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Castration refers to the surgical removal of the testes. The testes are comprised of the right and left testicles and epididymides. Castration is also referred to as orchiectomy, emasculation, gelding or cutting.


Pertinent Anatomy

Anatomy of a Testicle


Testicle & Epididymis: Structures that produce sperm cells and testosterone (sex hormones). These tissues, covered by a layer of tunica albuginea, are targeted (removed) during the castration procedure.

Vaginal Tunic: Tissue which houses the testicle, epididymus and spermatic cord on each side of the horse. The vaginal tunic is composed of two layers:

  • The visceral tunic (which adheres to the tunica albuginea) and

  • The parietal tunic (which is continuous with the parietal peritoneal lining of the abdomen).

Abdominal fluid fills the (vaginal) space between the visceral and parietal tunics.

Scrotum: The skin surrounding the testes. Each testicle resides within its own scrotal sac. The two scrotal sacs are separated along the midline by the median raphe.

Spermatic Cord: A plexus of structures which is comprised of the vaginal tunic, testicular artery, vein and nerve, ductus deferens, lymphatic vessels, cremaster muscle and genitofemoral nerve.

Gubernaculum: A thin fibrous band that acts as a "guide wire" to direct the testicle from the abdominal cavity (behind its respective kidney) through the inguinal canal and into the scrotum.

External (Superficial) Inguinal Ring: A portal (opening) connecting the inguinal canal and scrotum.

Inguinal Canal: An oblique passageway (about 15cm in length) between the abdominal cavity and the scrotum.

Internal (Deep) Inguinal Ring: A portal (opening) connecting the abdominal cavity and inguinal canal.


Crytorchidism is an anomaly wherein one or both testicles fail to descend into the scrotum.

  • Abominal Cryptorchidism. Retained testicle(s) reside within the abdominal cavity and have failed to reach the inguinal canal.

  • Inguinal Crytorchidism (also known as a "high flanker"). Retained testicle(s) reside within the inguinal canal but have failed to reach the scrotum.

Right and left testicles fail to descend into the scrotum with equal frequency. Interesting, the majority of retained left testicles reside within the abdomen (75%) whereas the majority of retained right testicles are inguinal (58%). Bilateral cryptorchidism (in which both testicles are retained) is uncommon, affecting around 10% of cryptorchid horses.


How Does Cryptorchidism Occur?

In the normal male fetus, each testicle develops within the abdominal cavity just behind its respective kidney. A retroperitoneal cord of mesenchyme attaches to the caudal (posterior) pole of each developing testicle. This mesenchymal cord (known as thegubernaculum) courses across the abdominal cavity (from the back of the testicle) and enters theinternal inguinal ring along the back of the abdominal wall. It then continues through theinguinal canal, exits through theexternal inguinal ring and finally terminates at its attachment along the internal aspect of thescrotum.

As the fetal testicle descends, it uses the gubernaculum as a "guide wire" to direct it from the abdominal cavity into the inguinal canal, which it typically reaches by 9-10 months of gestation. The testicle generally remains within the inguinal canal until several weeks after birth, at which time it continues its passage into the scrotum. It is only after the testicle has reached the scrotum that is becomes visible to the observer.

In cryptorchids, one or both of the testicles does not complete its journey from the abdominal cavity (where it develops) to the scrotum (where it resides for the remainder of the horse's life as a colt or stallion).

Why Do Cryptprochids Need to Be Castrated?

The indication for most castrations is to reduce masculine behavior in males not intended for future breeding.

Castration of cryptorchids is HIGHLY recommended for the following reasons:

  • Stallion behavior of cryptorchids is often greater than that of normal intact male horses.
  • Retained testicles produce and release as much hormone (testosterone) as descended testicles.
  • Due to temperature elevation within the horse's abdominal cavity or inguinal canal, retained testicles do not produce functional sperm and are therefore sterile.
  • Cryptorchidism is an inherited trait.


Preoperative Considerations

In the vast majority of cases, castration is an elective procedure. We therefore want to ensure that the horse is in good health and free of concurrent illness prior to planning the operation. Maximizing the surgical candidacy of the patient will minimize the risk for potential complication(s).

A thorough physical examination (sometimes including bloodwork) is an imperative part of the preoperative process. Any illness discovered during preoperative assessment is successfully treated prior to scheduling orchiectomy.

Unilateral (one-sided) or bilateral (both-sided) cryptorchidism is confirmed via manual palpation prior to scheduling surgery. Since some testicles have been known to descend in colts over 12 months of age, we often wait until the colt is at least 18 months old prior to recommending surgery, especially in inguinal (or "high-flanking") cases.

Castration is generally scheduled in the morning to facilitate close monitoring throughout the day of surgery.

An intravenous catheter is placed prior to anesthetic induction to allow to quick and easy administration of medication(s) during the procedure. Unlike almost all other surgical cases, the catheter is placed on the side opposite the cryptorchid testicle, because these horses are better recovered with the affected side DOWN (rather than up) and we want to facilitate access to the catheter during the recovery process.

Tetanus is a very real concern with regard to any violation of the horse's integumentary system (skin). We therefore confirm that a Tetanus Toxoid has been administered within 6 months of castration. If this can't be confirmed, then one is administered preoperatively.

Single doses of Procaine Penicillin (antibiotic) and Pheylbutazone (antiinflammatory) are administered immediately preceding the procedure.


How Are Cryptorchids Castrated?

Firstly, we should mention that it is considered unethical and bad medical practice to remove the descended testicle in a unilateral (one-sided) cryptorchid. Unilaterally-castrated cryptorchids are often marketed and sold as "geldings" by owners who would rather avoid the expense of general anesthesia.

Consequently, veterinarians are trained to either:

  • Remove the retained testicle prior to removing the descended testicle or

  • Leave both testicles in the horse until appropriate surgery can be performed.

Unlike most routine castrations performed at The Atlanta Equine Clinic, cryptorchid orchiectomy requires the use of general anesthesia. Accordingly, the procedure is somewhat more involved, time-consuming and expensive as compared to routine castration.


Cryptorchid Castration


Surgical Technique

The retained testicle is targeted first (for reasons explained above).

An incision is made in the skin parallel to and overlying theexternal inguinal ring. Soft tissues and blood vessels are bluntly dissected to expose theinguinal extension of the gubernaculumas it exits theinguinal canalon its way towards thescrotum.

Once the inguinal extension of the gubernaculum is identified, it can be utilized as a "fishing line" to retrieve the retained testicle. Gentle but constant traction is applied to pull the retained testicle from its current location towards the scrotum. Although adhesions between the testicle and surrounding abdominal / inguinal tissues can make testicle recovery more challenging in complicated cases, most cryptorchid castrations go relatively smoothly.

The length of the external inguinal ring is assessed following retained testicle removal. If the ring is more than 3cm in length, we usually elect to close it primarily using interrupted absorbable sutures. The subcutaneous tissue and skin are subsequently closed in separate layers.

The descended testicle is emasculated only after the retained testicle has been successfully removed. This site is left OPEN (as described HERE).


Castrated Testicle

The recovered tissues are carefully inspected to confirm that all target structures have been successfully excised. In general, cryptorchid testicles are much smaller and softer than descended testicles. The entire testicle and epididymis must be resected from each side; visible evidence of a portion of thevas deferens (which resides above the testicular tissues in the horse) confirms successful orchiectomy.

Click HERE to review the testicle inspection process.


Following cryptorchid orchiectomy, photographic images of the testicles are acquired to provide the owner with verification that the horse has been successfully (and completely) castrated.

Post-Operative Recommendations

Stall rest ONLY for 7 days. This will allow the external ring of the affected side to close adequately prior to challenging it with the distractive forces associated with exercise. After 7 days, we then recommend stall rest with 10 minutes handwalking per day for another 7 days. Turnout and/or light exercise may resume after 14 days (2 weeks).

Antimicrobial therapy. Since the horse will not be allowed to exercise freely to enhance surgical drainage of the open castration site, we typically recommend a course of post-operative (broad-spectrum) antibiotics for a period of 5-10 days.

Antiinflammatory therapy. Again, our inability to exercise the horse immediately following surgery usually exacerbates both swelling and discomfort associated with the surgical site(s). Phenylbutazone at a dose of 2 grams orally once daily (administered in the morning) for 5 days is generally recommended.

Further medical therapy may be warranted depending on the level of concern, the appearance of the castration sites and/ or the comfort and general condition of your horse.

We request that the owner carefully monitor both the closed and open castration sites twice daily for at least 2 weeks postoperatively. The sites are assessed for increased swelling, heat, pain, or any other abnormality(ies). Also, monitor your horse’s attitude, activity, appetite and temperature DAILY.

Call IMMEDIATELY if any questions or concerns arise: 678-867-2577.

Please note that your horse may successfully breed a mare for up to 10-14 days after castration. Change in demeanor and attitude as a result of castration generally takes 30-90 days, depending on the age of your horse.


If you have any questions regarding Cryptorchid Castration in the Horse please call our office at (678) 867-2577. We look forward to serving you!
THE ATLANTA EQUINE CLINIC: 1665 Ward Road, Hoschton, Georgia 30548 - ph. 678-867-2577

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