A Comparison of Hematological, Immunological, and Stress Responses to Capture and Transport in Wild White Rhinoceros Bulls (Ceratotherium simum simum) Supplemented With Azaperone or Midazolam

Dehorning Does Not Alter the Stress Response in Southern White Rhinoceroses (Ceratotherium simum simum) during Transport: A Preliminary Investigation

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 μg/kg) and five dehorned and seven nondehorned rhinoceroses with midazolam (64.61±9.28 μg/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, β-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.

Immobilization of Captive Kulans (Equus hemionus kulan) Without Using Ultrapotent Opioids

Etorphine is widely used in zoological medicine for the immobilization of large herbivores. All reported immobilization protocols for kulans use etorphine as the primary immobilizing agent. However, etorphine can trigger severe side effects and is highly toxic for humans, its availability is occasionally limited for use in wildlife medicine. Therefore, two different alpha-2 agonist-based protocols for the general anesthesia of kulans were investigated and compared with the standard etorphine immobilization. In total, 21 immobilizations were performed within the scope of routine husbandry management at the Serengeti-Park Hodenhagen. Kulans were darted using a ketamine–medetomidine–midazolam–butorphanol (KMMB) protocol (n = 8, treatment group (TG) 1), a tiletamine–zolazepam–medetomidine–butorphanol (TZMB) protocol (n = 7, treatment group (TG) 2), or an etorphine–acepromazine–detomidine–butorphanol (EADB) protocol (n = 6, control group). Vital parameters included heart rate, respiratory rate, arterial blood pressure (invasive), end tidal CO₂ (etCO₂), electromyography and core body temperature, which were all assessed every 10 min. For blood gas analysis, arterial samples were collected 15, 30, 45 and 60 min after induction. Subjective measures of quality and efficacy included quality of induction, immobilization, and recovery. Time to recumbency was longer for TG 1 (9.00 ± 1.67 min) and TG 2 (10.43 ± 1.79 min) compared to the induction times in the control group (5.33 ± 1.93 min). Treatment group protocols resulted in excellent muscle relaxation, normoxemia and normocapnia. Lower pulse rates combined with systolic arterial hypertension were detected in the alpha-2 agonist-based protocols. However, only in TZMB-immobilized kulans, sustained severe systolic arterial hypertension was observed, with significantly higher values than in the TG 1 and the normotensive control group. At 60 min following induction, medetomidine and detomidine were antagonized with atipamezole IM (5 mg/mg medetomidine or 2 mg/mg detomidine), etorphine and butorphanol with naltrexone IV (2 mg/mg butorphanol or 50 mg/mg etorphine), and midazolam and zolazepam with flumazenil IV (0.3 mg per animal). All three combinations provided smooth and rapid recoveries. To conclude, the investigated treatment protocols (KMMB and TZMB) provided a safe and efficient general anesthesia in kulans with significantly better muscle relaxation, higher respiration rates and improved arterial oxygenation compared with the immobilizations of the control group. However, the control group (EADB) showed faster recoveries. Therefore, EADB is recommended for ultra-short immobilizations (e.g., microchipping and collaring), especially with free-ranging kulans where individual recovery is uncertain, whereas the investigated treatment protocols are recommended for prolonged medical procedures on captive kulans.

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.

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 Passing‐Bablok 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.

The contribution of sleep to the neuroendocrine regulation of rhythms in human leukocyte traffic

Twenty-four-hour rhythms in immune parameters and functions are robustly observed phenomena in biomedicine. Here, we summarize the important role of sleep and associated parameters on the neuroendocrine regulation of rhythmic immune cell traffic to different compartments, with a focus on human leukocyte subsets. Blood counts of "stress leukocytes" such as neutrophils, natural killer cells, and highly differentiated cytotoxic T cells present a rhythm with a daytime peak. It is mediated by morning increases in epinephrine, leading to a mobilization of these cells out of the marginal pool into the circulation following a fast, beta2-adrenoceptor-dependent inhibition of adhesive integrin signaling. In contrast, other subsets such as eosinophils and less differentiated T cells are redirected out of the circulation during daytime. This is mediated by stimulation of the glucocorticoid receptor following morning increases in cortisol, which promotes CXCR4-driven leukocyte traffic, presumably to the bone marrow. Hence, these cells show highest numbers in blood at night when cortisol levels are lowest. Sleep adds to these rhythms by actively suppressing epinephrine and cortisol levels. In addition, sleep increases levels of immunosupportive mediators, such as aldosterone and growth hormone, which are assumed to promote T-cell homing to lymph nodes, thus facilitating the initiation of adaptive immune responses during sleep. Taken together, sleep-wake behavior with its unique neuroendocrine changes regulates human leukocyte traffic with overall immunosupportive effects during nocturnal sleep. In contrast, integrin de-activation and redistribution of certain leukocytes to the bone marrow during daytime activity presumably serves immune regulation and homeostasis.

Physiological Effects of Azaperone and Midazolam On Netgun-Captured Mule Deer (Odocoileus hemionus)

Netgun capture is a commonly used capture method for mule deer (Odocoileus hemionus) in North America. Mortalities during netgun captures are generally low, and most often caused by direct trauma and occasionally fatal capture myopathy. Capture is a stressful event for a wild animal, and subclinical capture myopathy is difficult to measure. The use of tranquilizers during netgun capture is not widespread. We compared physiologic variables from 250 netgun-captured deer (57 males and 193 females) that did or did not receive midazolam and azaperone (mean, 0.14 mg/kg; SD, 0.02 mg/kg; range, 0.08-0.21 mg/kg) at time of capture and before transporting to a processing location, with the goal of evaluating whether drug administration would improve or worsen the physiologic state of the animal. Deer were captured in association with management activities between December 2018 and March 2020, with 132 deer receiving midazolam and azaperone at time of capture. Variables recorded included chase times, time from capture to arrival at the processing location, time from capture to release, serial rectal temperatures, heart rates, respiratory rates, body condition, age, sex, O2 administration, creatine kinase, aspartate aminotransferase, packed cell volume, red blood cell concentration, and hemoglobin, as well as serial venous pH, pCO2, HCO3-, and base excess (BE). All animals were collared with GPS tracking devices and monitored after release. There was no difference in survival after capture between deer that did or did not receive midazolam and azaperone. All animals experienced severe metabolic lactic acidosis, which generally worsened with increasing chase time, highlighting the critical importance of limiting chase times during captures. Drug administration did not influence the degree of metabolic acidosis; however, it appeared to have a favorable effect on several stress-related indices, including rectal temperature, heart rate, respiratory rate, and packed cell volume.

Muscle tremors observed in white rhinoceroses immobilised with either etorphine-azaperone or etorphine-midazolam: An initial study

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.

Protein Electrophoresis and Haptoglobin Values for Captive Bongo (Tragelaphus eurycerus)

Serum samples collected from 37 clinically normal bongo (Tragelaphus eurycerus) and 13 abnormal bongo were tested using assays for acute-phase proteins (APPs) and by protein electrophoresis. Abnormal bongo samples (n = 27) had significantly higher levels of fibrinogen (FIB) (p < 0.001) and trending but not significantly increased haptoglobin (HP) (p = 0.07) vs. samples from normal bongo (n = 37). There were no significant differences in values for total white blood cell counts or for any of the fractions determined by protein electrophoresis. Clinically normal female bongo (n = 19) had significantly lower levels of FIB than normal males (n = 18) (p = 0.014), and this observation was also made with samples from the clinically abnormal group (p = 0.004). Many weak to moderate significant correlations were observed with increasing age, including increased globulins, FIB, and HP and decreased albumin-to-globulin (A/G) ratio and albumin. In clinical cases reviewed in this study, mild HP changes categorized this reactant as a minor APP, which contrasts with the major APP classification of HP in the related species of the cow. The preliminary data indicate that the quantitation of these APPs may offer value in assessing inflammation in this species, but additional studies are needed.