The sedative effect of intranasal administration of medetomidine using a mucosal atomization device in Japanese White rabbits.

To prevent aspiration in Japanese White (JW) rabbits, the maximum single volume of medetomidine administered intranasally is 0.3 mL per nostril using a mucosal atomization device (MAD). This study aimed to examine the sedative effect of intranasal administration of medetomidine using MAD in eight healthy female JW rabbits. Each rabbit received intranasal atomization (INA) of saline (Control treatment) along with three doses of 1 mg/mL medetomidine (0.3 mL to one nostril [MED0.3 treatment]; 0.3 mL each to both nostrils [MED0.6 treatment]; 0.3 mL twice to both nostrils [MED1.2 treatment]), with a washout period of at least 7 days between treatments. The actual doses of medetomidine were 82 (75-84) µg/kg (median [25th-75th percentile]), 163 (156-168) µg/kg, and 323 (295-343) µg/kg for the MED0.3, MED0.6, and MED1.2 treatments, respectively. A medetomidine-dose dependent sedative effect was detected, and the loss of righting reflex (LRR) was achieved in one rabbit at 18 min, seven rabbits at 11 (9-18) min, and eight rabbits at 7 (4-18) min after the MED0.3, MED0.6, and MED1.2 treatments, respectively. The LRR was maintained for 63 (29-71) min and 83 (68-101) min after the MED0.6 and MED1.2 treatments, respectively. Additionally, the INA of medetomidine produced a significant dose-dependent cardiorespiratory depression including a decrease in pulse rate, respiratory rate, percutaneous oxygen saturation, and arterial partial pressure of oxygen, and an increase in arterial partial pressure of carbon dioxide in the rabbits.

Combined resting state-fMRI and calcium recordings show stable brain states for task-induced fMRI in mice under combined ISO/MED anesthesia.

For fMRI in animal models, the combination of low-dose anesthetic, isoflurane (ISO), and the sedative medetomidine (MED) has recently become an advocated regimen to achieve stable neuronal states and brain networks in rats that are required for reliable task-induced BOLD fMRI. However, in mice the temporal stability of neuronal states and networks in resting-state (rs)-fMRI experiments during the combined ISO/MED regimen has not been systematically investigated. Using a multimodal approach with optical calcium (Ca2+) recordings and rs-fMRI, we investigated cortical neuronal/astrocytic Ca2+activity states and brain networks at multiple time points while switching from anesthesia with 1% ISO to a combined ISO/MED regimen. We found that cortical activity states reached a steady-state 45 min following start of MED infusion as indicated by stable Ca2+ transients. Similarly, rs-networks were not statistically different between anesthesia with ISO and the combined ISO/MED regimen 45 and 100 min after start of MED. Importantly, during the transition time we identified changed rs-network signatures that likely reflect the different mode of action of the respective anesthetic; these included a dose-dependent increase in cortico-cortical functional connectivity (FC) presumably caused by reduction of ISO concentration and decreased FC in subcortical arousal nuclei due to MED infusion. Furthermore, we report detection of visual stimulation-induced BOLD fMRI during the stable ISO/MED neuronal state 45 min after induction. Based on our findings, we recommend a 45-minute waiting period after switching from ISO anesthesia to the combined ISO/MED regimen before performing rs- or task-induced fMRI experiments.

Disentanglement of Cape fur seals (Arctocephalus pusillus pusillus) with reversible medetomidine-midazolam-butorphanol.

Anaesthesia in pinnipeds is considered a much higher risk than in most terrestrial mammals because of their frequent proximity to water and physiological and anatomical adaptations related to diving, which also influence their anaesthesia management. Anaesthetising and immobilising entangled seals does not allow for selection of animals that are at a safe distance from the water's edge. Medetomidine-midazolam-butorphanol (MMB) sedation was trialled on eight entangled Cape fur seals (CFS) (Arctocephalus pusillus pusillus) to determine if it was safe to use on animals that entered the water post-darting. The MMB was given at an estimated dose of 0.03 mg/kg, 0.2 mg/kg and 0.2 mg/kg, respectively, via remote darting. Sedation was reversed with intramuscular atipamezole (0.15 mg/kg) and naltrexone (0.4 mg/kg) to antagonise the effects of medetomidine and butorphanol, respectively. Moderate sedation was achieved in six animals. Six of the animals entered the water after being darted. There was a single mortality and a single animal that was too lightly sedated for capture. The preliminary results indicate that MMB produces suitable sedation for disentanglement of CFS. Additionally, MMB might be suitable for application to field-based biological research.

PHYSIOLOGICAL AND ANESTHETIC EFFECTS OF HAND INJECTION VERSUS DARTING TO INDUCE ANESTHESIA IN CHIMPANZEES (PAN TROGLODYTES).

Great ape anesthesia is reported to carry a significant risk. Therefore, techniques aiming to reduce stress and increase welfare, such as hand injection of anesthesia induction agents, have received considerable attention in zoo, laboratory, and captive wildlife environments. However, there is little evidence to support the superiority of such techniques. To investigate this issue, anesthesia records of healthy zoo-housed chimpanzees (Pan troglodytes) between 2012 and 2017 in which the animal was either darted or hand injected were analyzed (n = 50). Sex, age, induction, muscle relaxation, and overall anesthesia quality as well as recovery ratings, heart rate, systolic, mean and diastolic blood pressure, respiratory rate, end-tidal CO2, oxygen saturation (SpO2), and body temperature were analyzed. Chimpanzees that were darted showed statistically significantly higher heart rate, SpO2, and body temperature than those that were hand injected. It was found that darted chimpanzees were also significantly more likely to have poorer perianesthetic muscle relaxation and overall anesthesia rating scores. This study provides further evidence that the use of hand injection can reduce factors associated with stress and improve the quality of chimpanzee anesthesia.

BUTORPHANOL, AZAPERONE, AND MEDETOMIDINE ANESTHESIA IN FREE-RANGING EASTERN MOOSE (ALCES AMERICANUS).

Fifty-three free-ranging moose (Alces americanus) cows were darted from a helicopter with 3-4 ml of a premix combination of butorphanol (27.3 mg/ml), azaperone (9.1 mg/ml), and medetomidine (10.9 mg/ml; BAM), equivalent to estimated dosages of: butorphanol 0.26 ± 0.08 (mean ± SD) mg/kg, azaperone 0.09 ± 0.03 mg/kg, and medetomidine 0.11 ± 0.03 mg/kg. After a mean chase time (from sighting to darting) of 6.1 ± 5.5 min, the mean induction time (from darting to recumbency) was 8.3 ± 2.6 min. This combination provided a safe and reliable sedation for minor procedures that lasted 30-60 min. Heart rate (50.4 ± 7.0 beats/min), respiratory rate (21.3 ± 11.1 breaths/minute), ETCO2 via nasal canula (43.2 ± 7.0 mmHg), and rectal temperature (38.5°C ± 0.7°C) mostly remained at expected values for wild cervid and bovid species anesthetized with this drug combination. SpO2 (90.0% ± 3.7%) was suggestive of moderate hypoxemia despite intranasal oxygen supplementation (1 L per 100 kg/min). The recovery time to standing was 6.7 ± 3.8 min after reversal with IM naltrexone (3 mg/mg butorphanol) and atipamezole (5 mg/mg medetomidine). Despite a larger volume to inject, this protocol offers an alternative to highly potent opioids, and should be considered for practical or staff safety reasons. On the basis of the results of this study, the use of 4 ml of BAM is considered a safe and effective protocol for immobilization of cow moose under comparable settings.

Inadvertent injection of medetomidine in the cerebromedullaris cisterna of a dog during myelographic exam.

INTRODUCTION: A mixed breed dog was anesthetized for diagnostic myelography to investigate acute onset neck pain. Instead of contrast medium, 444 µg/kg medetomidine were inadvertently injected into the cerebromedullaris cisterna owing to a human error. Severe bradycardia, undetectable peripheral pulse, respiratory arrest and loss of pupillary, palpebral and corneal reflexes were observed immediately after injection. Profound hypothermia developed and esophageal temperature, measured 20 minutes after medetomidine injection, was 33 °C. Atipamezole at 1 mg/kg im was administered, followed by a second dose of 0,5 mg/kg iv 20 minutes thereafter. In the meantime, cardiorespiratory parameters and body temperature were monitored, and supportive care that included manually assisted pulmonary ventilation, active warming, and administration of 5 µg/kg/min dopamine was initiated. The dog's clinical condition improved within one hour from the beginning of supportive care, at which time ocular reflexes and swallowing returned, spontaneous ventilation was deemed as adequate and the trachea could be extubated. The dog was discharged in good clinical conditions five days later. Human error and distraction led to a potentially life-threatening complication in the dog of this report and could have possibly been prevented with the use of checklists and with a clearer definition of roles and responsibilities of the personnel involved prior to commencing the clinical procedure. Profound cardiovascular, respiratory, and thermoregulatory depression caused by intracisternal injection of medetomidine responded to parenteral administration of its antagonist and supportive care.

INTRODUCTION: Un chien croisé a été anesthésié pour une myélographie diagnostique afin d'étudier une douleur aiguë au niveau du cou. Au lieu du produit de contraste, 444 µg/kg de médétomidine ont été injectés par inadvertance dans la citerne cérébello-médullaire en raison d'une erreur humaine. Une bradycardie sévère, un pouls périphérique indétectable, un arrêt respiratoire et une perte des réflexes pupillaire, palpébral et cornéen ont été observés immédiatement après l'injection. Une hypothermie profonde s'est développée et la température oesophagienne, mesurée 20 minutes après l'injection de médétomidine, était de 33 °C. De l'atipamézole à 1 mg/kg im a été administré, suivi d'une seconde dose de 0,5 mg / kg iv 20 minutes après. Dans l'intervalle, les paramètres cardiorespiratoires et la température corporelle ont été surveillés et des soins de soutien comprenant une ventilation assistée manuellement, un réchauffement actif et l'administration de 5 µg/kg/min de dopamine ont été initiés. L'état clinique du chien s'est amélioré dans l'heure qui a suivi le début des soins, moment où les réflexes oculaires et la déglutition sont réapparus, la ventilation spontanée a été jugée adéquate et où on a pu procéder à l'extubation. Le chien est sorti dans de bonnes conditions cliniques cinq jours plus tard. Une erreur humaine et de la distraction ont conduit à une complication potentiellement mortelle chez le chien décrit dans ce rapport et auraient pu être évitées grâce à l'utilisation de listes de contrôle et avec une définition plus claire des rôles et des responsabilités du personnel impliqué avant le début de la procédure clinique. Une profonde dépression cardiovasculaire, respiratoire et de la thermorégulation causée par l'injection intracisternale de médétomidine a répondu à l'administration parentérale de son antagoniste et à des soins de soutien.

EVALUATING THE USE OF A BUTORPHANOL-AZAPERONE-MEDETOMIDINE FIXED-DOSE COMBINATION FOR STANDING SEDATION IN AFRICAN ELEPHANTS (LOXODONTA AFRICANA).

This study investigated the use of a fixed-dose combination of 30 mg/ml butorphanol, 12 mg/ml azaperone, and 12 mg/ml medetomidine for the standing sedation of captive African elephants (Loxodonta africana). In total, seven females (mean age 19.6 yr; range 6-31 yr) and six males (mean age 33.5 yr; range 9-35 yr) were sedated. The estimated dose was 0.0005 ± 0.0001 ml/kg and 0.006 ± 0.001 ml/cm shoulder height, which resulted in a dose of 0.016 ± 0.002 mg/kg or 0.19 ± 0.04 mg/cm shoulder height butorphanol, 0.006 ± 0.0008 mg/ kg or 0.076 ± 0.015 mg/cm shoulder height azaperone, and 0.006 ± 0.0008 mg/kg or 0.076 ± 0.015 mg/cm medetomidine. First signs of sedation were observed within 3-10 min (mean 6 ± 2 min) after darting, and monitoring of the animals started on average at 24 ± 9 min after darting. No bradycardia was observed in any of the elephants (mean heart rate 40.0 ± 6.55 beats/min), although all the animals were mildly hypotensive (mean blood pressure 118.5/86 [94.5]). Rectal temperatures fell within acceptable ranges, and respiratory parameters were stable in all the animals throughout sedation and fell within the standard ranges reported for conscious, standing elephants. Only one elephant had clinically significant hypoxemia characterized by a partial pressure of oxygen (PaO2) < 60 mm Hg. This elephant was also hypercapnic (PaCO2 > 50 mm Hg), although pH and peripheral capillary oxygen saturation fell within acceptable ranges. None of the elephants reacted to moderately painful stimuli while sedated. The combination was reversed with intramuscular injections of naltrexone (1 mg for every 1 mg butorphanol) and atipamezole (5 mg for every 1 mg medetomidine). Recovery was smooth and calm in all the animals. Time from injection of the reversals until the first signs of recovery was 4.6 ± 2.01 min (range 1-8 min).

EVALUATION OF TWO MEDETOMIDINE-AZAPERONE-ALFAXALONE COMBINATIONS IN CAPTIVE ROCKY MOUNTAIN ELK (CERVUS ELAPHUS NELSONI).

Alfaxalone has been successfully used intramuscularly (im) combined with medetomidine and azaperone for immobilization of small ungulates. An experimental 40 mg/ml alfaxalone solution (RD0387) was recently formulated for reduced injection volume. The objective of this study was to assess the efficacy and cardiopulmonary effects of high-concentration alfaxalone combined with medetomidine and azaperone for the intramuscular immobilization of captive Rocky Mountain elk (Cervus elaphus nelsoni). Seven adult female elk were used in a crossover design in which they were administered alfaxalone 1 mg/kg, medetomidine 0.05 mg/kg, and azaperone 0.1 mg/kg or alfaxalone 0.5 mg/kg, medetomidine 0.1 mg/kg, and azaperone 0.1 mg/kg im approximately 3 wk apart. Drugs were delivered to each elk in a chute by hand injection. Once recumbent, elk were placed in sternal recumbency for a period of 30 min, during which time level of sedation, response to minor procedures, heart rate, respiratory rate, rectal temperature, oxygen saturation, and direct arterial blood pressures were recorded every 5 min. Arterial blood gases were performed every 15 min. At 30 min, elk were administered atipamezole 0.25 or 0.5 mg/kg im and recovery quality and times were recorded. Statistical comparisons were made by t test, Wilcoxon signed rank test, and repeated measures analysis (significance level P < 0.05). Both drug combinations provided effective immobilization for 30 min, with induction and recovery time and quality similar to other medetomidine-based combinations used in elk. Cardiopulmonary effects included bradycardia, hypertension, and hypoxemia that resolved with oxygen supplementation. The average injection volume in the low-dose alfaxalone combination was approximately 5 ml. These combinations provided deep sedation and the ability to perform minor procedures in captive elk, with acceptable cardiopulmonary parameters as long as supplemental oxygen was provided.

FIELD ANESTHESIA AND GONADAL MORPHOLOGY OF IMMATURE WESTERN SANTA CRUZ TORTOISES (CHELONOIDIS PORTERI).

Evaluation of sex ratios is a critical component of chelonian captive breeding programs and may become increasingly useful to assess the demographics of free-living populations. In many reptile species, the sex of immature animals cannot be determined based on external features. Endoscopic sex identification is an accurate and safe method to identify the sex of immature individuals of some chelonian species. A number of studies describe this technique in controlled, hospital settings and report significant interspecies variations in gonad morphology; however, there are few reports describing this technique in field conditions. In the current study, the gonadal morphology of 40 immature Western Santa Cruz tortoises (Chelonoidis porteri) on Santa Cruz Island in Galapagos, Ecuador, was assessed. A previously described endoscopic protocol was used to perform sex identification under field conditions. Tortoises were anesthetized using an intramuscular injection of ketamine (10 mg/kg) and medetomidine (0.1 mg/kg), which provided an adequate plane of anesthesia. The medetomidine was reversed with atipamezole (0.5 mg/kg). Field conditions presented challenges such as limited control over lighting, suboptimal patient positioning, and restricted power supply for endoscopy equipment. The immature testicle in Western Santa Cruz tortoises was oval, reddish pink, and tightly adhered to the coelomic membrane ventral to the kidney. The surface of the gonads resembled other species with the notable exception that the ovaries lacked a significant number of primordial follicles. These gonadal characteristics were consistent, with only one individual identified as undetermined sex of the 40 samples. This field-based endoscopic gonadal evaluation was a safe and sensitive technique for determining the sex of free-living immature Western Santa Cruz Galapagos tortoises.

Mechanical ventilation restores blood gas homeostasis and diaphragm muscle strength in ketamine/medetomidine-anaesthetized rats.

NEW FINDINGS: What is the central question of the study? Does respiratory support ensure blood gas homeostasis and the relevance of experimental outcomes? What is the main finding and its importance? Spontaneous breathing during surgical intervention under anaesthesia results in impaired gas exchange and loss of diaphragm muscle strength in rats. Subsequent short-term mechanical ventilation restored blood gas homeostasis and diaphragm muscle strength. Blood gas homeostasis interferes substantially with experimental conditions and may alter study results. Monitoring and maintenance of blood gas balance is required to ensure quality and relevance of physiological animal experiments. ABSTRACT: In pre-clinical small animal studies with surgical interventions under general anaesthesia, animals are often left to breathe spontaneously. However, anaesthesia may impair respiratory functions and result in disturbed blood gas homeostasis. In turn, the disturbed blood gas homeostasis can affect physiological functions and thus unintentionally impact the experimental results. We hypothesized that short-term mechanical ventilation restores blood gas balance and physiological functions despite anaesthesia and surgical interventions. Therefore, we investigated variables of blood gas analyses and diaphragm muscle strength in rats anaesthetized with ketamine/medetomidine after tracheotomy and catheterization of the carotid artery under spontaneous breathing and after 20 min of mechanical ventilation following the same surgical intervention. Spontaneous breathing during general anaesthesia and surgical intervention resulted in unphysiological blood oxygen partial pressure (<65 mmHg) and carbon dioxide partial pressure (>55 mmHg). After subsequent short-term mechanical ventilation, blood gas partial pressures were restored to their physiological ranges. Additionally, diaphragm muscle strength of animals breathing spontaneously was lower compared to animals that received subsequent mechanical ventilation (P = 0.0063). We conclude that spontaneous breathing of rats under ketamine/medetomidine anaesthesia is not sufficient to maintain a physiological blood gas balance. Disturbed blood gas balance is related to reduced diaphragm muscle strength. Mechanical ventilation for only 20 min restores blood gas homeostasis and muscle strength. Therefore, monitoring and maintenance of blood gas balance should be conducted to ensure quality and relevance of small animal experiments.

Efeitos cardiovasculares da medetomidina e cetamina em Puma concolor e tempo de recuperação após aplicação de ioimbina ou atipamezole / [Cardiovascular effects of medetomidine and cetamine in Puma concolor and recovery time after application of ioimbin or atipamezole]

O objetivo deste estudo foi avaliar as alterações cardiorrespiratórias causadas pela medetomidina associada à cetamina, e o tempo de recuperação após aplicação intramuscular de atipamezole ou ioimbina em Puma concolor. Para isso, foi realizada a aplicação de medetomidina (100µg/kg) associada à cetamina (5mg/kg) em 11 onças-pardas, sendo os parâmetros cardiorrespiratórios registrados a cada 15 minutos, durante 90 minutos de avaliação. Em seguida, a anestesia foi revertida com aplicação intramuscular de ioimbina (0,4mg/kg; n=5) ou atipamezole (0,25mg/kg; n=6), sendo analisado o tempo até a recuperação. Dos parâmetros cardiorrespiratórios avaliados, houve diferença apenas na frequência respiratória (entre os momentos 60 e 90 minutos), estando esta, todavia, dentro do intervalo de referência para a espécie. Além disso, verificou-se tempo para decúbito esternal significativamente menor nos animais do grupo atipamezole (18±7 minutos), quando comparado ao grupo ioimbina (36±17 minutos), entretanto o tempo de recuperação completa foi estatisticamente igual entre os dois reversores analisados. Assim, a associação anestésica promoveu anestesia eficiente, segura e de rápida indução em onças-pardas, permitindo a imobilização dos animais durante os 90 minutos de avaliação, sem a ocorrência de complicações. Ao se comparar a reversão anestésica com atipamezole e ioimbina, observou-se equivalência dos fármacos no tempo de recuperação completa dos animais.(AU)

The aim of this study was to evaluate the cardiorespiratory changes caused by ketamine-associated medetomidine, and the recovery time after intramuscular application of atipamezole or yohimbine in Puma concolor. For this, the application of medetomidine (100µg/kg) associated with ketamine (5mg/kg) was performed in eleven brown ounces, and the cardiorespiratory parameters were recorded every 15 minutes during 90 minutes of evaluation. Afterwards, anesthesia was reversed with intramuscular application of yohimbine (0.4mg/kg; n=5) or atipamezole (0.25mg/kg; n=6), and time to recovery was analyzed. Of the cardiorespiratory parameters evaluated, there was a difference only in respiratory rate (between 60 and 90 minutes), however, within the reference range for the species. In addition, there was a significantly shorter time for sternal decubitus in the animals of the atipamezole group (18±7 minutes) when compared to the yohimbine group (36±17 minutes), however the complete recovery time was statistically equal between the two reversers analyzed. Thus, the anesthetic association promoted efficient, safe and fast induction anesthesia in puma, allowing the animals to be immobilized during the 90 minutes of evaluation without complications. Comparing anesthetic reversal with atipamezole and yohimbine, drug equivalence was observed in the complete recovery time of the animals.(AU)

Cats undergoing spay with medetomidine, ketamine and butorphanol develop arterial oxygen desaturation independent of surgical positioning and increased intraocular pressure in Trendelenburg position.

INTRODUCTION: This study observed the effects of three different surgical positions on arterial blood oxygenation measured noninvasively by pulse oximetry (SpO2) and on intraocular pressure (IOP) in anaesthetised cats undergoing spay. A total of 222 female feral cats were anaesthetised for a large-scale trap-neuter-return program with an intramuscular combination of medetomidine (0.03 - 0.05 mg/kg), ketamine (7 - 10 mg/kg) and butorphanol (0.4 mg/kg). Cats were randomly allocated to undergo spay in either Trendelenburg (70° downward head tilt), lateral or dorsal recumbency. SpO2 and pulse rate were measured at baseline, prior to surgical positioning, after one minute in surgical position and in one-minute intervals after surgical incision. Intraocular pressure was measured before positioning and at the end of surgery. At the end of surgery, all cats were placed into left lateral recumbency and all parameters were revaluated after five minutes. No significant differences between the three positions were found regarding SpO2, but an increase over time was observed. In total, 52 ± 10% (mean ± SD) of cats were hypoxaemic (SpO2 < 90%) at baseline. SpO2 improved over time, but 27 ± 3% (mean ± SD) of the cats remained hypoxaemic at the end of surgery. Trendelenburg position increased IOP during surgery (mean 31 ± 6 mmHg, individual max. 48 mmHg, versus 17 ± 4 mmHg in dorsal/lateral recumbency) but normalised after 5 mins in lateral recumbence. All cats recovered well from surgery and were released within 24 hours post-anaesthesia. Surgical position was shown to have no notable influence on SpO2 during anaesthesia in cats not receiving oxygen supplementation, whereas Trendelenburg position led to increased IOP. Oxygen supplementation is recommended with this anaesthetic protocol, as hypoxaemia is frequently observed.

INTRODUCTION: Dans cette étude, on a observé les effets de trois positions chirurgicales différentes sur l'oxygénation du sang artériel mesurée de manière non invasive par oxymétrie de pouls (SpO2) et sur la pression intraoculaire (PIO) chez des chattes anesthésiées subissant une stérilisation. Un total de 222 chattes sauvages ont été, dans le cadre d'un large programme de piégeage-castration-libération, anesthésiées avec une combinaison de médétomidine (0,03 à 0,05 mg/kg), de kétamine (7 à 10 mg/kg) et de butorphanol (0,4 mg/kg) par voie intramusculaire. Les chattes ont été réparties au hasard pour subir une stérilisation en Trendelenburg (inclinaison de la tête à 70 ° vers le bas), en décubitus latéral ou dorsal. La SpO2 et la fréquence du pouls ont été mesurées au départ, avant le positionnement chirurgical, après une minute en position chirurgicale et à des intervalles d'une minute après l'incision chirurgicale. La pression intraoculaire a été mesurée avant le positionnement et à la fin de la chirurgie. À la fin de la chirurgie, toutes les chattes ont été placées en décubitus latéral gauche et tous les paramètres ont été réévalués après cinq minutes. Aucune différence significative entre les trois positions n'a été constatée concernant la SpO2, mais une augmentation au fil du temps a été observée. Au total, 52 ± 10% (moyenne ± SD) des chattes étaient hypoxémiques (SpO2.

Evaluation of anaesthetic and cardiorespiratory effects after intramuscular administration of alfaxalone alone, alfaxalone-ketamine and alfaxalone-butorphanol-medetomidine in common marmosets (Callithrix jacchus).

BACKGROUND: Anaesthesia is often required in common marmosets undergoing various procedures. The aim of this study was to evaluate anaesthetic and cardiopulmonary effects of alfaxalone, alfaxalone-ketamine and alfaxalone-butorphanol-medetomidine in common marmosets. METHODS: The following treatments were repeatedly administered to seven female common marmosets: Treatment A, alfaxalone (12 mg kg-1 ) alone; treatment AK, alfaxalone (1 mg animal-1 ) plus ketamine (2.5 mg animal-1 ); treatment AMB, alfaxalone (4 mg kg-1 ), medetomidine (50 µg kg-1 ) plus butorphanol (0.3 mg kg-1 ); and treatment AMB-Ati, AMB with atipamezole at 45 minutes. RESULTS AND CONCLUSIONS: Marmosets became laterally recumbent and unresponsive for approximately 30 minutes in A and AK and for approximately 60 minutes in AMB. The animals showed rapid recovery following atipamezole injection in AMB-Ati. The decrease in heart rate and SpO2 was significantly greater in AMB compared to A and AK. Oxygen supplementation, anaesthetic monitors and atipamezole should be available especially when AMB is administered.

Effects of intramuscular vatinoxan (MK-467), co-administered with medetomidine and butorphanol, on cardiopulmonary and anaesthetic effects of intravenous ketamine in dogs.

OBJECTIVE: To investigate the impact of intramuscular (IM) co-administration of the peripheral α2-adrenoceptor agonist vatinoxan (MK-467) with medetomidine and butorphanol prior to intravenous (IV) ketamine on the cardiopulmonary and anaesthetic effects in dogs, followed by atipamezole reversal. STUDY DESIGN: Randomized, masked crossover study. ANIMALS: A total of eight purpose-bred Beagle dogs aged 3 years. METHODS: Each dog was instrumented and administered two treatments 2 weeks apart: medetomidine (20 µg kg-1) and butorphanol (100 µg kg-1) premedication with vatinoxan (500 µg kg-1; treatment MVB) or without vatinoxan (treatment MB) IM 20 minutes before IV ketamine (4 mg kg-1). Atipamezole (100 µg kg-1) was administered IM 60 minutes after ketamine. Heart rate (HR), mean arterial (MAP) and central venous (CVP) pressures and cardiac output (CO) were measured; cardiac (CI) and systemic vascular resistance (SVRI) indices were calculated before and 10 minutes after MVB or MB, and 10, 25, 40, 55, 70 and 100 minutes after ketamine. Data were analysed with repeated measures analysis of covariance models. A p-value <0.05 was considered statistically significant. Sedation, induction, intubation and recovery scores were assessed. RESULTS: At most time points, HR and CI were significantly higher, and SVRI and CVP significantly lower with MVB than with MB. With both treatments, SVRI and MAP decreased after ketamine, whereas HR and CI increased. MAP was significantly lower with MVB than with MB; mild hypotension (57-59 mmHg) was recorded in two dogs with MVB prior to atipamezole administration. Sedation, induction, intubation and recovery scores were not different between treatments, but intolerance to the endotracheal tube was observed earlier with MVB. CONCLUSIONS AND CLINICAL RELEVANCE: Haemodynamic performance was improved by vatinoxan co-administration with medetomidine-butorphanol, before and after ketamine administration. However, vatinoxan was associated with mild hypotension after ketamine with the dose used in this study. Vatinoxan shortened the duration of anaesthesia.

Improvement of a twice collection method of mouse oocytes by surgical operation.

Mouse oocytes are generally collected after euthanasia. However, if oocytes were collected without euthanasia, then mice could be used to collect oocytes again after recovery. This condition is especially useful for mice that are genotypically rare. In this study, we examined the reusability of mice after collecting oocytes via a surgical operation. When oocytes were collected using medetomidine/midazolam/butorphanol combination anesthesia and examined for the quality of oocytes after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI), they could develop to full term at the same rate as controls. When oocytes were collected from those mice a second time, the average number of oocytes was reduced by nearly 1/3. However, the blastocyst and offspring rates of those oocytes after IVF or ICSI were the same as those of the control regardless of the recovery day period. Although germinal vesicle (GV) oocytes can be collected from all reused mice, the final number of offspring did not increase. Interestingly, when oocytes were collected from the front position of the ampulla, 76% of the oviducts possessed oocytes after reuse, and the average number of oocytes significantly increased to a level comparable to that of the control. Finally, we examined whether reused mice can be used as recipient females, and then healthy offspring were obtained similarly as the control recipients. In conclusion, we provide a new method to collect a sufficient number of oocytes from reused mice without concern.

EVALUATION OF TWO ANESTHETIC COMBINATIONS IN LOWLAND NYALA (TRAGELAPHUS ANGASII).

Fourteen lowland nyala (Tragelaphus angasii) in managed care were successfully anesthetized for a total of 17 anesthetic events using either a combination of butorphanol (0.75 ± 0.15 mg/kg), azaperone (0.25 ± 0.05 mg/kg), and medetomidine (0.30 ± 0.06 mg/kg) (BAM) or medetomidine (0.17 ± 0.01 mg/kg), azaperone (0.22 ± 0.02 mg/kg), and alfaxalone (0.52 ± 0.08 mg/kg) (MAA) delivered intramuscularly via dart. Mean time to initial effect, sternal recumbency, lateral recumbency, handling, and intubation were recorded. The nyala were maintained in sternal recumbency with supplemental oxygenation until 60 min after initial injection. Cardiopulmonary effects were recorded every 5 min after handling until reversal. Arterial blood samples were collected every 15 min for analysis. Level of sedation and quality of recovery were scored. Anesthesia was antagonized with atipamezole (at 5 mg per mg of medetomidine) for both protocols and naltrexone (at 2 mg per mg of butorphanol) for the BAM protocol delivered intramuscularly via hand injection. Mean time to extubation, head control, and standing post reversal were recorded. No hyperthermia, acidemia, apnea, or tachycardia occurred; however, animals did display hypoxemia. Two animals in the BAM cohort required supplementation to facilitate handling. These drug combinations provided satisfactory levels of sedation in most cases for safe handling and minor procedures in lowland nyala under managed care.

Tissue Residue Levels of the Tranquilizer Combination of Butorphanol, Azaperone, and Medetomidine, and the Antagonists, Naltrexone, Atipamezole, and Tolazoline, in Black Bears (Ursus americanus) Postimmobilization.

The tranquilizer combination of butorphanol, azaperone, and medetomidine (BAM) has shown good efficacy for immobilization of wildlife, including black bears (Ursus americanus). BAM is antagonized with a combination of naltrexone and atipamezole. We immobilized 19 adult captive wild caught black bears and, except for three bears that were euthanized immediately, bears were recovered with naltrexone and atipamezole. Tissue residues (≥0.01 ppm) for the tranquilizers butorphanol, azaperone, and medetomidine were detected in liver and muscle of all three bears euthanized on day 0 postinjection (PI). Azaperone was not detected after 1 d PI. Residue for medetomidine was detected in two bears: in the liver 3 d PI and in the kidney 6 d PI. Butorphanol was reported in three bears: in fat 5 d PI, in kidney 6 d PI, and, surprisingly, in kidney, muscle, and fat 7 d PI. No tissue residues were detected in the three bears euthanized at 8 d PI. Tissue residues for the antagonists, naltrexone and atipamezole, were detected in bears euthanized 2 and 6 d PI, but not in tissues from animals euthanized at 7 or 8 d PI.

Field immobilization using alfaxalone and alfaxalone-medetomidine in free-ranging koalas (Phascolarctos cinereus): a randomized comparative study.

OBJECTIVE: To characterize and compare two intramuscular drug protocols using alfaxalone and alfaxalone-medetomidine combination for the field immobilization of free-ranging koalas. STUDY DESIGN: Blinded, randomized, comparative field study. ANIMALS: A total of 66 free-ranging koalas from the Mount Lofty Ranges, South Australia. METHODS: Koalas were randomly allocated into two groups. Group A animals were given alfaxalone alone at 3.5 mg kg-1. Group AM animals were given alfaxalone 2 mg kg-1 and medetomidine 40 µg kg-1, reversed with atipamezole at 0.16 mg kg-1. Blinded operators recorded heart rate (HR), respiratory rate (fR), cloacal temperature, depth of sedation and times to: first effect, sedation suitable for clinical interventions, first arousal and full recovery. Data were analysed using independent t test, Mann-Whitney U test, chi-square analysis and log-rank test at 5% level of significance. RESULTS: Suitable immobilization for clinical examination and sample collection was achieved in all animals. In groups A and AM, median time to working depth was 6.5 minutes (range: 3.4-15) and 8.1 minutes (range: 4.3-24) and time to complete recovery was 66 minutes (range: 12-138) and 34 minutes (range: 4-84), respectively, following reversal. Time to first effect was significantly shorter in group A (p = 0.013), whereas time to full arousal was significantly shorter in group AM (p = 0.007) probably due to the administration of atipamezole. Maximum HR was 117 ± 28 beats minute-1 in group A, which was a significant increase from baseline values (p < 0.0001), whereas group AM showed a significant tachypnoea of 67 ± 25 (normal fR 10-15; p < 0.0001). CONCLUSIONS AND CLINICAL RELEVANCE: Both the protocols produced immobilization, enabling clinical examination and sample collection; however, protocol AM was more suitable for field work due to shorter recovery times.

Efficacy comparison of intraperitoneal anaesthesia and post-operative analgesia regimens in laboratory rats.

INTRODUCTION: Effective and safe anesthesia for rodents has long been a leading concern among biomedical researchers. Intraperitoneal injection constitutes an alternative to inhalant anesthesia. PURPOSE: The aim of this study was to identify a safe, reliable, and effective anesthesia and postoperative analgesia protocol for laboratory rats exposed to painful procedures. MATERIAL AND METHODS: Twenty-seven female Wistar rats in an ongoing study that required surgery were randomized into groups for three different intraperitoneal anesthesia protocols and three different analgesia regimens. The anesthesia groups were (1) medetomidine + ketamine (MK), (2) ketamine + xylacine (KX), and (3) fentanyl + medetomidine (FM). Three analgesia groups were equally distributed among the anesthesia groups: (1) local mepivacaine + oral ibuprofen (MI), (2) oral tramadol + oral ibuprofen (TI), and (3) local tramadol + oral tramadol + + oral ibuprofen (TTI). A core was assigned to measure anesthesia (0-3) and analgesia (0-2) effectiveness; the lower the score, the more effective the treatment. RESULTS: The mean MK score was 0.44 versus 2.00 for FM and 2.33 for KX. Mean score for analgesia on the first postoperative day was TTI (4.66) TI (9.13), and MI (10.14). Mean score 48 hours after surgery was TTI (3.4), TI (6.71), and MI (9.5). These differences were statistically significant. CONCLUSION: MK was shown to be a reliable, safe, and effective method of anesthesia. The TTI analgesia regimen is strongly recommended in light of these results.

Different Reactions of Zebra Finches and Bengalese Finches to a Three-Component Mixture of Anesthetics.

Kawai et al. (2011) recently introduced a mixture of three anesthetic agents (here called MMB) that has an effect similar to ketamine/xylazine in mice, which might allow more effective reaction to changes in the animal condition, as an antagonist is available, and which can be used without license for handling narcotic drugs. Using Kawai's study as a baseline, we tested whether this anesthesia and its antagonist can also be used in avian studies. In the present study, we used two species, the zebra finch and the Bengalese finch, of the avian family Estrildidae. In zebra finches, anesthesia effects similar to the use of ketamine/xylazine and to those obtained in mice can be reached by the use of MMB if a higher dose is applied. MMB leads to more variable anesthesia, but has the advantage of a longer time window of deep anesthesia. An antagonist to one component of MMB reduced the awaking time, but was not as effective as in mice. For Bengalese finches, MMB cannot be generally recommended because of difficult handling and high mortality rate when used without antagonist, but could be used for perfusions instead of pentobarbital.