It’s time to have your young colt gelded, so you make an appointment with your veterinarian. He arrives on the designated day and examines the colt prior to the surgery, then informs you that your colt is a bilateral cryptorchid and will need more extensive surgery than just a simple castration–a bilateral cryptorchidectomy to be exact. Your first question is: What is a cryptorchid?

A cryptorchid is a horse that does not have two testes palpable in their entirity below the external inguinal rings. When one testicle is retained, the term used is unilateral (for one side) and if both are retained, the horse is termed a bilateral cryptorchid. Cryptorchidectomy is the surgical removal of a cryptorchid testicle. Cryptorchid is the Greek name for the retained testicle and “ectomy” means removal or resection. (More information on what causes problems with testicular descent can be found in the April 1999 issue of The Horse.)

Under the Knife

Surgical treatment involves surgical removal of the testicle(s). That is the only treatment that will be discussed in this article. Any other treatment is highly controversial and is considered unethical by many veterinarians.

Cryptorchid horses also are often referred to as rigs or ridglings. Remember, in the development of male horses, the testicles originate near the kidney and migrate from within the abdomen through the inguinal canal (the anatomical canal that connects the abdomen to the scrotum) to rest within the scrotum. The testicles complete their movement to the scrotum from several days before birth to within weeks after birth. So, if the testicle is not within the scrotum, where is it?

Failure of a testicle to develop is quite rare, so if the testicle is not within the scrotum, it must be somewhere between where it originated (the kidney) and the scrotum. The testicles can be retained within the abdomen, or within the