the dorsal nerve of the penis is strongly suspected following a test mating where no structural or musculoskeletal abnormalities are noted, yet the bull fails to achieve intromission. Definitive diagnosis of denervation of the dorsal nerve of the penis requires advanced diagnostics. The sensory nerve conduction velocity test evaluates nerve functional integrity via measurements of amplitude and velocity of delivered electrical signals. An efficient and rapid diagnosis of dorsal penile nerve injury is important to provide the owner a useful prognosis so that they can make an appropriate management decision to diminish economic losses.