BILATERAL ORCHIDECTOMY

Castration of young ruminants is a common procedure often done by lay people to improve meat quality and render males more manageable. It is appropriate for veterinarians to educate their livestock owners to minimize complications from this procedure. A clean, dry environment as well as fly control is encouraged to prevent postoperative infection.

The desired age at which the animal is castrated varies and depends on an owner’s expectation, ease of pro-cedure, and the intended use of the animal. Younger animals are easier to restrain, have a lesser risk of incisional complications, and have decreased aggressive behavior after castration. However, some livestock owners feel that castration at a later age is preferable for improved carcass characteristics and weight gain. In a review of the literature, castration had a mixed effect on weight gain of cattle.

Castration can be done pharmacologically by using immunization against GnRH or by insertion of an estrogen implant. Other techniques include using surgical and bloodless castration techniques. This chapter will focus on the latter two methods of castration.

All small ruminants that are castrated should receive a tetanus prophylaxis (ideally several weeks before the procedure) because tetanus acquisition is one of the main complications of this procedure. This can be in the form of colostral protection, tetanus antitoxin (250 to 500 IU) or two doses of tetanus toxoid (first one 3 to 4 weeks in advance of procedure).

Regardless of the technique used or species involved, it is essential to check that both testes have descended into the scrotum before surgery is contemplated. This prevents unilateral castration of cryptorchid animals, which would give the misleading external appearance of a castrated male. Fortunately, cryptorchidism is rare in calves, rams, and bucks.

CASTRATION OF CALVES AND SMALL RUMINANTS

Lambs and small goats are held, head down, between the operator’s knees or head up with the front and hind limbs on each side held together. Calves younger than one month of age are usually restrained in lateral recumbency. Typically, older calves are put into a squeeze chute or stocks. Many operators elect to use a local anesthetic in the skin and/or spermatic cord, although some young calves and lambs receive operations with only physical restraint. For a standing animal in stocks or head catch, the operator’s hand is placed at the base of the tail so that it can be lifted over the animal’s back. Lamb or kid sensitivity to local anesthetics necessitates reduction of the concentration of a local anesthetic being administered; lidocaine should be diluted from 2% to 0.5% or 1%. General anesthesia—or heavy sedation (xylazine hydrochloride 0.02 to 0.1 mg/kg IV or 0.04 to 0.2 mg/kg IM) and local anesthesia—are commonly used with larger animals and pets. The lower range should be used on goats and debilitated, aged, young, or depressed animals. Another drug combination that works well on goats is midazolam (0.1 to 0.2 mg/kg IV) in combination with butorphanol (0.02 mg/kg IV).

For animals less than 150 kg, the distal portion of the scrotum is grasped and pulled distally, thus displacing the testes proximally (Figure 12.1.1-1). The distal third of the scrotum is excised to expose the testes (Figure 12.1.1-2). Traction is applied to each testis, and the spermatic cord is freed by stripping the fascia proximally (Figure 12.1.1-3). At this point, the cord can be ligated and transected, emasculated, or stretched until the vasculature ruptures. The latter technique results in vasospasm, which is usually adequate hemostasis for smaller animals but could damage the inguinal ring in lambs and lead to a hernia. For this reason, use of a technique that closes (use of emasculator [Figure 12.1.1-4] or ligation) the spermatic cord is preferable. The wound is usually left open to heal by second intention.

Figure 12.1.1-1 The distal portion of the scrotum of a bull calf in dorsal recumbency is grasped and pulled distally, thus displacing the testes proximally.

Figure 12.1.1-2 The distal third of the scrotum is excised, exposing the testes.

Figure 12.1.1-3 The spermatic cord is exposed by stripping the fascia proximally and applying traction to each testis.

Figure 12.1.1-4 Emasculator. Note the serrated blade used for crushing the spermatic cord to cause hemostasis. When the emasculator is used, the cutting blade must be placed distal to the crushing blade.

Another surgical option for calves is to approach the testes by making a vertical incision in the lateral wall of the scrotum with a Newberry knife (Figure 4.4-6A). The Newberry knife blade is placed through the middle of the scrotum (Figure 4.4-6A) and rapidly pulled distally, thus making a cranial and caudal flap of the scrotal skin (Figure 4.4-6A). The same flaps can also be created with a scalpel. The testes are excised as mentioned previously, either with traction, an emasculator, or ligation and excision. The wound is typically left open.

Older animals are occasionally castrated, with the best results obtained when they are restrained in chutes or on a tilt table. Local anesthetic in the scrotal skin and spermatic cord is appropriate. The operator’s preferences dictate the surgical approach. The distal scrotum can be removed (Figure 12.1.1-5), or vertical incisions can be made on either side of the median raphe. Regardless, the testis is identified and freed from its surrounding fascia with blunt dissection. Once isolated, the spermatic cord is ligated and transected or emasculated. Generally, the vaginal tunic is not incised and is removed en bloc with the testis. If the vaginal tunic is incised, the testis and spermatic cord are ligated (or emasculated). Some prefer to split the spermatic vessels away from the pampiniform plexus and ligate (or emasculate) these structures separately. Regardless, the cremaster muscle is ligated with the vaginal tunic, and both are transected approximately 2 cm distal to the ligations. Transfixation sutures help prevent ligature slippage. If primary closure is to be performed, at least a partial resection of the redundant scrotal skin is necessary to minimize dead space. The subcutaneous tissues are closed with a pursestring-type suture (superficial and deep bites) using an absorbable suture material. A subcuticular or skin closure should be done with an absorbable suture if primary closure is elected.

Figure 12.1.1-5 Yearling bull being castrated. The distal end of the scrotum has been removed, exposing the testes.

UNILATERAL ORCHIDECTOMY

Injury or illness that involves one testis may detrimentally affect the contralateral tests to the extent that removal of the affected testis provides the best option for returning the bull or ram to fertility. This may be the case in unilateral hydrocele, hematocele, testicular tumor, epididymitis, abscess, varicocele (Figure 12.1.1-6A) or other conditions. In such cases the contralateral testis may be compromised by pressure or increased local temperature. Careful removal of one testis results in preservation of the remaining testis, and some compensatory hypertrophy and increased sperm production by the remaining testis may be expected.

Figure 12.1.1-6 A, Mature ram with unilateral varicocele. Note the enlarged asymmetric scrotum. B, Intraoperative view before resection.

(Courtesy of Dr. Mary Smith; Cornell University.)

Abnormalities are usually detected during physical and routine breeding soundness examination or may be noticed by an astute owner or herdsman. The abnormality can involve the scrotum, testis, epididymis, ductus deferens, vaginal tunic, or vasculature of the testis. Unilateral disease can result in abnormal semen quality as the heat generated by the abnormal testis affects the contralateral testis. Fortunately, studies have shown the effect on semen quality is reversed after the abnormal testis is removed. Care must be taken to limit postsurgical hemorrhage and inflammation and to prevent the detrimental effects of postoperative pressure or elevated temperature on the remaining testis.

The surgical procedure for unilateral orchidectomy is as follows. The animal is restrained or anesthetized in lateral recumbency. The upper hind limb is abducted and secured in a fixed position; the scrotum may be held by a towel clamp to facilitate preparation (Figure 12.1.1-6B). After preparation of the surgical site, a vertical incision is made on the lateral aspect of the affected side approximately the entire length of the testis. The initial dissection extends the skin incision through the scrotal fascia, and the testis is bluntly dissected within the vaginal tunic. The vaginal tunic is incised the length of the testis, and the spermatic cord isolated, double-ligated, and transected or emasculated. The tunic can be transected and oversewn with an absorbable suture material. It is usually necessary to remove excess scrotal skin. This will help minimize dead space and prevent postoperative seroma formation. The scrotal fascia is closed by using a continuous pattern with an absorbable suture. The subcutaneous tissues and skin are closed routinely. Studies have shown that semen quality returned to normal 22 days after unilateral castration in normal bulls. There are other case reports of successful return to production following surgery in several animals with unilateral disease. Currently, surgery is recommended for valuable animals with nonheritable unilateral disorders other than herniation.

BLOODLESS CASTRATION

Several techniques for castrating farm animals without performing a surgical incision are available. These so-called “bloodless techniques” create ischemia of the testis with subsequent atrophy or necrosis. In very young animals, the most common technique is to use an elastic band. The band and applicator pliers should be soaked in disinfectant before use. Once the animal is restrained, the band is applied around the neck of the scrotum by using the pliers (Figure 12.1.1-7A and B). Other commercially available tools are designed to place heavy-walled latex tubing around the neck of the scrotum in older animals. The scrotum and testes usually slough within 3 weeks of band application. This technique is used quite commonly in small ruminants less than one month of age. Ambulatory clinicians at our institution have been successful with using a callicrate bander^* in bulls up to 400 kg (Figure 12.1.1-8). Rare failure has been associated with band breakage. Older, small ruminants should be handled the same as older calves with sedation and surgery; however, one should always be mindful of small ruminant sensitivity to lidocaine. The callicrate bander has been used successfully on older goats after the long hair was clipped from the neck of the scrotum.

Figure 12.1.1-7 A, Elastrator used to apply elastic bands when castrating a young kid. B, Close-up view.

Figure 12.1.1-8 Callicrate bander.

Another bloodless technique is to use a Burdizzo emasculatome (Figure 12.1.1-9) to crush the spermatic cord within the scrotum. After this, the testes atrophy but usually do not slough. This instrument is best used by crushing a portion of the scrotum while holding the spermatic cord over the side that is crushed. One can crush the spermatic cord twice while manipulating the cord within the scrotum. These crushes should be staggered without crossing the midline; so no pressure is applied across the entire scrotum, thus minimizing the risk of impairing vascular supply. All animals treated with nonsurgical castration techniques should receive tetanus prophylaxis (ideally several weeks before the procedure) because tetanus acquisition is one of the complications of this procedure.

Figure 12.1.1-9 Burdizzo emasculatome.