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 humectants to protect the exposed skin and cover the damaged tissues with a length of orthopedic stockinette or other light bandage material. Frequent bandage changes and fresh application of dressings combined with daily cold water hosing should continue until the penis can be retracted into the prepuce. Continue preputial lavage with antiseptics and application of antibiotic ointments or emollients for at least a week after the penis is returned to the sheath. Even with aggressive early treatment, return to service is unlikely and the chance for a successful outcome decreases the longer treatment is delayed following injury.
Figure 15.18 Paraphimosis following traumatic injury to the preputial trauma. The exposed penile and preputial epithelium desiccates rapidly and the free portion of the penis forms a spiral.
Paraphimosis may sometimes be associated with the presence of a penile papilloma on the distal penis large enough to prohibit retraction through the preputial orifice. Surgical removal of the wart can be curative.
Penile Hematoma (Rupture of the Tunica Albuginea of the Penis)
While any extravascular accumulation of blood in the vicinity of the penis could technically be termed a penile hematoma, in the bull the terms “hematoma of the penis” and “penile hematoma” are usually reserved to describe the breeding injury that results in rupture of the tunica albuginea of the CCP. The penis of ruminants is well equipped to withstand high intrapenile pressure created within the CCP. At the time of erection, venous outflow to the CCP is obstructed and contraction of the ischiocavern osus muscles increases pressure within the penis to 14 000 mmHg (1.87 MPa) or greater [3]. Pressures of this magnitude are easily contained by the thick fibrous tunica albuginea of the penis which encompasses the CCP. However, if a cow or heifer collapses during coitus or if an ill‐timed breeding lunge accidently forces the erect penis against the escutcheon, sudden angulation of the penile shaft may increase intrapenile pressure to greater than the 70 000 mmHg (9.3 MPa) required to rupture the tunica albuginea [34]. Although occasionally seen at other sites [35, 36], rupture of the tunica albuginea almost inevitably occurs on the dorsum of the penis opposite the attachment of the retractor penis muscles on the distal bend of the sigmoid flexure.
Rupture of the tunica albuginea is accompanied by extravasation of the blood contained in the CCP and formation of a hematoma which is visible as a symmetrical enlargement at the site of the rupture. While
