33rd Annual Scientific Meeting proceedings

Castration is one of the most common surgical procedures performed in the horse. Different surgical techniques have been described, consisting in an open, closed, or half-closed technique by a scrotal or inguinal incision, with the horse recumbent under general anesthesia or standing [1].

It is often considered a routine procedure, but incidence of post-operative complications is high; a recent review reports a rate of complications ranging from 10.2% to 60% [2]. Most of them are mild, but some of them are life-threating conditions [3-6].

Main castration complications are excessive scrotal and/or preputial swelling, infection (funiculitis), hemorrhage, eventration; less commonly, septic peritonitis, iatrogenic penile damage, hydrocele, continued stallion-like behavior, and anesthetic complications are reported [2-6].

The term cryptorchidism refers to a congenital condition characterized by the failure of one or both testicles to descend into the scrotum [7]. It is the most common developmental defect in the horse [1]. Different forms of cryptorchidism are recognized: complete or incomplete abdominal cryptorchid, and inguinal cryptorchid [1].

Removal of an abdominal retained testis can be performed by several techniques, with the horse recumbent under general anesthesia or standing [1, 7].

Laparoscopic cryptorchidectomy has become an accepted method of identifying and removing intra-abdominal testes in horses [7-10]. It provides several advantages, such as easy identification of retained testes, no need for disruption of the vaginal ring minimizing the risk of evisceration, decreased morbidity through smaller incisions and shorter post-operative recovery, better cosmesis, decreased risk of herniation, early return to exercise, possibility to avoid general anesthesia [1, 7].

Once the abdominal retained testis has been located by laparoscopic approach, it can be ligated and transected using several methods, including extracorporeal ligation and emasculation [11, 13], intra-abdominal loop suture [9], bipolar vessel sealing devices like Ligasure [13], electrosurgical instrumentation [14], staples, and ultrasonic devices [7].

In case of horses with one retained testis and the other one normally descended in the scrotum, the latter can be removed either conventionally under general anesthesia or in standing by a traditional scrotal approach [1]; we do not think that neither of these methods could be considered ideal, since in the first case general anesthesia, with its associated costs and risks, is required, and in the latter, tissue handling is important and risks are many [2-6].

Alternatively, it has been reported a technique consisting in the enlargement of the vaginal ring followed by re-location of the testis from a scrotal to an intra-abdominal position [15], but the trauma on the vaginal ring can be serious.

Laparoscopic standing castration without orchiectomy for normally descended scrotal testes is a well described technique in literature: it involves the ligation and/or transection of the mesorchium, including the testicular artery and vein and the ductus deferens just above the internal inguinal ring, leaving the testis in situ undergoing avascular necrosis [15-19].

Due to the hypothesis of a possible alternate blood supply to the testis by vessels derived from the cremasteric and/or external pudendal artery that may prevent necrosis of the testis in 7-11% of horses with normally descended or inguinally retained testes, this technique has not been considered a reliable method for castration in inguinal cryptorchids and normal stallions, and therefore has been partially abandoned [20].

It has been described a technique for monolateral abdominal cryptorchid horses combining intra-abdominal ligation of both spermatic cords with open castration by scrotal approach for the normally descended testis [21].

We strongly believe that laparoscopic standing castration without orchiectomy should be re-evaluated, since it provides enormous advantages over traditional castration techniques, especially for some specific categories of horses, such as monolateral abdominal cryptorchid horses with the contralateral testis descended in the scrotum.

We have performed standing laparoscopic castration without orchiectomy in 48 horses with bilateral or monolateral normally descended testes (with the controlateral testes already removed by traditional approach), 11 monolateral abdominal cryptorchid horses with the controlateral testis in the scrotum and 6 monolateral inguinal cryptorchid horses with the controlateral testis in the scrotum.

Horses with bilateral scrotal descended testes are restrained in standing stocks, sedated and the procedure is performed in the same way from both flanks.

After aseptic preparation of the flank, two portal sites in the paralumbar fossae are created, after local desensitization with 2% lidocaine (20 ml subcutaneously per situ).

The ipsilateral internal inguinal ring is identified, and local anesthetic (20 ml of 2% lidocaine) is infiltrated in the spermatic cord. The mesorchium, including the testicular artery and vein, and the ductus deferens are sealed and transected with bipolar electrosurgical forceps (Ligasure) just proximal to the vaginal ring [19].

The resection must be accurate and deep of the entire plica vasculosa, ensuring that the distal part of the spermatic stamp is retracted completely into the inguinal canal.

The testis is left in place in the scrotum and undergoes ischemic necrosis.

In case of monolateral abdominal cryptorchid horses with the controlateral testis in the scrotum, laparoscopic access is performed from the side where the testis is in the scrotum, on the opposite side to the retained abdominal testis.

Three laparoscopic ports are required, since an instrumental one is needed for grasping and holding the retained testis. By the aid of a hand per rectum, the descending colon is elevated [1, 9], allowing the laparoscope, followed by grasping forceps, to visualize the controlateral abdominal retained testis. The retained testis is then grasped, infiltrated with local anesthetic, which helps both in decreasing the horse reaction to the manipulation of the testis, and in relaxing the mesorchium, making it easier to bring the testis into the controlateral side (the side of the scrotal testis). At this point, testicular vessels and the ductus deferens are sealed and transected with Ligasure. After complete isolation of the retained testis, it is held with grasping forceps until the end of the surgery.

The scrotal descended testis is approached as described earlier. The abdominal testis is removed from the abdomen, enlarging one of the portal incisions, if needed. The laparoscope and instruments are removed, and incisions are closed cutaneous with reabsorbable suture.

We have found that in most cases passive pneumoperitoneum has allowed good visualization, without the need to insufflate the abdomen with carbon dioxide.

Laparoscopic castration without orchiectomy, leaving the testis in situ to undergo avascular necrosis, decreases and in some case eliminates the risk of complications of conventional castration techniques, such as excess oedema, hemorrhage, infection of the spermatic cord, incisional infection, evisceration; it is also attractive because it is performed with the horse standing, without the need of general anesthesia and without the several risks of standing scrotal castration [2-6]; moreover, post-operative recovery time and returned to athletic activity is fast [19].

In all the horses we have castrated by this technique, we have had only one horse, which had bilateral scrotal testes, that kept being a stallion after surgery. During the surgery, there was a bleeding coming from the transection of the spermatic cord on the left side, which has prevented us having good visualization of the surgical field. After surgery, the right testis atrophied as expected, while the left one has never started to really atrophy, at palpation it has only mildly decreased in volume; by blood exams, the horse has kept having high testosterone level, compatible with stallion value. Therefore, we removed both testes by a standing scrotal approach and histopathologic examination revealed a necrotic right testis and an almost normal left one.

We believe that this failure was attributable to a technical error during the surgery, in particular an incomplete transection of the mesorchium due to poor visibility given by the bleeding.

Even if the possibility of a revascularization by an alternate blood supply to the testis by vessels derived from the external pudendal artery or cremasteric artery cannot be excluded, this has not been seen directly on horses, but rather assumed from studies on other species; our opinion is that the surgical technique is a key factor in the success of the surgery, because we think that if the transection of the ductus deferens and spermatic cord is not deep and total, this can prevent the necrosis of the testis.

Moreover, even if a revascularization may occur, this has been described in a small percentage of horses (3.4% of normally descended testes) [20]; for the numerous advantages of a laparoscopic technique of castration over the traditional techniques, we do not think that this possibility of failure could be a reason to abandon the technique.

To achieve more information on this issue, we hope for a large multicenter study.

References

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