Читать книгу Bovine Reproduction - Группа авторов - Страница 225

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.