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 inguinal canal. They also can have passed through the inguinal canal and just not be lying within the scrotum. Testicles that have passed through the inguinal canal, but are carried high in the flank rather than within the scrotum, are not considered retained. A horse with a testicle in this position is referred to as a "high-flanker." A "high-flanker" is an inguinal cryptorchid, and can be castrated normally. This can often be accomplished with the use of sedation.
Sedation helps the horse relax, and the testicle often can be more easily palpated if it has descended through the inguinal canal. Veterinarians also can use ultrasound to look for a retained testicle. An ultrasound examination performed per rectum can determine if a testicle is retained within the abdomen. Furthermore, the inguinal area can be examined via ultrasound to determine if there is a testicle within or just outside the inguinal canal. In this way, a veterinarian can determine prior to anesthetizing a horse if a testicle is retained within the abdomen.
Why is this so important?
Cryptorchid testicles cannot be removed in the same fashion as normally descended testicles, so to avoid unnecessary anesthesia and expense, it is better to know before surgery. Unfortunately, sometimes the descended testicle is removed and the cryptorchid testicle is left. When that happens, the horse will appear to be a gelding, but, of course, he still has one testicle and therefore will act like a stallion. In that special case, your veterinarian can test the horse’s blood for the presence of hormones to determine if the horse is a cryptorchid.
Now that you know your horse is a cryptorchid and what that means, what do you do about it? What are your options?
There are two basic techniques for performing cryptorchidectomies, either conventional or laparoscopic. There also are several different ways to perform each technique. For example, with conventional cryptorchidectomies, there are five different approaches; meaning there are five different areas on the horse’s body through which a retained testicle can be removed.
The most common conventional surgery probably is an inguinal approach. The inguinal area is that area on the underside of the horse where the testicle descends from the abdomen into the scrotum. The remaining approaches involve making incisions along the underside (ventral aspect) of the horse’s belly to gain access to the retained testicle. The flank approach involves making an incision low on the flank of a standing horse to find and remove the testicle.
All of the techniques except for the flank approach require the horse to be anesthetized and lying on his back (dorsal recumbency). All of the techniques, or sometimes a combination, can be used to remove one or both cryptorchid testicles. These techniques also all have their own set of advantages and disadvantages.
For example, from an owner’s standpoint, those approaches on the ventral aspect of the horse will not leave a visible scar. However, most surgeons have their own preference as far as approach, due to surgical advantages and because of techniques they are comfortable performing.
Conventional cryptorchidectomies are those surgical techniques that use an incision either in the inguinal area, near the prepuce, or in the flank to gain access to the retained testicle. The advantage of the conventional inguinal approach, from a surgeon’s point of view, is that sometimes the retained testicle can be removed using a non-invasive approach, meaning the abdomen is not "invaded" by the surgeon’s hands or instruments to retrieve the testicle. This usually happens when the testicle is within the inguinal canal. If the testicle is within the abdomen, however, then an invasive approach will have to be used to remove the testicle.
A surgeon, if using the conventional approach on a horse, initially will use an inguinal approach to determine if the testicle lies within the inguinal canal. If unsuccessful in locating the testicle, he or she will proceed with another technique to retrieve the testicle from the abdomen. The advantages of these techniques are specific for each procedure and include exposure, ease of performing, incisional healing, and the amount of time required for the procedures to be performed. The disadvatages for conventional techniques are the requirements for general anesthesia (in all but a standing flank approach), risk of eventration (movement of intestine from the abdomen through the inguinal canal into and sometimes through the incision), risk of peritonitis (infection in the abdomen), and risk of surgical failure (inability to locate the retained testicle).
Surgical failure can happen since none of the conventional techniques allow for good viewing of the abdomen to locate the testicle—it’s all done by touch. One of the main disadvantages of the conventional techniques is not knowing which testicle is retained on horses which have had the descended testicle removed, or dealing with horses which have had multiple surgeries to remove a testicle with no change in stallion-like behavior. Those cases can be very challenging as often both sides of the horse must be explored in order to find the retained testicle. This adds up to prolonged surgical and anesthesia time and increased risk for the horse. However, with the advent of laparoscopic techniques for removing retained testicles, even in horses with unknown history or multiple castrations, the retained testicles can be located and removed quite easily.
Laparoscopic cryptorchidectomy is the surgical procedure for removing retained testicles using a laparoscope. Laparoscopy in general was first described in the early 1900s. However, it has been only in the last five to 10 years that it has become a common procedure performed in the horse. A laparoscope is a small telescope used to view the abdominal cavity. Lapar is the Greek name for the flank, and "scope" is using a camera to view or examine. Laparoscopy is a surgical technique using this tiny telescope (about 1 cm in diameter and approximately 50 cm in length) to view the abdominal cavity and perform surgery.
Although an incision still has to be made through the skin and muscle tissue of the flank to insert the camera, the incision is much smaller than conventional laparotomy incisions (flank incisions made to gain access to the abdomen). The laparoscope has a camera that projects an image onto a large monitor for excellent viewing. In order to view the contents of the abdomen better, the abdomen is distended with gas, usually with carbon dioxide, to give the surgeons more room to look around. In that way, the abdomen can be explored through an incision which is about 1 cm in diameter rather than the 10-15 cm incision needed for conventional techniques. In addition to the camera, long-handled instruments are used to grasp, cut, or suture tissue. The instruments can be introduced into the abdomen through incisions that are only 0.5 - 1 cm long.
Laparoscopic cryptorchidectomies can be performed either with the horse standing or under general anesthesia. With standing laparoscopic cryptorchidectomies, the horse is sedated and local anesthesia is used to desensitize the skin where the camera will be introduced. General anesthesia is not necessary for this approach. In standing approaches, the camera is placed through the horse’s flank. The caudal abdomen then can be explored to see if a retained testicle is present within the abdomen. Once identified, the testicle is grasped, cut, and subsequently removed from the abdomen. In cases of unilateral cryptorchids, after removal of the retained testicle, the descended testicle is removed through a standing castration, or the horse is anesthetized and the descended testicle is removed routinely.
Laparoscopic removal of retained testicles can be performed with the horse under general anesthesia. Many surgeons prefer this technique if the horse doesn’t appear to be amenable to a standing approach (if the horse is difficult to restrain or is unpredictable even when sedated). For that method, the horse is anesthetized and placed on his back. For cryptorchidectomies, the horse is further tilted with his head lowered to allow a large amount of intestines to fall away from the caudal (back portion) of the abdomen where the retained testicles are located.
The camera is placed through the horse’s umbilicus (belly button), and the abdomen is distended with gas. In addition to the small incision for the camera (called a portal), usually two more small incisions are made. They allow introduction of long-handled instruments used to grasp the testicle and to enable the surgeon to interrupt the blood supply to the testicle so that when it is removed, the remaining stump doesn’t bleed.
To remove the testicle, one of the instrument portal incisions is enlarged just a bit and the testicle is pulled from the abdomen. The instrument portals require minimal suture material for closure. One of the biggest advantages of laparoscopic cryptorchidectomy is that surgical failure, or failure to located the retained testicle, almost never happens. In conventional approaches, it can be a common problem.
Laparoscopic cryptorchidectomy is ideal for horses which have been castrated numerous times with unacceptable residual stallion-like behavior. Those horses are especially difficult to approach using the conventional methods, as there often is a great deal of scar tissue from the previous surgeries. Furthermore, if the abdomen was explored previously, there might be adhesions of the bowel to the inguinal area, making a second surgery more risky. Using laparoscopy, the surgeon can very quickly and easily determine if there is a retained testicle within the abdomen, while completely avoiding the previous surgical sites. That makes the procedure not only minimally invasive, but also of low risk to the health of the horse.
The other great advantage of laparoscopy is that the incisions are very small and the horse has a short recovery period. Often with conventional approaches, the horse will be confined to a stall postoperatively for two weeks, then allowed only hand walking for several weeks, with return to full exercise in four to six weeks. With laparoscopy, the horses are confined to a stall for 24 hours, then can be hand walked the following day, with return to full exercise in two weeks. So, for a horse which currently is in training and needs cryptorchidectomy, laparoscopy saves a great deal of what would otherwise be down time.
The disadvantages of laparoscopy are few. This surgery usually is a bit more expensive than the conventional approach, due to the expense of the laparoscope and associated equipment. The only other disadvantage is that some horses experience a bit of abdominal discomfort the day after surgery. This is due to the carbon dioxide within the abdomen that is irritating the surfaces of the bowel. The irritation is mild and is easily treatable with Banamine. Usually the horse is depressed for 12 hours, then recovers uneventfully. In our hospital, horses are discharged the day after surgery if they are eating normally and not depressed.
Another advantage of laparascopic surgery is that the incisions are very small, making the risk of incision complications (drainage or infection) quite low when compared to conventional approaches. For both laparoscopic approaches (standing or under general _anesthesia), the horse must be fasted for 48 hours prior to surgery in order for the large colon to decrease in bulk and, therefore, in size. That enables the surgeon to get a much better view of the abdomen. For the conventional approaches, food generally is withheld for 12 hours.
When to Castrate a Cryptorchid
Many people ask when they should castrate a cryptorchid? I always reply, "As soon as possible."
Cryptorchid horses, just like stallions with both descended testicles, will exhibit stallion-like behavior and develop masculine physical characteristics—thickened neck, large jowl, etc. Even if the cryptorchid is not fertile, the hormones are there driving the body. Some cryptorchid horses are even more rank (difficult to handle) than normal stallions, for unknown reasons. But as for all intact males, the sooner he is castrated, the less likely there will be residual stallion-like behavior. Some people believe that if they geld a horse early (before two years of age), he will not develop properly. This is completely untrue. In fact, it has been shown that by gelding young, the horse will grow even taller than his intact cropmates. Furthermore, the smaller the testicle when the horse is castrated, the less complicated the surgical procedure.
Horses castrated young (less than one year) have less chance for excessive bleeding postoperatively as well as reduced chance of incisional swelling or infection. Some people choose not to castrate colts in the middle of the summer due to the increased fly population. In our hospital, even with unilateral cryptorchids, the descended testicle is removed and the incision closed. There is no open wound. Therefore, not performing the surgery in the middle of summer to avoid the flies might not even be a valid concern.
The second most commonly asked question about cryptorchids is how long after surgery will it take for the stallion-like behavior to cease? In all stallions, even cryptorchids, it often takes up to six weeks after castration for all the male hormones to leave the body and for an improvement in behavior to be noticed. You will see gradual improvement over the six weeks, but it often takes the full time for all stallion-like behavior to subside. Some stallions which are castrated at an older age or after having bred mares will not lose all of their stallion-like behavior, even if all testicular tissue is removed.
Cryptorchid castration historically has been a difficult procedure with occasionally poor end results, especially for those horses which had undergone multiple procedures to rid them of stallion-like attitudes. Now, with the advent of laparoscopy, removal of retained testicles has become a much simpler and safer procedure with a very quick recovery.
About the Author
Christina S. Cable, DVM, Dipl. ACVS, owns Early Winter Equine in Lansing, New York. The practice focuses on primary care of mares and foals and performance horse problems.
POLL: University Equine Hospitals