the presence of large penile fibropapillomas.
Stenosis or stricture of the preputial lumen can occur following preputial injury despite appropriate and apparently successful medical or surgical management. Scar tissue replaces damaged elastic tissues, and contracture and cicatrix formation may constrict the preputial lumen and result in preputial stenosis sufficient to prevent extension of the penis (Figure 15.9). If circumferential constriction of the preputial cavity occurs distal to the end of the tip of the non‐erect penis, sexual arousal and engorgement of the penis will force the distal portion of the penis down the prepuce until the restriction is encountered and the preputial lamina will then be forced out the preputial orifice without exposure of the free portion of the penis. Strictures sometimes interfere with the evacuation of urine from the preputial cavity. Non‐circumferential scar formation at the site of a healed preputial laceration may also compromise the preputial lumen and prevent penile extension.
Figure 15.9 Phimosis due to circumferential stricture of the preputial cavity following preputial laceration.
Source: Courtesy of Craig Easley.
Extension of the penis requires appropriate function of the elastic tissues and severe damage prevents the gliding action that permits the free portion of the penis and internal lamina of the prepuce to exit the preputial orifice. Formation of adhesions between the penis, the elastic tissues, and overlying skin following trauma may effectively limit the movement of the penis and result in partial or complete failure of extension. The site of the adhesions may sometimes be identified by a visible deformation of the contour of the overlying skin at the time of attempted erection.
Phimosis may also result due to the presence of a penile wart (papilloma) larger than the external opening of the preputial orifice. Incision of the internal lamina of the prepuce to allow extension of the penis and removal of the wart followed by primary closure of the incised preputial tissue can be curative if the value of the bull is sufficient to justify the expense of surgery (Figure 15.10). Restraint on a tilt table and administration of local analgesia by blocking the dorsal nerves of the penis or administration of an internal pudendal nerve block facilitate this procedure.
Figure 15.10 Phimosis due to the presence of a penile fibropapilloma larger than the preputial orifice. The tip of the free portion of the penis has been grasped with sponge forceps (a). Following incision of the internal lamina of the prepuce to enlarge the preputial orifice, the penis was extended and the fibropapilloma surgically excised (b).
Many bulls with phimosis are culled. In cases of preputial stenosis, restoration of the preputial lumen may be accomplished by resection of the compromised tissues and anastomosis of the remaining prepuce if sufficient healthy preputial tissues remain. Similarly, surgical scar revision can be useful for restoring the integrity of the preputial lumen when the amount of healthy preputial skin is insufficient for preputial resection. Both techniques are described in Chapter 19. No treatment is effective if adhesions of the elastic tissues are severe.
Avulsion of the Prepuce
The attachment of the reflection of preputial skin to the free portion of the penis is susceptible to avulsion injury at the time of breeding, but this injury occurs more commonly when semen is collected with an AV. If the AV is inappropriately sized or not properly lubricated, preputial skin will not easily slide down the interior of the latex liner and can be avulsed or torn from its attachment to the penis at the time of the ejaculatory lunge. This injury can often be recognized immediately following service with the AV when blood is seen at the external preputial orifice. Extension of the penis allows visual observation of the avulsion injury, typically located on the ventrum of the penis (Figure 15.11) [21]. Unlike preputial lacerations which occur at the time of breeding, the underlying tissues are not severely traumatized and immediate repair by direct suture of the avulsed tissues is recommended. Prognosis following early detection and repair is good [21]. If not noticed early and repaired immediately, hemorrhage and wound sepsis may complicate management but careful dissection and reattachment of the avulsed tissue can still be successful.
Figure 15.11 Preputial avulsion. Notice the separation of the attachment of the preputial skin from its attachment at the base of the glans penis. Such injuries most commonly occur during collection of semen in a poorly prepared AV but sometimes, as in this case, occur during natural breeding.
Source: Image courtesy Jessica Rush.
When collecting semen with an AV the person collecting the semen should be appropriately trained, a suitable AV and liner should be selected and properly prepared, and bulls should always be observed closely following collection [21].
Abnormalities of the Penis
Congenital Abnormalities
Congenital abnormalities of the penis occur sporadically and are sometimes associated with other disorders of sexual development.
Hypospadias
Hypospadias, an abnormal opening in the urethra that occurs when the embryonic urethral groove fails to close or closes incompletely anywhere along its length, has been reported in bulls and other species. In some cases the entire length of the penile urethra may be involved and may be easily observed at birth [22]. Cases that involve only the distal urethra may go unobserved until the bull is examined during a breeding soundness examination [23]. Slight caudal relocation of the urethral meatus may not significantly affect fertility.
Congenital Short Penis
Congenital short penis is seen uncommonly and must be differentiated from a partial phimosis secondary to preputial injury or fibrosis of the retractor penis muscles. Some affected bulls may sire calves by natural service during their first or second breeding season, but copulation becomes impossible as they reach mature body size. Diagnosis is made by observation of breeding and measurement of the distance from the preputial orifice to the tip of the extended penis. The etiology of congenital short penis is unknown [24]. Affected bulls are unable to breed naturally and should be culled.
Diphallus
Diphallus, or duplication of the penis, is reported sporadically [25, 26]. Duplication may involve only the glans
