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Conference paper2004

Pulmonary gas exchange and acid-base status in immobilized black rhinoceros (Diceros bicornis) and white rhinoceros (Ceratotherium simum) in Zimbabwe

Fahlman Åsa, Chris Foggin, Nyman Görel


Few studies have described arterial blood gas values in black rhinoceros 1 (Diceros bicornis) and white rhinoceros 2-5 (Ceratotherium simum), and only one involved free-ranging animals 3. The aim of this study was to evaluate pulmonary gas exchange and acid-base status in immobilized black and white rhinoceros. Arterial blood samples were collected from 13 black and four white rhinoceros during 19 immobilization procedures, which included ear notching, snare removal, and translocation. Sixteen free-ranging rhinoceros were darted from a helicopter with a combination of an opioid, an alpha2-agonist, azaperone, and hyaluronidase (Table 1). Once immobilized, nalorphine was given i.v. to improve respiration by partial reversal of the opioid effect. One boma-held black rhinoceros (subadult) was immobilized three times due to a snare injury, using 1.7 mg etorphine and 30-45 mg azaperone. Pulse oximetry derived oxyhemoglobin saturation (SpO2), rectal temperature, heart and respiratory rates were recorded every 10 min. Thirty-nine samples were taken from auricular arteries 6-76 min after darting, and processed in the field using an i-STAT Portable Clinical Analyzer (Abbott Scandinavia AB, Box 509, SE-169 29 Solna, Sweden). The samples were analyzed for pH, PaCO2, PaO2, base excess, HCO3-, SaO2, and lactate. Supplemental oxygen (10 L/min) was provided through a nasal tube to one black and one white rhinoceros. All free-ranging rhinoceros developed acidemia (pH 7.13-7.34), hypercapnia (PaCO2 48-77 mm Hg) and hypoxemia (PaO2 40-79 mm Hg). Least physiological changes were observed in the boma-held black rhinoceros. Metabolic acidosis was present in all free-ranging rhinoceros, and initially high lactic acid levels decreased during the course of immobilization. In 28 out of 35 readings SaO2 were lower than SpO2. Oxygen supplementation markedly improved oxygenation (PaO2 108-194 mm Hg). In conclusion, hypercapnia and hypoxemia, indicative of impaired pulmonary gas exchange, and lactic acidemia were evident in both species of free-ranging rhinoceros with the capture method and drug combinations used in this study. ACKNOWLEDGMENTS Special thanks to the staff at the Wildlife Veterinary Unit, Parks and Wildlife Management Authority, World Wide Fund for Nature (Southern African Regional Program Office) and their Senior Ecologist Raoul du Toit, Bubiana Conservancy, and Malilangwe Trust, for valuable assistance during preparations and field operations in Zimbabwe. Also, many thanks to the helicopter pilot John McTaggart. We wish to acknowledge U.S. Fish and Wildlife Service, the Animal Welfare Association in Växjö, Sweden, and Abbott Scandinavia in Solna, Sweden, for their generous support to this study. LITERATURE CITED 1. Ball, R., D. Murphy, J.H. Olsen, and G. Dumonceux. 2001. Multiple anesthesia in a captive black rhinoceros (Diceros bicornis). Proc. AAZV / AAWV / ARAV / NAZWV Joint Conf. 2001: 176-178. 2. Cornick-Seahorn, J.L., S.K. Mikota, D.O. Schaeffer, G.S. Ranglack, and S.B. Boatright. 1995. Isoflurane anesthesia in a rhinoceros. J. Am. Vet. Med. Assoc. 206: 508-511. 3. Hatting, J., C.M. Knox, and J.P. Raath. 1994. Arterial blood pressure and blood gas composition of white rhinoceroses under etorphine anaesthesia. S. Afr. J. Wildl. Res. 24: 12-14. 4. Heard, D.J., J.H. Olsen, and J. Stover. 1992. Cardiopulmonary changes associated with chemical immobilization and recumbency in a white rhinoceros (Ceratotherium simum). J. Zoo Wildl. Med. 23: 197-200. 5. Walzer, C., F. Gšritz, H. Pucher, R. Hermes, T. Hildebrandt, and F. Scwarzenberger. 2000. Chemical restraint and anesthesia in white rhinoceros (Ceratotherium simum) for reproductive evaluation, semen collection and artificial insemination. Proc. Am. Assoc. Zoo Vet. / Intl. Assoc. Aquat. Anim. Med. 2000: 98-101. Table 1. Age, sex, and range of drug doses used in two species of free-ranging rhinoceros

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Publisher: Charlotte Kirk Baer (Proceedings Editor)


American Association of Zoo Veterinarians, American Association of Wildlife Veterinarians, Wildlife Disease Association Joint Conference