Surgery of the Male Reproductive Tract

Preparation of Teaser Bucks

There are many situations in which the presence of a teaser animal is desirable. A teaser can be used to stimulate the onset of cyclicity at the beginning of the breeding season or in the off season (male effect).

A teaser animal may also be more efficient than a human caretaker at eliciting or observing signs of estrus, including tail wag, buck-seeking behavior, and willingness to stand. The teaser, then, generally simplifies protocols involving superovulation, artificial insemination, or breeding to a distant buck. It can also be used to detect returns to estrus when rebreeding must be to the same distant buck or buck in a straw. One study showed a decrease in the duration of estrus and an increase in fertility to artificial insemination (from 59 to 74%) when a vasectomized buck serviced the does before artificial insemination was performed (Romano et al. 2000). Finally, the owner can be more sure of the last possible due date, as for induction of parturition, if there was no postbreeding exposure to a fertile buck.

Angora goats are reported to be inactive outside the nor­mal breeding season, and selection and preparation of a less seasonal goat such as the Boer have been recom­mended for use as an early-season teaser in South Africa (Van der Westhuysen et al. 1988).

Non-surgical Teasers

There is a teaser to fit almost every situation. If a small herd has only one buck, that animal can be fitted with an apron to ensure that copulation does not occur. If no bucks are present, other animals can be substituted. One of the simplest teasers is the intersex goat. This infertile animal usually has no idea that it is a genetic female. Where year- round masculine behavior is not desired or the expense of maintaining an otherwise non-productive animal is too great, a temporary teaser can be created with hormones.

Penile Translocation

The owner of a large herd may want one or more surgically prepared teasers. A penile translocation (deviation) is the surgery of choice if later breeding to the selected buck might be desirable (Barker 1977). The buck should be held off feed and water 12 hours before surgery, because he will be positioned in dorsal recumbency. If surgery is done under general anesthesia, a cuffed endotracheal tube should be used. If the buck is only tranquilized and analge­sia is provided with local injection of 1% lidocaine, the head should be positioned lower than the neck. The abdo­men is clipped and scrubbed and a new location, above the fold of the flank and on an angle from the base of the scro­tum that is 45° off midline, is chosen for the preputial opening. The right flank is preferred if a right-handed per­son is trying to collect semen from the buck with an AV at a later date. A circle of skin and cutaneous trunci muscle (4-5 cm in diameter, lower edge 1 cm above the fold of the flank) is removed and discarded (Edmondson et al. 2012; Tibary et al. 2017). Next, a circumferential skin incision approximately the same size as that of the target hole (5 cm diameter) is made around the preputial orifice and extended along the midline, over the shaft of the penis, from the preputial incision two-thirds of the way to the base of the scrotum (Figure 13.14).

Figure 13.14 Location of incisions for penile deviation is shown by the dashed lines, while local anesthetic is infiltrated along the dotted line.

contamination as the penis is pulled through a subcutane­ous tunnel to the flank incision with the aid of long for­ceps. Finally, the prepuce is sutured into its new location with two layers of interrupted absorbable sutures, being careful to locate the reference suture dorsally. The midline incision is closed except for the most cranial aspect, which is left open for drainage (Edmondson et al. 2012). Postoperative penicillin and tetanus prophylaxis are war­ranted. Hot-packing or anti-inflammatory drugs may be needed for several days to control swelling at the prepu­tial orifice. The buck thus prepared can still breed an AV. He can also breed a cooperative doe, given adequate time for maneuvering, and he should not be allowed to run loose with the does unless aproned or sterilized with a further surgery.

Vasectomy

If no additional breeding with the animal is planned, a vasectomy can be used to create a permanent teaser. Possibilities for anesthesia (see Chapter 17) include seda­tion and local infiltration, epidural anesthesia, or general anesthesia. The procedure is as for rams and has been well described elsewhere (Copland 1986; Tibary et al. 2017). Briefly, the neck of the scrotum is prepared for surgery and draped. An incision can be made anteri­orly, laterally, or posteriorly, according to the surgeon’s preference. It is also possible to perform a bilateral vasec­tomy through a single cranial midscrotal incision (Lofstedt 1982). The firm, cord-like ductus deferens is located and ligated twice, and a section 2-3 cm long is removed between the ligatures.

Inflammatory and degenerative changes have been reported after vasectomy. Palpable granulomas, anecho- genic on ultrasound and consisting of dead sperm, develop in the firm and enlarged tail of the epididymis. Efferent ductules may rupture, causing extravasation of spermatozoa into the tissues and evoking an immune response with multinucleated giant cells (Batista et al. 2002a). Some bucks showed degeneration of seminiferous tubules by four months after vasectomy. In another report, anechoic granulomas developed in the deferent duct of six bucks and in the head of the epididymis of a seventh. Only in the latter animal, with obstruction of the epididymis occur­ring close to the testis, were ultrasonographic changes vis­ible in the parenchyma of the testis by five months after vasectomy (Ahmad and Noakes 1995).

Epididymal Surgery

An alternative to vasectomy is destruction or removal of the tail of the epididymis. Tranquilization or infiltration of a local analgesic should be used, although neither is mentioned in the original descriptions.

Castration

Castration is commonly performed to avoid undesirable odors and aggressive sexual behavior in male goats kept as pets, and to prevent breeding by bucks deemed to be of inferior genetic quality. The flavor of the meat of males raised past puberty is also affected by castration, although in some societies, especially where meat is served with plenty of spices, the rank buck remains quite acceptable. An intact male is preferred for some religious feasts (such as Muslim), so producers should plan according to their intended markets.

Numerous methods of castration are covered in standard surgery and medicine textbooks (Edmondson et al. 2012; Tibary et al. 2017). The procedure is usually performed by an experienced producer; the veterinarian is asked to castrate the maturing pet or the buck with a scrotal lesion (abscess, hernia). Tetanus prophylaxis is advised for all techniques. (See discussion in Chapter 18.) Small goats are restrained on their rumps with front and hindlimbs held together on each side by an assistant. Larger (tranquilized) goats are held in a standing or laterally recumbent position. Postcastration analgesia can be supplied with a non-steroidal anti­inflammatory drug such as oral meloxicam at 1-2 mg/kg.

When a goat is to be kept as a pet wether, delaying castra­tion until puberty permits separation of urethral process and glans penis from the prepuce, thus simplifying manip­ulations to examine or catheterize the goat if urolithiasis develops. Delaying castration also may lead to some additional increase in diameter of the urethra (Kumar et al. 1982). In general, anyone willing to plan this far ahead to prevent deaths caused by urolithiasis should be encouraged to choose a doe kid as a pet instead or to manage the diet carefully. Ejaculatory behavior may be retained for months after castration of adult bucks (Hart and Jones 1975).

Surgical Castration

Young kids (less than 1 month old) are often castrated by producers by the knife method, without anesthesia. By the time the well-fed kid is several months old, surgical removal of the testes is the preferred technique unless envi­ronmental conditions make an open wound unacceptable. By this age the desirability of anesthesia is also evident; older bucks sometimes die very quickly after being sub­jected to the stress and pain of castration.

Large bucks are tranquilized lightly. Diluted (0.5-1%) and buffered lidocaine can be injected with a fine needle to avoid provoking as much reaction from the injections as castration itself would have engendered. Depending on the size of the goat, 1-2 mL is deposited in each of four sites: high in the cord and at the distal end of the scrotal sac bilaterally. Alternatively (and especially in larger animals), an intratesticular injection can be made, placing 2-10 mL of 1% local anesthetic into each side, with most of this being injected into the testis and the remainder being deposited subcutaneously in the bottom of the scrotum (Hall and Clarke 1983).

A U-shaped skin incision is made over each testis or the distal third of the scrotum is cut off. Testes, still within their tunics, are expressed and removed by scraping the cords with a sterile knife or (for larger bucks) by an emas- culator with a crushing blade. Caprine testicular size approaches that of a stallion, and a good, well-used equine emasculator is appropriate. If such an instrument is not available, the cords of a mature buck should be transfix ligated with absorbable suture and a secure knot such as a miller's knot, constrictor knot, or strangle knot (Hazenfield and Smeak 2014). An alternative technique for bloodless castration of a large buck is use of a Henderson Castrating Instrument (Stone Manufacturing, Kansas City, MI, USA). This device is clamped across tunic and cord above but close to the testis, and rotated with a variable-speed drill until tissue separation occurs. General anesthesia (see Chapter 17) in addition to the local anesthetic seems ideal.

If very young kids are castrated by simply pulling on the testis until the cord snaps, a finger should be placed at the inguinal ring to avoid enlarging it while traction is being applied, with subsequent risk of herniation. In warm weather, a fly repellant is needed and the kid should ideally be kept on clean grass rather than in a dirty pen or on saw­dust. Hands and equipment should be disinfected between animals.

If the animal is cryptorchid (see above) and a pet, castra­tion is best done under general anesthesia, from a flank, inguinal, or parainguinal approach after the testis has been located by ultrasound. Laparoscopic cryptorchidectomy has also been described (Tibary et al. 2017).

Rubber Rings and Banding

Very young kids are commonly castrated with elastrator rings, very heavy rubber rings that are first soaked in alco­hol or iodine to disinfect them and then placed around the neck of the scrotum with a special applicator. The scrotal sac and whatever has been trapped within it (hopefully both testes and none of the penis) become ischemic and eventually drop off several weeks later. There is no hemor­rhage and no open wound, but there is an increased risk of tetanus relative to several of the other techniques, and blowflies may be attracted to the gangrenous scrotum in hot weather (Van der Westhuysen et al. 1988). Rubber bands also evoke more prolonged signs of pain in older ani­mals than does surgical castration (Shutt et al. 1988), but this can be attenuated by injection of buffered lidocaine intratesticular and into the neck of the scrotum in advance of application. A device designed by the Moredun Research Institute (Penicuik, UK) for castrating and docking lambs (Numnuts®) automatically injects the lidocaine before releasing the castration band. On humane grounds, it seems preferable to restrict the use of rubber rings to kids younger than 3 weeks of age. There is a very real danger of an incomplete castration if the operator is not careful to verify the entrapment of both testes in the scrotum below the band. While fertility is probably decreased because of the elevated temperature of a testis forced into an inguinal position, testosterone production (and thus male behavior and odor) will continue. Some unwanted pregnancies might occur if the improperly castrated male is allowed to run with females. If the retained testis is to be removed, wait until all inflammation related to the banding has resolved and provide local anesthesia with a line block over the testis and intratesticular lidocaine.

Special instruments have been produced to tightly stretch solid rubber tubing around the neck of the scrotum of bulls. These same devices, such as the Callicrate® bander (No-Bull Enterprises, St. Francis, KS, USA) can be used to castrate mature bucks. The band is applied close to the dorsal aspect of the testes, because higher placement results in a larger skin defect when the scrotum sloughs. The animal should receive two doses of tetanus toxoid in advance. With the aid of light tranquilization, 7-10 mL of 1% lidocaine is infiltrated into the skin of the neck of the scrotum and into the sper­matic cords or testes before the band is applied. The scrotum should be amputated about 2.5 cm distal to the band two or three days later and the stump sprayed with a fly repellant. This technique is especially useful for avoiding hemorrhage or when the animal must be bedded on shavings, which would otherwise contaminate an open castration wound. Meloxicam should be used for several days after banding for pain relief and systemic antibiotic treatment is also advised. Recently a method has been devised for impregnating lido­caine into castration bands of various sizes for slow release into the tissue of calves, with therapeutic concentrations achieved for a week (Saville et al. 2020). If these bands reach the market, they should be evaluated on goats.

Burdizzo

The small Burdizzo emasculatome can be used to crush the contents of the cord above each testis (Edmondson et al. 2012; Gilbert and Fubini 2017). Each cord in turn is held tightly against the lateral aspect of the scrotum with one hand, while the instrument is applied twice on each side. The crushes are made approximately 1-2 cm apart, both above the testis, and should not cross the midline of the scrotum (to avoid sloughing skin) or include the penis. The testis is manipulated vigorously while the instrument is in place in an attempt to snap the cord. The kid should be evaluated one month or longer afterward to ensure that

Figure 13.15 Necrotic testicular parenchyma and crimp lines on the cords above the testes following Burdizzo castration. The testes were too large when the procedure was performed to be resorbed. Source: Courtesy of Dr. M.C. Smith.

both testes have atrophied. Improper technique or a sprung instrument (as from using it to dock tails) gives the Burdizzo method a bad reputation. If castration is delayed until the testes enlarge with spermatogenesis, too much tissue will be present to be completely resorbed. The infarcted testis (often with a viable epididymis, see Figure 13.15) remains as a palpable mass in the scrotum, engendering uncertainty in the owner's mind as to the sterility of the wether.

The chief advantages of this technique are the absence of hemorrhage and open wounds and the decreased risk of tetanus. Anesthesia is usually not used, except when the buckling is dehorned at the same time. A small (to avoid toxicity) quantity of lidocaine can be injected into the cords before crushing. Disadvantages include swelling or slough­ing of the scrotum or survival of a testis if the clamp is not applied properly.

Similar results might be obtained using a pinhole castra­tion technique recently described for calves and rams (Ponvijay 2007; Fazili et al. 2009). Under local anesthesia, the spermatic cord is forced laterally, and an 18-gauge nee­dle is used as a guide to pass absorbable suture through the scrotum. The needle is then withdrawn, the cord forced medially, and the needle reinserted through the same holes, to permit passage of the suture to now completely encircle the cord. After ligation to constrict the cord within the neck of the scrotum, the knot is trimmed short and becomes subcutaneous.

Manipulation of the Testes into the Inguinal Ring

It has been reported that in Venezuela, producers twist each testis around the spermatic cord and push it back into the inguinal canal (Gall 1981). This takes manual dexterity and must be done at an early age. The animal is rendered sterile without risk of hemorrhage, infection, or tetanus, and without the need for any specialized equipment. The more rapid growth characteristics and carcass composition of the buck kid are retained. The results of a short scrotum castration (elastrator band intentionally applied below the testes) would have similar effects on growth, although the potential for partial fertility has not been studied in bucks.

Chemical Castration

In the United States, an 88% solution of lactic acid was briefly marketed for castration of calves (Chemcast®, Bio- Ceutic Labs, St. Joseph, MO, USA). This product was used on lambs and kids also. A 20-gauge or smaller needle (to avoid leakage from the injection site) was inserted from above, downward into the center of each testis. A small quantity (0.3-0.5 mL) of solution was deposited; larger amounts leaked back and caused adhesions between testis and scrotum or draining tracts (Blackburn 1985). Although this method was praised by the manufacturer as being supe­rior to the Burdizzo technique, verification of castration before “wethers” are allowed to run with females of breed­ing age should be mandatory. Other sclerosing chemicals such as cadmium chloride (200 μg∕kg; Kar 1962) have also been injected to destroy testicular tissue, without considera­tion of possible meat contamination. More recently, inject­able zinc gluconate has been licensed for castrating dogs (Levy et al. 2008), but evaluation of efficacy in goats has not been reported. By contrast, calcium chloride at 40 mg/kg bodyweight per testis in 2 mL of normal saline has success­fully rendered mature bucks sterile (Jana et al. 2005).