Use of butorphanol during immobilization of free-ranging white rhinoceros (Ceratotherium simum)

Effects of Butorphanol on Respiration in White Rhinoceros (Ceratotherium simum) Immobilized with Etorphine-Azaperone

This article reports on respiratory function in white rhinoceros (Ceratotherium simum) immobilized with etorphine-azaperone and the changes induced by butorphanol administration as part of a multifaceted crossover study that also investigated the effects of etorphine or etorphine-butorphanol treatments. Six male white rhinoceros underwent two immobilizations by using 1) etorphine-azaperone and 2) etorphine-azaperone-butorphanol. Starting 10 min after recumbency, arterial blood gases, limb muscle tremors, expired minute ventilation, and respiratory rate were evaluated at 5-min intervals for 25 min. Alveolar to arterial oxygen gradient, expected respiratory minute volume, oxygen consumption, and carbon dioxide production were calculated. Etorphine-azaperone administration resulted in hypoxemia and hypercapnia, with increases in alveolar to arterial oxygen gradient, oxygen consumption, and carbon dioxide production, and a decrease in expired minute ventilation. Muscle tremors were also observed. Intravenous butorphanol administration in etorphine-azaperone-immobilized white rhinoceros resulted in less hypoxemia and hypercapnia; a decrease in oxygen consumption, carbon dioxide production, and expired minute ventilation; and no change in the alveolar to arterial oxygen gradient and rate of breathing. We show that the immobilization of white rhinoceros with etorphine-azaperone results in hypoxemia and hypercapnia and that the subsequent intravenous administration of butorphanol improves both arterial blood oxygen and carbon dioxide partial pressures.

Development of a novel immobilisation protocol for black-faced impala (Aepyceros melampus ssp. petersi) in Etosha National Park

Black-faced impala (Aepyceros melampus ssp. petersi) are endemic to Namibia where conservation management involves immobilisation and translocation, and mortality with current protocols is common. Critically evaluated field immobilisation protocols are needed to maximise animal safety. This prospective study was done in two phases: the first compared etorphine- and thiafentanil-based combinations, the second evaluated the influence of oxygen in impala receiving the thiafentanil-based combination. Animals (10 per group) received 50 mg ketamine (K) and 10 mg butorphanol (B), with either 2.0 mg etorphine (E) or 2.0 mg thiafentanil (T). A third group of ten impala were anaesthetised using TKB with supplemental nasal oxygen (O) at a rate of 5 L/minute. Behavioural, metabolic and physiological variables were assessed within five minutes of recumbency and at 10, 15, and 20 minutes post-recumbency. Statistical analyses for non-parametric data were performed to compare the treatment groups as well as time points; p ≤ 0.05 considered significant. Following darting, 7/10 EKB animals were standing when approached, compared to 2/20 in the thiafentanil treatment groups. Time to first effect was significantly higher for EKB (155 ± 105.7 seconds) compared to TKBO (61.5 ± 21.4 seconds). Time to sternal after darting was significantly higher with EKB (411.6 ± 174 seconds) compared to TKB (160.5 ± 85.4 seconds) and TKBO (166 ± 77.3 seconds). This study builds on previous work investigating the effects of potent opioids on impala and is the first evaluating their use in a field setting. The thiafentanil combination had a faster onset and resulted in a smoother induction than the etorphine combination. Additionally, oxygenation improved in animals receiving oxygen supplementation.

EFFECT OF CAPTURE AND IMMOBILIZATION ON BOMA ADAPTATION IN FREE-RANGING WHITE RHINOCEROS (CERATOTHERIUM SIMUM) IN KRUGER NATIONAL PARK, SOUTH AFRICA

Ninety-six white rhinoceros (Ceratotherium simum) were captured between February and October 2009-2011 in Kruger National Park, South Africa and placed in boma confinement before translocation. Of these, 19 rhinoceros did not adapt to the bomas and required early release (n=18) or died (n=1). The available immobilization data and physiologic parameters, including blood gas analyses, were compared between adapted and maladapted rhinoceros to determine whether predisposing causes could be identified. There were no statistical differences in age category, sex, or body weight at capture between adaptation cohorts. The recorded immobilization data, physiologic values, blood gas analytes, hematologic, or serum chemistry values were not statistically different between adapted and maladapted rhinoceros at capture, except maladapted rhinoceros had lower median serum aspartate aminotransferase, blood urea nitrogen, and phosphorus values; however, these statistically different values were not clinically important. Therefore, observable demographic or capture-related factors did not appear to predispose white rhinoceros to maladaptation to boma confinement. Further investigations into factors affecting adaptation should be performed to minimize the effect on rhinoceros health and welfare.

Arterial Blood Gases and Cardiorespiratory Parameters in Etorphine-Medetomidine-Midazolam Immobilized Free-Ranging and Game-Farmed Southern White Rhinoceroses (Ceratotherium simum simum) Undergoing Electro-Ejaculation

With the rapid loss of individuals in the wild, semen cryopreservation has gained importance to safeguard the genetic diversity of white rhinoceroses (Ceratotherium simum). For semen collection via electro-ejaculation, immobilization of free-ranging individuals requires the potent opioid etorphine, which is routinely combined with azaperone, but causes hypoxemia, hypercarbia, acidemia, muscle rigidity, tachycardia, and systemic hypertension. In this study, the suitability of two alternative immobilization protocols including etorphine, medetomidine, and midazolam at different doses (high vs. low etorphine) was evaluated in adult white rhinoceros bulls in two different management systems (free-ranging vs. game-farmed) and undergoing electro-ejaculation. Fourteen free-ranging (Group 1) and 28 game-farmed rhinoceroses (Group 2) were immobilized with ≈2.5 μg/kg etorphine (high dose), ≈2.5 μg/kg medetomidine, ≈25 μg/kg midazolam and 1,500–1,700 IU hyaluronidase and received ≈2.5 μg/kg of butorphanol intravenously at first handling. Twenty game-farmed animals (Group 3) received ≈1 μg/kg etorphine (low dose), ≈5 μg/kg medetomidine, ≈25 μg/kg midazolam and 1,700 IU hyaluronidase. Respiratory rate, heart rate and peripheral hemoglobin oxygen saturation (SpO₂) were measured at 5-min intervals; non-invasive oscillometric blood pressures and arterial blood gases at first handling and before reversal of the immobilization; serum clinical chemistry analytes and hematocrit at first handling. Generalized mixed models (fixed factors: group, time, recumbency; random factor: individual rhinoceros) were applied to compare longitudinal changes between free-ranging and game-farmed rhinoceroses immobilized with the higher etorphine dose (Groups 1 and 2), and between the two protocols tested in the game-farmed rhinoceroses (Groups 2 and 3). All animals were successfully immobilized, presented with normal lactate concentrations (<5 mmol/L), experienced no muscle tremors and recovered uneventfully. Hypoxemia and hypertension persisted throughout the immobilization in all groups. Acidemia and hypercarbia were absent in Group 1, but present in the game-farmed animals. The lower etorphine dose in Group 3 resulted in significantly longer induction times, however, tachycardia was not observed. SpO₂ was higher for sternal vs. lateral recumbency. Semen-rich fractions were recovered following electro-stimulation in 46 out of the 62 animals. Our findings suggest that etorphine-medetomidine-midazolam provides effective immobilization with fewer side effects compared to previous reports in white rhinoceroses and is suitable for successful electro-ejaculation.

Cardiopulmonary Parameters and Arterial Blood Gases During Etorphine-Medetomidine-Midazolam Immobilization in Free-Ranging Black Rhinoceroses (Diceros bicornis) Undergoing Electro-Ejaculation-A Preliminary Study

Conservation management interventions for the critically endangered black rhinoceros (Diceros bicornis) require immobilization, which offer opportunities for semen collection and cryopreservation to establish genetic reservoirs. In free-ranging rhinoceroses, a combination of the potent opioid etorphine and the tranquilizer azaperone is routinely used for chemical immobilization but is associated with muscle rigidity and severe cardiopulmonary changes. Additionally, azaperone inhibits semen emission. Seven free-ranging, male, sexually mature black rhinoceroses were immobilized with an alternative protocol consisting of 4.5 mg etorphine, 5 mg medetomidine, 50 mg midazolam and 2,500 IU hyaluronidase delivered remotely by darting from a helicopter. During the immobilization, electro-ejaculation was performed with a portable electro-ejaculator, and a species-specific rectal probe. Animals were observed for muscle tremors. Longitudinal changes in respiratory rate, heart rate and peripheral oxyhemoglobin saturation, measured at 5 min intervals, were assessed using a general mixed model. Non-invasive oscillometric blood pressure and arterial blood gas variables were measured at first handling and before reversal and compared using the Wilcoxon rank sum test. All animals were successfully immobilized, showed no muscle tremors, presented with normal heart rates and lactate concentration (<5 mmol/L), recovered uneventfully, but experienced acidemia, hypoxemia and hypercapnia. Induction time and total time in recumbency were 4.2 ± 0.41 and 38.4 ± 6.9 min, respectively. Electro-stimulation commenced after 11.7 ± 3.98 min and completed after 24.3 ± 6.65 min. Semen-rich fractions were successfully collected from six animals. Our observations indicate that etorphine-medetomidine-midazolam provides a promising immobilization protocol for free-ranging black rhinoceroses, that allows for successful electro-ejaculation.

Effect of Azaperone on Induction Times in Etorphine-Immobilized White Rhinoceros (Ceratotherium simum)

We describe induction time in six white rhinoceros (Ceratotherium simum) when they received etorphine intramuscularly (IM) or etorphine plus azaperone IM. The median induction time was reduced from 8.9 min for etorphine alone to 6.25 min with azaperone; however, there was no difference in immobilization quality between treatments.

THE PULMONARY AND METABOLIC EFFECTS OF SUSPENSION BY THE FEET COMPARED WITH LATERAL RECUMBENCY IN IMMOBILIZED BLACK RHINOCEROSES (DICEROS BICORNIS) CAPTURED BY AERIAL DARTING

Aerial translocation of captured black rhinoceroses (Diceros bicornis) has been accomplished by suspending them by their feet. We expected this posture would compromise respiratory gas exchange more than would lateral recumbency. Because white rhinoceroses (Ceratotherium simum) immobilized with etorphine alone are hypermetabolic, with a high rate of carbon dioxide production (VCO2), we expected immobilized black rhinoceroses would also have a high VCO2. Twelve (nine male, three female; median age 8 yr old [range: 4-25]; median weight 1,137 kg [range: 804-1,234] body weight) wild black rhinoceroses were immobilized by aerial darting with etorphine and azaperone. The animals were in lateral recumbency or suspended by their feet from a crane for approximately 10 min before data were collected. Each rhinoceros received both treatments sequentially, in random order. Six were in lateral recumbency first and six were suspended first. All animals were substantially hypoxemic and hypercapnic in both postures. When suspended by the feet, mean arterial oxygen pressure (PaO2) was 42 mm Hg, 4 mm Hg greater than in lateral recumbency (P=0.030), and arterial carbon dioxide pressure (PaCO2) was 52 mm Hg, 3 mm Hg less than in lateral recumbency (P=0.016). Tidal volume and minute ventilation were similar between postures. The mean VCO2 was 2 mL/kg/min in both postures and was similar to, or marginally greater than, VCO2 predicted allometrically. Suspension by the feet for 10 min did not impair pulmonary function more than did lateral recumbency and apparently augmented gas exchange to a small degree relative to lateral recumbency. The biological importance in these animals of numerically small increments in PaO2 and decrements in PaCO2 with suspension by the feet is unknown. Black rhinoceroses immobilized with etorphine and azaperone were not as hypermetabolic as were white rhinoceroses immobilized with etorphine.

Midazolam Alters Acid-Base Status Less than Azaperone during the Capture and Transport of Southern White Rhinoceroses (Ceratotherium simum simum)

Acidemia represents a major life-threatening factor during rhinoceros capture. The acid-base status during rhinoceros transport is unknown. The purpose of this study was to describe changes in acid-base status during rhinoceros capture and transport and compare these changes between rhinoceroses sedated with azaperone or midazolam. Twenty-three wild white rhinoceros bulls were road-transported 280 km for reasons unrelated to this study. Rhinoceroses were captured with etorphine-azaperone (Group A) or etorphine-midazolam (Group M). During transport, azaperone (Group A) or midazolam (Group M) was re-administered every 2 h and venous blood collected. Changes in blood pH and associated variables were compared over time and between groups using a general linear mixed model. Rhinoceroses of both groups experienced a respiratory and metabolic acidosis during capture (pH 7.109 ± 0.099 and 7.196 ± 0.111 for Group A and Group M, respectively) that was quickly compensated for by the start of transport (pH 7.441 ± 0.035 and 7.430 ± 0.057) and remained stable throughout the journey. Rhinoceroses from Group M showed a smaller decrease in pH and associated variables at capture than rhinoceroses from Group A (p = 0.012). The use of midazolam instead of azaperone could therefore improve the success of rhinoceros capture and thus, contribute to the outcome of important conservation translocations.

Odd haemoglobins in odd-toed ungulates: Impact of selected haemoglobin characteristics of the white rhinoceros (Ceratotherium simum) on the monitoring of the arterial oxygen saturation of haemoglobin

BACKGROUND

Due to the current poaching crisis in Africa, increasing numbers of white rhinoceroses (Ceratotherium simum) require opioid immobilisation for medical interventions or management procedures. Alarmingly, the results of both blood gas analysis and pulse oximetry regularly indicate severe hypoxaemia. Yet, the recovery of the animals is uneventful. Thus, neither of the techniques seems to represent the real oxygenation level. We hypothesized that unusual haemoglobin characteristics of this species interfere with the techniques developed and calibrated for the use in human patients.

METHODS

Haemoglobin was isolated from blood samples of four adult, white rhinoceroses. Oxygen dissociation curves at pH 7.2 and 7.4 (37°C) were determined based on the absorbance change of haemoglobin in the Soret-region (around 420 nm). Absorbance spectra of oxy- and deoxyhaemoglobin extending into the infrared region were measured.

RESULTS

Oxygen dissociation curves of rhinoceros haemoglobin showed the typical high oxygen affinity (p50 of 2.75 ± 0.07 and 2.00 ± 0.04 kPa for pH 7.2 and 7.4, respectively) under near-physiological conditions with respect to pH, temperature and DPG. The infrared absorbance spectra of oxy- and deoxyhaemoglobin showed only marginal deviations from standard human spectra, possibly due to the presence of a few percent of methaemoglobin in vitro.

CONCLUSIONS

Our data enables the development of a rhinoceros-specific blood gas analysis algorithm, which allows for species-specific calculation of SaO2 levels in anaesthetized animals. The inconspicuous absorbance spectra do not contribute to the systematic underestimation of SpO2 by pulse-oximetry.

Etorphine-Ketamine Constant Rate Infusion for Maintenance of Anaesthesia in a Compromised White Rhinoceros (Ceratotherium simum)

A subadult white rhinoceros bull presented for oesophageal endoscopic evaluation and foreign body removal under general anaesthesia. The animal had a history of nasal and oral regurgitation of water and ingesta with weight-loss for 6 days prior to the procedure and had been diagnosed with oesophageal obstruction caused by a bailing wire. Anaesthesia was induced with intramuscular etorphine and azaperone delivered remotely by dart, followed by an intravenous bolus of ketamine. The trachea was intubated, and anaesthesia was maintained with an etorphine-ketamine constant rate infusion (CRI). The rhinoceros did not respond predictably to induction of anaesthesia and developed life-threatening systemic hypotension throughout the 90-minute procedure. A mega-vertebrate demand ventilator was successfully used to provide intermittent positive pressure ventilation when the rhinoceros developed apnoea. This case report describes the maintenance of anaesthesia of a white rhinoceros using an etorphine-ketamine CRI and the causes and management of hypotension and respiratory impairment observed in this patient.

Use of butorphanol and diprenorphine to counter respiratory impairment in the immobilised white rhinoceros (Ceratotherium simum)

Opioid-induced immobilisation results in severe respiratory impairment in the white rhinoceros. It has therefore been attempted in the field to reverse this impairment with the use of opioid agonist-antagonists, such as nalorphine, nalbuphine, butorphanol and diprenorphine; however, the efficacy of some of these treatments has yet to be determined. The efficacy of butorphanol, either alone or in combination with diprenorphine both with and without oxygen insufflation, in alleviating opioid-induced respiratory impairment was evaluated. The study was performed in two parts: a boma trial and a field trial. Rhinoceroses were immobilised specifically for the study, according to a strict protocol to minimise confounding variables. A two-way analysis of variance was used to compare the physiological responses of the rhinoceroses to the different treatments and their effects over time. The intravenous administration of butorphanol (at 3.3 mg per mg etorphine) plus diprenorphine (at 0.4 mg per mg etorphine) did not offer any advantage over butorphanol (at 15 mg per mg etorphine) alone with regard to improving P_aO₂, P_aCO₂ and respiratory rates in etorphine-immobilised white rhinoceroses. Both butorphanol + diprenorphine + oxygen and butorphanol + oxygen, at the doses used, significantly improved the etorphine-induced hypoxaemia in both boma- and field-immobilised white rhinoceroses. Clinically acceptable oxygenation in field-immobilised white rhinoceroses can be achieved by using either treatment regimen, provided that it is combined with oxygen insufflation.

Assessment of a portable lactate meter for field use in the white rhinoceros (<i>Ceratotherium simum</i>)

Blood lactate is a predictor of mortality in critically ill humans and animals. Handheld lactate meters have the potential to be used in the field to evaluate the condition of severely injured rhinoceroses but have not been compared with laboratory-based methods. Agreement between a handheld lactate meter and a laboratory method was assessed, as was the stability of rhino blood lactate in the anticoagulant sodium fluoride/potassium oxalate (fluoride/oxalate). Blood samples were obtained from 53 white rhinos that had been immobilised for management reasons. Lactate was measured by means of a handheld meter using whole blood in heparin (WBHEP), whole blood in fluoride/oxalate (WBFO) and fluoride/oxalate plasma (PFO). Results were recorded in both blood (BL) and plasma (PL) modes and compared to an established laboratory method for measuring plasma lactate. To assess the stability of lactate over time, blood lactate in fluoride/oxalate was measured on the handheld meter at intervals for up to 91 h. Agreement was best using WBFO in PL mode, with small bias (−0.16), tight 95% limits of agreement (LOA) (−1.46, 1.14) and a Pc (95% CI) of 0.97 (0.92, 0.99). The agreement was improved for all sample types when using the PL mode compared to the blood lactate (BL) mode. Blood lactate was stable in fluoride/oxalate for 91 h, with a mean change from baseline of 0.15 (−0.178, 0.478) mmol/L (mean, 95% CI). The handheld meter was found to be suitable for field use in white rhinos but provided more reliable results with the device in PL mode. Furthermore, rhino blood lactate was found to be stable in fluoride/oxalate for as long as 3 days.

Method comparison and generation of plasma biochemistry RIs for the White rhinoceros on a point-of-care and wet chemistry analyzer

BACKGROUND

Plasma biochemistry analysis may aid the management of White rhinoceros with poaching or other injuries. Analyzer- and species-specific RIs are necessary to evaluate health status and identify abnormalities.

OBJECTIVES

The purpose of the study was to perform a comparison study between the IDEXX VetTest and Roche Cobas Integra 400 Plus, and to generate analyzer-specific RIs for White rhinoceros according to published guidelines.

METHODS

Comparison was carried out using White rhinoceros plasma samples from healthy and diseased animals. Reference intervals for albumin, ALT, AST, CK, creatinine, GGT, globulins, glucose, phosphorus, total proteins, and urea were determined from a sample group of chemically immobilized healthy adult White rhinoceros from the Kruger National Park, South Africa.

RESULTS

There was a significant analytic bias for all analytes between the 2 analyzers. Results for glucose and total protein were clinically equivalent based on total allowable error limits. Reference intervals were generated from 51 individuals (26 male, 25 female) for all analytes except ALT on the VetTest.

DISCUSSION

The type, direction, and magnitude of bias between the VetTest and Cobas appeared to be species- and analyzer-specific, when compared to other studies. These measures of bias may be used for comparability testing. Reference intervals for total proteins (VetTest 77-108 g/L, Cobas 77-110 g/L) and globulins (VetTest 47-79 g/L, Cobas 51-87 g/L) were high compared to other uneven-toed ungulates.

CONCLUSION

Plasma samples from White rhinoceros can be evaluated on both the VetTest and Cobas. Results from this study will aid conservation efforts directed toward this species.

Postinduction butorphanol administration alters oxygen consumption to improve blood gases in etorphine-immobilized white rhinoceros

OBJECTIVE

To investigate the effects of postinduction butorphanol administration in etorphine-immobilized white rhinoceros on respiration and blood gases.

STUDY DESIGN

Randomized crossover study.

ANIMALS

A group of six sub-adult male white rhinoceros.

METHODS

Etorphine, or etorphine followed by butorphanol 12 minutes after recumbency, was administered intramuscularly [2.5 mg etorphine, 25 mg butorphanol (1000-1250 kg), or 3.0 mg etorphine, 30 mg butorphanol (1250-1500 kg)]. Sampling started at 10 minutes after initial recumbency, and was repeated at 5 minute intervals for 25 minutes. Arterial blood gases, limb muscle tremors, expired minute ventilation and respiratory frequency were measured at each sampling point. Calculated values included alveolar-arterial oxygen gradient [ [Formula: see text] ], expected respiratory minute volume (V˙e), tidal volume (Vt), oxygen consumption ( [Formula: see text] ) and carbon dioxide production ( [Formula: see text] ).

RESULTS

Etorphine administration resulted in an initial median (range) hypoxaemia [arterial partial pressure of oxygen 25.0 (23.0-28.0) mmHg], hypercapnia [arterial partial pressure of carbon dioxide 76.2 (67.2-81.2) mmHg], increased [Formula: see text] [41.7 (36.6-45.1) mmHg, [Formula: see text] [11.1 (10.0-12.0) L minute^-1] and muscle tremors. Butorphanol administration was followed by rapid, although moderate, improvements in arterial partial pressure of oxygen [48.5 (42.0-51.0) mmHg] and arterial partial pressure of carbon dioxide [62.8 (57.9-75.2) mmHg]. In rhinoceros administered butorphanol, [Formula: see text] [4.4 (3.6-5.1) L minute^-1] and [Formula: see text] [4.2 (3.8-4.4) L minute^-1] were lower than in those not administered butorphanol. Increased arterial oxygen tension was associated with lower oxygen consumption (p=0.002) which was positively associated with lower muscle tremor scores (p<0.0001).

CONCLUSIONS AND CLINICAL RELEVANCE

Hypoxaemia and hypercapnia in etorphine-immobilized rhinoceros resulted from an increased [ [Formula: see text] ] and increased [Formula: see text] and [Formula: see text] associated with muscle tremors. Rather than being associated with changes in V˙e, it appears that improved blood gases following butorphanol administration were a consequence of decreased [Formula: see text] associated with reduced muscle tremoring.

Tremors in white rhinoceroses (<i>Ceratotherium simum</i>) during etorphine-azaperone immobilisation

Little is known about the mechanisms causing tremors during immobilisation of rhinoceros and whether cardiorespiratory supportive interventions alter their intensity. Therefore, we set out to determine the possible mechanisms that lead to muscle tremors and ascertain whether cardiorespiratory supportive interventions affect tremor intensity. We studied tremors and physiological responses during etorphine–azaperone immobilisation in eight boma-held and 14 free-living white rhinoceroses. Repeated measures analysis of variance and a Friedman test were used to determine differences in variables over time and between interventions. Spearman and Pearson correlations were used to test for associations between variables. Tremor intensity measured objectively by activity loggers correlated well (p < 0.0001; r² = 0.9) with visual observations. Tremor intensity was greatest when animals were severely hypoxaemic and acidaemic. Tremor intensity correlated strongly and negatively with partial pressure of oxygen (PaO₂) (p = 0.0003; r² = 0.9995) and potential of hydrogen (pH) (p = 0.02, r² = 0.97). It correlated strongly and positively with adrenaline concentrations (p = 0.003; r² = 0.96), and adrenaline correlated strongly and negatively with PaO₂ (p = 0.03; r² = 0.95) and pH (p = 0.03; r² = 0.94). Therefore, hypoxaemia and acidaemia were likely associated with the intensity of tremors through their activation of the release of tremorgenic levels of adrenaline. Tremors can be reduced if circulating adrenaline is reduced, and this can be achieved by the administration of butorphanol plus oxygen insufflation. Furthermore, to assist with reducing the risks associated with rhinoceros immobilisation, tremor intensity could be used as a clinical indicator of respiratory and metabolic compromise.

CARDIOVASCULAR EFFECTS OF ETORPHINE, AZAPERONE, AND BUTORPHANOL COMBINATIONS IN CHEMICALLY IMMOBILIZED CAPTIVE WHITE RHINOCEROS (CERATOTHERIUM SIMUM)

Chemical capture is an essential tool in the management and conservation of white rhinoceros ( Ceratotherium simum ); however, cardiovascular responses in immobilized megaherbivores are poorly understood. Blood pressure and heart rate responses in rhinoceros immobilized with etorphine or etorphine plus azaperone, and the effects of subsequent i.v. butorphanol administration were investigated. Six white rhinoceros were used in a randomized crossover study design with four interventions: 1) etorphine i.m.; 2) etorphine plus azaperone i.m.; 3) etorphine i.m. and butorphanol i.v.; and 4) etorphine plus azaperone i.m., and butorphanol i.v. Etorphine resulted in hypertension and tachycardia in immobilized rhinoceros on initial measurements. Over the 25-min study period, blood pressures and heart rate declined. Heart rates were slower, although the rhinoceros were still tachycardic, and blood pressures lower during the whole study period in animals immobilized with etorphine and azaperone compared with those that received only etorphine. Butorphanol administration resulted in lower arterial blood pressures and heart rates in etorphine-immobilized rhinoceros. In rhinoceros immobilized with etorphine and azaperone, heart rate slowed following administration of butorphanol i.v., although blood pressures remained unchanged. Azaperone reduced hypertension associated with etorphine immobilization, but animals remained tachycardic. Administration of butorphanol to etorphine/azaperone-immoblized rhinoceros lowered heart rate to values approaching normal resting levels without altering blood pressure.

EVALUATION OF ETORPHINE AND MIDAZOLAM ANESTHESIA, AND THE EFFECT OF INTRAVENOUS BUTORPHANOL ON CARDIOPULMONARY PARAMETERS IN GAME-RANCHED WHITE RHINOCEROSES (CERATOTHERIUM SIMUM)

Nineteen white rhinoceroses ( Ceratotherium simum ) were anesthetized with 4 mg of etorphine hydrochloride; 35-40 mg of midazolam; and 7,500 international units of hyaluronidase for dehorning purposes at a game ranch in South Africa, to investigate this anesthetic combination. Median time to recumbency was 548 sec (range 361-787 sec). Good muscle relaxation and no muscle rigidity or tremors were observed in 18 animals, and only 1 individual showed slight tremors. In addition, all animals received butorphanol i.v. 5 min after recumbency at the ratio of 10 mg of butorphanol per 1 mg of etorphine. Blood gas and selected physiologic parameters were measured in the recumbent animal, immediately before and 10 min after the administration of butorphanol. Statistically significant improvements were observed in blood gas physiologic and cardiopulmonary parameters 10 min after the administration of butorphanol, with a reduction in arterial partial pressure of carbon dioxide, systolic blood pressure, and heart rate and an increase in pH, arterial partial pressure of oxygen, oxygen saturation, and respiratory rate (all P < 0.005). After i.v. naltrexone reversal, recovery was uneventful, and median time to walking or running was 110 sec (range 71-247 sec). The results indicate etorphine and midazolam combination is an effective alternative anesthetic protocol and produces good muscle relaxation. Furthermore, i.v. butorphanol was associated with improved blood gas values and cardiopulmonary function for at least 10 min postinjection.

Pulmonary gas exchange and acid-base status during immobilisation of black rhinoceroses (<i>Diceros bicornis</i>) in Zimbabwe

When immobilising wildlife, adverse side effects can include hypoxaemia, acidosis and hypertension. Pulmonary gas exchange and acid–base status were evaluated during immobilisation of 25 free-ranging and one boma-held black rhinoceros (Diceros bicornis) in Zimbabwe. The effect of different body positions on arterial oxygenation was evaluated. A combination of the following drugs was used: an opioid (etorphine or thiafentanil), azaperone and an α₂-adrenoceptor agonist (detomidine or xylazine). Respiratory and heart rates, rectal temperature and pulse oximetry–derived haemoglobin oxygen saturation were recorded. Serial arterial blood samples were analysed immediately in the field. Marked hypoxaemia and hypercapnia were recorded in immobilised free-ranging black rhinoceroses. Arterial oxygenation was higher during sternal compared to lateral recumbency. Most rhinoceroses developed acidaemia of respiratory and metabolic origin. Initially high lactate concentrations in free-ranging rhinoceroses decreased during immobilisation. Pulse oximetry was unreliable in the detection of hypoxaemia. Positioning in sternal recumbency and routine use of oxygen supplementation are recommended in the management of immobilised rhinoceroses as measures to improve arterial oxygenation.

Butorphanol use in laboring patients with preeclampsia or chronic hypertension

OBJECTIVE

The American College of Obstetricians and Gynecologists (ACOG) recommends against the use of butorphanol in patients diagnosed with preeclampsia or chronic hypertension secondary to a theoretical concern that the drug will further elevate blood pressures. No past study has examined the drug's potential to elevate blood pressures in laboring patients.

METHODS

In this retrospective cohort study all chronic hypertensive and preeclamptic patients who underwent an induction of labor and delivered a viable, singleton pregnancy between the dates of 1/1/2013 and 12/31/2014 at a single academic hospital were included.

RESULTS

The use of butorphanol in chronically hypertensive patients during labor was not associated with the presence of severe range blood pressures during labor (OR=0.92 95% CI: (0.04-19.34) P=0.96). In preeclamptic patients there was similarly no change in the frequency of severe range blood pressures with the use of the drug (OR=0.59 95% CI: (0.19-1.83) P=0.36).

CONCLUSION

In laboring patients with chronic hypertension or preeclampsia butorphanol is not associated with severe range blood pressures, and therefore it is a reasonable option for providing pain relief in these populations.

EVALUATION OF CARDIORESPIRATORY, BLOOD GAS, AND LACTATE VALUES DURING EXTENDED IMMOBILIZATION OF WHITE RHINOCEROS (CERATOTHERIUM SIMUM)

Ten white rhinoceros (Ceratotherium simum) were immobilized for a total of 13 procedures in holding facilities in Kruger National Park using etorphine, azaperone, and hyaluronidase to assess the effect of extended immobilization on serial cardiorespiratory, blood gas, and lactate values. Butorphanol was administered intravenously following initial blood collection and physiologic assessment (t=0). Respiratory and cardiovascular parameters, body temperature, and arterial blood gases were monitored at 10-min intervals for a total of 100 min. Initial parameters at the time of recumbency revealed severe hypoxemia, hypercapnia, tachycardia, an increased alveolar-arterial (A-a) gradient, and mildly elevated lactate levels. At 10 min and 20 min, there were significant (P<0.05) changes in the following physiologic parameters: heart rate decreased [96 and 80 beats/min, respectively, vs. 120 beats/min], arterial partial pressure of oxygen (PaO2) increased [48 and 45 mm Hg, respectively vs. 30 mm Hg], arterial hemoglobin oxygen saturation increased [79% and 74%, respectively, vs. 47%], A-a gradient decreased [29.13 and 30.00 mm Hg, respectively, vs. 49.19 mm Hg], and respiratory rate decreased [5 and 5 breaths/min vs. 7 breaths/min]. Blood lactate levels also decreased from 2.54 mM/L to 1.50 and 0.89 mM/L, respectively. Despite initial improvements in blood oxygen levels at t=10 and 20 min, the rhinoceros remained severely hypoxemic for the remainder of the procedure (median PaO2=50.5 mm Hg, 95% confidence interval, 43.8-58.1). Median values for respiratory rate (5 breaths/min) and arterial partial pressure of carbon dioxide (PaCO2; 68.5 mm Hg) did not change significantly for the remaining 80 min. Median lactate, base excess, bicarbonate, and pH values improved between 20 and 100 min despite the persistent hypercapnia, indicating that the animals adequately compensated for respiratory and lactic acidosis. White rhinoceros were immobilized for 100 min with no negative effects, a desirable outcome if procedures require extended chemical immobilization without oxygen supplementation.

Butorphanol with oxygen insufflation improves cardiorespiratory function in field-immobilised white rhinoceros (Ceratotherium simum)

Opioid-induced immobilisation results in severe respiratory compromise in the white rhinoceros (Ceratotherium simum). The effectiveness of oxygen insufflation combined with butorphanol in alleviating respiratory depression in free-ranging chemically immobilised white rhinoceroses was investigated. In this prospective intervention study 14 free-ranging white rhinoceroses were immobilised with a combination of etorphine, azaperone and hyaluronidase. Six minutes (min) after the animals became recumbent, intravenous butorphanol was administered and oxygen insufflation was initiated. Previous boma trial results were used for comparison, using repeated measures two-way analysis of variance. The initial immobilisation-induced hypoxaemia in free-ranging rhinoceroses (arterial partial pressure of oxygen [P_aO₂] 35.4 mmHg ± 6.6 mmHg) was similar to that observed in boma-confined rhinoceroses (P_aO₂ 31 mmHg ± 6 mmHg, n = 8). Although the initial hypercapnia (P_aCO₂ 63.0 mmHg ± 7.5 mmHg) was not as severe as that in animals in the boma trial (79 mmHg ± 7 mmHg), the field-immobilised rhinoceroses were more acidaemic (pH 7.10 ± 0.14) at the beginning of the immobilisation compared with boma-immobilised rhinoceroses (pH 7.28 ± 0.04). Compared with pre-intervention values, butorphanol with oxygen insufflation improved the P_aO₂ (81.2 mmHg ± 23.7 mmHg, p < 0.001, 5 min vs 20 min), arterial partial pressure of carbon dioxide (55.3 mmHg ± 5.2 mmHg, p < 0.01, 5 min vs 20 min), pH (7.17 ± 0.11, p < 0.001, 5 min vs 20 min), heart rate (78 breaths/min± 20 breaths/min, p < 0.001, 5 min vs 20 min) and mean arterial blood pressure (105 mmHg ± 14 mmHg, p < 0.01, 5 min vs 20 min). Oxygen insufflation combined with a single intravenous dose of butorphanol improved oxygenation and reduced hypercapnia and acidaemia in immobilised free-ranging white rhinoceroses.

Butorphanol with oxygen insufflation corrects etorphine-induced hypoxaemia in chemically immobilized white rhinoceros (Ceratotherium simum)

Background

Opioid-induced immobilization is associated with severe respiratory depression in the white rhinoceros. We evaluated the efficacy of butorphanol and oxygen insufflation in alleviating opioid-induced respiratory depression in eight boma-managed rhinoceros.

Results

Chemical immobilization with etorphine, azaperone and hyaluronidase, as per standard procedure for the white rhinoceros, caused severe respiratory depression with hypoxaemia (P_aO₂ = 27 ± 7 mmHg [mean ± SD]), hypercapnia (P_aCO₂ = 82 ± 6 mmHg) and acidosis (pH =7.26 ± 0.02) in the control trial at 5 min. Compared to pre-intervention values, butorphanol administration (without oxygen) improved the P_aO₂ (60 ± 3 mmHg, F_(3,21) =151.9, p <0.001), P_aCO₂ (67 ± 4 mmHg, F_(3,21) =22.57, p <0.001) and pH (7.31 ± 0.06, F_(3,21) =27.60, p <0.001), while oxygen insufflation alone exacerbated the hypercapnia (123 ± 20 mmHg, F_(3,21) =50.13, p <0.001) and acidosis (7.12 ± 0.07, F_(3,21) =110.6, p <0.001). Surprisingly, butorphanol combined with oxygen fully corrected the opioid-induced hypoxaemia (P_aO₂ = 155 ± 53 mmHg) and reduced the hypercapnia over the whole immobilization period (p <0.05, areas under the curves) compared to the control trial. However, this intervention (butorphanol + oxygen) did not have any effect on the arterial pH.

Conclusions

Oxygen insufflation combined with a single intravenous dose of butorphanol improved the immobilization quality of boma-managed white rhinoceros by correcting the opioid-induced hypoxaemia, but did not completely reverse all components of respiratory depression. The efficacy of this intervention in reducing respiratory depression in field-captured animals remains to be determined.

Intravenous butorphanol improves cardiopulmonary parameters in game-ranched white rhinoceroses (Ceratotherium simum) immobilized with etorphine and azaperone

Abstract We immobilized 47 white rhinoceroses (Ceratotherium simum) for dehorning with 1-4 mg of etorphine HCl, 10-40 mg of azaperone, and 7,500 IU of hyaluronidase, at a game ranch in South Africa in November 2012. Forty-four received butorphanol intravenously 5 min after recumbency, at the rate of 10 mg of butorphanol per 1 mg of etorphine, and three animals did not. When possible, blood gas and physiologic parameters were measured immediately before butorphanol administration and 10 min later. Statistically significant improvements were observed, with a reduction in pH, partial pressure of carbon dioxide in arterial blood, heart rate, systolic blood pressure, and diastolic blood pressure, and with an increase in arterial partial pressure of oxygen, arterial hemoglobin oxygen saturation, and respiratory rate in animals administered butorphanol. In the three animals that did not receive butorphanol, no improvement was apparent. Butorphanol given to recumbent white rhinoceroses immediately after immobilization was associated with improved blood gas values and cardiopulmonary function for at least 10 min. Studies on the sustainability of these effects are necessary.