Dr Francois van Niekerk
Humansdorp Veterinary Clinic
01 Place ram in sitting position on table [mules bed/cradle works well, so does a wheelbarrow, deep type, used by builders for concrete].
02 With sheep shears shear/clip wool on abdomen cranial to scrotum [about 10cm] and on cranial aspect of the neck of the scrotum.
03 The surgical area is the cranial aspect of the neck of the scrotum prepare the site for surgery.
04 With lignocaine produce a line block about 6 cm long in the median plane and infiltrate the subcutaneous tissues.
05 Make a single incision about 4 – 5cm long in the median plane over the scrotal groove.
06 Dissect through the subcutaneous tissues [tunica dartos, spermatic fascia and tunica vaginalis (parietal layer)] into the vaginal cavity, until a sterile finger can be inserted into the incision and hooked around the right spermatic cord.
07 Lift the spermatic cord into the incision and identify the ductus deferens by rolling between thumb and finger. It is about matchstick thickness and has a firm cord-like character. Carefully incise the mesorchium [mesoductus deferens] over the duct avoiding the blood vessels associated with the duct and the large adjacent pampiniform plexus. [The mesorchium is a fold of the tunica vaginalis which covers the spermatic cord. The mesoductus deferens is that portion of the mesorchium which suspends the ductus deferens.]
08 Dissect the duct free with scissors, exerting gentle traction.
09 After having achieved maximum exteriorization of the duct, apply gentle traction and clamp the proximal end of the freed duct against the dorsal end of the incision with mosquito forceps. Transect the duct proximally and repeat distally thus removing about 7 – 12cm of duct depending on the size of the ram.
10 Repeat the procedure on the left cord.
11 With a puffer bottle squirt wound powder into the wound
12 Close skin incision with a simple continuous nylon suture [the tunica vaginalis (parietal layer) need not be sutured].
Trengrove [JSAVA 36(1), 1965] described an apparently commonly used method using a caudal approach to the scrotum with the ram lying on its side. However, the advantages of the Herbst technique [so named after well-known sheep practitioner, Dr Ian Herbst of Caledon] are
It is easier and thus quicker to isolate the duct and incise over it in the wound than through the skin. Especially on the ram’s left for a right-handed person and vice versa.
The dirty under-side of the scrotum need not be handled.
A long piece of duct can be removed [7 – 12cm], thus obviating the need for tying off the duct.