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.

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.

High-Throughput Sequencing Reveals a Dynamic Bacterial Linkage between the Captive White Rhinoceros and Its Environment

Soil is an essential part of the animal habitat and has a large diversity of microbiota, while the animal body was colonized by a complex bacterial community; so far, the relationship between the animal host microbial community and the soil microbial ecosystem remains largely unknown. In this study, 15 white rhinoceros from three different captive grounds were selected and the bacterial community of the gut, skin, and environment of these rhinoceros were analyzed by 16S rRNA sequencing technology. Our results showed that Firmicutes and Bacteroidota were the predominant phyla in the gut microbiome, whereas skin and environment samples share similar microbiome profiles and are dominated by the phyla of Actinobacteriota, Chloroflexi, and Proteobacteria. Although the bacterial composition of the gut differs from that of the skin and environment, the Venn diagrams showed that there were 22 phyla and 186 genera shared by all the gut, skin, and environmental microbes in white rhinoceroses. Further cooccurrence network analysis indicated a bacterial linkage based on a complex interaction was established by the bacterial communities from the three different niches. In addition, beta diversity and bacterial composition analysis showed that both the captive ground and host ages induced shifts in the microbial composition of white rhinoceroses, which suggested that the bacterial linkage between the captive white rhinoceros and its environment is dynamic. Overall, our data contribute to a better understanding of the bacterial community of the captive white rhinoceros, especially for the relationship between the environment and animal bacterial communities. IMPORTANCE The white rhinoceros is one of the world's most endangered mammals. The microbial population plays a key role in animal health and welfare; however, studies regarding the microbial communities of the white rhinoceros are relatively limited. As the white rhinoceros has a common behavior of mud baths and thus is in direct contact with the environment, a relationship between the animal microbial community and the soil microbial ecosystem appears possible, but it remains unclear. Here, we described the characteristics and interaction of bacterial communities of the white rhinoceros in three different niches, including gut, skin, and environment. We also analyzed the effects of captive ground and age on the composition of the bacterial community. Our findings highlighted the relationship among the three niches and may have important implications for the conservation and management of this threatened species.

EFFECT OF BOMA CONFINEMENT ON HEMATOLOGIC AND BIOCHEMICAL VALUES IN FREE-RANGING WHITE RHINOCEROS (CERATOTHERIUM SIMUM) IN KRUGER NATIONAL PARK, SOUTH AFRICA

Boma adaptation is an important component of rhinoceros translocations to allow transition to new diets, restricted space, and quarantine for disease screening. However, up to 20% of recently captured white rhinoceros (Ceratotherium simum) do not adjust to captivity, resulting in early release or even death. The causes and physiologic consequences of maladaptation to boma confinement are poorly understood. The aim of this investigation was to evaluate hematologic and serum biochemical changes in maladapted rhinoceros compared to animals that adapted under the same boma conditions. Ninety-six white rhinoceros were captured between 2009 and 2011 in Kruger National Park, South Africa and placed in bomas prior to translocation. Weight, complete blood count, and serum biochemical panel results were recorded when rhinoceros were placed in the boma and repeated on the day of release. In this study, the mean duration of boma confinement for maladapted white rhinoceros was 13 d (range 8-16 d) compared to 89.9 d (range 39-187 d) for adapted animals. Mean weight loss between capture and release was significantly greater in maladapted rhinoceros (224.0 versus 65.9 kgs; P<0.001). Although adapted rhinoceros had statistically significant changes in some hematologic and biochemical values, most were not considered clinically relevant. In contrast, the maladapted rhinoceros had significant changes at the time of early release from the boma, including evidence of leukocytosis with left shift, lymphopenia, eosinopenia, decreased red blood cell count and hematocrit, increased serum creatine kinase, and decreased serum calcium, phosphorus, and magnesium values. Along with loss of body condition, these findings were consistent with a stress-associated catabolic response. These changes occurred in the first 2 wk of confinement, and the results provide a foundation for evaluating adaptation in white rhinoceros. Future studies should focus on factors that improve adaptation and welfare of recently confined free-ranging white rhinoceros.

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.

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.

A Model for Dental Age Verification Using Ultrastructural Imaging for Modern and Fossil Representatives of the Rhinocerotidae Family

The analyses were performed on a right third premolar (P₃) of a white rhinoceros female (Ceratotherium simum, Burchell 1817). The specimen was born in captivity at London Zoo (Zoological Society of London), then in the 1970s transferred to Kiev Zoo (Peremohy Avenue), Ukraine, and was kept there until it died at a documented chronological age of 48 years. The female died because of its age, which indicates it was kept in good conditions adequate to the requirements of this species. Photographs and micrographs with radiological documentation were taken on the said tooth. Its structural characteristics were determined, and on the occlusal surface areas and points of anatomical constitution of its crown were identified. The tooth was also histologically evaluated via sections taken horizontally in a mesial-distal plane through the crown, horizontally in a mesial-distal plane through the coronal portion of the root, and longitudinally in a lingual-buccal plane through the crown and the root. Preparations with ground sections were made and observed in white, polarized, and reflected light. In the subsequent stage X-ray and SEM imaging has also been used, for analysis of the distribution of annual growth layers of mineralized dental tissues of cement and dentine, counted from the root canal center to the buccal surface. An attempt was also made to confirm the annual season in which the animal died, based on cement growth lines. It was observed that the growth lines were visible in all the analyzed sections, in dentine and cement. In the cement, the lines were relatively few and did not represent the attested age of the animal. The analysis of the coloration of the cement lines indicated that the animal was regularly fed a diet that was not seasonally differentiated. From the X-ray examination comes a conclusion that the animal did not suffer from periodontal diseases. Visible growth lines were observed on the dentine. On the horizontal section through the crown growth lines in the dentine were few and unclear. On the longitudinal section, both on the caudal and rostral roots, these lines were clearly visible and much more numerous than expected considering the known age of the animal, as more than 50 were counted. On horizontal sections through the upper part of both roots, distinct growth lines were observed in the dentine, and their number-48 for both roots-corresponded precisely to the age of the animal. The results of our study indicate that this method has significant potential for application to verify the age at death for modern and fossil representatives of rhinoceros.

Rehabilitation, Translocation and Post-Release Observations

White rhinoceros (Ceratotherium simum) is one of the most famous victims of poachers in Africa. One of the methods for dealing with decreasing rhino numbers is rehabilitating wounded and/or orphaned animals to successfully release them back into the wild. The status of rescued animal differs among individuals, but general procedures must be established and constantly improved. This study presents the history of successful release of three orphaned white rhino females; rehabilitated for 15 months in Wildlife Rehabilitation Centre in a private game reserve in South Africa. Female A was three years old, female B was one year old and the youngest female was three months old on arrival. The animals were rehabilitated together despite the differences in their age and size, with particular attention paid to keeping them as wild as possible. After being weaned and becoming old enough to go back to the wild, they were released at a distance from the rehabilitation centre, which required immobilization and translocation. Since the rhinos were released, they have been successfully living in the wild. All procedures used in this study proved to be sufficient for preparing the animals for life in the wild and can be recommended for other centres.

IDENTIFICATION OF A NASOCONCHAL PARANASAL SINUS IN THE WHITE RHINOCEROS ( CERATOTHERIUM SIMUM)

  African rhinoceros are poached for their horns using indiscriminate and aggressive methods. Rhinoceros that survive these attacks often have severe facial trauma, and treatment is limited by a lack of understanding and published information of the normal anatomy. This study was performed to investigate and describe the anatomy of the most commonly injured area of the head of the white rhinoceros ( Ceratotherium simum). Two white rhinoceros cadaver heads were imaged by computed tomography and grossly dissected. A combined dorsal conchal sinus and nasal sinus (named the nasoconchal sinus) was identified and confirmed to be readily exposed by horn removal. The nasoconchal sinus communicates via a relatively large opening with the middle nasal meatus of the nasal cavity. Awareness of the combined sinus space and its single communicating pathway will assist with accurate assessment and treatment of trauma to the dorsal facial region of the white rhinoceros.

Ovulation induction in anovulatory southern white rhinoceros (Ceratotherium simum simum) without altrenogest

All species in the extant Rhinocerotidae family are experiencing increased threats in the wild, making captive populations essential genetic reservoirs for species survival. However, managed species face distinct challenges in captivity, resulting in populations that are not self-sustaining. Captive southern white rhinoceros (Ceratotherium simum simum) have low reproductive rates and presumed acyclicity is common among females. Although many females fail to ovulate, follicle growth may occur and ovulation can be hormonally induced. Female southern white rhino (n = 6), housed as a bachelorette group, were determined to be ovulatory (n = 1) or anovulatory (n = 5) by serial ultrasound and fecal progestagen analysis. When follicles reached pre-ovulatory size (~35 mm), females (n = 4) were induced to ovulate in 11 trials with a GnRH analog (4.5 mg, SucroMate™) via single intramuscular injection. Nine trials resulted in ovulation (81.8%), all between 36 and 48 hours post-treatment. Ovulations were confirmed by progestagen elevation above baseline coincident with visualization of a corpus luteum (CL). Luteal phases were characterized as short (<50 days) or long (≥50 days). Between short and long cycles, only the number of days of progestagen above baseline was significantly different (P < 0.05), while days with visible luteal structures was not significant (P = 0.11). Both cycle types were observed following both spontaneous and induced ovulations. Furthermore, we showed that longer cycle lengths do not necessarily indicate early pregnancy loss as none of the females were bred or inseminated during the study. While anovulation is common in the southern white rhino captive population, ovulation induction can be achieved efficiently and predictably for use in conjunction with artificial insemination or to facilitate natural breeding. This information will lead to more efficient use of assisted reproductive technologies to overcome reproductive challenges in this species and to generate genetically healthy captive populations as a hedge against extinction.

PHARMACOKINETICS OF A SINGLE ORAL DOSE OF FLUNIXIN MEGLUMINE IN THE WHITE RHINOCEROS (CERATOTHERIUM SIMUM)

Flunixin meglumine, a nonsteroidal anti-inflammatory medication, has been used in rhinoceros species at doses extrapolated from domestic animals. There is increasing evidence to suggest significant variations exist in metabolism of drugs in exotic species. Due to the differences in drug metabolism, dose extrapolation from domestic animals may not be appropriate for exotic species. The objective of this study was to investigate the pharmacokinetics of flunixin meglumine in five white rhinoceroses (Ceratotherium simum) administered a single (1 mg/kg) oral dose of a commercial equine flunixin meglumine paste. Concentrations of flunixin and its metabolite 5-OH flunixin were analyzed, and pharmacokinetic parameters were estimated for each animal. Mean observed plasma concentrations peaked at 1,207 ± 601 ng/ml and occurred at 3 ± 1 hr. The geometric mean of the apparent elimination half-life after oral administration was 8.3 ± 1.2 hr. This data suggests that flunixin meglumine appears to be slowly metabolized or slowly absorbed in this species. No adverse clinical effects were observed during the study period. A single dose of 1 mg/kg appears safe for use in the white rhinoceros. Multidose studies are needed to determine if plasma accumulation of flunixin meglumine occurs and to evaluate safety.

Conservation of White Rhinoceroses Threatened by Bovine Tuberculosis, South Africa, 2016-2017

During 2016–2017, when Kruger National Park, South Africa, was under quarantine to limit bovine tuberculosis spread, we examined 35 white and 5 black rhinoceroses for infection. We found 6 infected white rhinoceroses during times of nutritional stress. Further research on Mycobacterium bovis pathogenesis in white rhinoceroses is needed.

A commercial ELISA for detection of interferon gamma in white rhinoceros

Bovine tuberculosis (bTB), caused by Mycobacterium bovis, is endemic in Kruger National Park, South Africa, home to the largest population of white rhinoceros (Ceratotherium simum) in the world. In 2016, the first cases of naturally occurring bTB were reported in white rhinoceros; however, there is a lack of understanding of infection and disease process in this species. Prevention and control of transmission depends on the availability of accurate tools to detect M. bovis infection. Interferon gamma (IFN-γ) assays are a reliable detection method for TB in other animal species, and studies have indicated that these tests can be used in white rhinoceros. We sought to screen and optimize a commercial IFN-γ enzyme-linked immunosorbent assay (ELISA) to detect endogenous white rhinoceros IFN-γ in mitogen-stimulated whole blood as a basis for developing a test for M. bovis infection. Optimizations included identifying ELISA antibodies and determining the effect of sample matrix, ELISA plate incubation temperature, ELISA linearity, assay reproducibility, and the assay's limit of quantification. The optimized assay employed an equine IFN-γ antibody pair that was used to create a commercial ELISA kit. This ELISA had a linear response to recombinant equine and endogenous rhinoceros IFN-γ (range: 7.8-125 pg/mL). When incubated at 37°C, the ELISA was highly reproducible, with an optimal recovery and a low limit of quantification, indicating that the Mabtech equine IFN-γ ELISA^PRO kit is a robust assay for measuring white rhinoceros IFN-γ.

Pharmacokinetics of an intravenous and oral dose of enrofloxacin in white rhinoceros (Ceratotherium simum)

South Africa currently loses over 1000 white rhinoceros (Ceratotherium simum) each year to poaching incidents, and numbers of severely injured victims found alive have increased dramatically. However, little is known about the antimicrobial treatment of wounds in rhinoceros. This study explores the applicability of enrofloxacin for rhinoceros through the use of pharmacokinetic-pharmacodynamic modelling. The pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin were evaluated in five white rhinoceros after intravenous (i.v.) and after successive i.v. and oral administration of 12.5 mg/kg enrofloxacin. After i.v. administration, the half-life, area under the curve (AUC_tot ), clearance and the volume of distribution were 12.41 ± 2.62 hr, 64.5 ± 14.44 μg ml^-1  hr^-1 , 0.19 ± 0.04 L h^-1  kg^-1 , and 2.09 ± 0.48 L/kg, respectively. Ciprofloxacin reached 26.42 ± 0.05% of the enrofloxacin plasma concentration. After combined i.v. and oral enrofloxacin administration oral bioavailability was 33.30 ± 38.33%. After i.v. enrofloxacin administration, the efficacy marker AUC₂₄ : MIC exceeded the recommended ratio of 125 against bacteria with an MIC of 0.5 μg/mL. Subsequent intravenous and oral enrofloxacin administration resulted in a low Cmax: MIC ratio of 3.1. The results suggest that intravenous administration of injectable enrofloxacin could be a useful drug with bactericidal properties in rhinoceros. However, the maintenance of the drug plasma concentration at a bactericidal level through additional per os administration of 10% oral solution of enrofloxacin indicated for the use in chickens, turkeys and rabbits does not seem feasible.

Contrasting evolutionary history, anthropogenic declines and genetic contact in the northern and southern white rhinoceros (Ceratotherium simum)

The white rhinoceros (Ceratotherium simum) has a discontinuous African distribution, which is limited by the extent of sub-Saharan grasslands. The southern population (SWR) declined to its lowest number around the turn of the nineteenth century, but recovered to become the world's most numerous rhinoceros. In contrast, the northern population (NWR) was common during much of the twentieth century, declining rapidly since the 1970s, and now only two post-reproductive individuals remain. Despite this species's conservation status, it lacks a genetic assessment of its demographic history. We therefore sampled 232 individuals from extant and museum sources and analysed ten microsatellite loci and the mtDNA control region. Both marker types reliably partitioned the species into SWR and NWR, with moderate nuclear genetic diversity and only three mtDNA haplotypes for the species, including historical samples. We detected ancient interglacial demographic declines in both populations. Both populations may also have been affected by recent declines associated with the colonial expansion for the SWR, and with the much earlier Bantu migrations for the NWR. Finally, we detected post-divergence secondary contact between NWR and SWR, possibly occurring as recently as the last glacial maximum. These results suggest the species was subjected to regular periods of fragmentation and low genetic diversity, which may have been replenished upon secondary contact during glacial periods. The species's current situation thus reflects prehistoric declines that were exacerbated by anthropogenic pressure associated with the rise of late Holocene technological advancement in Africa. Importantly, secondary contact suggests a potentially positive outcome for a hybrid rescue conservation strategy, although further genome-wide data are desirable to corroborate these results.

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.

A study of the pharmacokinetics and thromboxane inhibitory activity of a single intramuscular dose of carprofen as a means to establish its potential use as an analgesic drug in white rhinoceros

The alleviation of pain and prevention of suffering are key aspects of animal welfare. Unfortunately, analgesic drugs are not available for all species. White rhinoceros (Ceratotherium simum), representing one of such species, which survive poaching attempts inflicted with severe facial injuries and gunshot wounds, nonetheless require analgesic support. To improve treatment conditions, this study explored the use of carprofen for the treatment of pain and inflammation in white rhinoceros. The pharmacokinetics of 1 mg/kg intramuscular carprofen was evaluated in six healthy white rhinoceros. The half-life of λ_z and mean residence time was 105.71 ± 15.67 and 155.01 ± 22.46 hr, respectively. The area under the curve and the maximum carprofen concentration were 904.61 ± 110.78 μg ml^-1  hr^-1 and 5.77 ± 0.63 μg/ml, respectively. Plasma TXB₂ inhibition demonstrated anti-inflammatory properties and indicated that carprofen may be effective for a minimum of 48 hr in most animals. With its long half-life further indicating that a single dose could be effective for several days, we suggest that carprofen may be a useful drug for the treatment of white rhinoceros.

EVALUATION OF BLOOD GAS VALUES IN ANESTHETIZED SOUTHERN WHITE RHINOCEROS ( CERATOTHERIUM SIMUM) VENTILATED WITH A NOVEL DEMAND VENTILATOR IN A ZOOLOGICAL PARK SETTING

Rhinoceros conservation efforts are essential to the survival of the species. One such effort is focused on using advanced reproductive technologies to produce viable northern white rhinoceros ( Ceratotherium simum cottoni) embryos for implantation into southern white rhinoceros ( Ceratotherium simum simum) surrogates. Anesthesia may be required to facilitate necessary procedures in these surrogate rhinoceros, but commonly reported side effects including hypercapnia and hypoxemia limit anesthetic recumbency time due to animal safety concerns. Although many interventions have been attempted, success in improving these physiologic parameters to date is mixed. The objective of this report is to describe arterial pH (pHa), blood gas (PaO₂ and PaCO₂), bicarbonate, base excess, lactate, and cardiovascular (heart rate, direct arterial blood pressure) values recorded in seven intubated and ventilated female southern white rhinoceros anesthetized for reproductive examinations in a zoological park setting. Anesthetic induction was accomplished using etorphine, medetomidine, butorphanol, and midazolam. The primary hypotheses were that PaO₂ and PaCO₂ would improve after intubation and mechanical ventilation. Induction and recovery observations were also summarized. Physiologic and laboratory data were analyzed using a mixed linear regression model using ranks. Statistical significance was set at P < 0.05. The PaO₂ increased significantly ( P < 0.001) following ventilation from a median value of 58 (range, 38-67) to 123 (range, 42-184) mm Hg. The PaCO₂ significantly ( P = 0.003) decreased from 63 (range, 55-73) to 52 (range, 30-75) mm Hg, with a corresponding improvement ( P = 0.068) in pHa from 7.33 (7.25-7.34) to 7.37 (7.24-7.58) units. Intubation and ventilation improve respiratory parameters and may facilitate safe prolongation of anesthetic duration in white rhinoceros.

The Kinetics of the Humoral and Interferon-Gamma Immune Responses to Experimental Mycobacterium bovis Infection in the White Rhinoceros (Ceratotherium simum)

Mycobacterium bovis is the cause of tuberculosis (TB) in a wide range of species, including white rhinoceroses (Ceratotherium simum). Control of the disease relies on the indirect detection of infection by measuring pathogen-specific responses of the host. These are poorly described in the white rhinoceros and this study aimed to characterize the kinetics of immune responses to M. bovis infection in this species. Three white rhinoceroses were infected with M. bovis and their immune sensitization to this pathogen was measured monthly for 20 months. Cell-mediated immunity was characterized in whole blood samples as the differential release of interferon-gamma in response to bovine purified protein derivative (PPDb) and avian PPD (PPDa) as well as the release of this cytokine in response to the M. bovis proteins 6 kDa early secretory antigenic target (ESAT-6)/10 kDa culture filtrate protein (CFP-10). Humoral immunity was quantified as the occurrence or the magnitude of antibody responses to the proteins ESAT-6/CFP-10, MPB83, MPB83/MPB70, and PPDb. The magnitude and duration of immune reactivity varied between individuals; however, peak responses to these antigens were detected in all animals circa 5-9 months postinfection. Hereafter, they gradually declined to low or undetectable levels. This pattern was associated with limited TB-like pathology at postmortem examination and appeared to reflect the control of M. bovis infection following the development of the adaptive immune response. Measurement of these markers could prove useful for assessing the disease status or treatment of naturally infected animals. Moreover, immune responses identified in this study might be used to detect infection; however, further studies are required to confirm their diagnostic utility.

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.

SOLITARY OSTEOCHONDROMA OF THE DISTAL THIRD METACARPAL BONE IN A TWO-YEAR-OLD WHITE RHINOCEROS (CERATOTHERIUM SIMUM)

A privately owned, 2-yr-old, 600-kg, intact male white rhinoceros presented with a progressive lameness of the left front limb of 8-mo duration with a focal swelling situated over the dorsoproximal aspect of third metacarpophalangeal joint. Radiographs of the affected limb showed a 28 mm × 26 mm exostosis at the dorsodistal third metacarpal bone. Surgical removal of the exostosis was performed and histopathologic examination confirmed a solitary osteochondroma. A follow-up examination 1 yr after surgical removal revealed total abolishment of the left front limb lameness. This report documents the first diagnosis and treatment of solitary osteochondroma in a white rhinoceros.

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.

Acute hepatic necrosis and death in a subadult southern white rhinoceros (Ceratotherium simum) associated with exposure to sterigmatocystin in forage contaminated with Aspergillus nidulans

A young male southern white rhinoceros (Ceratotherium simum), which was resident in a zoo as part of a multi-rhinoceros group, died suddenly. Necropsy and histopathological findings supported a diagnosis of death from acute hepatic necrosis. The microscopic distribution of liver lesions was suggestive of hepatotoxicosis. Further investigation revealed potential exposure to a mycotoxin, sterigmatocystin, present in spoiled lucerne hay contaminated with Aspergillus nidulans. It was concluded that mycotoxicosis was the likely cause of the hepatic necrosis and death in this animal.

A SCORING SYSTEM TO IMPROVE DECISION MAKING AND OUTCOMES IN THE ADAPTATION OF RECENTLY CAPTURED WHITE RHINOCEROSES (CERATOTHERIUM SIMUM) TO CAPTIVITY

Ninety-four subadult and adult white rhinoceroses (Ceratotherium simum) were captured between February and October, 2009-11, in Kruger National Park and placed in holding bomas prior to translocation to other locations within South Africa. A simple three-category system was developed based on appetite, fecal consistency/volume, and behavior to assess adaptation to bomas. Individual animal and group daily median scores were used to determine trends and when rhinoceroses had successfully adapted to the boma. Seventeen rhinoceroses did not adapt to boma confinement, and 16 were released (1 mortality). No differences in boma scores were observed between rhinoceroses that adapted and those that did not, until day 8, when the first significant differences were observed (adapted score=13 versus nonadapted score=10). The time to reach a boma score determined as successful adaptation (median 19 d) matched subjective observations, which was approximately 3 wk for most rhinoceroses. Unsuccessful adaptation was indicated by an individual boma score of less than 15, typically during the first 2 wk, or a declining trend in scores within the first 7-14 d. This scoring system can be used for most locations and could also be easily adapted to other areas in which rhinoceroses are held in captivity. This tool also provides important information for assessing welfare in newly captured rhinoceroses.

CLINICAL MANAGEMENT OF BILATERAL CUTANEOUS SQUAMOUS CELL CARCINOMA OF THE HIND FEET PADS IN A SOUTHERN WHITE RHINOCEROS (CERATOTHERIUM SIMUM SIMUM)

The current report describes the temporary regression, due to intensive symptomatic treatment, of ulcerative skin lesions caused by squamous cell carcinoma in a white rhinoceros. A captive, 40-yr-old southern white rhinoceros (Ceratotherium simum simum) developed profound, ulcerative skin lesions on the pads of both hind feet. At the peak of the disease, at least one quarter of the pads was affected. A diagnosis of squamous cell carcinoma was made via biopsy. Treatment included anti-inflammatory drugs, antibiotics, and local care. The lesions regressed on both feet until they seemed clinically healed. It was presumed that long-term, anti-inflammatory treatment and local bandaging had induced the temporary regression of the lesions. Two years later, however, a small ulcerative lesion reappeared on one pad and post mortem examination confirmed that the carcinoma was also histologically present in the clinically intact tissue. No metastasis was found and computed tomography showed normal digital bones.

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.

Baseline Hematologic Results for Free-ranging White Rhinoceros (Ceratotherium simum) in Kruger National Park, South Africa

Complete blood counts (n = 115) and red blood cell analytes (n = 80) were assessed in free-ranging white rhinoceros (Ceratotherium simum) from Kruger National Park (KNP), South Africa. Blood was collected from healthy animals immobilized between February and September 2009-11 for management purposes. Our objectives were to establish baselines for KNP's white rhinoceros population and to compare results based on sex and age group. Significant differences in total white blood cells, total eosinophils, and hemoglobin were found between adult and subadult rhinoceros. Female rhinoceros had significantly higher total white blood cells and lower hemoglobin compared with males. Hematologic analytes were similar to those published for other rhinoceros populations, although the impact of capture and sampling methods, nutritional status, and habitat should be considered when comparing data. This baseline hematology for healthy free-ranging white rhinoceros in KNP may be useful in assessing health status for translocation and medical interventions, including treatment of poaching cases.

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.

Towards establishing a rhinoceros-specific interferon-gamma (IFN-γ) assay for diagnosis of tuberculosis

Mycobacterium bovis is the causal agent of bovine tuberculosis (BTB), with a diverse host range, extending from livestock to domestic and captive wild animals as well as free-ranging wildlife species. In South Africa, BTB is endemic in the Kruger National Park (KNP) and the Hluluwe iMfolozi National Park (HiP), where the high prevalence of M. bovis infections in buffalo herds has led to infection of a number of wildlife species. This has raised concerns about the spillover into the rhinoceros population, a species known to be susceptible to both M. bovis and Mycobacterium tuberculosis, jeopardizing breeding and relocation projects that serve to conserve and protect this species. In view of the advantages of the interferon-gamma (IFN-γ) assay in the diagnosis of BTB in a variety of species worldwide, such an assay has been developed for rhinoceroses by Morar and co-workers in 2007. In this study, this assay was optimized using recombinant eukaryotic rhinoceros IFN-γ and the lower detection limit was calculated to be 0.5 ng/ml. Subsequently, assessing the detection of native rhinoceros IFN-γ protein in whole-blood samples revealed stimulation with each of the mitogens: pokeweed (PWM), phytohaemagglutinin (PHA) & phorbol 12-myristate 13-acetate and calcium ionophore (PMA/CaI), though most prominently with the latter two. In addition, samples collected from 52 clinically healthy rhinoceroses, of presumed negative BTB status, from two different areas in South Africa were used to determine the cut-off value for a negative test result. This was calculated to be 0.10 (OD490 nm ) and as determined in this study is a preliminary recommendation based on IFN-γ responses observed in samples from BTB-free rhinoceroses only.