Abstract Background Etorphine, a highly potent opioid widely used in wildlife immobilisation, is known to cause cardiorespiratory compromise. This study aimed to investigate the effects of a serotonergic agonist, BIMU-8 and an alpha-2 adrenoreceptor antagonist, vatinoxan on pulmonary hypertension and cardiovascular function in etorphine-immobilised sheep, as a model for wild ungulates. Six sheep were immobilised three times in a randomised, prospective, controlled crossover design using intramuscular etorphine (0.05 mg·kg−1). Seven minutes later, sheep received intravenous BIMU-8 (1.5 mg·kg−1), vatinoxan (0.15 mg·kg−1), or sterile water (control). Respiratory rate, pulmonary arterial, systemic arterial and central venous pressures, electrocardiography, heart rate, and cardiac output were recorded. Data were collected at resting state, six minutes post-etorphine, and at six-minute intervals post-treatment. Naltrexone was administered 19 minutes post-treatment to reverse immobilisation. Linear mixed-effects models were used for statistical analysis. Results Etorphine induced bradypnea, pulmonary hypertension, dysrhythmias, and tachycardia in sheep. BIMU-8 significantly reduced mean pulmonary arterial pressure (F2,91 = 4.17, p = 0.02) and mean arterial pressure (F2,89 = 6.01, p < 0.01) but was associated with severe tachydysrhythmia. Vatinoxan decreased respiratory rate (F2,91 = 4.13, p < 0.01), increased cardiac output (F2,91 = 10.88, p < 0.01), and reduced body temperature (F6,85 = 2.2, p = 0.05), while having no effect on pulmonary or systemic arterial pressures. Conclusion BIMU-8 reduces etorphine-induced pulmonary and systemic hypertension, but causes tachydysrhythmias, requiring further evaluation. Vatinoxan improves cardiac output, without alleviating pulmonary hypertension in etorphine-immobilised sheep.

Etorphine, a highly potent opioid, disrupts multiple steps of the oxygen cascade, including alveolar ventilation, pulmonary gas exchange, systemic oxygen transport, and tissue-level oxygen utilisation, resulting in hypoxaemia and cellular hypoxia during immobilisation of wild ungulates. To evaluate potential mitigating agents, a randomised, prospective, controlled crossover design was used in etorphine-immobilised sheep (0.05 mg·kg−1, intramuscularly, n = 6). After etorphine administration, animals received either the serotonergic agonist BIMU-8 (1.5 mg·kg−1), the alpha-2 adrenoceptor antagonist vatinoxan (0.15 mg·kg−1), or sterile water (control) intravenously with a four-week washout period. Immobilisation was reversed with naltrexone 19 min after treatment administration. Sequential steps of the oxygen cascade were assessed using thoracic electrical impedance-derived variables (respiratory rate (RREIT) and tidal impedance variation (TIV)) for ventilation, blood gas analysis and venous admixture for pulmonary gas exchange, oxygen delivery (DO2) for oxygen transport, and oxygen extraction ratio (ER) for tissue oxygen utilisation. Measurements were obtained at baseline, after etorphine administration, at five-minute intervals following treatment, and after naltrexone. Data was analysed using linear mixed-effects models. Etorphine induced respiratory depression, characterised by reduced RREIT (p < 0.001) and TIV (p = 0.01), and impaired gas exchange, indicated by increased venous admixture (p < 0.001) compared with baseline, causing hypercapnia and hypoxaemia in all treatments. Neither BIMU-8 nor vatinoxan improved these variables compared with the control. Consequently, progressive decreases in arterial partial pressure of oxygen (F3,90 = 104.82, p < 0.001) were observed across treatments during immobilisation, resulting in persistently reduced DO2 (F3,84 = 51.55, p < 0.001) and increased ER (F3,90 = 8.09, p < 0.001) at similar levels in all treatments. All variables normalised after naltrexone administration. Etorphine profoundly impaired multiple sequential steps of the oxygen cascade in sheep, resulting in hypoxaemia, reduced DO2, and compensatory increases in ER. BIMU-8 and vatinoxan did not effectively mitigate these disturbances at any level of the cascade compared with the control. Future research is needed to develop targeted strategies that address the key mechanisms underlying the disruptions in the oxygen cascade during etorphine immobilisation.

Rhabdomyolyses is a clinical sign of capture myopathy in wild animals and may be linked to glycogen metabolism. To study potential mechanisms, 26 wild blesbok were chased for 15 min and immobilised, whereafter 12 of these blesbok were doused with ice-water (n = 14 chased only group; n = 12 chased + cooled group). An additional 12 blesbok served as resting (not chased) uncooled controls. Vastus lateralis biopsies were obtained after immobilisation for biochemical analyses. Biopsies obtained at initial capture, 3- and 16-days post exercise were analysed for glycogen content. Blesbok muscles contained predominantly myosin heavy chain (MHC) IIA (∼50 ± 9 %), followed by IIX (32 ± 10 %) and MHC I (18 ± 5 %), with no difference between groups. Citrate synthase (mean: 87 ± 48), 3-hydroxyacetyl co A dehydrogenase (47 ± 17), lactate dehydrogenase (1567 ± 654), phosphorylase (162 ± 94), phosphofructokinase (250 ± 123) and creatine kinase (12,455 ± 6372) activities (in μmol/min/g prot) were not different between groups. Similarly, superoxide dismutase (7.9 ± 7 U/mg prot), catalase (8.8 ± 5.8 mmol/min/g prot), and overall antioxidant capacity (ORAC: 23055 ± 18,460 μmol/g prot) were not different between groups. Glycogen content was reduced in both chased groups and not replenished by day 3. Glycogen supercompensation was observed on day 16 in both chased groups (∼33 % higher than resting control group). The results confirm that blesbok have high muscle metabolic capacities, and that glycogen resynthesis is slow, which could lead to metabolite deficiency during prolonged chase events (>15 min).

BACKGROUND:Skeletal and possible cardiac muscle damage has been reported in chemically immobilized and transported African rhinoceros during conservation-related activities. The extent of cardiac muscle injury in these rhinoceros is unknown due to a lack of validated cardiac troponin I (cTnI) assays. However, recently, five human cTnI assays were deemed suitable for analytical validation in African rhinoceros based on cTnI sequencing results. OBJECTIVES:The first objective was to validate two cTnI immunoassay point-of-care analyzers (POCAs) in African rhinoceros and, secondly, to perform quality control (QC) validation for the POCAs. METHODS:Analytical validation of the Stratus CS Acute Care Troponin I cTnI immunoassay and Atellica VTLi high sensitivity cTnI (hs-cTnI) assay was performed using rhinoceros serum samples and species-specific cardiac muscle homogenate. Experiments included precision studies, reportable range, hemoglobin interference studies, recovery studies, and detection limit studies, with results assessed against prescribed total allowable error (TEa) performance goals. Commercial quality control material (QCM) data were used to calculate bias and imprecision for QC validation. RESULTS:Imprecision was acceptable (1.9%-10.3%) and met low cTnI concentration performance goals. Reportable ranges were similar to the manufacturer's specifications. High hemoglobin concentrations in white rhinoceros resulted in a positive bias in the Stratus CS. A simple 13s QC rule using two levels of QCM and a TEa of 70% could be used in both analyzers, except at very low cTnI concentrations in the Atellica VTLi. CONCLUSIONS:Both cTnI POCAs are suitable for use in African rhinoceros, and analytical performance goals for low cTnI concentrations in hs-cTnI assays were met.

White rhinoceros are a sentinel species for important ecosystems in southern Africa. Their conservation requires active management of their population, which, in turn, requires immobilization of individuals with an ultra-potent opioid such as etorphine. Unfortunately, when immobilized with etorphine, they develop severe hypoxaemia that may contribute to morbidity and mortality. We hypothesized that (i) etorphine causes sympathetic upregulation that is responsible for physiological complications that produce hypoxaemia and (ii) butorphanol, a partial μ opioid agonist, mitigates sympathetic upregulation, thereby improving arterial oxygen content (CaO2) and delivery (DO2). Six subadult male white rhinoceros were administered two treatments in random order: etorphine-saline (ES) and etorphine-butorphanol (EB). After intramuscular etorphine (~2.6 μg kg−1), rhinoceros became recumbent (time 0 min [t0]) and were instrumented. Baseline data were collected at t30, butorphanol (0.026 mg/kg) or 0.9% saline was administered intravenously at t37, and data were collected again at t40 and t50. At baseline, plasma noradrenaline concentration was >40 ng ml−1, approximately twice that of non-immobilized rhinoceros (t test, P < 0.05); cardiac output (Qt, by thermodilution) and metabolic rate (VO2, by spirometry/indirect calorimetry) were greater than predicted allometrically (t test, P < 0.05), and pulmonary hypertension was present. After butorphanol, noradrenaline concentration remained greater than in non-immobilized rhinoceros; in EB, CaO2 was greater, while Qt, DO2, VO2, and pulmonary pressures were less than in ES (linear mixed effect model, all P < 0.05). Increased noradrenaline concentration with increased Qt and hypermetabolism supports etorphine-induced sympathetic upregulation. Butorphanol partly attenuated these effects, increasing CaO2 but reducing Qt and, thus, DO2. Since plasma noradrenaline concentration remained increased after butorphanol administration while Qt, DO2, and VO2 decreased, a pathway independent of plasma noradrenaline concentration might contribute to the cardiopulmonary and hypermetabolic effects of etorphine. Developing treatments to combat this sympathomimesis could reduce capture-related morbidity in white rhinoceros.

As a relatively nascent discipline, conservation physiology has struggled to deliver science that is relevant to decision-makers or directly useful to practitioners. A growing body of literature has revealed that co-produced research is more likely to generate knowledge that is not only relevant, but that is also embraced and actionable. Co-production broadly involves conducting research collaboratively, inclusively, and in a respectful and engaged manner-spanning all stages from identifying research needs to study design, data collection, interpretation and application. This approach aims to create actionable science and deliver meaningful benefits to all partners involved. Knowledge can be co-produced with practitioners/managers working for regulators or stewardship bodies, Indigenous communities and governments, industry (e.g. fishers, foresters, farmers) and other relevant actors. Using diverse case studies spanning issues, taxa and regions from around the globe, we explore examples of co-produced research related to conservation physiology. In doing so, we highlight benefits and challenges while also identifying lessons for others considering such an approach. Although co-production cannot guarantee the ultimate success of a project, for applied research (such as what conservation physiology purports to deliver), embracing co-production is increasingly regarded as the single-most important approach for generating actionable science to inform conservation. In that sense, the conservation physiology community would be more impactful and relevant if it became commonplace to embrace co-production as demonstrated by the case studies presented here.

African rhinoceros undergo chemical immobilization and prolonged transport during translocations for conservation purposes and, hence, experience several pathophysiologic changes, including skeletal muscle injury. Potential concurrent myocardial injury has not been investigated due to a lack of validated immunoassays. We aimed to use inferred cardiac troponin I (cTnI) amino acid sequences of southern white (Ceratotherium simum simum) and southern-central black (Diceros bicornis minor) rhinoceros to assess the potential usefulness of several commercial cTnI immunoassays for detecting cTnI in African rhinoceros. We extracted RNA from the myocardium of deceased rhinoceros (2 white, 1 black rhinoceros) followed by primer design, cDNA synthesis via RT-PCR, and Sanger sequencing. The inferred cTnI amino acid sequences were obtained from the mRNA transcript sequences. The homology of epitope binding sites recognized by capture and detection antibodies in 6 human immunoassays was visually evaluated using aligned inferred rhinoceros cTnI amino acid sequences. Percentage identity between white and black rhinoceros cDNA nucleotide sequences was 99%; inferred amino acid sequences were identical. There were 5 amino acid differences between humans and rhinoceros in the epitope binding sites of immunoassay antibodies; 5 assays contained antibodies against epitopes that were not conserved. For one assay, the single capture antibody targeted a short heterologous epitope (residue 87-91), and cross-reactivity with rhinoceros cTnI was deemed unlikely. For the other 5 assays, complete antibody-epitope homology, or the inclusion of multiple detection or capture antibodies, or targeting of long epitopes, indicated that these assays could be suitable for further investigation of cTnI measurement in African rhinoceros.

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.

Despite translocation being a useful conservation strategy in rhinoceros management, morbidities and mortalities occurring during transportation pose a significant concern to rhinoceros managers, veterinarians, and scientists. The objectives of this study were to better understand the effects of transport on rhinoceros and to gain insights from veterinarians involved in rhinoceros translocations about current practices and potential interventions that could improve welfare. A weblink and QR code to an online questionnaire with a total of 46 questions in Google Forms was sent to veterinarians who had experience in African rhinoceros transportation, through personal emails and social network forums. Results demonstrated that despite dehydration and negative energy balance being reported as the major causes of morbidities and mortalities during transport and post-release, most veterinarians (30/35; 86%) involved in rhinoceros translocation did not offer water, parenteral fluids, or feed to transported animals, for logistical reasons and the knowledge or perception of rhinoceros' resistance to taking ad lib food and water during transport. However, 52% (15/29) and 41% (15/34) of participants suggested that parenteral fluids could be used as an intervention to mitigate dehydration and negative energy balance respectively. To reduce stress, 94% (33/35) of respondents suggested the use of tranquilisers and sedatives. This study is the first to systematically investigate and report on practices by veterinarians involved in rhinoceros translocations globally. The study highlights that further research is required to explore optimal and pragmatic techniques in the field to mitigate reported welfare challenges in rhinoceros during transport.

Comparatively little is known about the distribution and ecology of Aardvark (Orycteropus afer) and Temminck's Ground Pangolin (Smutsia temminckii). Both are elusive species that are normally nocturnal, solitary, and fossorial. Formally collected records have been used to map the distribution of these species, and social media records provide a tool to gather information on their distribution and ecology. We obtained 680 photographs and videos of aardvarks and 790 of ground pangolins in southern Africa from publicly available posts on Facebook and Instagram (2010-2019). The images provide new insights into the distribution, activity, drinking, and predation-and confirm that aardvarks are more diurnally active when they are in poor body condition. Social media can provide useful supplementary information for understanding of elusive mammals. These "soft" data can be applied to other species. We collected 680 images and videos of the Aardvark and 790 of Temminck's Ground Pangolin from southern Africa using social media platforms. The images provided new insights on the distribution and ecology of these elusive species, including predation and drinking behavior. They also confirmed a recent research finding that poor body condition is associated with greater diurnal activity in aardvarks. Social media offers a useful supplementary source of information for understanding elusive mammals.

ABSTRACT While translocations of white rhinoceroses have become an important conservation tool, dehydration during long‐distance transports has been identified as a welfare concern. Intravenous (iv) fluid administration might therefore be useful to mitigate dehydration; however, special requirements need to be met to make iv fluid administration suitable for large, wild rhinoceroses during transport. Requirements include a portable and robust system that is capable of delivering high flow rates, is easy to set up, and remains patent and operating for long periods of time while allowing the animals to freely stand or lay down in the transport crates. Due to the lack of suitable fluid administration systems, we developed a custom‐made system consisting of 8 L drip bags, a three‐part, 4.4‐m–long, large bore and partially coiled administration set, and a robust, battery‐operated infusion pump, which allowed us to successfully administer iv fluids at a maintenance rate of 1–2 mL/kg/h to eight rhinoceroses for 24 h during a mock transport. While iv fluid administration in transported rhinoceroses is time intensive and the large amount of drip bags required during lengthy transports might pose a limitation, the developed system may be useful for the long‐distance transport of small groups of rhinoceroses. Furthermore, this system would be of value for injured or sick rhinoceroses, which require parenteral fluid therapy when commercially available infusion pumps cannot provide the large fluid volumes needed.

Translocation and dehorning are common and important practices for rhinoceros management and conservation. It is not known if dehorning causes a stress response or negatively affects rhinoceroses during transport. Twenty-three subadult wild Southern white rhinoceros (Ceratotherium simum simum) bulls were immobilized and translocated >280 km for population management reasons. Ten animals were dehorned at capture, and 13 animals were transported without dehorning. For transport, five dehorned and six nondehorned rhinoceroses were sedated with azaperone (62.38 +/- 9.54 mu g/kg) and five dehorned and seven nondehorned rhinoceroses with midazolam (64.61 +/- 9.28 mu g/kg). Blood samples were collected at capture, start of transport, and after 6 h of transport. Measurements included 10 physiologic variables: hematocrit, total serum protein, creatine kinase (CK), aspartate aminotransferase, gamma-glutamyl transferase (GGT), creatinine, urea, cholesterol, beta-hydroxybutyrate, and glucose; and four stress response variables: cortisol, epinephrine, neutrophil-to-lymphocyte ratio, and leukocyte coping capacity. Using a linear mixed model, CK and GGT were higher in dehorned compared with nondehorned rhinoceroses. There were no significant differences in the other variables between the two groups. The likely cause of these differences is that dehorned animals spent more time in the crate before the start of transport than nondehorned rhinoceroses (3.11 +/- 0.54 h vs. 1.12 +/- 0.56 h, P<0.001). These results indicate that dehorning does not negatively alter the white rhinoceros' physiologic and stress responses during translocation, supporting its use for antipoaching measures.

Translocations of Rhinocerotidae are commonly performed for conservation purposes but expose the animals to a variety of stressors (e.g. prolonged fasting, confinement, novel environment, etc.). Stress may change the composition of gut microbiota, which can impact animal health and welfare. White rhinoceroses in particular can develop anorexia, diarrhea and enterocolitis after translocation. The aim of this study was to investigate the associations of age, sex and translocation on the rhinoceros' fecal bacterial microbiota composition. fecal samples were collected from rhinoceroses at capture (n = 16) and after a >30-hour road transport (n = 7). DNA was isolated from these samples and submitted for 16S rRNA V3-V4 phylotyping. Alpha diversity indices of the rhinoceros' fecal microbiota composition of different age, sex and before and after transport were compared using non-parametric statistical tests and beta diversity indices using Permutational Multivariate Analysis Of Variance (PERMANOVA). Resulting P-values were alpha-corrected (Padj.). Alpha and beta diversity did not differ between rhinoceroses of different age and sex. However, there was a significant difference in beta diversity between fecal samples collected from adult animals at capture and after transport. The most abundant bacterial phyla in samples collected at capture were Firmicutes and Bacteroidetes (85.76%), represented by Lachnospiraceae, Ruminococcaceae and Prevotellaceae families. The phyla Proteobacteria (Padj. = 0.009) and Actinobacteria (Padj. = 0.012), amongst others, increased in relative abundance from capture to after transport encompassing potentially pathogenic bacterial families such as Enterobacteriaceae (Padj. = 0.018) and Pseudomonadaceae (Padj. = 0.022). Important commensals such as Spirochaetes (Padj. = 0.009), Fibrobacteres (Padj. = 0.018) and Lachnospiraceae (Padj. = 0.021) decreased in relative abundance. These results indicate that the stressors associated with capture and transport cause an imbalanced fecal microbiota composition in white rhinoceroses that may lead to potentially infectious intestinal disorders. This imbalance may result from recrudescence of normally innocuous pathogens, increased shedding of pathogens or increased vulnerability to new pathogens.

African buffalo (Syncerus caffer) are frequently immobilised for veterinary interventions, disease screening and translocations. Concerns over user and animal safety, costs, and irregularities in opioid supply, have led to the development of alternative immobilisation protocols. This study compared immobilisation of 12 boma-habituated African buffalo with thiafentanil-azaperone (TA) vs. thiafentanil-medetomidine-azaperone (TMA) in a randomised crossover study. Each buffalo received a combination of thiafentanil (6-7 mg) + azaperone (40 mg) and thiafentanil (1 mg) + medetomidine (3-4 mg) + azaperone (40 mg) with a three-week washout period between immobilisations. Induction and recovery times were recorded, quality of induction and immobilisation were scored subjectively, and physiological variables were monitored. The TMA combination induced immobilisation with 1/7th of the TA thiafentanil dose and at a quarter of the cost. Induction times for the TA combination were significantly faster at 5.7 +/- 1.6 min and more reliable compared to the TMA combination at 10.95 +/- 3.9 min. Both combinations resulted in severe hypoxaemia, however hypoxaemia was overall more pronounced in the TMA (PaO2 44 +/- 14 mmHg) combination compared to the TA (PaO2 51 +/- 13,33 mmHg) combination and resulted mainly from decreased pulmonary oxygen exchange rather than hypoventilation; PaCO2 values were mostly within the normal expected physiological range. Supplementary oxygen and close monitoring of blood oxygenation is considered essential with either combination. Although the reduction in costs could be beneficial for the wildlife industry, longer induction times, and risks from severe hypoxaemia need to be taken into consideration when the TMA combination is used.

Abstract Background Monitoring blood oxygenation is essential in immobilised rhinoceros, which are susceptible to opioid-induced hypoxaemia. This study assessed the reliability, clinical performance and trending ability of the Nonin PalmSAT 2500 A pulse oximeter’s and the Masimo Radical-7 pulse co-oximeter’s dual-wavelength technology, with their probes placed at two measurement sites, the inner surface of the third-eyelid and the scarified ear pinna of immobilised white rhinoceroses. Eight white rhinoceros were immobilised with etorphine-based drug combinations and given butorphanol after 12 min, and oxygen after 40 min, of recumbency. The Nonin and Masimo devices, with dual-wavelength probes attached to the third-eyelid and ear recorded arterial peripheral oxygen-haemoglobin saturation (SpO2) at pre-determined time points, concurrently with measurements of arterial oxygen-haemoglobin saturation (SaO2), from drawn blood samples, by a benchtop AVOXimeter 4000 co-oximeter (reference method). Reliability of the Nonin and Masimo devices was evaluated using the Bland-Altman and the area root mean squares (ARMS) methods. Clinical performance of the devices was evaluated for their ability to accurately detect clinical hypoxemia using receiver operating characteristic (ROC) curves and measures of sensitivity, specificity, and positive and negative predictive values. Trending ability of the devices was assessed by calculating concordance rates from four-quadrant plots. Results Only the Nonin device with transflectance probe attached to the third-eyelid provided reliable SpO2 measurements across the 70 to 100% saturation range (bias − 1%, precision 4%, ARMS 4%). Nonin and Masimo devices with transflectance probes attached to the third-eyelid both had high clinical performance at detecting clinical hypoxaemia [area under the ROC curves (AUC): 0.93 and 0.90, respectively]. However, the Nonin and Masimo devices with transmission probes attached to the ear were unreliable and provided only moderate clinical performance. Both Nonin and Masimo devices, at both measurement sites, had concordance rates lower than the recommended threshold of ≥ 90%, indicating poor trending ability. Conclusions The overall assessment of reliability, clinical performance and trending ability indicate that the Nonin device with transflectance probe attached to the third-eyelid is best suited for monitoring of blood oxygenation in immobilised rhinoceros. The immobilisation procedure may have affected cardiovascular function to an extent that it limited the devices’ performance.

African wildlife species are increasingly being immobilised with combinations of a low dose of potent opioids combined with medetomidine and azaperone. The physiological effects of these combinations in comparison to conventional potent opioidazaperone combinations have scarcely been evaluated. In this cross-over study conducted on eight captive blesbok, we compared the physiological variables of blesbok immobilised with 2 mg of thiafentanil + 10 mg of azaperone (TA); 0.5 mg thiafentanil + 1.5 mg medetomidine (TM), and 0.5 mg thiafentanil + 1.5. mg medetomidine + 10 mg azaperone (TMA). Thiafentanil's effects were antagonised with naltrexone at 10 mg naltrexone per mg thiafentanil, and the medetomidine effects with atipamezole at 5 mg atipamezole per mg medetomidine. The physiological variables were compared between treatment groups using descriptive statistics and repeated measures ANOVA. The TA combination resulted in the shortest induction and recovery times, higher heart rates, respiratory rates, PaO2, SpO2, and lower MAP and A-a gradients, but with less muscle relaxation. The TM and TMA combinations caused marked bradycardia and hypoxaemia. The hypoxaemia was most severe in animals immobilised with TMA, and four of eight blesbok immobilised had a PaO2 < 35 mmHg at the 10- or 15-minute sampling point. These blesbok were provided supplementary oxygen, which corrected the hypoxaemia. The TA combinations caused the lowest degree of physiological compromise. All three combinations were effective for the immobilisation of blesbok, but as the low-dose thiafentanil and high-dose medetomidine combinations caused marked hypoxaemia, supplementary oxygen is recommended when using these combinations.

BACKGROUND:Enterprise Point-of-Care (EPOC) blood analysis is used routinely in wildlife veterinary practice to monitor blood oxygenation, but the reliability of the EPOC calculated arterial oxygen-hemoglobin saturation (cSaO2 ) has never been validated in the white rhinoceros (Ceratotherium simum), despite their susceptibility to hypoxemia during chemical immobilization.OBJECTIVES:We aimed to evaluate the reliability of the EPOC cSaO2 by comparing it against arterial oxygen-hemoglobin saturation (SaO2 ) measured by a co-oximeter reference method in immobilized white rhinoceroses.METHODS:Male white rhinoceroses in two studies (both n = 8) were immobilized by darting with different etorphine-based drug combinations, followed by butorphanol or saline (administered intravenously). Animals in both studies received oxygen via intranasal insufflation after 60 min. Blood samples were drawn, at predetermined time points, from a catheter inserted into the auricular artery and analyzed using the EPOC and a co-oximeter. Bland-Altman (to estimate bias and precision) and area root mean squares (ARMS) plots were used to determine the reliability of the EPOC cSaO2 compared with simultaneous co-oximeter SaO2 readings.RESULTS:The rhinoceros were acidotic (pH of 7.3 ± 0.1 [mean ± standard deviation]), hypercapnic (PaCO2 of 73.7 ± 10.5 mmHg), and normothermic (body temperature of 37.4 ± 1.8°C). In total, 389 paired cSaO2 -SaO2 measurements were recorded (the cSaO2 ranged between 13.2% and 99.0%, and the SaO2 ranged between 11.8% and 99.9%). The EPOC cSaO2 readings were unreliable (inaccurate, imprecise, and poor ARMS) across the entire saturation range (bias -6%, precision 5%, and ARMS 8%).CONCLUSIONS:The EPOC cSaO2 is unreliable and should not be used to monitor blood oxygenation in immobilized white rhinoceroses.