Figure 21.11 (a and b) Suturing of preputial mucosa to the sheath skin.
Source: Illustration by Mal Hoover.
The preputial orifice obliteration is accomplished by removing approximately 5 mm of the sheath skin and prepuce mucosal junction around the entire preputial orifice (Figure 21.12). This incision is closed in three layers: preputial epithelium, subcutaneous layer, and skin. The Penrose drain and sutures can be removed in two weeks. Allow three weeks of postoperative recovery time prior to utilizing the teaser bull [5].
Figure 21.12 Excision of 5 mm of the preputial epithelium and sheath skin junction.
Source: Illustration by Mal Hoover.
The critical step in the preputial pouch technique is the size of the fistula. If the fistula is too small, proper urine flow is obstructed. If the fistula is too large, penile extension can occur with potential breeding. Therefore it is recommended to perform a vasectomy or epididymectomy to ensure sterility of the bull. Some bulls may pool urine in their preputial pouch and require postoperative flushing of the pouch. Thus this technique is not recommended for Bos indicus breeds since their pendulous sheath would predispose them to urine pooling and calculi formation [5].
Other Procedures
Other teaser bull procedures include iatrogenic preputial stenosis, artificial corpus cavernosal thrombosis, transection of the apical ligament, and penectomy. These procedures are briefly discussed, since their use has fallen out of favor due to high risk of failure, complication rates, and diminished libido.
Iatrogenic preputial stenosis involves a ventral midsheath approach to the prepuce and penis. The prepuce is identified and a stainless‐steel rod or Steinmann pin is secured and tightened around the prepuce. Care must be taken to tighten the ring sufficiently to prevent penile extension, but loose enough to prevent urine pooling and balanoposthitis [5, 9]. Mixed success rates accompany this procedure. Complications associated with this procedure include excessive ring closure resulting in urine retention and balanoposthitis, complete stenosis resulting in subcutaneous urine accumulation, lack of stenosis resulting in penile extension and intromission, and excessive tissue reaction to the stainless‐steel ring.
Corpus cavernosal thrombosis involves injection of an acrylic material into the corpus cavernosum of the penis [10]. The acrylic material results in thrombus formation that prevents erection. This method is performed with standing restraint under a caudal epidural. A midline incision is made over the penis. The distal sigmoid flexure is identified by locating the retractor penis muscle, with the proximal sigmoid flexure being approximately 15 cm proxi mally. A 14‐gauge needle is inserted at the dorsolateral aspect of the penis at the proximal sigmoid flexure and the acrylic is injected. Non‐absorbable stay sutures are placed at the lateral aspect of the penis at the level of the retractor penis muscle to prevent penile prolapse. Potential complications of this procedure include inadequate injection of acrylic into the corpus cavernosum resulting in procedure failure, or accidental injection into the corpus spongiosum or urethra resulting in urethral obstruction [5].
Transection of the apical ligament involves intentional transection of the apical ligament of the penis creating a ventral penile deviation and preventing intromission. The bull is restrained in lateral recumbency, either with heavy sedation and rope restraint or utilization of a tilt table. The penis is extended and a towel clamp is placed around the apical ligament of the penis to maintain penile extension. Prepare the penis and prepuce aseptically. Just proximal to the clamp, 2% lidocaine is infused subcutaneously under the epidermis of the penis. An approximately 2‐cm skin incision is made longitudinally along the dorsum of the penis. Once the apical ligament of the penis is isolated, the ligament is transected extending to the tunica albuginea. The skin incision is closed with interrupted absorbable suture. Possible complications of this procedure include excessive hemorrhage with secondary seroma or abscess formation. Additionally, inadequate transection of the apical ligament could occur or healing of the ligament could allow breeding occurrence, so a vasectomy or epididymectomy is recommended in conjunction with this procedure.
Penectomy involves amputation of the penis. This can be performed by amputation of the glans penis at the fornix and suturing of the prepuce to the urethral mucosa [11]; alternatively this can be performed at the perineal region, suturing urethral mucosa to the skin [5, 11]. Amputation of the glans penis at the fornix results in teaser bulls that experience pain during breeding attempts, thus decreasing libido and herd retention time [5]. With penectomy via the perineal approach, bulls often lose interest and experience decreased libido due to the lack of coitus [11]. With either approach, urethral stricture is a risk factor.
Summary
Accurate heat detection is essential to any AI or embryo transfer program and teaser bulls are the best at detecting heat. There are multiple procedures for creating a teaser bull, with no single procedure being perfect. Each procedure has its advantages and disadvantages. Ultimately, the decision of which procedure to perform depends on the needs and expectations of the client (longevity of bull, postoperative complications, assured sterility). Additional factors that may impact procedural choice include facilities, veterinarian preference, cost, and herd status.
References
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8 8 Hoffsis G, Maurer L. (1972). Preparation of detector bulls by penile retraction and fixation. Proceedings of the Annual Convention of the American Association of Bovine Practitioners, pp. 114–116.
9 9 Aanes, W. and Rupp, G. (1984). Iatrogenic preputial stenosis for preparation of teaser bulls. J. Am. Vet. Med. Assoc. 184: 1474–1476.
10 10 Wolfe, D. (1986). Surgical procedures of the reproductive system of the bull. In: Current Therapy in Theriogenology, 2e (ed. D.A. Morrow), 353–380. Philadelphia: WB Saunders.
11 11 Straub, O. and Kendrick, J. (1965). Preparation of teaser bulls by penectomy. J. Am. Vet. Med. Assoc. 147: 373–376.
