normal nerve function [17]. In bulls with impairment of sensation to the distal penis, erection is not impaired but the searching motions made with the penis are ineffective and the bull will be unable to achieve intromission and complete the breeding act. Affected bulls often place the penis to the side of the tail head, on the cow's hip, or below the vulva near the udder (Figure 15.24). Observation of typical signs at the time of test mating coupled with a history of reproductive failure is usually sufficient for diagnosis, but definitive electrodiagnostic testing of nerve function [39, 42] is available at some veterinary teaching hospitals (Figure 15.25).
Figure 15.24 Failed attempt at copulation due to denervation injury of the penis. During repeated breeding attempts during test mating, the bull was unsuccessful in locating the vulva with the penis. Note the location of the penis beside the tail head of the cow.
Figure 15.25 Electrodes and stimulator in place for nerve conduction study of dorsal penile nerves. Electrical stimulation applied through the electrode on the free portion of the penis is recorded as the signal passes the proximally placed electrodes.
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