Journal Articles

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Author: search.filters.author.Meyer LCRSubject: search.filters.subject.azaperone

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    Muscle tremors observed in white rhinoceroses immobilised with either etorphine-azaperone or etorphine-midazolam: An initial study
    (AOSIS, 2021-06-28) Nasr M; Meyer LCR; Buss P; Fàbregas MC; Gleed RD; Boesch JM; Pohlin F
    Etorphine-azaperone is the most commonly used drug combination for chemical immobilisation of free-ranging white rhinoceroses, but causes several profound physiological disturbances, including muscle tremors. The addition of benzodiazepine sedatives, such as midazolam, has been proposed to reduce the muscular rigidity and tremors in immobilised rhinoceroses. Twenty-three free-ranging, sub-adult white rhinoceros bulls were darted and captured using a combination of etorphine plus either azaperone or midazolam. Skeletal muscle tremors were visually evaluated and scored by an experienced veterinarian, and tremor scores and distance run were compared between groups using the Wilcoxon rank sum test. No statistical differences were observed in tremor scores (p = 0.435) or distance run (p = 0.711) between the two groups, and no correlation between these variables was detected (r = -0.628; p = 0.807). Etorphine-midazolam was as effective as etorphine-azaperone at immobilising rhinoceroses, with animals running similar distances. Although the addition of midazolam to the etorphine did not reduce tremor scores compared to azaperone, it might have other beneficial immobilising effects in rhinoceroses, and further investigation is necessary to elucidate possible methods of reducing muscle tremoring during chemical immobilisation of rhinoceroses.
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    Efficacy and safety of three different opioid-based immobilisation combinations in blesbok (Damaliscus pygargus phillipsi)
    (Medpharm Publications, 2023) Roug A; Smith C; Raath JP; Meyer LCR; Laubscher LL
    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 opioid-azaperone 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.
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    A comparison of immobilisation quality and cardiorespiratory effects of etorphine-azaperone versus etorphine-midazolam combinations in blesbok
    (Medpharm Publications on behalf of the South African Veterinary Association, 2022-06-01) Laubscher LL; Meyer LCR; Laurence M; Raath JP; Pfitzer S
    The study compared immobilisation of blesbok (Damaliscus pygargus phillipsi) with etorphine and azaperone vs etorphine and midazolam. Twelve female blesbok, weighing 59.4 ± 2.8 kg, were used. Each animal randomly received Treatment 1 (T1) (etorphine, 0.07 ± 0.003 mg/kg + azaperone, 0.36 ± 0.02 mg/kg) and Treatment 2 (T2) (etorphine, 0.07 ± 0.003 mg/kg + midazolam, 0.20 ± 0.01 mg/kg) with a one-week washout period between treatments. Induction times were recorded followed by physiological monitoring for 45 minutes of immobilisation. Immobilisation was reversed with naltrexone (20 mg per mg etorphine). Recovery times were also recorded. Induction, immobilisation and recovery were scored with subjective measures. Inductions and recoveries did not differ between combinations, but the quality of immobilisation was significantly better with T1. Rectal temperature and blood pressure were significantly lower during T1. Both treatments resulted in severe hypoxaemia and impaired gas exchange, although overall hypoxaemia was more pronounced for T1. Animals treated with T2, however, exhibited a deterioration in respiration as the monitoring period progressed, possibly as a result of impaired ventilatory muscle function due to the effects of midazolam. Both combinations are suitable for adequate immobilisation of blesbok and should be selected based on the specific capture situation. Supplementation with oxygen is highly recommended.
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    Comparison of the immobilisation and cardiorespiratory effects of thiafentanil-azaperone versus thiafentanil-medetomidine-azaperone in African buffalo (Syncerus caffer)
    (Medpharm Publications on behalf of the South African Veterinary Association, 2024-03-01) Faber VE; Burroughs REJ; Meyer LCR; Hansen HJ; Gerber D; Koeppel KN
    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.
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    Evaluation of two different etorphine doses combined with azaperone in blesbok (damaliscus pygargus phillipsi) immobilisation
    (South African Veterinary Association, 2021-12-09) Gaudio E; Laubscher LL; Meyer LCR; Hoffman LC; Raath JP; Pfitzer S
    Chemical immobilisation is essential for veterinarians to perform medical procedures in wild African ungulates. Potent opioids combined with neuroleptic drugs are most often used for this purpose. The present study aimed at comparing the quality of immobilisation and effects on physiological variables between a high (high etorphine-azaperone [HE]: 0.09 mg kg-1) and low etorphine dose (low etorphine-azaperone [LE]: 0.05 mg kg-1), both combined with azaperone (0.35 mg kg-1), in 12 adult female boma-acclimatised blesbok. It was hypothesised that a reduction in etorphine's dose in combination with azaperone would result in less cardiorespiratory impairment but likely worsen the quality of immobilisation. Both treatments resulted in rapid induction and recovery times. Overall inter-treatment differences occurred in pulse rate (HE and LE: 52 ± 15 and 44 ± 11 beats minute-1, p < 0.0001), respiratory rate (HE and LE: 15 ± 4 and 17 ± 4 breaths minute-1, p < 0.006), partial pressure of exhaled carbon dioxide (HE and LE: 62.0 ± 5.0 and 60.0 ± 5.6 millimetre of mercury [mmHg], p < 0.028) and arterial carbon dioxide (HE and LE: 58.0 ± 4.5 and 55.0 ± 3.9 mmHg, p < 0.002). Both HE and LE led to bradycardia, hypertension and marked hypoxia to a similar extent. Furthermore, quality of induction, immobilisation and recovery were similar in both treatments. The role of azaperone in the development of cardiorespiratory compromise and gas exchange impairment that occurred when these combinations were used is still unclear. Further studies are recommended to elucidate drug- and dose-specific physiological effects in immobilised antelope.
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    Midazolam alters acid-base status less than azaperone during the capture and transport of southern white rhinoceroses (Ceratotherium simum simum)
    (MDPI (Basel, Switzerland), 2020-07-31) Pohlin F; Buss P; Hooijberg EH; Meyer LCR
    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.