Equine Cryptorchidectomy Surgical Techniques

1. EQUINE CRYPTORCHIDECTOMY Intra-operation Considerations

2. INGUINAL/ PARAINGUINAL SURGICAL APPROACH • The horse is anaesthetized and placed into dorsal recumbency. • A 12 to 15 cm skin incision is made over the external inguinal ring and is continued through the superficial fascia. • Sharp dissection is then abandoned in favor of blunt dissection with fingertips to separate the subcutaneous inguinal fascia and to expose the external inguinal ring. • Large branches of the external pudendal vein are in this region, and trauma to these vessels should be avoided. Dissection is continued beyond the external inguinal ring and through the inguinal canal until the vaginal ring is located with the finger.

3. INGUINAL/ PARAINGUINAL SURGICAL APPROACH • With and inguinal cryptorchid, the testis contained within the common vaginal tunic would be located in the canal at this time. The common tunic is isolated, and the testis is removed as previously described for a normal castration. A closed castration technique is generally used. • With an abdominal cryptorchid, however, the testis will not be obvious. In this situation, the vaginal ring is located, and curved sponge forceps are carefully introduced through the inguinal canal so that the jaws are placed through the vaginal ring into the vaginal process. • The partially opened jaws of the forceps are pressed against the vaginal process and are closed.

4. INGUINAL/ PARAINGUINAL SURGICAL APPROACH • Thee forceps grasp the vaginal process and associated gubernaculum testis, and the forceps are then withdrawn. This is the critical part of the technique and the most difficult part for the inexperienced surgeon, because excessive force ruptures the vaginal process. • The cordlike gubernaculum may then be palpated within the everted vaginal process by rolling it between the thumb and forefinger. • When the gubernaculum is identified, the vaginal process is opened with Metzenbaum scissors, and the gubernaculum is grasped with Ochsner forceps. • Traction on the gubernaculum causes the tail of the epididymis to be presented.

5. INGUINAL/ PARAINGUINAL SURGICAL APPROACH • Generally, gentle traction on the epididymis pulls the testes through the vaginal ring. • Pushing around the vaginal ring with the fingers at the same time usually is sufficient to deliver the testes, but manual dilation of the vaginal ring is necessary in some cases. • At this point, the testis is positively identified and is emasculated. In some instances, the testis cannot be retracted sufficiently to enable emasculation, so the cord is ligated and the testis sharply amputated. • If the opening made in the vaginal process to deliver the testicle is considerable and if intestinal herniation is a possibility, the external inguinal ring is closed using a large diameter synthetic absorbable suture

6. INGUINAL/ PARAINGUINAL SURGICAL APPROACH • It is closed using either a preplaced interrupted pattern or simple continuous pattern. • The strong aponeurosis of the external abdominal oblique muscle is opposed to the fascia on the opposite side of the ring. • The dead space is then closed using a no. 2-0 synthetic absorbable suture material. • Conversely, a sterile gauze bandage may be packed over the external inguinal ring; this protects against herniation while normal swelling obliterates the inguinal canal. • Finally, the sink is sutured with a synthetic absorbable suture, either in a continuous pattern or with simple interrupted sutures with long ends.

7. INGUINAL/ PARAINGUINAL SURGICAL APPROACH • If the opening in the vaginal process is small (barely enough to squeeze the testicle through), packing will usually be unnecessary.

8. LAPAROSCOPIC APPROACH • The advantages of the laparoscopic castration of an abdominal cryptorchid are: • Better visualization resulting in easier and fast localization of the abdominal testis. • No disruption of the internal inguinal/vaginal ring, therefore minimizing risk of evisceration. • Early return to exercise (only 3 small flank incisions). • Can be performed on the standing horse (no general anesthesia required).

9. LAPAROSCOPIC APPROACH • The disadvantages: • Expense of the equipment and often more expensive surgery. • Experienced and properly trained surgeon needed to avoid complications such as • accidental puncture an intestine or blood vessel

10. LAPAROSCOPIC APPROACH • Two instrument portal sites in the paralumbar fossae are locally desensitized using 2% mepivacaine. • The scope portal is located between the 17th and 18th rib. • Following trocar and laparoscope insertion, the ipsilateral testicle, mesorchium, and ductus deferens are easy to identify.

11. LAPAROSCOPIC APPROACH • The testis is located by inspecting the area around the internal inguinal ring. • The mesorchium is easy to identify and pulling on this cord will reveal the testis and epididymis. • The mesorchium is desensitized with local anaesthetic.

12. LAPAROSCOPIC APPROACH • The cranial mesorchium is coagulated with bipolar electrosurgical forceps (Lina or LigaSure). • The mesorchium, ductus deferens, and ligament of the tail of the epididymis are then transected in a cranial to caudal direction using laparoscopic scissors.

13. LAPAROSCOPIC APPROACH • Once the testis is freed, the transected mesorchium is inspected for hemorrhage and the testis is removed through one of the instrument portals, which is slightly enlarged. • If the testes are retained bilaterally, the retained contra lateral testis is removed similarly through the opposite paralumbar fossae.

14. LAPAROSCOPIC APPROACH • The left abdominal testis is passed to the right and both testes are then removed through the right paralumbar fossae.