Vasectomy in ruminants (and other species)
Keywords: vasectomy, ductus, deferens, vas, surgery, ruminants
Domestic ruminants are vasectomized to enable detection of estrus for routine breeding as well as for artificial insemination. Sometimes, vasectomized ruminants are also used to stimulate the onset and synchrony of estrous cycles, especially n sheep. In wild life sanctuaries, vasectomy is commonly used to prevent unwanted procreation. Indeed, the technique shown here has been be adopted in several non-domestic species, including carnivores.
A common surgical site for vasectomy in ruminants is on the high caudal aspect of the scrotum because the ductus is located at the caudomedial aspect of the testis in those animals. However, a caudal approach can lead to difficulty in locating the ductus. This is explained as follows: In the image below, a cranio-medial view of the right scrotal half of a bull, the testis has been rotated slightly on its dorso-ventral axis, to bring the ductus cranially, exposing it more than otherwise. If the surgeon uses a caudal approach and enters the vaginal cavity medial to the mesorchium, the ductus is easily located. However, if the approach leads to an entry into the vaginal cavity that is lateral to the mesorchium, the ductus will not be visible.
Image size 2020 x 1366px
An alternative approach to vasectomy is described here. It uses a single cranial midscrotal incision and allows for simple location of the ductus deferens.
Image size: 1897 x 1320px
Surgical Procedure
Bulls are cast with the aid of xylazine and restrained in lateral recumbency. Small ruminants are also tranquillized and restrained in lateral recumbency or in a sitting position. Epidural anesthesia can be used in small ruminants, obviating the need to local anesthesia in the scrotum.
The scrotum is prepared as is appropriate for surgery. Depending on the size of the animal, six to 12 m1 of 2% xylocaine is infiltrated into the area of the spermatic cord. In addition, the cranial scrotal midline and underlying tunica dartos are infiltrated with 2% xylocaine over a distance of 4 to 5 cm from the middle to the upper third of the testes.
A midline skin incision is made and the tunica dartos is divided until the parietal vaginal tunics are encountered. An incision approximately 1 cm long is then made through either the left or right parietal vaginal tunic, and the cranial edge of this incision is grasped with Allis forceps. The incision site easily is lost if it is not grasped immediately! Also, the glistening visceral vaginal tunic (covering the testis) will be visible through this incision, making it easy for one to recognize that one has entered the vaginal cavity.
A second Allis forceps is inserted in a caudal direction into the vaginal cavity and advanced caudally, as far as possible i.e. until the caudal reflection of the vaginal tunic. The ductus deferens is the only tubular structure in this area and can easily be grasped blindly with the Allis forcep. The ductus deferens is then exteriorized slowly through the incision in the parietal vaginal tunic and separated from the mesoductus by sliding artery forceps or even one arm of the Allis forceps itself under the ductus deferens. The ductus is then ligated as far proximally and distally as possible. A large section of the interposing duct is removed to prevent anastomosis of the ends of the ductus. The procedure is repeated on the opposite side of the scrotum through the same midline skin incision used for the first side.
The small incisions through the parietal vaginal tunics need not be sutured, but dead space in the tunica dartos should probably be eliminated. The skin is closed in a routine manner and tetanus antitoxin is administered. Antibiotic therapy is optional.
Note: It is important in some cases to retain the removed sections of the ductus deferens and submit them for histological examination for legal purposes. In such cases, the author has retained a long section from the left (LEFT = LONG) and a shorter section from the right. These are stored for histopathogy in the same bottle of formalin.
To test this surgical method, it was employed by the author on 6 rams, 2 bucks (male goats), and one bull. In those cases, it was found to be simple, rapid, and without postoperative complications.
Image size 1434 x 7687px
Acknowledgement: The author acknowledges the superb artistic talent (and tolerance of mess and formalin!) of Mr Dean Biechler (ISU. Ames Iowa) in creating these images.
Selected references
International federation of association of anatomists
5. Ott, RS. et al. 1979 Effect of presence of the male on Initiation of estrous cycle activity of goats. Theriogenology 13: 183-190
6. Roberts, S.J. 1971 Veterinary Obstetrics and Genital Diseases. Ithaca, NY, Published by the author, p 441
7. Schinkel, P. G. 1953. The effect of the ram on the incidence and occurrence of oestrus in ewes. Aust Vet J 30: 189-195
| Ductus or vas? According to the International federation of association of anatomists (IFAA) acceptable terms for this structure include: Latin: Ductus deferens English: Ductus deferens English synonym: Vas deferens However, the Nomina anatomica veterinaria no longer includes the term vas deferens. Nevertheless, in surgical terminology the term vasectomy is acceptable and widely used. On the contrary, the term ductusdeferensectomy is never used by surgeons and is both cumbersome and even comical. Therefore in deference (!) to the IFAA and colleagues who perform this operation, the term vasectomy is used in this entry. The term ductus deferens is used only when referring to the structure itself. |
Domestic ruminants are vasectomized to enable detection of estrus for routine breeding as well as for artificial insemination. Sometimes, vasectomized ruminants are also used to stimulate the onset and synchrony of estrous cycles, especially n sheep. In wild life sanctuaries, vasectomy is commonly used to prevent unwanted procreation. Indeed, the technique shown here has been be adopted in several non-domestic species, including carnivores.
A common surgical site for vasectomy in ruminants is on the high caudal aspect of the scrotum because the ductus is located at the caudomedial aspect of the testis in those animals. However, a caudal approach can lead to difficulty in locating the ductus. This is explained as follows: In the image below, a cranio-medial view of the right scrotal half of a bull, the testis has been rotated slightly on its dorso-ventral axis, to bring the ductus cranially, exposing it more than otherwise. If the surgeon uses a caudal approach and enters the vaginal cavity medial to the mesorchium, the ductus is easily located. However, if the approach leads to an entry into the vaginal cavity that is lateral to the mesorchium, the ductus will not be visible.
An alternative approach to vasectomy is described here. It uses a single cranial midscrotal incision and allows for simple location of the ductus deferens.
Image size: 1897 x 1320px
Surgical Procedure
Bulls are cast with the aid of xylazine and restrained in lateral recumbency. Small ruminants are also tranquillized and restrained in lateral recumbency or in a sitting position. Epidural anesthesia can be used in small ruminants, obviating the need to local anesthesia in the scrotum.
The scrotum is prepared as is appropriate for surgery. Depending on the size of the animal, six to 12 m1 of 2% xylocaine is infiltrated into the area of the spermatic cord. In addition, the cranial scrotal midline and underlying tunica dartos are infiltrated with 2% xylocaine over a distance of 4 to 5 cm from the middle to the upper third of the testes.
A midline skin incision is made and the tunica dartos is divided until the parietal vaginal tunics are encountered. An incision approximately 1 cm long is then made through either the left or right parietal vaginal tunic, and the cranial edge of this incision is grasped with Allis forceps. The incision site easily is lost if it is not grasped immediately! Also, the glistening visceral vaginal tunic (covering the testis) will be visible through this incision, making it easy for one to recognize that one has entered the vaginal cavity.
A second Allis forceps is inserted in a caudal direction into the vaginal cavity and advanced caudally, as far as possible i.e. until the caudal reflection of the vaginal tunic. The ductus deferens is the only tubular structure in this area and can easily be grasped blindly with the Allis forcep. The ductus deferens is then exteriorized slowly through the incision in the parietal vaginal tunic and separated from the mesoductus by sliding artery forceps or even one arm of the Allis forceps itself under the ductus deferens. The ductus is then ligated as far proximally and distally as possible. A large section of the interposing duct is removed to prevent anastomosis of the ends of the ductus. The procedure is repeated on the opposite side of the scrotum through the same midline skin incision used for the first side.
The small incisions through the parietal vaginal tunics need not be sutured, but dead space in the tunica dartos should probably be eliminated. The skin is closed in a routine manner and tetanus antitoxin is administered. Antibiotic therapy is optional.
Note: It is important in some cases to retain the removed sections of the ductus deferens and submit them for histological examination for legal purposes. In such cases, the author has retained a long section from the left (LEFT = LONG) and a shorter section from the right. These are stored for histopathogy in the same bottle of formalin.
To test this surgical method, it was employed by the author on 6 rams, 2 bucks (male goats), and one bull. In those cases, it was found to be simple, rapid, and without postoperative complications.
| A far as the author is aware, the ductus deferens always runs caudo-medially in the scrotum of land mammals. Accordingly, feedback on this technique after others have used it in various species (including wild felids) suggests that it may be adapted for use on almost any male animal. One must however remember the that the "cranial" aspect of the testes as described in this technique is not always cranial! In equids and canids for example, what is cranial in ruminants, is actually ventral. In felids and porcine species where the cauda epididymus is more dorsal than the caput epidiymus, the "cranial" aspect of the scrotum will face caudo-ventrally. See below: As for all LORI images, click on the image to see a larger version.  |
Image size 1434 x 7687px
Acknowledgement: The author acknowledges the superb artistic talent (and tolerance of mess and formalin!) of Mr Dean Biechler (ISU. Ames Iowa) in creating these images.
Selected references
International federation of association of anatomists
1. Badinand, F. 1973 Techni ue de la vasectomie dans differentes eSpeces animales. Reel Me Vet 149: 315-327
2. Copland, M.D. Vasectomy, in Morrow DA (ed). 1980 Current Therapy in Theriogenology. Philadelphia, WB Saunders Co, pp 962-964
4. Oehme, F. W. and Prier, J.E. 1974 Textbook of Large Animal Surgery. Baltimore, Md, Williams and Wilkins Co, p 489
6. Roberts, S.J. 1971 Veterinary Obstetrics and Genital Diseases. Ithaca, NY, Published by the author, p 441
7. Schinkel, P. G. 1953. The effect of the ram on the incidence and occurrence of oestrus in ewes. Aust Vet J 30: 189-195
8. Trengrove, R.B. 1966 Vasectomy of rams under field conditions. J S Afr Vet Assoc 36:119-121,
