The complex blood supply to the equine testis as a cause of failure in laparoscopic castration

Abstract

Summary Reasons for performing study: Intra‐abdominal ligation/transection of the spermatic cord may result in necrosis of the testis; castration of abdominal cryptorchids via laparoscopy has therefore become common. Notwithstanding some adaptations of the technique, a small percentage of operations fail, prompting research into the anatomical background and clinical relevance of the procedure. Hypothesis: That an alternate blood supply may prevent complete necrosis of the testis after spermatic cord transection. Objective: To establish the prevalence of the problem in normal and cryptorchid stallions. Methods: In a preliminary study, the spermatic cords of 8 normal stallions were ligated and transected at different sites and in various manners. Five weeks later the testes were removed and the vitality of both the testes and epididymes was evaluated. In a prospective clinical trial, intra‐abdominal spermatic cord transection was performed in 241 cryptorchid and normal stallions. In cases of surgical failure, the testes were removed and histology performed. Results: Examination of the specimen removed from the 8 animals of the preliminary study revealed that all epididymes were completely or largely spared. All except one testis were completely necrotic. In the patients that underwent surgery all abdominally retained testes (n = 123) were necrotic, while 5 out of 88 inguinally retained and 8 out of 236 normally descended testes had partially survived. The pattern of survival differed between inguinally retained and normally descended testes. The epididymes of these 13 horses were (largely) vital. The (partial) survival of the epididymes and inguinally retained testes was ascribed to an alternate blood supply via anastomosing vessels derived from the cremasteric artery. A tributary from the external pudendal artery was considered responsible for the partial survival of normally descended testes. Conclusions and potential relevance: After intra‐abdominal transection of the entire spermatic cord, 5.6% of inguinally retained and 3.4% of normally descended testes failed to become completely necrotic, as a result of an alternate blood supply via the cremasteric and/or external pudendal artery. Therefore, laparoscopic castration without orchidectomy cannot be recommended as a trustworthy method for castration of inguinal cryptorchids and normal stallions.

Evaluation of success rate of laparoscopic castration without orchidectomy in 32 mature horses

“…; Voermans et al . ). In our population, all horses but one castrated in this fashion were able to go back to work in less than a week, which is an economical consideration for horses in training.…”

“…Epididymis were preserved as described previously by Voermans et al . (). However, it is well recognised that androgens are not produced by the epididymis and therefore epididymal tissue cannot influence masculine behaviour (Cox et al .…”

“…According to Voermans et al . (), cut‐off value to confirm a castration is <0.09 nmol/l and according to Arighi and Bosu (), concentration of ≤0.83 nmol/l is diagnostic of absence of testicular tissue.…”

A Review of Equine Laparoscopy

“…However, it has subsequently been shown that the testis can revascularize and still produce testosterone [69, 70]. The testis has a complex blood supply that allows the testis to revascularize from vessels in the tunic, especially the cremaster vessels and the external pudendal artery [71]. …”

Laparoscopic castration of the normal horse: Is it indicated?

“…This study has confirmed that the blood supply to the testicle may be preserved via the external pudendal artery when only the mesorchium is transected, as shown by Voermans et al . (). On reading the study by Voermans et al .…”