To control the number of baboons (Papio hamadryas) in Safari Beekse Bergen, Hilvarenbeek, The Netherlands, 26 out of 35 female baboons were sterilized by laparoscopic tubal coagulation. One hybrid gibbon (Hylobates lar x Hylobates pileatus) was sterilized the same way to prevent the development of a hybrid line of gibbons.
In zoos, successful reproduction in a significant number of exotic species is no longer a problem. Veterinarians first praised for their success in reproduction, are confronted with the problems associated with birth control. Implants, PZP vaccines and long-acting progestogen injections are used as alternatives to more invasive surgical methods as castration or sterilization.
In Safari Beekse Bergen, Hilvarenbeek, The Netherlands, surgical methods of contraception such as vasectomy of a male lion (Panthera leo), ovariohysterectomy of lionesses and an African wild dog (Lycaon pictus) and castration of a hybrid male gibbon (Hylobates lar x Hylobates concolor), were performed previously. Although surgical methods of birth control are invasive and permanent, they do not have the potential side effects of contraceptive drugs.
In order to control the population of the 70 baboons (Papio hamadryas), there was an urgent need for some method of birth control. These baboons, living together with 5 African elephants (Loxodonta africana africana), had always been a very stable social group, consisting of 35 males and 35 females. To prevent overpopulation, a solution of laparoscopic sterilization of the females was chosen. This method of sterilization was performed by laparoscopic tubal coagulation as performed in humans. The intention was that sexual behavior would still occur, the social ranking within the group would not change, nursing behavior would not be lost and the total number of baboons would not increase. Maintaining a stable social group would hopefully be achieved with this method.
Former DNA work on the gibbons of the park showed one female to be a hybrid (Hylobates lar x Hylobates pileatus). To prevent the development of a hybrid line of gibbons, birth control was necessary. Instead of doing an ovariohysterectomy, sterilization was preferred, so sexual behavior would still be present.
The baboons and the gibbon were first sedated with ketamine (Dopharma, Raamsdonkveer, The Netherlands, 100 mg/ml), 10–15 mg/kg b.w. using Telinject blowdarts through a Telinject blowpipe. They were then checked by ultrasound (Sonorex RK 100, Bandelin, Berlin, Germany; Animed, Barneveld, The Netherlands) for pregnancy, because in late gestation the procedure is difficult to perform, due to the enlargement of the uterus. In total, 26 out of 35 female baboons were brought, one after the other, to an improvised surgical area to be sterilized. Intubation was necessary, because despite using atropine HCl (AUV, Cuyk, The Netherlands) 0.1–0.2 mg/kg b.w., salivation was a problem.
After intubation, maintenance of anesthesia with oxygen and halothane was uneventful. Pulse oximetry (Nellcor N 180, 's-Hertogenbosch, The Netherlands) and capnography (Lameris, Utrecht, The Netherlands) were used to monitor anesthesia.
The monkeys were put in dorsal recumbency, clipped, cleaned and draped. A 1-cm incision was made in the right lateral abdominal wall for a disposable surgical trocar (Endopath, Ethicon, Summerville, NJ, USA) through which the coagulator could be inserted into the abdomen. A second incision was made in the umbilical area for the laparoscope (Storz, Tilburg, The Netherlands) with mini-camera. A television monitor at the end of the operation table was used to follow the intra-abdominal procedure.
In humans, the abdomen is filled with carbon dioxide to obtain better visualization. This frequently demands that machine-controlled respiration be performed. To prevent this, a Laparofan was used to create space in the abdomen to work in. The Laparofan was also used as a trocar through which the laparoscope is brought into the abdomen.
The oviducts were coagulated by means of a unipolar coagulator, which also functions as a forceps. One or two stitches (Vicryl 3-0, Instruvet, Amerongen, The Netherlands) were used to suture the incision in the abdomen, followed by an uninterrupted subcutaneous suture. All the monkeys were microchipped during the procedure (Trofan, The Netherlands), and received a long-acting antibiotic ampicillin (Albipen LA, Mycofarm, The Netherlands) 40 mg/kg b.w. and 0.2 mg/kg b.w. Dectomax (Pfizer, Capelle a/d IJssel, The Netherlands) for deworming.
All monkeys survived and no behavioral problems were observed after the procedure. Since there were no stitches to be removed, no complications or infections were observed. One year later the group is stable, there is no fighting and there are no changes in the social ranking.
The goal of not interfering with the social behavior of this large group of baboons was achieved with laparoscopic sterilization. Sexual behavior was assumed to be normal and nursing behavior was not lost.
The Laparofan proved to be very helpful in this procedure. The avoidance of inflating the abdomen with carbon dioxide is a practical advantage. Respiratory problems due to anterior pressure of the diaphragm are avoided this way.
Laparoscopic sterilization is a very efficient contraception technique taking 5–10 min to perform. The alternative exploratory laparotomy would be a longer surgical procedure and potentially have more postoperative complications. Recovery time after laparoscopy also was observed to be quicker.
In humans, clips or small rings are often used for transfixing tissue; however, because baboons and gibbons have thinner oviducts these were not used. The thinner oviducts of baboons and gibbons are difficult to grasp with the larger bipolar coagulator, so a unipolar coagulator was used in these monkeys.
A definitive form of contraception like surgical sterilization is not a problem as long as there are enough females in the group that remain fertile to stabilize the number of animals in the group. In fact, the procedure might be necessary again in the future, since nine adult females are still fertile and five female infants will become fertile in the future.
The authors wish to thank individuals of St. Elizabeth Ziekenhuis: Mr. Van Beurden, fa Storz; Mr. Van Dijk, TD Medical; Mrs. Omtzigt, gynaecologist; Mrs. Wessels, surgical technician; Mr. Schraffordt Koops, assistant gynaecologist; Mr. Lugtigheid, DVM; Mrs. Van Drunen, vet. technician; Mrs. Heeren, vet. technician; and the zookeepers of Safari Beekse Bergen.