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Penile–prepuce translocation (“sidewinder”) is the surgical transposition of the penis and prepuce from the ventral midline to the right or left flank of a bull. This procedure allows normal protrusion and erection but does not permit intromission. In general, “sidewinders” are preferred by producers due to longevity and herd retention of the teaser animal. Bulls with a penile–prepuce translocation maintain better and longer libido since this procedure allows normal protrusion and does not cause pain during erection. Some bulls are able to compensate and learn how to breed females despite the translocation of the penis and prepuce. Therefore it is recommended that a vasectomy or epididymectomy is performed to ensure sterility of the bull.

Penile–prepuce translocation is performed in lateral recumbency, so general anesthesia is the preferred method of restraint. If general anesthesia is not possible, heavy sedation with rope restraints and local infiltration of 2% lidocaine can be used. Ideally, food should be withheld for 24 hours and water for 12 hours before performing the procedure.

Prior to placing the bull in recumbency, the translocation site for the preputial orifice should be identified. The translocation site should be just outside the flank fold and lateral to the original preputial orifice site [3]. An 18‐gauge needle can be used to abrade the epidermis so the location is not altered after placing the animal in recumbency and skin stretching occurs. The ventral abdomen from the umbilicus to just cranial to the scrotum and the site of translocation of the flank should be clipped and aseptically prepared. Flush the prepuce with dilute iodine solution.

Before making the initial incision, place one simple interrupted suture at the dorsal aspect of the preputial orifice to serve as a marker and prevent twisting of the prepuce during translocation. A circumferential skin incision around the preputial orifice is made 4 cm from the orifice or a total diameter of 8–10 cm (Figure 21.3) [3, 4]. Extend the skin incision on the ventral midline from the preputial orifice to just cranial to the scrotum (Figure 21.4). Carefully dissect the penis and prepuce from the ventral abdomen. Avoid lacerating the prepuce; packing or tubing can be placed in the prepuce to aid with proper identification. While dissecting the penis and prepuce, avoid incising the dorsal penile vessels and control hemorrhage as it is encountered. Once the penis and prepuce are dissected, make a circular skin incision equivalent to the diameter of the preputial orifice at the desired translocation site (Figure 21.4). Use a sponge forceps to create a tunnel toward the flank incision. As the forceps is retracted, open it slightly to help facilitate penile translocation. This tunnel can also be accomplished with a cold sterilized polyvinyl chloride (PVC) pipe (Figure 21.5).

Figure 21.3 Circumferential incision 4 cm from the preputial orifice is performed with an interrupted suture placed at the dorsal aspect of the preputial orifice to prevent twisting during translocation.

Source: Photo courtesy of Tom Thompson.

Figure 21.4 Ventral midline incision extending caudally with circumferential incision at the translocation site.

Source: Photo courtesy of Tom Thompson.

Figure 21.5 Use of a cold sterilized PVC pipe to facilitate tunneling of penile translocation and skin incision for the translocation site.

Source: Photo courtesy of Tom Thompson.

Place a sterile glove or sleeve over the preputial orifice to minimize contamination of the subcutaneous tissues. Then run a sponge forceps from the flank incision to the ventral midline incision and grasp the preputial orifice. Manipulate the preputial orifice to the flank incision, taking care not to twist the prepuce (use a stay suture to ensure proper alignment). Suture the skin around the preputial orifice using #3 non‐absorbable sutures with a cruciate or horizontal mattress pattern (Figure 21.6) [1]. Close the subcutaneous layer of the ventral midline incision with #3 absorbable suture, closing as much dead space as possible to prevent seroma formation. Close the skin with #3 non‐absorbable suture in a Ford interlocking pattern. Place a cruciate suture at the cranial aspect of the incision to be removed for drainage if a seroma does occur.

Figure 21.6 Closure of new preputial orifice with interrupted sutures and ventral midline with Ford interlocking pattern.

Source: Photo courtesy of Tom Thompson.

The teaser bull should be monitored closely for 24 hours postoperatively to ensure he is able to urinate properly. Antibiotics should be administered for three to five days postoperatively to prevent infection. Allow four to six weeks of recovery time before using the teaser bull [3–5]. Penile–prepuce translocation is not a technically difficult procedure, but it is more invasive and can result in more postoperative complications. The most common complications are obviously seroma and abscess formation from the excessive dead space created. Another complication would be not translocating the preputial orifice high enough on the flank and thus the bull would still be capable of breeding a female animal. There is also one case report of a teaser bull developing paraphimosis with a penile–prepuce translocation [7].