Biochemical Variables in Free-ranging White-tailed Deer (Odocoileus virginianus) after Chemical Immobilization in Clover Traps or Via Ground-darting

Blood analytes of clinically normal and diseased neonatal and weaned farmed white-tailed deer (Odocoileus virginianus) fawns

Recent research focused on farmed deer has exposed many knowledge gaps regarding health assessment protocols for white-tailed deer (WTD). The objectives of this study were to establish de novo blood analyte reference intervals for farmed WTD fawns at birth (1-2 days of age; n = 84) and again at weaning (76-125 days of age; n = 28), to compare data at birth and at weaning to understand how these analytes are affected by the intrinsic factors age and sex in clinically normal WTD fawns, and to compare between clinically normal and sick WTD weanlings (respiratory disease n = 12; orbivirus-infected n = 6). Reference intervals were established for WTD fawns at birth and weaning. Female WTD neonates had significantly higher red blood cell counts, hematocrit, and hemoglobin compared to males. Most blood analytes were significantly different in clinically normal WTD neonates compared to weanlings, suggesting an effect of age. The observed sex- and age-related variations in WTD highlight the need to establish reference intervals that account for intrinsic factors. The comparison of clinically normal and sick WTD weanlings in this study identified higher MCHC and absolute monocytes in sick weanlings but these findings were presumably not biologically relevant given the small sample size for sick fawns. While the reference interval data presented herein will be useful for the veterinary care of WTD fawns at critical time periods in a high-density farm setting, this study also demonstrates the need to identify more sensitive and specific biomarkers for the assessment of health status in farmed WTD with specific underlying diseases.

Arterial oxygenation and acid-base status before and during oxygen supplementation in captive European bison (Bison bonasus) immobilized with etorphine-acepromazine-xylazine

Chemical immobilization of captive European bison (Bison bonasus) is often required for veterinary care, transportation, or husbandry practices playing an important role in conservation breeding and reintroduction of the species. We evaluated the efficiency and physiological effects of an etorphine-acepromazine-xylazine combination with supplemental oxygen in 39 captive European bison. Animals were darted with a combination of 1.4 mg of etorphine, 4.5 mg of acepromazine, and 20 mg of xylazine per 100 kg based on estimated body mass. Arterial blood was sampled on average 20 min after recumbency and again 19 min later and analyzed immediately with a portable i-STAT analyzer. Simultaneously, heart rate, respiratory rate, and rectal temperature were recorded. Intranasal oxygen was started after the first sampling at a flow rate of 10 mL.kg^-1.min^-1 of estimated body mass until the end of the procedure. The initial mean partial pressure of oxygen (P_aO₂) was 49.7 mmHg with 32 out of 35 sampled bison presenting with hypoxemia. We observed decreased respiratory rates and pH and mild hypercapnia consistent with a mild respiratory acidosis. After oxygen supplementation hypoxemia was resolved in 21 out of 32 bison, but respiratory acidosis was accentuated. Bison immobilized with a lower initial drug dose required supplementary injections during the procedure. We observed that lower mean rectal temperatures during the immobilization event were significantly associated with longer recovery times. For three bison, minor regurgitation was documented. No mortality or morbidity related to the immobilizations were reported for at least 2 months following the procedure. Based on our findings, we recommend a dose of 0.015 mg.kg^-1 etorphine, 0.049 mg.kg^-1 acepromazine, and 0.22 mg.kg^-1 xylazine. This dose reduced the need for supplemental injections to obtain a sufficient level of immobilization for routine management and husbandry procedures in captive European bison. Nevertheless, this drug combination is associated with development of marked hypoxemia, mild respiratory acidosis, and a small risk of regurgitation. Oxygen supplementation is strongly recommended when using this protocol.

COMPARISON OF TILETAMINE-ZOLAZEPAM COMBINED WITH DEXMEDETOMIDINE OR XYLAZINE FOR CHEMICAL IMMOBILIZATION OF WILD FALLOW DEER (DAMA DAMA)

This study compared dexmedetomidine or xylazine in combination with tiletamine-zolazepam for chemical immobilization of wild fallow deer (Dama dama) in a prospective, randomized, blinded clinical study. Forty fallow deer were divided into two groups: tiletamine-zolazepam-xylazine (TZX) and tiletamine-zolazepam-dexmedetomidine (TZD). The TZX group was immobilized with 1.9 ± 0.05 mg/kg of xylazine and 1.48 ± 0.05 mg/kg of tiletamine-zolazepam, whereas the TZD group was immobilized with 34.15 ± 1.1 µg/kg of dexmedetomidine and 0.97 ± 0.03 mg/kg of tiletamine-zolazepam by dart. The induction time was recorded. During the immobilization, heart rate, respiratory rate, body temperature, hemoglobin oxygen saturation, blood lactate concentration, and quality of immobilization were recorded at 10, 20, and 30 m after drug administration. The time of achievement of sternal recumbency and that of standing were also recorded. The TZD group showed a significantly shorter induction time (8 ± 1.6 m, TZX group; 4 ± 0.5 m, TZD group), significantly higher quality of immobilization score (2[1-2], TZX group; 4[4-4], TZD group), and significantly lower lactate levels (5[3-7] mmol/L, TZX group; 2[1-3] mmol/L, TZD group). The time to sternal recumbency was 7 ± 1.6 m (TZX group) and 4 ± 0.5 m (TZD group), and time to quadrupedal standing was 20 ± 1.6 m (TZX group) and 16 ± 0.8 m (TZD group) (P = 0.001). Dexmedetomidine combined with tiletamine-zolazepam is a viable alternative to xylazine for the chemical immobilization of fallow deer.

Clinical and pathological findings in a Dwarf Red Brocket Mazama rufina (Mammalia: Cetartiodactyla: Cervidae) attacked by dogs

Capture myopathy is a common fatal syndrome in wild ungulates resulting from anthropogenic stressful events such as the capture or transport of specimens.  There are, however, few published data on this issue due to predator attacks.  The present report describes for the first time the capture myopathy syndrome in a Dwarf Red Brocket Mazama rufina following dog Canis familiaris attack.  Clinical signs included pale mucous with increase capillary refill time, tachycardia, tachypnea, hypertension, hypothermia, hypoglycemia, and red brown urine.  Muscle tremors, ataxia, prostration, paralysis, and opisthotonus were progressively observed.  Laboratory tests showed increased levels of cortisol, creatinine, creatine kinase, lactate dehydrogenase, and potassium; decreased blood urea nitrogen-creatinine ratio; and myoglobinuria.  The animal died 72 hours after hospital admission.  At necropsy, findings included injuries on both hindlimbs with edema, emphysema, and soft-friable texture in affected muscles, dark kidneys and brown urine in bladder.  Histopathological exams were indicative of skeletal-cardiac muscle degenerative lesions and myoglobinuric nephrosis.  Immuno-histochemistry revealed myoglobin depletion in degenerate muscles and myoglobin accumulation in renal tissues.  We strongly recommend that treatment for capture myopathy be initiated when a wild ungulate is admitted with history of predator attack, since the syndrome may have already established.  This report adds to the instances of negative impacts caused by domestic dogs on threatened wildlife species.   

Blood L-Lactate Concentration as an Indicator of Outcome in Roe Deer (Capreolus capreolus) Admitted to a Wildlife Rescue Center

Simple Summary

Roe deer are among the most frequent wild animals admitted to rescue centers in Italy. Reasons for admission include trauma, predation, starvation, and imprinting, with the final aim of hospitalization being full recovery and release into the wild for all cases. An accurate triage procedure is vital for predicting the outcome, to avoid unnecessary time spent in captivity, and an excessive allocation of time and resources on animals with a minimal chance of recovery. Since lactacidosis is often associated with death in hospitalized animals, and has been associated with poor prognosis in humans and domestic animals, we proposed an evaluation of blood L-lactate using a rapid whole blood test in order to predict the outcome of hospitalized roe deer. A cut-off of 10.2 mmol/L was identified as the best, in order distinguish animals with minimal chance of surviving and release. For these animals, humane euthanasia should be considered as an option.

Abstract

Roe deer (Capreolus capreolus) are among the most frequent patients of rescue centers in Italy. Three outcomes are possible: natural death, euthanasia, or treatment and release. The aim of the present study is to propose blood L-lactate concentration as a possible prognostic biomarker that may assist veterinarians in the decision-making process. Sixty-three roe deer, admitted to one rescue center in the period between July 2018 and July 2019, were sampled and divided into 4 groups according to their outcome: (1) spontaneous death (17 cases), (2) humanely euthanized (13 cases), (3) fully recovered and released (13 cases), and (4) euthanized being unsuitable for release (20 cases). In addition, blood samples from 14 hunted roe deer were analyzed as controls. Whole blood lactate concentrations were measured with a point of care lactate meter. Differences among groups were close to statistical significance (p = 0.51). A cut-off value of 10.2 mmol/L was identified: all the animals with higher values died or were humanely euthanized. The results suggest that roe deer with lactatemia higher than 10.2 mmol/L at admission, have a reduced prognosis for survival during the rehabilitation period, regardless of the reason for hospitalization and the injuries reported. Therefore, humane euthanasia should be considered for these animals.

Cardiovascular effects of intravenous vatinoxan (MK-467) in medetomidine-tiletamine-zolazepam anaesthetised red deer (Cervus elaphus)

OBJECTIVE

To determine the effect of intravenous vatinoxan administration on bradycardia, hypertension and level of anaesthesia induced by medetomidine-tiletamine-zolazepam in red deer (Cervus elaphus).

STUDY DESIGN AND ANIMALS

A total of 10 healthy red deer were included in a randomised, controlled, experimental, crossover study.

METHODS

Deer were administered a combination of 0.1 mg kg^-1 medetomidine hydrochloride and 2.5 mg kg^-1 tiletamine-zolazepam intramuscularly, followed by 0.1 mg kg^-1 vatinoxan hydrochloride or equivalent volume of saline intravenously (IV) 35 minutes after anaesthetic induction. Heart rate (HR), mean arterial blood pressure (MAP), respiration rate (f_R), end-tidal CO₂ (Pe'CO₂), arterial oxygen saturation (SpO₂), rectal temperature (RT) and level of anaesthesia were assessed before saline/vatinoxan administration (baseline) and at intervals for 25 minutes thereafter. Differences within treatments (change from baseline) and between treatments were analysed with linear mixed effect models (p < 0.05).

RESULTS

Maximal (81 ± 10 beats minute^-1) HR occurred 90 seconds after vatinoxan injection and remained significantly above baseline (42 ± 4 beats minute^-1) for 15 minutes. MAP significantly decreased from baseline (122 ± 10 mmHg) to a minimum MAP of 83 ± 6 mmHg 60 seconds after vatinoxan and remained below baseline until end of anaesthesia. HR remained unchanged from baseline (43 ± 5 beats minute^-1) with the saline treatment, whereas MAP decreased significantly (112 ± 16 mmHg) from baseline after 20 minutes. Pe'CO₂, f_R and SpO₂ showed no significant differences between treatments, whereas RT decreased significantly 25 minutes after vatinoxan. Level of anaesthesia was not significantly influenced by vatinoxan.

CONCLUSIONS AND CLINICAL RELEVANCE

Vatinoxan reversed hypertension and bradycardia induced by medetomidine without causing hypotension or affecting the level of anaesthesia in red deer. However, the effect on HR subsided 15 minutes after vatinoxan IV administration. Vatinoxan has the potential to reduce anaesthetic side effects in non-domestic ruminants immobilised with medetomidine-tiletamine-zolazepam.

A review of methods used to capture and restrain introduced wild deer in Australia

Six non-native deer species have established wild populations in Australia, and most are expanding in distribution and abundance. There is therefore increasing focus on the need to understand and manage these species. Capturing and immobilising wild deer is essential for many research and management applications, but the best methods for doing this have not been identified for the Australian situation. To address this knowledge gap, we systematically reviewed methods used to physically capture and chemically immobilise the six wild deer species in Australia. A variety of physical and chemical restraint methods have been used to capture wild deer in Australia, but these have seldom been reported in peer-reviewed publications. Physical capture methods have employed a variety of trapping and netting configurations. Some chemical immobilisation approaches have used oral baiting, but most have relied on darting of free-ranging animals or hand-injection of physically restrained deer. There is uncertainty about the efficacy and animal welfare impacts of the techniques currently used to capture wild deer in Australia. Improved reporting of capture outcomes would facilitate the identification of ‘best practice’ techniques for capturing wild deer in Australian environments.

Ameliorating the adverse cardiorespiratory effects of chemical immobilization by inducing general anaesthesia in sheep and goats: implications for physiological studies of large wild mammals

Chemical immobilization is necessary for the physiological study of large wild animals. However, the immobilizing drugs can adversely affect the cardiovascular and respiratory systems, yielding data that do not accurately represent the normal, resting state. We hypothesize that these adverse effects can be ameliorated by reversing the immobilizing agent while holding the animal under general anaesthesia. We used habituated sheep Ovis aries (N = 5, 46.9 ± 5.3 kg body mass, mean ± SEM) and goats Capra hircus (N = 4, 27.7 ± 2.8 kg) as ungulate models for large wild animals, and measured their cardiorespiratory function under three conditions: (1) mild sedation (midazolam), as a proxy for the normal resting state, (2) immobilization (etorphine and azaperone), and (3) general anaesthesia (propofol) followed by etorphine antagonism (naltrexone). Cardiac output for both sheep and goats remained unchanged across the three conditions (overall means of 6.2 ± 0.9 and 3.3 ± 0.3 L min^-1, respectively). For both sheep and goats, systemic and pulmonary mean arterial pressures were significantly altered from initial midazolam levels when administered etorphine + azaperone, but those arterial pressures were restored upon transition to propofol anaesthesia and antagonism of the etorphine. Under etorphine + azaperone, minute ventilation decreased in the sheep, though this decrease was corrected under propofol, while the minute ventilation in the goats remained unchanged throughout. Under etorphine + azaperone, both sheep and goats displayed arterial blood hypoxia and hypercapnia (relative to midazolam levels), which failed to completely recover under propofol, indicating that more time might be needed for the blood gases to be adequately restored. Nonetheless, many of the confounding cardiorespiratory effects of etorphine were ameliorated when it was antagonized with naltrexone while the animal was held under propofol, indicating that this procedure can largely restore the cardiovascular and respiratory systems closer to a normal, resting state.

Comparative health assessment of urban and non-urban free-ranging mule deer (Odocoileus hemionus) in southeastern British Columbia, Canada

Background

The provincial wildlife management agency, British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development, performed a translocation to control the urban mule deer (Odocoileus hemionus; uMD) overpopulation and supplement the declining non-urban mule deer (nuMD) population in the Kootenay region, British Columbia, Canada. The objectives of this cross-sectional study were to evaluate the health of the urban and nuMD populations by comparing pathogen exposure, body condition scores (BCS) and pregnancy rates, to characterize the health risks associated with the translocation and to investigate the role of infectious diseases in the decline of the nuMD deer population.

Methods

Two hundred free-ranging mule deer were captured in urban and non-urban environments in the Kootenay region from 2014 to 2017. BCS and morphometric examinations were performed for each deer. Blood samples collected from each deer were tested for exposure to selected pathogens and pregnancy status.

Results

Body condition scores averaged 3.4 on a five-point scale, was greater in nuMD, and significantly differed between years. Antibodies were detected for adenovirus hemorrhagic disease virus (38.4% (uMD 43.7%, nuMD 33.3%)), bluetongue virus (0.6% (uMD 1.2%, nuMD 0%)), bovine respiratory syncytial virus (8.4% (uMD 4.6%, nuMD 12.1%)), bovine viral diarrhea virus (1.1% (uMD 0%, nuMD 2.2%)), bovine parainfluenza-3 virus (27.0% (uMD 27.6%, nuMD 26.4%)), Neospora caninum (22.1% (uMD 24.4%, nuMD 19.7%)) and Toxoplasma gondii (8.2% (uMD 12.3%, nuMD 3.9%)). No antibodies against epizootic hemorrhagic disease virus were detected. Pregnancy rates did not differ between the two deer populations (90.7% (uMD 90.6%, nuMD 90.9%)). Exposure to N. caninum was associated with a reduced probability of being pregnant. uMD were more likely to be exposed to T. gondii than nuMD.

Discussion

Comparison of BCS, pregnancy rates and pathogen exposure of uMD and nuMD showed that the health of the two populations did not significantly differ, suggesting uMD translocations do not pose a severe risk of pathogen transmission between mule deer populations and that these selected pathogens do not factor in the decline of the nuMD population. However, inclusion of additional health indicators and creation of a robust predictive disease model are warranted to further characterize the health of mule deer and the health risks associated with uMD translocations. These results should be considered as part of a formal risk assessment for future uMD translocations in southeastern British Columbia.

Influence of Ambient Temperature and Confinement on the Chemical Immobilization of Fallow Deer ( Dama dama )

We used physiological parameters and the duration and quality of anesthesia to compare the effects of two ambient temperatures and of the duration of pre-immobilization confinement on the chemical immobilization of fallow deer. We divided 45 free-ranging fallow deer ( Dama dama ) into two groups: Group A were deer captured in winter (average 12 C), using 1 mg/kg of xylazine and 1 mg/kg of tiletamine-zolazepam; and Group B were deer captured in spring (average 24 C), using 2 mg/kg of xylazine and 1.5 mg/kg of tiletamine-zolazepam, after being confined in a pen. We observed lower mean respiratory rate and oxygen saturation in Group B. In contrast, the mean body temperature and the mean blood lactate concentration were significantly higher in Group B, and quality of anesthesia was better in Group A. Mean induction time (time to achieve recumbency) and durations of recumbency were the same in Groups A and B: approximately 8 and 50 min, respectively. Despite the lower drug dosage, better sedation was obtained in Group A than in group B. The time of year, most likely associated with differences in ambient temperature and in confinement, influenced the recommended dosage for xylazine and tiletamine-zolazepam in fallow deer. As all the animals were sound, we concluded that the only factors that influenced the outcome of the present study were the ambient temperature and the level of stress caused by confinement in the pen.

BEST-PRACTICE GUIDELINES FOR FIELD-BASED SURGERY AND ANESTHESIA OF FREE-RANGING WILDLIFE. I. ANESTHESIA AND ANALGESIA

Field anesthesia is often necessary for both invasive and noninvasive procedures on wild animals. We describe basic principles of safe anesthetic delivery, monitoring, and recovery for application in procedures involving free-ranging wildlife. For invasive procedures, the potential for immediate and lasting pain must be addressed and appropriate analgesia provided. In situations where the minimum standard of safe anesthesia and effective analgesia cannot be provided, the investigator and approving bodies should rigorously evaluate the risk to the patient against the value of the data obtained. This document is intended to serve as a resource for Institutional Animal Care and Use Committees, biologists, veterinarians, and other researchers planning projects that involve free-ranging wildlife in field conditions.

Chemical immobilization and anesthesia of free-living aardvarks (Orycteropus afer) with ketamine-medetomidine-midazolam and isoflurane

Abstract We evaluated the effectiveness of a ketamine-medetomidine-midazolam drug combination administered intramuscularly by remote injection followed by isoflurane anesthesia in free-living aardvarks (Orycteropus afer). Seven aardvarks weighing 33-45 kg were immobilized to perform surgical implantation of temperature loggers using 3.8 mg/kg ketamine, 0.1 mg/kg medetomidine, and 0.25 mg/kg midazolam. Immobilized aardvarks were transported to a surgical theater and received 0.5-1% isoflurane in oxygen after tracheal intubation. After surgery, medetomidine was antagonized with 0.5 mg/kg atipamezole, and aardvarks were released at the site of capture. We recorded induction and recovery times, clinical and physiologic parameters, and conducted blood gas analyses before and during isoflurane administration. Aardvarks showed initial effects within 3 min and reached lateral recumbency within 7 min after drug administration. Heart rate (50-67 beats/min), respiratory rate (10-15 breaths/min), oxygen hemoglobin saturation (SaO2; 90-97%), and rectal temperature (34.0-37.5 C) were within acceptable physiologic ranges. Mean arterial blood pressure was initially high (146 ± 12 mmHg), but the hypertension resolved over time. Rectal temperature dropped significantly during anesthesia. Four animals had to be treated to relieve apnea. Blood gas analyses revealed mild to moderate hypercapnia but no hypoxaemia. The ketamine-medetomidine-midazolam combination provided effective immobilization. Combined with a low concentration of isoflurane, it can be used for prolonged surgical procedures in wild aardvarks. However, caution is needed, and monitoring of clinical parameters is required.

Physiologic effects of three different protocols of isoflurane anesthesia in captive brown brocket deer (Mazama gouazoubira)

This study evaluates the cardiorespiratory and physiologic effects of three different protocols of chemical restraint using isoflurane in captive brown brocket deer (Mazama gouazoubira). Six adult deer, two males and four females, aged 3-6 yr old and weighing 16.3 +/- 1.5 kg (mean +/- SD), were used. The deer were physically restrained and anesthetized using one of three protocols: protocol 1 (P1), anesthesia was induced directly with isoflurane using a facemask and maintained for 1 hr with isoflurane delivered by endotracheal tube; protocol 2 (P2), oral premedication with midazolam was followed 1 hr later by induction and maintenance of anesthesia with isoflurane, as in P1; and protocol 3 (P3), intravenous anesthesia using a combination of ketamine, xylazine, and atropine was followed by isoflurane anesthesia, as in P1. Cardiorespiratory variables were recorded during physical restraint (TO); 5 min after intubation (T5); and every 10 min during anesthesia (T15-T55). Venous and arterial blood gas analysis was conducted at TO (venous blood only), T15, T35, and T55. Data were analyzed by the appropriate statistical tests. P values < 0.05 were considered significant. Under P1, three deer regurgitated during induction and one of them died because of aspiration pneumonia. The end-tidal isoflurane concentration differed significantly between P1, P2, and P3 (2.6 +/- 0.2, 2.3 +/- 0.5, and 0.9 +/- 0.3%, respectively). Hypotension was observed during anesthesia (T15-T55). Respiratory acidosis occurred at all times and protocols, and pH was significantly lower in P1 compared to P2 and P3. Metabolic acidosis was also observed following physical restraint (T0-T35) in all protocols. The use of isoflurane via facemask for anesthesia induction is not a safe method in deer that are not premedicated. Isoflurane used alone or in combination with midazolam and ketamine-xylazine-atropine combination causes hypotension and dose-dependent respiratory acidosis.

Use of portable blood physiology point-of-care devices for basic and applied research on vertebrates: a review

Non-human vertebrate blood is commonly collected and assayed for a variety of applications, including veterinary diagnostics and physiological research. Small, often non-lethal samples enable the assessment and monitoring of the physiological state and health of the individual. Traditionally, studies that rely on blood physiology have focused on captive animals or, in studies conducted in remote settings, have required the preservation and transport of samples for later analysis. In either situation, large, laboratory-bound equipment and traditional assays and analytical protocols are required. The use of point-of-care (POC) devices to measure various secondary blood physiological parameters, such as metabolites, blood gases and ions, has become increasingly popular recently, due to immediate results and their portability, which allows the freedom to study organisms in the wild. Here, we review the current uses of POC devices and their applicability to basic and applied studies on a variety of non-domesticated species. We located 79 individual studies that focused on non-domesticated vertebrates, including validation and application of POC tools. Studies focused on a wide spectrum of taxa, including mammals, birds and herptiles, although the majority of studies focused on fish, and typical variables measured included blood glucose, lactate and pH. We found that calibrations for species-specific blood physiology values are necessary, because ranges can vary within and among taxa and are sometimes outside the measurable range of the devices. In addition, although POC devices are portable and robust, most require durable cases, they are seldom waterproof/water-resistant, and factors such as humidity and temperature can affect the performance of the device. Overall, most studies concluded that POC devices are suitable alternatives to traditional laboratory devices and eliminate the need for transport of samples; however, there is a need for greater emphasis on rigorous calibration and validation of these units and appreciation of their limitations.