Figure 15.14 (a) Spiral deviation of the penis demonstrated during a test mating. (b) Spiral deviation of the penis induced with an electroejaculator during semen collection. Spiraling of the penis during electroejaculation is common and should not be confused with the pathologic deviation prior to achieving intromission shown in (a).

      Source: Image courtesy of Clint Hilt.

      A diagnosis of spiral deviation is suspected based on history and a description of the penis during the breeding attempt, but diagnosis can only be confirmed by an observed test mating. Because the penis of many normal bulls will spiral under the artificial stimulus of electroejaculation, diagnosis following observation of spiraling during stimulation with an electroejaculator is insufficient (Figure 15.14b). Deviation may be intermittent, especially early in the development of the condition, and repeated observations of test matings may be required to confirm the diagnosis.

      No medical therapy is available to correct spiral deviation of the penis. Surgical correction of spiral deviation relies on induction of fibrous tissue to strengthen the attachments of the dorsal apical ligament to the penis. The available surgical techniques are described in Chapter 19. Spiral deviation is sometimes seen in association with damage to the dorsal nerves of the penis and careful observation at the time of test mating to rule out penile denervation should precede any attempted surgical correction.

      Ventral Deviation

Ventral deviation of the penis is less common than spiral deviation and the etiology is uncertain. The penis assumes a ventral curvature as erection progresses and has been described as a “rainbow” due to the arc formed by the erect penis. Like spiral deviation, ventral deviation is best diagnosed with an observed test mating, but observation under stimulation with an electroejaculator is useful because, unlike spiral deviation, ventral deviation is not a normal phenomenon. The area of ventral deviation usually originates in the shaft of the penis proximal to the origin of the dorsal apical ligament (Figure 15.15), meaning that surgical correction of ventral deviation with techniques to supplement the ligament are unlikely to be successful. The occasional reports of successful correction by pexy of the dorsal apical ligament are limited to cases in which the deviation is restricted to the free portion of the penis [32] (Figure 15.16).

Figure 15.15 Ventral deviation of the penis demonstrated during stimulation with an electroejaculator. Note that the deviation begins proximal to the origin of the dorsal apical ligament of the penis. Surgical repair has been unsuccessful in such cases.

      Source: Courtesy of Robert L. Carson and Dwight Wolfe.

Figure 15.16 Ventral deviation of the penis demonstrated during a test mating. Note that in this case the deviation begins distal to the origin of the dorsal apical ligament of the penis. Surgical supplementation of the dorsal apical ligament may be attempted in these cases.

      Source: Courtesy of Richard Hopper.

      S‐Shaped Deviation

S‐shaped deviation of the penis is the least common type of penile deviation. It develops in mature bulls and the serpentine curvature of the penis appears to result from a mismatch of the length of the penis and dorsal apical ligament. The penis may appear excessively long or the apical ligament may have undergone contracture following repeated injury. The dorsal apical ligament prevents the fully erect penis from assuming its normal straight orientation and the bull may be unable to control the penis sufficiently to locate the vulva of the cow. Semen from affected bulls could be collected for use in artificial insemination, but no effective treatment for the condition exists.

      Persistent Frenulum

      Persistent frenulum has been described under “Abnormalities of the Prepuce.” Diagnosis by observation is obvious but may sometimes be confused with phimosis in bulls with excessive redundant preputial skin when the ventral bending of the prepuce prevents extension of the glans beyond the preputial orifice (Robert L. Carson, personal communication).

Penile Injury

      Urethral Fistula

A urethral fistula may develop following laceration of the urethra, constrictive injury from a penile hair ring, or urethral necrosis associated with the presence of a urethral calculus (Figure 15.17). The bull's ability to deposit semen properly in the cranial vagina may be compromised depending on the location of the fistula [33].

Figure 15.17 Urethral fistula.

      Source: Courtesy of Richard Hopper.

      Paraphimosis

Paraphimosis, the inability to retract the penis into the preputial cavity, may occur following penile laceration or preputial trauma. Edema effectively reduces the diameter of the preputial orifice and the non‐erect penis remains exposed beyond the preputial orifice. The exposed preputial and penile epithelium desiccates rapidly and the superficial layers become necrotic and slough. The exposed penis is typically discolored and assumes a mild corkscrew orientation (Figure 15.18). Paraphimosis resulting from breeding injuries warrants a grave prognosis and treatment must be initiated early to be successful. Apply emollient ointments and

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