Abstract
Few studies have described arterial blood gas values in black rhinoceros1 (Diceros bicornis) and white rhinoceros (Ceratotherium simum),2-5 and only one involved free-ranging animals3. 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 4 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 IV 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 minutes. Thirty-nine samples were taken from auricular arteries 6–76 minutes after darting and processed in the field using an i-STAT Portable Clinical Analyzer (Abbott Scandinavia AB, Solna, Sweden). The samples were analyzed for pH, PaCO2, PaO2, base excess, HCO3-, SaO2, and lactate. Supplemental oxygen (10 L/minute) was provided through a nasal tube to one black and one white rhinoceros.
Table 1. Age, sex, and range of drug doses used in two species of free-ranging rhinoceros
|
Species
|
Black rhinoceros
|
White rhinoceros
|
|
Age
|
Adult
|
Subadult
|
Calf
|
Subadult
|
Calf
|
|
Number of animals and sex
|
7Ma, 2Fb
|
1M, 1F
|
1M
|
2M, 1F
|
1M
|
|
Etorphinec (mg) nd=14
|
3.2–4.3
|
2.8
|
1.5
|
2.8–3.5
|
2.0
|
|
A3080e (mg) n=2
|
3.0
|
2.0
|
–
|
–
|
–
|
|
Detomidinef (mg) n=8
|
3.5–4.5
|
2.5
|
1.0
|
3.5–4.5
|
–
|
|
Xylazineg (mg) n=8
|
20–45
|
20
|
–
|
–
|
22
|
|
Azaperoneh (mg) n=16
|
70–90
|
40–50
|
20
|
50–60
|
35
|
|
Hyaluronidasei (IU) n=16
|
2000–8000
|
4000–5000
|
4000
|
4000
|
1250
|
|
Nalorphinej (mg) n=16
|
1.0–8.0
|
2.0–2.5
|
3.0
|
20–26
|
6.0
|
aMale
bFemale
cM99®, 9.8 mg/ml, Novartis South Africa (Pty) Ltd., Spartan, Kempton Park, South Africa
dNumber of immobilization procedures the drug was used in
eA3080, 10 mg/ml, Wildlife Pharmaceuticals, Inc., Fort Collins, Colorado, USA
fDomosedan®, 10 mg/ml, Novartis South Africa (Pty) Ltd., Spartan, Kempton Park, South Africa
gRompun®, 100 mg/ml, Bayer, Leverkusen, Germany
hStresnil®, 40 mg/ml, Janssen Animal Health, South Africa
iHyaluronidase, lyophilized powder, 5000 IU/vial, Kyron Laboratories (Pty) Ltd., Benrose, South Africa
jNalorphine®, 20 mg/ml, Kyron Laboratories (Pty) Ltd., Benrose, South Africa
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 physiologic 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, Worldwide 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
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