Reduction of capture-induced hyperthermia and respiratory depression in ungulates

When wild animals are captured they often develop capture-related side-effects that may result in morbidity and mortality. During chemical capture of wild ungulates, capture-induced hyperthermia and opioid-induced respiratory depression occur commonly. Little is known about the mechanisms of capture-induced hyperthermia, and the effects of opioid drugs on respiratory function still need to be clarified. Also, current methods of reversing opioid-induced respiratory depression are inadequate. I therefore investigated the mechanisms and patterns of capture-induced hyperthermia, by continuously measuring body temperatures of impala during different capture procedures. I also investigated the effects of opioid drugs on respiratory function and pulmonary performance by examining the changes of cardiorespiratory variables before and during opioid immobilization of goats and impala. Concurrently, I investigated whether serotonergic ligands could be used to reverse the opioid-induced respiratory depression that occurred in these animals. I found stress to be the major factor associated with capture-induced hyperthermia, with exercise playing a minor role. I also found that environmental thermal conditions and the pharmacological effects of the capture drugs played no role in inducing capture-induced hyperthermia. I found that the opioid drug etorphine, which is commonly used to chemically capture wild animals, not only causes depression in respiratory rhythm and ventilation, but also a decrease in alveolar-arterial oxygen exchange. I demonstrated that serotonergic ligands with agonist effects at 5-HT1A and 5-HT4 receptors partially reversed opioid-induced respiratory depression and hypoxia, predominantly by improving alveolar-arterial oxygen exchange, presumably by increasing pulmonary perfusion and improving ventilation perfusion ratios, but also, in some cases, by improving ventilation. I advise that to limit the morbidity and mortality associated with capture-induced hyperthermia, procedures that cause the least stress should be used and animals should be exposed to stressors for the shortest time possible. The use of anxiolytic drugs to reduce stress may also be considered. If animals are captured by chemical immobilization with opioid drugs their respiratory function should be monitored closely. Counting breaths does not adequately monitor respiratory function and methods to assess carbon dioxide and oxygen levels in arterial blood should be used. If respiratory depression occurs, efforts to reverse this depression should not focus only on improving ventilation but also should aim at improving gas exchange in the lungs. Serotonergic ligands with agonist effects at 5-HT1A and 5-HT4 receptors could be used to achieve these aims. Although some of these ligands can cause arousal in immobilized animals, if they are administered with the opioid they enhance the induction of catatonic-immobilization, and their use in a dart may not only improve knock down times, thereby minimising stress and capture-induced hyperthermia, but they may also prevent opioid-induced respiratory depression

New study : Welfare and survival of Africa’s arid mammals under threat of climate change

Dr Ned Snelling, Senior Lecturer in the Department of Anatomy and Physiology and Prof Leith Meyer, Director of the Centre for Veterinary Wildlife Studies, both from the Faculty of Veterinary Science have just published a new study on the welfare and survival of Africa’s arid-dwelling mammals under the threat of climate change. Originally published as HTML file, converted to PDF with Adobe Acrobat 9 Pro Version 9.0.0.News articles with colour photos about what's happening at the Faculty of Veterinary Science, University of Pretoria.ab202

Comparison of thiafentanil-medetomidine to etorphine-medetomidine immobilisation of impalas (Aepyceros melampus)

Impalas (Aepyceros melampus) are increasingly valuable in the South African wildlife industry, and there is a greater need to chemically immobilise them, ideally with minimal risk. This study aimed to compare the times to recumbency and physiological effects of thiafentanilmedetomidine versus etorphine-medetomidine immobilisation. A combination of thiafentanil (2 mg) + medetomidine (2.2 mg) and etorphine (2 mg) + medetomidine (2.2 mg) was administered (to nine impalas; crossover design) via a dart. After darting, a stopwatch was started to record times to recumbency (time from darting until recumbent without attempts to stand). If apnoea was present, the impalas received one or more boluses of butorphanol (1:1 potent opioid dose). Data collection included arterial blood gas analysis and the number of butorphanol boluses. Two-sample t-tests were used to compare differences between combinations. The time to recumbency for thiafentanil-medetomidine was 12.2 (± 6.8) min and no different from 14.5 (± 5.2) min for etorphine-medetomidine (p = 0.426). The thiafentanilmedetomidine combination required more butorphanol boluses (median: 2; interquartile range: 2–3) compared to etorphine-medetomidine (median: 0; interquartile range: 0–1) (p = 0.001). Despite butorphanol treatment and resolution of apnoea, all impalas suffered hypoxaemia (PaO2 ± 44.0 mmHg). Thiafentanil-medetomidine did not immobilise impalas more rapidly than etorphine-medetomidine, and resulted in more apnoea that required rescue butorphanol boluses. Marked hypoxaemia resulted from both combinations, mainly because of right-to-left intrapulmonary shunting and not because of hypoventilation. Butorphanol and oxygen supplementation should be considered as essential rescue interventions for all impalas immobilised with these potent opioid combinations.The Hannover and Wuppertal Zoos, University of Hannover and the University of Pretoria, the South African Veterinary Association (SAVA) Wildlife Group and the South African Veterinary Foundation.http://www.jsava.co.za/am2017Paraclinical Science

Reference intervals for selected hematology and clinical chemistry measurands in Temminck's pangolin (Smutsia temminckii)

Pangolins are the world’s most trafficked non-human mammals. A significant number of Temminck’s pangolins (Smutsia temminckii) are presented for veterinary care and rehabilitation in southern Africa. Little is known about the physiology and normal health of this species, making diagnosis and medical management difficult. This study aimed to establish reference intervals (RIs) for hematology and plasma clinical chemistry in the Temminck’s pangolin. RIs were generated according to international guidelines using samples from 27 healthy free-living (n = 18) and rehabilitated (n = 9) pangolins. Hematology was performed using the Abaxis VetScan HM5 analyzer with manual differentials; clinical chemistry was performed using heparin plasma on the Abaxis VetScan VS2 and Cobas Integra 400 Plus analyzers. Hematology RIs were: RBC 3.88–8.31 × 1012/L, HGB 73–150 g/L, HCT 26–51%, MCV 59–72 fL, MCH 15.6– 21.4 pg, MCHC 257–325 g/L, RDW 14.3–19.1%, WBC 1.80–10.71 × 109/L. Vetscan VS2 clinical chemistry RIs were: albumin 27–41 g/L, ALP 26–100 U/L, ALT 25–307 U/L, amylase 267–826 U/L, bilirubin 4–10 μmol/L, calcium 2.1–2.2 mmol/L, globulin 21–55 g/L, glucose 3.8–10.0 mmol/L, phosphate 1.3–2.6 mmol/L, potassium 3.6–5.9 mmol/L, sodium 132–140 mmol/L total protein 52–84 g/L, and urea 5.3–11.4 mmol/L. RIs for creatinine were not calculated as analytical imprecision exceeded analytical performance goals. Cobas Integra clinical chemistry RIs were: albumin 22–33 g/L, ALP 20–104 U/L, ALT 17–291 U/L, amylase 466–1,533 U/L, bilirubin 1–14 μmol/L, calcium 2.0–2.4 mmol/L, creatinine <58 μmol/L, globulin 23–49 g/L, glucose 3.6–10.1 mmol/L, phosphate 1.0–2.2 mmol/L, potassium 3.1–5.8 mmol/L, sodium 137–150 mmol/L, total protein 47–72 g/L, and urea 6.0–12.5 mmol/L. There was significant bias between the two chemistry analyzers for several measurands. Differences were found for some analytes between free-living and rehabilitated animals, probably reflecting differences in nutrition and hydration. These are the first RIs generated for Temminck’s pangolin. These results will allow veterinarians to better determine pangolin health status, formulate optimal treatment plans and increase patient survival rates in this endangered species.The South African Veterinary Foundation, the Health and Welfare Sector Education and Training Authority of South Africa, dnata4good-UP’s Wild over Wildlife (WoW) program and Johannesburg Wildlife Veterinary Hospital.https://www.frontiersin.org/journals/veterinary-science#am2022Companion Animal Clinical StudiesParaclinical Science

Ampakine CX1942 attenuates opioid-induced respiratory depression and corrects the hypoxaemic effects of etorphine in immobilized goats (Capra hircus)

OBJECTIVES : To determine whether CX1942 reverses respiratory depression in etorphineimmobilized goats, and to compare its effects with those of doxapram hydrochloride. STUDY DESIGN : A prospective, crossover experimental trial conducted at 1753 m.a.s.l. ANIMALS : Eight adult female Boer goats (Capra hircus) with a mean ± standard deviationmass of 27.1 ± 1.6 kg. METHODS : Following immobilization with 0.1 mg kg−1 etorphine, goats received one of doxapram, CX1942 or sterile water intravenously, in random order in three trials. Respiratory rate, ventilation and tidal volume were measured continuously. Arterial blood samples for the determination of PaO2, PaCO2, pH and SaO2 were taken 2 minutes before and then at 5 minute intervals after drug administration for 25 minutes. RESULTS : Doxapram corrected etorphine-induced respiratory depression but also led to arousal and hyperventilation at 2 minutes after its administration, as indicated by the low PaCO2 (27.8 ± 4.5 mmHg) and ventilation of 5.32 ± 5.24 L minute−1 above pre-immobilization values. CX1942 improved respiratory parameters and corrected etorphine's hypoxaemic effects more gradually than did doxapram, with a more sustained improvement in PaO2 and SaO2 in comparison with the control trial. CONCLUSIONS : CX1942 attenuated opioid-induced respiratory depression and corrected the hypoxaemic effects of etorphine in immobilized goats. CLINICAL RELEVANCE : Ampakines potentially offer advantages over doxapram, a conventional treatment, in reversing etorphine-induced respiratory depression without causing unwanted side effects, particularly arousal, in immobilized animals.A Faculty Research Committee Grant, University of the Witwatersrand, awarded to AJH, and a Thuthuka grant from the National Research Foundation, South Africa, awarded to LCRM.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1467-29952017-09-30hb2017Paraclinical Science

Hypoxia following etorphine administration in goats (Capra hircus) results more from pulmonary hypertension than from hypoventilation

BACKGROUND : Etorphine, a potent opioid agonist, causes pulmonary hypertension and respiratory depression. Whether etorphine-induced pulmonary hypertension negatively influences pulmonary gas exchange and exacerbates the effects of ventilator depression and the resultant hypoxemia is unknown. To determine if these effects occurred we instrumented twelve goats with peripheral and pulmonary arterial catheters to measure systemic and pulmonary pressures before and after etorphine administration. Concurrent cardiopulmonary and arterial blood gas variables were also measured. RESULTS : Etorphine induced hypoventilation (55% reduction to 7.6 ± 2.7 L.min−1, F(11,44) = 15.2 P < 0.0001), hypoxia (40 mmHg, F(11,44) = 5.6 P < 0.0001) and pulmonary hypertension (mean 23 ± 6 mmHg, F(11,44) = 8.2 P < 0.0001). Within 6 min of etorphine administration hypoxia was twice (F(11,22) = 3.0 P < 0.05) as poor than that expected from etorphine-induced hypoventilation alone. This disparity appeared to result from a decrease in the movement of oxygen (gas exchange) across the alveoli membrane, as revealed by an increase in the P(A-a)O2 gradient (F(11,44) = 7.9 P < 0.0001). The P(A-a)O2 gradient was not correlated with global changes in the ventilation perfusion ratio (P = 0.28) but was correlated positively with the mean pulmonary artery pressure (P = 0.017, r2 = 0.97), indicating that pulmonary pressure played a significant role in altering pulmonary gas exchange. CONCLUSION : Attempts to alleviate etorphine-induced hypoxia therefore should focus not only on reversing the opioid-induced respiratory depression, but also on improving gas exchange by preventing etorphine-induced pulmonary hypertension.Faculty Research Committee Grant, University of the Witwatersrand, a Thuthuka Grant from the National Research Foundation, South Africa, and a Research Grant from the Wildlife Group of the South African Veterinary Association.http://www.biomedcentral.com/bmcvetreshb201

Comparison of three hematocrit measurement methods in the southern white rhinoceros (Ceratotherium simum simum)

BACKGROUND: Hematocrit (HCT) determination is an integral part of health and disease assessments in captive and wild white rhinoceroses. Several affordable automated hematology analyzers have been developed for in-clinic and field use and have the advantage of being able to measure a large number of additional measurands. However, the accuracy of these analyzers for rhinoceros HCT measurements has not yet been investigated. OBJECTIVES: We aimed to compare the HCT results generated by the EPOC portable analyzer system and the Abaxis VetScan HM5 with the gold standard of a manual packed cell volume (PCV) measured using the microhematocrit method. METHODS: Hematocrits were measured with the EPOC and the Abaxis VetScan HM5 (bovine setting) and compared with the PCVs of 69 white rhinoceros whole blood samples. Results were compared using Bland–Altman difference plots and PassingBablok regression analysis. A total allowable analytical error of 10% was set as the performance goal. RESULTS: A significant positive bias, with a mean of 7.7% for the EPOC and 17.9% for the Abaxis, was found compared with the manual PCV method. CONCLUSIONS: The allowable error goal of 10% was not exceeded with the EPOC analyzer. Although not analytically equivalent to the gold standard, the EPOC results could therefore be used as approximations in critical situations where manual measurements cannot be performed. The Abaxis exceeded this allowable error and overestimated HCTs in rhinoceroses. Therefore, method-specific reference intervals should be used.International Rhino Foundation; Veterinary Wildlife Services, Kruger National Park; Zebra Foundation for Veterinary Zoological Education; South African National Parks; University of Pretoriahttp://www.wileyonlinelibrary.com/journal/vcpdm2022Centre for Veterinary Wildlife StudiesCompanion Animal Clinical StudiesParaclinical Science

Efficacy of different cooling methods for capture-induced hyperthermia in antelope

The capture of wild animals is a stressful event which may cause a capture-induced hyperthermia, resulting in morbidity or mortality. We investigated whether various cooling techniques were effective at lowering the body temperature of hyperthermic animals. To achieve this, we implanted miniature temperature-sensitive data loggers into the abdomens of 12 blesbok (Damaliscus pygargus phillipsi ). Five animals were cooled by dousing with water of different temperatures (4°C, 17°C, 28°C) and fanning after dousing with 28°C water. Seven animals were cooled by ice-packs, a fine mist spray of 28°C water, intravenous (IV) infusion of one litre of 4°C saline solution or 28°C water-dousing. The body temperature after capture was significantly elevated to as high as 41°C to 42°C. Water-dousing interventions significantly decreased minimum body temperature but there was no difference in the minimumbody temperature reached or the magnitude of cooling between the different water temperatures or by the addition of fanning. The ice-packs also lowered body temperature, whereas mist spraying did not.The use of ice packs and dousing with water between 4°C and 28°C were the most effective techniques to reduce capture-induced hyperthermia in blesbok.Water-dousing,when done appropriately, is the most practical and effective method to cool an animal with capture-induced hyperthermia.This study was funded by the National Research Foundation, South Africa.http://www.sawma.co.za/am201

Reliability of the enterprise point-of-care (EPOC) blood analyzer's calculated arterial oxygen-hemoglobin saturation in immobilized white rhinoceroses (Ceratotherium simum)

CONCLUSIONS: The EPOC cSaO2 is unreliable and should not be used to monitor blood oxygenation in immobilized white rhinoceroses.Please read abstract in the article.Agriculture Sector Education Training Authority; Centre for Veterinary Wildlife Research; Department of Paraclinical Sciences, University of Pretoria; Department of Veterinary Tropical Diseases, University of Pretoria; Dnata Wild-over-Wildlife; South African Government Health and Welfare Sector Education and Training Authority; Wiederhold Foundation.http://www.wileyonlinelibrary.com/journal/vcpAnatomy and PhysiologyCentre for Veterinary Wildlife StudiesParaclinical SciencesProduction Animal Studie