Bovine Reproduction. Группа авторов
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in a manner identical to that described for B. indicus bulls, but the outcome is often altered by phenotype. B. taurus breeds are more likely to retract all the damaged tissues into the preputial cavity following injury and as a result the wound is less likely to be noticed early. The visible preputial swelling may be confined to a well‐defined area adjacent to the bull's sheath, or may be more diffuse and occasionally extend from the preputial orifice caudally toward the scrotum. Because the compromised elastic tissues within the preputial cavity are contaminated with bacteria, cellulitis and phlegmon develop rapidly, often progressing to abscess formation.
Retropreputial abscess formation is more likely in bulls of B. taurus than B. indicus influenced breeds due to lack of redundant skin and generally tighter sheath conformation. Affected bulls present with an obvious swelling visible through the overlying skin of the sheath that may be accompanied by the presence of pus or blood at the preputial orifice. Diagnosis is based on physical examination and palpation, sometimes augmented by ultrasound imaging of the tissues. The differential diagnosis for preputial inflammation with visible disruption of the normal contour of the sheath must include the enlargement of the elastic tissues seen following rupture of the tunica albuginea of the penis. In contrast to the lesion seen with rupture of the tunica albuginea, retro preputial abscesses are usually non‐symmetrical and located distal to the sigmoid flexure nearer the level of the preputial fornix (Figure 15.8). Retropreputial abscess formation is associated with poor prognosis for future breeding. Destruction and impairment of the elastic tissues frequently result in adhesion formation within the elastic tissues of the prepuce and the overlying skin, or in compromise of the diameter of the preputial lumen, either of which may prevent extension of the penis [17].
Figure 15.8 Retropreputial abscess following preputial laceration in a young bull. Note location of the swollen tissues in the distal sheath.
Therapy for retropreputial cellulitis, phlegmon, and abscessation relies on systemic antibiotic administration and local wound management. Daily flushing of the preputial tissues with dilute antiseptic solutions and cold water hosing of the sheath aid in resolution of cellulitis. Drainage of a retropreputial abscess into the preputial lumen at the site of the original injury may facilitate recovery but is difficult to accomplish. No attempt should be made to drain a retropreputial abscess through the overlying skin of the sheath as inflammation and sepsis of the underlying elastic tissues are inevitable and subsequent formation of peripenile adhesions will decrease the chance of a successful outcome [17, 18]. Even with aggressive therapy the prognosis is guarded to poor and many affected bulls never return to service [17].
Phimosis
Phimosis, the inability to extend the penis, effectively prevents the bull from breeding and may be diagnosed at the time of an observed breeding or by induction of erection with an electroejaculator. Phimosis may be due to stenosis of the preputial opening or lumen, adhesions within the elastic layers of the prepuce and surrounding skin, or occasionally abnormalities of the distal penis including 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 (