Abstract

The African (Loxodonta africana) and Asian (Elephas maximus) elephants are the largest living land mammals and both are in danger of extinction. Due to massive efforts from a number of zoo professionals, both natural breeding and artificial insemination programs have produced an unprecedented number of captive offspring in recent years. Transrectal ultrasound has been utilized to evaluate the reproductive tract and confirm pregnancy in both species.^1-4 As the fetus grows, transrectal imaging becomes impossible due to the depth at which the fetus develops.

In April of 2000, a combination of observed matings, hormonal monitoring and transrectal ultrasound imaging confirmed pregnancy in a 32-yr-old female African elephant naturally mated with a 22-yr-old African bull elephant. As the fetus developed, transrectal imaging became useless. Based on previous successes at the Kansas City Zoo (KCZ) with transabdominal gestational monitoring of an Eastern black rhinoceros (Diceros bicornis michaeli), Bornean orangutan (Pongo pygmaeus pygmaeus)⁵ and African lion (Panthera leo), we devised a technique for monitoring fetal viability in the African elephant and extended this to Asian elephants (Dennis Schmitt, personal communication 2000).

We utilized a real-time B mode ultrasound scanning system (Ausonics Impact VFI, Universal Medical Systems, Bedford Hills, Pennsylvania, USA) with a 2.5 MHz variable sector probe. The elephant was conditioned to enter a standard elephant restraint device. Once restrained, the abdomen was cleaned and scrubbed with warm water. An initial skin imprint was made for future reference points. Standard ultrasonic gel was used to fill skin fold crevices and provide better imaging of the fetus. Most procedures took less than 1 hr to complete.

From November 2000 and through September 2001, we monitored fetal viability approximately weekly through a specific triangular “window” defined by the caudal extent of the rib cage, ventral abdominal wall and the cranial extent of the femoral muscles. Images of the fetal trunk, feet, ear, spinal column, tail, heart, placental membranes, uterus, and amnion were routinely observed and recorded. Fetal movement was easily observed. In addition, fetal movement was documented through tactile sensation of the abdomen. We noted occasional preclusion of images by intestinal content. This was easily differentiated from the fetus by documenting intestinal wall thickness, uniformity of fecal material, and consistent intestinal peristalsis. The uterine wall consistently measured 2.4–2.7cm in thickness, whereas the intestinal wall averaged less than 1 cm in thickness. Similar results have subsequently been achieved with several other African elephants and Asian elephants (Schmitt, personal communication).

Unfortunately, a fetal malposition (anterior presentation, head to the left) prevented a successful delivery, and the calf is retained in the uterus as of this writing. We continue to monitor the reproductive tract through transabdominal and transrectal ultrasound to ascertain fetal mummification and cervical status. The cow is maintained on rotational antibiotics, and low dose flunixin meglumine (Banamine, Schering-Plough Animal Health, Union, New Jersey, USA) to aid in preventing absorption of endotoxins. Weekly complete blood counts and select serum biochemistries are obtained to monitor systemic effects and physiologic response to mummification/necrosis of the calf. Weekly fecal cultures are also evaluated and adjustments made in antibiotic usage depending upon aerobic bacterial sensitivities.

In retrospect, transabdominal ultrasound performed 1 wk and at 24 hr prior to the onset of labor probably demonstrated fetal death. Noticeable decreases in fetal movement were observed but attributed to the large size and space requirement of the fetus, precluding much movement.

This technique describes the use of transabdominal ultrasound monitoring of fetal viability in an African elephant. No specialized ultrasound equipment is needed, and the technique is less invasive than conventional methods. Additional techniques for evaluating internal organs of elephants through ultrasound are being developed.

The combination of hormonal monitoring, artificial insemination, transrectal and transabdominal ultrasound imaging provides valuable insights into the reproductive processes of elephants.

Acknowledgments

The author gratefully acknowledges the pioneering work of Dr. Dennis Schmitt, Dr. Thomas Hildebrandt, Dr. Robert Hermes, Dr. Naida Loskatoff, Dr. Murray Fowler, Dr. Michael J. Schmidt, Dr. William J. Boever, Dr. Susan Mikota, Debbie Olson, John Lenhardt, Scott and Heidi Riddle. In addition the tireless efforts of the KCZ elephant staff; Conrad Schmitt, Linda Wachsberg, Jody Watkins, Theresa Schwang, Scott McCall, Tim Wild, Becky Johnson, Steve Venne, Stephanie Sharp, Michael Labanik, Kelly Rogers, Amy Jirsa, Dr. Dawn Faircloth, Lani Castaner, RVT, Jennifer Pollard, RVT and all of the zoo professionals striving to save these species from extinction.

Literature Cited

1.  Hermes R, D Olson, F Goritz, JL Brown, DL Schmitt, D Hagan, JS Peterson, G Fritsch, TB Hildebrandt. 2000. Ultrasonography of the estrous cycle in female African elephants (Loxodonta africana). Zoo Biol. 19:369–382.

2.  Hildebrandt TB, F Goritz, NC Pratt, JL Brown, RJ Montali, DL Schmitt, G Fritsch, R Hermes 2000. Ultrasonography of the urogenital tract in elephants (Loxodonta africana and Elephas maximus): an important tool for assessing female reproductive function. Zoo Biol. 19:321–332.

3.  Hildebrandt TB, F Goritz, NC Pratt, DL Schmitt, S Quandt, J Raath, RR Hofmann. 1998. Reproductive assessment of male elephants (Loxodonta africana and Elephas maximus) by ultrasonography. J. Zoo Wildl. Med. 29(2): 114–128.

4.  Hildebrandt TB, F Goritz, NC Pratt, DL Schmitt, J Lehnhardt, R Hermes, S Quandt, J Raath, G West, RJ Montali. 1997. Assessment of health and reproductive status in African and Asian elephants by transrectal ultrasonography. Proc. Am. Assoc. Zoo Vet. Pp. 207–211.

5.  Suedmeyer WK, D Stewart 1999. Pregestational, gestational, and postgestational serum progesterone, β Human chorionic gonadotropin, and estradiol levels in a Bornean orangutan (Pongo pygmaeus pygmaeus). Proc Am. Assoc. Zoo Vet. Pp. 239–242.