LAPAROSCOPY: Advances in surgical techniques easier on horses
by Jennifer Lansdowne, Ludovic Bouré, Simon Pearce Department of Clinical Studies Ontario Veterinary College University of Guelph

Cryptorchidism is a developmental defect in both animals and humans that is characterized by failure of one or both testes to descend into the scrotum. Descent of the testes normally occurs in the male fetus. The testes move from within the abdominal cavity through a space called the inguinal canal, to a position outside the body cavity within the scrotum. In male foals, this process is generally completed by two weeks of age. Interruption in this process will result in one or both testis being retained anywhere along its route. Thus the testes may be located inside the abdomen, within the inguinal canal or under the skin in the inguinal (groin) area.

Retained testicles are not fertile (they do not produce viable sperm), but do produce male hormones (testosterone), causing the cryptorchid horse to have the behavioral characteristics of a stallion. Many veterinarians and breeders believe that chryptorchidism is heritable. This means that a stallion that has one chryptorchid testis and one normal fertile testis can pass on the trait to his offspring. Retained testes have a tendency to become cancerous in horses, and testes that are retained in the inguinal area may be associated with hind limb lameness in some horses. For these reasons, castration of cryptorchid horses is recommended.

Drs. Ludovic Boure and Simon Pearce perform a laparoscopic cryporchidectomy on a horse under general anesthesia. The procedure may also be done in a standing, sedated horse. This less invasive surgical techique is being mastered at the OVC, and is also proving successful for removing ovaries in problem mares. The research team continues to investigate new applications for this procedure.

A laparotomy is the typical procedure used to castrate cryptorchid stallions. A laparotomy requires general anesthesia and is an invasive surgery, resulting in a large incision in the body wall. In the last six years, laparoscopic cryptorchidectomy has been successfully developed and performed in horses. Laparoscopy has many advantages over laparotomy in the surgical correction of cryptorchidism. Laparoscopy is a less invasive procedure, requiring three or four 1-cm incisions. These small incisions decrease the time required in surgery and in closing the surgical incisions, as well as decrease the time required for the horse to be off exercise while the incision heals. The retained testis can easily be identified using laparoscopy, thus there is less chance of accidental trauma to the abdominal organs during the surgery.

Laparoscopy can also be very useful for the evaluation and the treatment of male horses with no palpable testes but with a known history of displaying stallion-like tendencies. Often, these horses are required to go through an exploratory laparotomy under general anesthesia. This surgery is invasive and requires exploration of both inguinal areas up to the abdominal cavity. Laparoscopy in these horses permits a non-invasive exploration of the abdominal cavity and the accurate distinction between a gelding and a cryptorchid. During the surgery, if a retained testis is found, it can be easily removed.

The major disadvantages of laparoscopy are cost of equipment and training. The equipment necessary to perform laparoscopic evaluation of the abdominal cavity is likely too expensive for the average practitioner, but many veterinary teaching institutions are equipped with the latest in laparoscopic technology. There is a high level of expertise and training required to perform this technique.

Laparoscopic cryptorchidectomy is a safe procedure, but the anesthetized horse must be monitored by a veterinarian specialized in equine anesthesia. Potential complications do exist, but these can be kept to a minimum through the mastering of the laparoscopic technique by the veterinary surgeon and through meticulous monitoring and observation of the horse. Laparoscopic technology is currently available at the Ontario Veterinary College, and as such is readily accessible to horse owners.

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Updated: October 2005.