Penciclovir pharmacokinetics after oral and rectal administration of famciclovir in African elephants (Loxodonta africana) shows that effective concentrations can be achieved from rectal administration, despite lower absorption.

OBJECTIVE: To evaluate the pharmacokinetics of famciclovir and its metabolite penciclovir following a single dose administered orally and rectally in African elephants (Loxodonta africana). ANIMALS: 15 African elephants (6 males and 9 females) of various ages. METHODS: Famciclovir (15 mg/kg) was administered orally or per rectum once, with at least a three-week washout period between administrations. Blood was collected at 13 different timepoints per administration for 6 elephants, occurring between February and March 2020. An additional 9 elephants were sampled at variable timepoints per administration utilizing a sparse sampling design between July 2020 and January 2021. Plasma famciclovir and penciclovir levels were measured via HPLC and fluorescence detection. Pharmacokinetic analysis was completed in the summer of 2021 using noncompartmental analysis and nonlinear mixed-effects modeling. RESULTS: Famciclovir was not detected in any sample, suggesting complete metabolism. Key pharmacokinetic parameters for penciclovir following oral administration were time to maximum concentration (tmax; 2.12 hours), area under the concentration-versus-time curve (AUC; 33.93 µg·h/mL), maximum observed concentration (Cmax; 3.73 µg/mL), and absorption half-life (t1/2; 0.65 hours). Following rectal administration, the values were: tmax, 0.65 hours; AUC, 15.62 µg·h/mL; Cmax, 2.52 µg/mL; and absorption t1/2, 0.13 hours. CONCLUSIONS: Famciclovir was rapidly metabolized to penciclovir. Oral administration resulted in slower absorption but higher maximum plasma concentration and higher AUC compared to rectal administration. CLINICAL RELEVANCE: African elephants administered famciclovir via oral and rectal routes resulted in measurable serum penciclovir, and these findings may be utilized by clinicians treating viral infections in this species.

BIOLOGICAL VARIATION OF HEMATOLOGY PARAMETERS AND CLINICAL APPLICATION IN AFRICAN ELEPHANTS (LOXODONTA AFRICANA).

Detailed knowledge of biological variation can facilitate accurate interpretation of clinical pathology parameters. A recent biological variation study in Asian elephants (Elephas maximus) found that hematology parameters had high individuality, which suggests that population-derived reference intervals may be an insensitive diagnostic tool. In elephant medicine, sensitive hematology-related diagnostics are crucial for clinical decision-making, particularly in elephants at risk for elephant endotheliotropic herpesvirus hemorrhagic disease (EEHV-HD). The objective of this study was to assess biological variation of hematology parameters in African elephants to determine whether population-derived reference intervals are a sensitive diagnostic tool for interpreting results and to provide a useful alternative. Eight healthy African elephants had blood collected under behavioral training every other week for 8 wk. Complete blood cell count (CBC) analysis was performed in duplicate to assess analytical variation. Previous methods were used to determine between-individual variation, within-individual variation, index of individuality, and reference change values (RCV). This study found that most hematology parameters displayed intermediate-to-high individuality, which suggests that alternatives to population-derived reference intervals are necessary to detect pathologic changes. To test the results of our biological variation data, a case of EEHV-HD was retrospectively evaluated. Individual normal values and calculated RCV detected a clinically significant monocytopenia, leukopenia, and thrombocytopenia associated with EEHV2 viremia. However, none of these parameters fell outside a population-derived reference interval. This study highlights the utility of biological variation in clinical decision-making and demonstrates that individual normal values and RCV may be important diagnostic tools for CBC interpretation in African elephants.

Vesicular stomatitis virus in two species of rhinoceros at a California zoological park.

OBJECTIVE: To describe an outbreak of vesicular stomatitis virus (VSV) in southern white rhinoceros (SWR; Ceratotherium simum simum) and greater one-horned rhinoceros (GOHR; Rhinoceros unicornis) at a safari park in San Diego, CA, from May to September 2023. ANIMALS: 21 SWR and 5 GOHR in professionally managed care. METHODS: Rhinoceros of both species presented with a range of clinical signs and severities. Lesion locations were categorized as cutaneous (coronary bands, heels and soles, limbs, ventrum, neck folds, and ears) and mucocutaneous (lips, nostrils, mucous membranes of the oral cavity, and vulva). Clinical signs included lethargy, lameness, difficulty with prehension, hyporexia to anorexia, and hypersalivation. Severely affected rhinoceros had clinical pathology findings consistent with systemic inflammation. RESULTS: Vesicular stomatitis New Jersey virus was confirmed via PCR from swabs of lesions in 10/26 (38%) rhinoceros. Of these 10 confirmed cases, 9 (90%) were SWR and 1 (10%) was a GOHR. A further 6/26 (24%) were considered probable cases, and 10/26 (38%) were considered suspect cases based on clinical signs, but the inability to appropriately sample due to the housing environment precluded confirmation. Histopathology samples from 3 rhinoceros were consistent with VSV, and viral RNA was localized in histologic lesions via RNA in situ hybridization for 1 case. All rhinoceros survived infection despite severe systemic illness in 2 animals. CLINICAL RELEVANCE: This case series describes the clinical appearance and progression of VSV in 2 rhinoceros species. To the authors' knowledge, this is the first report of VSV in a rhinoceros.

Parturition and Neonatal Parameters of Three Species of Rhinoceros under Managed Care in the United States.

Rhinoceros species range from near threatened to critically endangered due to habitat loss and poaching. A sustainable ex situ breeding population is critically important to maintain genetic diversity and help ensure the survival of the species; however, not all populations under human care are self-sustaining. While rhinoceros reproductive physiology and pathology have been well studied, there is still a paucity of information describing the normal parameters of parturition and neonatal landmarks. Using video recordings, medical records, and keeper logs, we reviewed and compared data regarding the parturition of three rhinoceros species (black rhinoceros (BR) (Diceros bicornis), n = 4; greater one-horned rhinoceros (GOHR) (Rhinoceros unicornis), n = 21; and southern white rhinoceros (SWR) (Ceratotherium simum simum), n = 22) managed under human care in the United States. Using equine parameters as a model for comparison, we compiled the following data: the signs of impending parturition, durations of the parturition phases, calving presentation, frequency of dystocia or stillbirth, and time from birth to neonatal landmarks. Data from 47 births, including 26 videos, were examined. The durations of parturition phases I, II, and III had median lengths of 153 min (n = 18), 28 min (n = 21), and 205 min (n = 15), respectively. Anterior presentation of the calf was observed in 59% births, whereas posterior presentation occurred in 41% births. Posterior calving presentation was associated with a longer phase II of parturition (p = 0.04), although more data are needed to determine whether the posterior presentation of the calf carries a higher risk for stillbirth. Most (83%) stillbirths occurred in GOHR, indicating that this species might be at a higher risk for stillbirth compared to SWR (17%) (p = 0.07). The median time from birth to the calf standing was longer in the GOHR (64 min) compared to the SWR (30 min) (p = 0.02). Detailed descriptions of the parturition parameters and neonatal landmarks in rhinoceros will aid facilities with rhinoceros breeding programs to recognize abnormalities in the parturient or post-partum periods and guide indications for veterinary intervention.

Pharmacokinetics of intravenous propofol in southern white rhinoceros (Ceratotherium simum simum) after intramuscular etorphine-butorphanol-medetomidine-azaperone.

OBJECTIVE: To determine the pharmacokinetics of a single bolus of intravenous (IV) propofol after intramuscular administration of etorphine, butorphanol, medetomidine, and azaperone in 5 southern white rhinoceros to facilitate reproductive evaluations. A specific consideration was whether propofol would facilitate timely orotracheal intubation. ANIMALS: 5 adult, female, zoo-maintained southern white rhinoceros. PROCEDURES: Rhinoceros were administered etorphine (0.002 mg/kg), butorphanol (0.02 to 0.026 mg/kg), medetomidine (0.023 to 0.025 mg/kg), and azaperone (0.014 to 0.017 mg/kg) intramuscularly (IM) prior to an IV dose of propofol (0.5 mg/kg). Physiologic parameters (heart rate, blood pressure, respiratory rate, and capnography), timed parameters (eg, time to initial effects and intubation), and quality of induction and intubation were recorded following drug administration. Venous blood was collected for analysis of plasma propofol concentrations using liquid chromatography-tandem mass spectrometry at various time points after propofol administration. RESULTS: All animals were approachable following IM drug administration, and orotracheal intubation was achieved at 9.8 ± 2.0 minutes (mean ±SD) following propofol administration. The mean clearance for propofol was 14.2 ± 7.7 ml/min/kg, the mean terminal half-life was 82.4 ± 74.4 minutes, and the maximum concentration occurred at 2.8 ± 2.9 minutes. Two of 5 rhinoceros experienced apnea after propofol administration. Initial hypertension, which improved without intervention, was observed. CLINICAL RELEVANCE: This study provides pharmacokinetic data and insight into the effects of propofol in rhinoceros anesthetized using etorphine, butorphanol, medetomidine, and azaperone. While apnea was observed in 2 rhinoceros, propofol administration allowed for rapid control of the airway and facilitated oxygen administration and ventilatory support.

DETECTION OF ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS 1A IN ARCHIVAL TISSUE USING RNASCOPE® IN SITU HYBRIDIZATION.

Hemorrhagic disease due to elephant endotheliotropic herpesvirus infection (EEHV-HD) is an important cause of calf mortality in managed and free-ranging Asian (Elephas maximus) and African elephant (Loxodonta spp.) populations. Consequently, infection has profound implications for elephant population growth and sustainability. The mechanisms of disease caused by EEHV (i.e., infection, dissemination, shedding, latency) are relatively undefined, in part because of a lack of robust validated assays for detecting viral gene products in relevant samples. To address this issue, we used RNAscope® in situ hybridization (ISH) based on EEHV1A DNA polymerase and terminase genes to detect EEHV1A RNA in archival formalin-fixed, paraffin-embedded Asian elephant heart and tongue from PCR-confirmed cases (n = 4) of EEHV-HD and Asian elephants (n = 2) that died from other causes. EEHV1A-positive cases had positive hybridization signal in endothelial cell nuclei of both tissues for both DNA polymerase and terminase. EEHV-negative cases lacked signal. In positive cases, the number of positive nuclei was manually assessed to provide an estimate of the viral load and compare sensitivity of the two probes. In all cases, heart had greater signal than tongue for both probes (Wilcoxon rank test; P ≤ 0.01). Overall, terminase hybridization signal was greater than DNA polymerase signal (Wilcoxon rank test; P ≤ 0.01). Results indicate RNAscope ISH is a valuable tool for detection of EEHV in archival samples and for confirming infection. Additionally, the terminase gene is the optimal target and heart is preferable to tongue for detection in cases of EEHV-HD. Results will inform future investigations of viral tropism in EEHV-HD cases due to EEHV1A.

COMPARISON OF DIAGNOSTIC PREDICTORS OF NEONATAL SURVIVABILITY IN NONDOMESTIC CAPRINAE.

This retrospective study evaluated whether six methods (glutamyltransferase, glutaraldehyde coagulation test, sodium sulfite precipitation test, total serum protein, glucose, and fibrinogen) used to assess passive transfer status in ruminants were predictive of survival of nondomestic Caprinae neonates in a zoological collection. A total of 184 neonates from 10 nondomestic Caprinae species had one or more testing methods performed within 7 d of birth. Results of each test were compared with the clinical condition (alive or dead) at 7, 30, and 90 d of age. Total protein (TP) results were not considered for statistical significance in this study. No statistical correlations between results of the serum gamma glutamyltransferase (GGT), glutaraldehyde coagulation test, or sodium sulfite precipitation test (BOVA-S) and survival at any age were found. A higher glucose level within 7 d of birth was associated with a greater probability of survival. Fibrinogen levels were found to have a strong negative association with survival at 30 and 90 d. Increased glucose concentration was negatively associated with the probability of an infectious cause of mortality and the need for medical intervention. In contrast, increased fibrinogen levels were associated with higher probabilities of infectious death and the need for major medical care. Neonates who were confirmed to have nursed had a lower likelihood of requiring major medical intervention. These findings suggest that glucose and fibrinogen levels are better predictors of neonatal survival in nondomestic Caprinae when compared to the other three tests reviewed in this study. Using survival as an indicator of adequate passive transfer in this group of neonates failed to identify a gold standard of diagnosis of failure of passive transfer, so more than one diagnostic test should be utilized.

A COMPARISON OF A SINGLE-DART VERSUS STAGED TWO-DART ANESTHESIA INDUCTION PROTOCOL IN PRZEWALSKI'S HORSES (EQUUS FERUS PRZEWALSKII).

Przewalski's horses (Equus ferus przewalskii) are an endangered equid species. Anesthesia administered by remote delivery is often needed to provide medical care. Behavioral and physiologic parameters were prospectively compared in 14 horses (8 females and 6 males, 3-18 yr) after a single-dart or staged two-dart anesthesia induction protocol with intramuscular medetomidine (0.06 mg/kg), butorphanol (0.05 mg/kg), thiafentanil (0.02 mg/kg), and ketamine (1 mg/kg). Seven horses were randomly assigned to receive all drugs in a single dart, and the other seven to receive medetomidine and butorphanol 10 min prior to thiafentanil and ketamine in a second dart. Induction and recovery quality were scored on a scale from 1 to 5 (worst to best), and video recordings were assessed for frequency of specific behaviors. Need for supplemental propofol was recorded. Median induction score was significantly better (P = 0.01) after two darts (4/5) compared to a single dart (3/5). Degree of muscle fasciculation (undesirable) during induction was significantly lower (P= 0.006) with the two-dart protocol. During the transition to recumbency, 71% versus 14% of horses transitioned headfirst (undesirable) after a single dart versus two darts, respectively (P= 0.07). Supplemental propofol administration was necessary in 43% of horses after two darts and in 100% of horses after a single dart (P= 0.10) to facilitate intubation and reach a working depth of anesthesia. Physiologic and recovery parameters were not significantly different between groups. Improved induction quality was observed clinically using a staged two-dart versus a single-dart protocol and should be considered when anesthetizing captive Przewalski's horses using this drug combination.

NONINVASIVE SAMPLING FOR DETECTION OF ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS AND GENOMIC DNA IN ASIAN (ELEPHAS MAXIMUS) AND AFRICAN (LOXODONTA AFRICANA) ELEPHANTS.

Elephant endotheliotropic herpesvirus (EEHV) hemorrhagic disease (EEHV-HD) threatens Asian elephant (Elephas maximus) population sustainability in North America. Clusters of cases have also been reported in African elephants (Loxodonta africana). Risk to range country elephant populations is unknown. Currently, EEHV detection depends upon sampling elephants trained for invasive blood and trunk wash collection. To evaluate noninvasive sample collection options, paired invasively collected (blood, trunk wash and oral swabs), and noninvasively collected (chewed plant and fecal) samples were compared over 6 wk from 9 Asian elephants and 12 African elephants. EEHV shedding was detected simultaneously in a paired trunk wash and fecal sample from one African elephant. Elephant γ herpesvirus-1 shedding was identified in six chewed plant samples collected from four Asian elephants. Noninvasively collected samples can be used to detect elephant herpesvirus shedding. Longer sampling periods are needed to evaluate the clinical usefulness of noninvasive sampling for EEHV detection.

REPEATED USE OF A THIAFENTANIL-BASED ANESTHESIA PROTOCOL IN AN OKAPI (OKAPIA JOHNSTONI).

Seven anesthesia events were performed over 6 wk on a 1.5-yr-old female okapi (Okapia johnstoni) being managed for a fetlock injury. A combination of butorphanol (B) (median; range) (0.045; 0.031-0.046 mg/kg), medetomidine (M) (0.037; 0.031-0.037 mg/kg), ketamine (K) (0.553; 0.536-1.071 mg/kg), and thiafentanil (T) (0.0045; 0.0040-0.0046 mg/kg) was administered in a padded stall. One dart containing all drugs was used for the first two anesthesias. Subsequently, BM was administered 10 min prior to KT using two darts. Time (median; range) from initial injection to first effects (6; 3-7 min) and recumbency (14; 4-20 min) were recorded. Induction quality with the one-dart protocol was poor or fair and was good or excellent with the two-dart protocol. Following recumbency, the okapi was intubated and ventilated, and physiological parameters were recorded. Anesthesia was consistently achieved with BMKT, but induction was smoother with the staged two-dart approach. Neither resedation nor renarcotization was observed post-reversal.

Chlamydia pneumoniae Polioencephalomyelitis and Ganglionitis in Captive Houston Toads (Anaxyrus houstonensis).

Chlamydia pneumoniae is a ubiquitous pathogen causing disease in humans, mammals, birds, reptiles, and amphibians. Since 2012, C. pneumoniae infection has caused neurologic disease and mortality in a breeding colony of endangered Houston toads (Anaxyrus houstonensis) at the Houston Zoo. The purpose of this report is to present the histopathologic and ultrastructural characteristics of C. pneumoniae infection in Houston toads. Fourteen cases were evaluated by histopathology and 1 case was evaluated by electron microscopy. The major histopathologic finding was necrotizing and histiocytic polioencephalomyelitis and ganglionitis. Bacteria formed intracytoplasmic inclusions within neurons but frequently extended into the surrounding tissue from necrotic cells. Ultrastructural evaluation showed the bacteria formed reticulate and elementary bodies characteristic of Chlamydia spp.

VAGINOSCOPIC IDENTIFICATION OF A VERTICAL VAGINAL SEPTUM IN ONE PRIMIPAROUS AND THREE NULLIPAROUS SOUTHERN WHITE RHINOCEROS (CERATOTHERIUM SIMUM SIMUM).

Vaginoscopy using a 10-mm, 30° forward viewing rigid endoscope was used to evaluate the caudal reproductive tract of four subadult southern white rhinoceros (Ceratotherium simum simum). A vertical vaginal septum was documented in all four animals, including a primiparous cow that gave birth to a stillborn calf 14 months before vaginoscopy. Vaginoscopy using a 57-cm-long, 10-mm, 30° forward viewing endoscope provides adequate visualization of the caudal reproductive track in the southern white rhinoceros, and a detailed description of the vertical vaginal septum is presented. Additionally, the presence of a vertical vaginal septum in a primiparous southern white rhinoceros suggests the presence of this anatomic structure cannot be used as a proxy of nulliparity for captive southern white rhinoceros.

CONGESTIVE HEART FAILURE ASSOCIATED WITH PREGNANCY IN OKAPI (OKAPIA JOHNSTONI).

Acute signs associated with cardiovascular disease occurred in three pregnant okapi ( Okapia johnstoni ) during early to midgestation and progressed to congestive heart failure. Congestive heart failure was diagnosed antemortem using echocardiography and plasma cardiac troponin levels. Clinical signs included decreased activity, hyporexia, tachypnea, dyspnea, flared nostrils, and productive coughing with copious amounts of foamy nasal discharge. Parenteral and oral treatment with furosemide, enalapril, and spironolactone controlled clinical signs in the three okapi allowing each to carry out one pregnancy to term. Two okapi carried the first pregnancy to term after showing signs, while one okapi aborted the first calf and gave birth to a healthy calf in a subsequent pregnancy. Subsequent pregnancy in one okapi ended with abortion and associated dystocia and endometritis. Following parturition, clinical signs associated with heart failure resolved in all three individuals; serial echocardiography in two individuals showed improvement in fractional shortening and left atrial size and all three okapi showed markedly decreased pleural effusion and resolution of pulmonary edema. However, subsequent pregnancies in all three okapi induced respiratory distress and recurrence of congestive heart failure; one okapi died from congestive heart failure associated with subsequent pregnancy. This case series describes the clinical presentation and pathologic findings of congestive heart failure during pregnancy in adult okapi.

CLINICAL INFECTION OF CAPTIVE ASIAN ELEPHANTS (ELEPHAS MAXIMUS) WITH ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS 4.

Elephant endotheliotropic herpesvirus (EEHV) can cause lethal hemorrhagic disease in juvenile Asian elephants. A number of EEHV types and subtypes exist, where most deaths have been caused by EEHV1A and EEHV1B. EEHV4 has been attributed to two deaths, but as both diagnoses were made postmortem, EEHV4 disease has not yet been observed and recorded clinically. In this brief communication, two cases of EEHV4 infection in juvenile elephants at the Houston Zoo are described, where both cases were resolved following intensive treatment and administration of famciclovir. A quantitative real-time polymerase chain reaction detected EEHV4 viremia that correlated with clinical signs. High levels of EEHV4 shedding from trunk wash secretions of the first viremic elephant correlated with subsequent infection of the second elephant with EEHV4. It is hoped that the observations made in these cases--and the successful treatment regimen used--will help other institutions identify and treat EEHV4 infection in the future.

CLINICAL INFECTION OF TWO CAPTIVE ASIAN ELEPHANTS (ELEPHAS MAXIMUS) WITH ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS 1B.

The ability of prior infection from one elephant endotheliotropic herpesvirus (EEHV) type to protect against clinical or lethal infection from others remains an important question. This report describes viremia and subsequent shedding of EEHV1B in two juvenile 4-yr-old Asian elephants within 3 wk or 2 mo following significant infections caused by the rarely seen EEHV4. High levels of EEHV1B shedding were detected in the first elephant prior to emergence of infection and viremia in the second animal. The EEHV1B virus associated with both infections was identical to the strain causing infection in two herd mates previously. High EEHV viremia correlated with leukopenia and thrombocytopenia, which was followed by leukocytosis and thrombocytosis when clinical signs started to resolve. The observations from these cases should be beneficial for helping other institutions monitor and treat elephants infected with EEHV1, the most common virus associated with lethal hemorrhagic disease.

Efficacy of fenbendazole and levamisole treatments in captive Houston toads (Bufo [Anaxyrus] houstonensis).

Effective disease monitoring and prevention is critical to the success of captive amphibian care. Nematodes, including the genera Rhabdias and Strongyloides, are known to contribute to mortality in captive amphibians and have been identified in the Houston Zoo's endangered Houston toad (Bufo [Anaxyrus] houstonensis) captive assurance colony. Five years of fecal data for the toad colony were compiled and analyzed in order to investigate the efficacy of two anthelminthic medications, fenbendazole (FBZ) and levamisole (LMS), which were used to control nematode infections. Both FBZ (dusted onto food items) and topical LMS (6.5 to 13.5 mg/kg) significantly reduced the number of nematode eggs, larvae, and adults observed by fecal parasitologic examination. There were no significant differences between treatments, and egg reappearance periods were difficult to compare as a result of low sample size. No adverse effects from either anthelminthic treatment were observed. Both topical LMS and oral FBZ appear to be safe and efficacious treatments for the reduction of the internal nematode burden in captive Houston toads.

Serum gamma-glutamyltransferase as a prognostic indicator of neonatal viability in nondomestic ruminants.

Rapid assessment of immune status in neonatal ruminants of endangered species facilitates early intervention in cases of inadequate passive transfer of maternal immunoglobulins. Serum gamma-glutamyltransferase (GGT) was used to evaluate suspected passive transfer status in 25 North Indian muntjac (Muntiacus muntjak vaginalis), 45 Cretan goats (Capra algagrus cretica), 20 white-lipped deer (Cervus albirostris), 25 Mhorr gazelles (Gazella dama mhorr), and 31 Soemmerring's gazelles (Gazella soemmerringi soemmerringi). Serum GGT, measured within 48 hr of birth, was compared with clinical condition at 5 days of age. Neonatal Soemmerring's and Mhorr gazelles with GGT > 600 U/L were likely to survive without medical intervention, whereas GGT < 400 U/L was a good indicator that the gazelle neonate would need medical intervention. Neonatal muntjac with GGT > 200 U/L were also likely to survive without medical intervention. Because there is no gold standard for evaluating passive transfer status in neonatal nondomestic ruminants, it is recommended to evaluate the results of more than one diagnostic test, as well as clinical condition, in considering health status and disposition of neonatal ruminants of endangered species.

Transposition of the biceps tendon to reduce lateral scapulohumeral luxation in three species of nondomestic ruminant.

Open reduction of lateral luxation of the scapulohumeral joint was performed in a Mhorr gazelle (Gazella dama mhorr), a southern pudu (Pudu puda), and an Alpine ibex (Capra ibex ibex) by transposition of the biceps brachii tendon lateral to the greater tubercle of the humerus. The ibex had a very large greater tubercle that required a second osteotomy to allow successful lateral transfer of the tendon. Although all three animals were non-weight bearing in the first 2-3 wk after surgery, ambulation improved at 3 wk and was almost normal by 6 wk after surgery. Postoperative follow-up of 8 yr, 7 mo, and 3 mo in the gazelle, pudu, and ibex, respectively, revealed normal ambulation with no gait deficits. The gazelle was euthanized 8 yr after surgery for unrelated disease and necropsy demonstrated mild to moderate degenerative joint disease. Similar lateral shoulder luxations in comparably sized, nondomestic ruminants, without concurrent fractures or significant joint abnormality, have a good prognosis for return to function after surgical reduction using a biceps tendon transposition.

Chemical immobilization of rhebok (Pelea capreolus) with carfentanil-xylazine or etorphine-xylazine.

Twelve adult rhebok (Pelea capreolus) were immobilized using a combination of 0.4 mg/kg xylazine and either 0.01 mg/kg of carfentanil (n = 6) or 0.01 mg/kg etorphine (n = 6), delivered i.m. using a remote injection system. Induction and recovery times, heart rate, respiratory rate, rectal temperature, oxygen saturation, end-tidal CO2 (ETCO2), anesthetic depth, indirect blood pressure, and arterial blood gases were recorded. Rhebok were not intubated but nasal oxygen was administered. Forty minutes after induction, anesthesia was antagonized with naltrexone and yohimbine. Mean initial heart rate was significantly higher in the carfentanil group than in the etorphine group. Mean initial oxygen saturation was consistent with hypoxia in both the carfentanil group and the etorphine group. In both groups, arterial pH decreased and partial pressure of carbon dioxide increased during the first 15 min of anesthesia, and values were similar in both groups. These findings were consistent with respiratory acidosis and decreased ventilation. Values for respiratory rate, temperature, oxygen saturation, ETCO2, and blood pressure were similar for both groups at all time periods. During the first 5 min of anesthesia, rhebok in the carfentanil group were more responsive to stimuli than rhebok in the etorphine group. After administration of antagonists, time to first arousal was significantly shorter in the etorphine group than in the carfentanil group. Although cardiopulmonary values were similar for the two groups, rhebok in the carfentanil group were at a comparatively lighter plane of anesthesia, and some individuals in this group required additional manual and chemical restraint for medical procedures to be performed. In conclusion, for captive adult rhebok, 0.01 mg/kg of etorphine and 0.4 mg/kg of xylazine are recommended over 0.01 mg/kg carfentanil and 0.4 mg/kg xylazine because of qualitatively better anesthetic episodes and shorter recovery times.