Normal separation is sometimes delayed and may result in an inability to fully extend the penis at the time of a breeding soundness examination or during an observed breeding attempt (Figure 14.1). The attachment will spontaneously regress in most bulls given adequate time to mature but assisted separation by gentle application of manual traction to the penis is sometimes advocated in cases where partial separation has already occurred (Figure 14.1b,c).

Young bulls sometimes tear the epithelial attachment prematurely and hemorrhage into the epithelium, resulting in formation of a localized hematoma. Such injuries may go unnoticed and are often self-limiting.¹⁰ Should bacteria gain access to the damaged tissues and hematoma, the formation of an abscess may result in phimosis if the bull’s ability to extend the penis is compromised. Case management should emphasize isolation from other animals to discourage sexual role-play accompanied by broad-spectrum antibiotic treatment to minimize complications.

Persistent frenulum

The frenulum is a thin band of tissue found in juvenile bulls that extends from the midline of the ventrum of the tip of the free portion of the penis to the attachment of the preputial epithelium near the base of the free portion. Similar to the epithelial connection between the penis and prepuce, this band of tissue normally separates as the bull matures. Unlike the epithelial tissues of the penis and prepuce, the frenulum often contains a large vein. When the process of normal separation fails, the frenulum may persist and the result is a band of epithelium and connective tissue joining the tip of the penis with the preputial epithelium near the junction of the prepuce and free portion of the penis (Figure 14.2). A persistent frenulum results in a sharp ventral bend of the distal penis as it becomes erect. Persistent frenulum is often detected in young bulls during a routine pre-service breeding soundness examination,¹¹ but occasionally is not detected until the bull attempts natural service.

The cause or causes of failure of separation of the preputial epithelium and/or frenulum are unknown. Although unproven, a genetic association is suspected in some breeds.^12,13 Surgical transection of the frenulum is curative^13,14 but use of affected animals only as terminal sires is recommended.

Preputial laceration

Although bulls with a pendulous sheath and excessive preputial skin may traumatize the preputial tissues independent of the breeding act, most serious preputial injuries occur at the time of the ejaculatory lunge. As the free portion of the penis enters the vagina during coitus, preputial skin slides caudally up the shaft of the penis toward the abdomen of the bull and folds of redundant skin gather at the preputial orifice. This “bunching” of preputial skin usually occurs without incident, but when preputial tissue is trapped between the abdomen of the bull and the bony pelvis of the female at the time of intromission compressive forces generated by the ejaculatory lunge can be focused on the entrapped tissues. In mild cases the preputial epithelium remains intact and the accumulation of edema in the damaged tissues results in an uncomplicated preputial prolapse. More serious injury occurs when compression of the entrapped prepuce disrupts the epithelium, with subsequent exposure and damage of the underlying elastic tissues. Although commonly referred to as preputial laceration, the injury is actually the result of bursting of preputial tissues in response to compressive force.¹⁵

Preputial lacerations initiated during the breeding act predictably occur on the ventrum of the prepuce, with the initial injury in the preputial tissues oriented longitudinally, parallel to the long axis of the bull’s body. Following the injury, as the penis is retracted the damaged preputial tissues are drawn toward the preputial orifice and the disrupted tissues at the site of the laceration fail to maintain normal alignment. As a result, the defect becomes oriented transversely (Figure 14.3). If the preputial tissues cannot be retracted through the preputial orifice, the transverse orientation of the lacerated tissues results in shortening of the caudal aspect of the exposed prepuce and the characteristic “elephant trunk” appearance of the prolapsed tissues (Figure 14.4).

Trauma and disruption of the preputial epithelium and underlying elastic tissues result in inflammation and edema and the open wound inevitably becomes septic. As dependent edema in the prolapsed tissues increases the size and weight of the externalized prepuce, traction on the prepuce results in increasing amounts of preputial tissue becoming exposed. Additional trauma, mutilation, or desiccation of the unprotected preputial tissues complicates wound management and treatment. Wound contracture at the site of the injury further distorts the tissues as the reoriented wound undergoes fibrosis (Figure 14.5).

The preputial retractor muscles serve to elevate the prepuce and this elevation can minimize edema formation in damaged tissues. Because many polled bulls lack retractor prepuce muscles, preputial prolapse following laceration in naturally hornless bulls tends to become more severe.¹⁶

Wolfe and Carson have constructed a four-point classification scheme that incorporates the severity of the preputial injury to estimate the prognosis for return to function and guide treatment decisions (Table 14.1).

Medical management of preputial laceration and prolapse is aimed at control of sepsis, reduction of edema, and eventual return of the damaged tissues to the preputial cavity. Application of emollients to prevent desiccation and topical antibiotics should be combined with light bandaging. Careful cleansing and flushing of the wound with dilute antiseptic solutions combined with debridement of devitalized tissues is necessary. Topical antibiotic therapy is usually sufficient if wound management is adequate. Bandaging of the exposed preputial tissues must be done carefully to avoid restricting blood flow and devitalizing tissues but proper application of a circumferential bandage to prevent desiccation and to apply mild compression is useful. To apply a bandage following cleansing and application of an emollient antibiotic ointment, first place a short length of latex tubing into the preputial orifice and position it with one end in the preputial cavity proximal to the torn epithelial tissues and the other end exiting the preputial orifice to allow urine egress from the prepuce. Then place a piece of clean 5-cm orthopedic stockinette over the exposed preputial tissues and snugly apply an elastic tape bandage over the stockinette, prepuce, and urine egress tube beginning at the distal end of the prolapsed tissue, overlapping the tape as it advances up the prepuce to the preputial orifice where it can be secured to the haired skin of the sheath (Figure 14.6). Following bandaging, the edematous prepuce may be suspended by application of a bib or sling made of net material or burlap supported by straps encircling the bull’s abdomen (Figure 14.7). Frequent bandage changes are necessary and the wound should be treated locally each time it is exposed. Cold water hosing for 10–15 min at each bandage change will reduce edema and remove necrotic debris. With diligent treatment many bulls may be returned to service without surgery¹⁷ but repeat injury is common.

Surgical treatment following preputial laceration can improve outcome¹⁸ and is indicated when the bull’s value and remaining breeding life is sufficient to justify the expense.^18,19 Surgery must always be preceded by preoperative wound management. Excellent descriptions of the surgical options appear elsewhere in this book (see Chapter 17).

Retropreputial abscess

Preputial injury and laceration are not limited to Bos indicus influenced breeds. In Bos taurus bulls preputial injury may occur at the time of breeding in a manner identical to that described for Bos indicus bulls but the outcome is often altered by phenotype. Bos 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 compromised elastic tissues within the preputial cavity are contaminated with bacteria and cellulitis and phlegmon rapidly develop and often progress to abscess formation. The preputial swelling may be confined to a well-defined area adjacent to the sheath, or may be more diffuse and occasionally extend from the preputial orifice caudally toward the scrotum.

Retropreputial abscess formation is more likely in bulls of Bos taurus than Bos 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. This condition must be differentiated from 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, retropreputial abscesses are generally nonsymmetrical and located distal to the sigmoid flexure nearer the level of the preputial fornix (Figure 14.8). Retropreputial abscess formation carries 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.²⁰

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 aids in resolution of cellulitis. Drainage of a retropreputial abscess into the preputial lumen at the site of the original injury is difficult but if possible may facilitate recovery. No attempt should be made to drain a retropreputial abscess through the overlying skin of the sheath as damage and sepsis of the underlying elastic tissues is inevitable and formation of peri-penile adhesions will decrease the chance of a successful outcome.^17,20 Even with aggressive therapy the prognosis is guarded to poor and many affected bulls will never return to service.²⁰

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 to 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 14.9). If circumferential constriction of the preputial cavity occurs distal to the end of the tip of the nonerect penis, sexual arousal and engorgement of the penis will force the distal portion of the penis down the prepuce until the constriction is encountered and the preputial lamina will 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. Noncircumferential scar formation at the site of a healed preputial laceration may also compromise the preputial lumen enough to prevent penile extension.