Abstract

Elephant population management has become a significant conservation issue in most of Southern Africa. The breeding behaviors of free ranging elephants indicate that several dominant bull elephants are responsible for the majority of breeding within the various matriarchal herds. A vasectomy of these bull elephants would decrease population growth rates but maintain normal social and breeding behaviors. Anatomically, elephants have intra-abdominal testes. Advances in minimally-invasive laparoscopic techniques have allowed this type of surgery to be realistic in very large animals and in field conditions.

Introduction

Elephant population control is one of the most critical conservation issues facing southern Africa. Growth in protected elephant populations in Botswana, Swaziland, and South Africa are causing negative changes to the ecosystem and to the diversity of plants and animals it supports. Without a long-term population management plan, ecosystem destruction is expected to worsen and have potential irreversible consequences.

Historically, wildlife officials have utilized culling and translocation as the primary methods of population control. Currently, translocation is no longer an option because most parks are not able to accommodate additional animals. Large scale culling was discontinued in the 1990s, but has been proposed to restart by wildlife officials in South Africa. Other methods of population control such as immunocontraception have shown some utility in small parks where vaccines can be administered to elephant cows.

Surgical sterilization is a permanent contraceptive technique, and is one of the most common methods of birth control in both animals and humans. For free ranging animals, a vasectomy has the advantage of maintaining normal hormone levels and thus breeding and natural social behaviors are preserved. Elephants that have been vasectomized will continue to go into musth, breed (without being fertile), and maintain their social status among other elephants.

Unlike most terrestrial mammals, elephant testes are intra-abdominal and are located just caudal to the kidneys. Therefore, to access the testes and spermatic cord, the abdomen must be entered.

Advances in medical technology have provided laparoscopic instrumentation, which can be used for this minimally invasive surgery (i.e., laparoscopy). This has many advantages for free ranging animals. A much smaller incision is required with laparoscopy, which then translates to less chance of infection, less postoperative pain and quicker healing times. When working with free ranging animals, this is critical because the animals will not be hospitalized or have the ability to be treated with antibiotics or analgesics after the surgery.

Immobilization

Using a helicopter, specific breeding bulls are identified and darted with a combination of etorphine (M99®, Wildlife Pharmaceuticals Incorporated, Fort Collins, CO, USA) and azaperone (Stresnil®, Wildlife Pharmaceuticals Inc.). After induction, an endotracheal tube is placed in the elephant’s trachea and the elephant’s respirations are assisted using a portable ventilator system. While anesthetized, the elephant’s blood pressure, oxygen saturation, end total carbon dioxide, body temperature, heart rate, respiratory rate, and blood gas analysis are all monitored. Throughout the procedure additional small boluses of intravenous etorphine are administered as required. Intravenous azaperone is also utilized as an anesthetic agent, and to assist in decreasing etorphine induced hypertension. At the completion of surgery, the elephants are reversed with intravenous naltrexone hydrochloride (Trexonil®, Wildlife Pharmaceuticals Inc.) and diprenorphine (M5050®, Wildlife Pharmaceuticals Inc.).

Patient Positioning

A crane truck is utilized to move the elephant to a suitable surgical location and then suspend the animal in an upright standing position throughout the surgery. This position enhances the safety of the anesthesia and allows improved visualization of the testes with the laparoscope.

This modified upright standing position is accomplished using a series of five-ton capacity, padded, rope slings. These are looped around each leg and tusk. At the front legs, the ropes are positioned in the axillary region. In the rear, the ropes are positioned in each inguinal space. The tusk ropes attach at the base of each tusk just at the gingival margin. The end of each loop of rope is joined together and attached at a single point on the crane. The crane can lift or lower the elephant so that each foot rests squarely on the ground. Once the elephant is in a suspended position, wooden splints are attached to the legs and are used to lock each limb in extension. In this way, the elephant’s legs continue to support the majority of its weight and there is minimal pressure on the suspension ropes.

After the elephant has been placed in a standing position, surgical equipment is moved into place. A 14-inch flat screen monitor is placed in a specialized cradle on the elephant’s caudal dorsum for laparoscopic viewing. The flat bed portion of the crane truck is transformed into a field operating room with surgical tables and electrical equipment powered by a portable generator.

Surgical Procedure

The surgical sites on both sides of the elephant are cleaned and scrubbed for surgery. Initially a firm bristled scrub brush is used to clean the skin, followed by a complete surgical scrub with alternating applications of betadine scrub and alcohol. After the surgical scrub, each site is draped sterilely for surgery. The primary incision is approximately 15 cm long and is located just cranial to the tuber coxae. The incision is carried through the body wall, and the fibro-elastic peritoneum is identified. A modified human chest Finnochetto retractor is utilized to separate the sides of the incision and provide visualization of the fibro-elastic peritoneum. Tumor forceps are utilized to firmly grasp the fatty connective tissue that covers the peritoneum and withdraw it through the incision. In general, a 14 × 14 × 14 cm portion of this fatty connective tissue must be resected before the peritoneum can be isolated and incised. A 3.5 cm incision is placed through the peritoneum and a laparoscopic cannula is inserted. The abdomen is insufflated with ambient air using a specifically designed device capable of rapid and regulated air flow. In general, a high intra-abdominal pressure of 1 psi (52 mm Hg) is required to provide operating space and enhance visualization during surgery. An elephant laparoscope, designed by Karl Storz Endoscopy (175 Cremona Dr. Goleta, CA, USA), is inserted through the cannula for visualization of the abdominal viscera. This laparoscope has a 10 mm instrument operating channel and thus minimizes the number of additional instrument ports that need to be placed. The testis is identified just caudal to the kidney, suspended from the dorsum. From the caudal pole of the testis, the epididymus and deferent duct can be visualized traveling in the mesorchium. A secondary instrument portal is created approximately 15–20 cm from the primary incision by making a 2 cm incision through the skin and body wall. A hooked scissor is placed within this cannula and penetration through the peritoneum can be visualized through the laparoscope directly.

A section of the deferent duct approximately 15 cm from the epididymus is identified and grasped via the second portal. A 6–10 cm section of deferent duct is resected using laparoscopic scissors through the operating scope. The transected duct is transferred to a grasping forceps with the operating scope and removed from the abdomen. This tissue is placed in formalin and sent for histopathologic confirmation.

While the laparoscopic surgeons are working, a second set of surgeons make an incision on the contralateral side. Once the vasectomy is complete on side one, the elephant is lifted in its standing position and rotated 180 degrees. The laparoscopic surgeons will now complete the vasectomy on the second side while the other surgical team closes the incision from the completed side. The peritoneum is closed with a simple continuous pattern using an absorbable suture material. The external muscle layers are also closed with a simple continuous suture pattern and absorbable suture material. The skin is then closed with #2 nylon in a modified far-far-near-near (tension relieving) suture pattern. During the procedure the patients receive a long-acting penicillin injection and a single dose of a nonsteroidal anti-inflammatory drug. After the closure is complete, the animal is rinsed with water and lowered from the crane for anesthetic reversal.

Postoperative Monitoring

During the surgery, each animal is fitted with a VHF biotelemetry collar. On-site elephant researchers, along with ranger staff, follow the elephants after their surgery. During the first 2 weeks the animals are viewed every 1–2 days. Digital photographs are taken to document wound healing and any change in body condition. Other behavioral data is collected including activity, appetite, and social interactions. After the initial 2-week monitoring period, observations are done weekly. A full year of digital images and behavioral data is recorded.

Findings

In July 2006, at the Welgevonden Game Reserve, four adult bull elephants had complete laparoscopic vasectomies performed on four consecutive days. Surgical times were approximately 2.5 hours, and total anesthetic times were approximately 3.5 hours. All four animals recovered from anesthesia and were ambulatory within 5 minutes. The incisions on all four animals have healed and no significant complications were noted from the laparoscopic vasectomy procedure. Behavioral observations have documented normal behaviors since the surgery, including maintenance of social status and breeding.

Conclusion

Laparoscopic vasectomy of free ranging bull elephants is a viable surgical option for reproductive sterilization. This management tool is probably not realistic for very large elephant populations (>10,000), but should be considered for small and medium size elephant populations. Further research is currently underway to make this an efficient and practical field technique and to fully understand any negative impact this procedure may have on the individual elephant, the elephant population, or the ecosystem.

This is an international collaborative effort which brings together conservation organizations, universities, government entities, and private industry to address this complex problem. It is our hope that this work may provide a useful management tool which balances ecosystem health and animal welfare concerns.

Acknowledgments

We are indebted to the Karl Storz Company for the design and manufacture of the elephant laparoscopic equipment. We would also like to thank and acknowledge the following individuals for their participation and support of our work through the years: Beth Ament LVT; Nancy Boedeker, DVM; Lidia Castro, LVT; Greg Fleming, DVM, ACZM; Don Neiffer, VMD, ACZM; Mark Penning, BVSc, MSc; PK Robbins, MRCVS; Anne Savage, PhD; Cora Singleton, DVM; Julia Sweet, LVT; Scott Terrell, DVM, ACVP; and Laura Wheeler, LVT. This work would not have been possible without key partnerships with conservation groups in Africa, including CC Africa/Phinda (Kevin Pretorius and Helene Druce), the Makalali Game Reserve (Audrey Delsink and Ross Kettle), and the Welgevonden Game Reserve (David Powrie and Hanno Kilian).