Effect of local anesthesia of the penis and dorsal penile neurectomy on the mating ability of bulls.

Eleven bulls were used to study the effect of the loss of nerve sensitivity in the free portion of the penis and glans penis on their ability to copulate. The loss of sensitivity was induced by topical anesthesia, infiltration anesthesia, and dorsal penile neurectomy. Topical anesthesia of the glans penis reduced the ability of the bulls to search for and to locate the vagina and to complete copulation; however, all bulls eventually copulated. Topical anesthesia of the free portion of the penis and glans penis blocked the ability of all bulls to copulate. Infiltration of the glans penis with lidocaine resulted in bulls failing to ejaculate, indicating the need for input from deep nerve receptors. Ten of the eleven bulls with unilateral neurectomy were able to copulate, but a longer time was required. In the one bull that failed to complete intromission and ejaculation, the sectioned nerve made up 75% of the nerve mass to the distal end of the penis, leaving only a small number of functional fibers. With this small number of fibers, there may have been insufficient sensory input to elicit the thrusting responses and to cause the animal to ejaculate. Bulls with bilateral neurectomy were unable to copulate.