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Concept: Medetomidine

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A total of 58 American beavers ( Castor canadensis) was immobilized with butorphanol, azaperone, and medetomidine (BAM) for the purpose of health assessments, sex determination, and placement of very high-frequency tail transmitters in a subset of animals. Isoflurane gas anesthesia was available to aid with induction when needed, and all animals received supplementary oxygen. Thirty-one beavers immobilized with a mean (SD) dose of 0.65 (0.15) mg/kg butorphanol, 0.22 (0.05) mg/kg azaperone, and 0.26 (0.06) mg/kg medetomidine did not require supplemental isoflurane during induction and the mean induction time was 8 min (range: 3-21 min). This dose was equivalent to 0.024 (0.005) mL of BAM per kilogram. A total of 29 beavers that was immobilized with a mean (SD) of 0.51 (0.07) mg/kg butorphanol, 0.17 (0.02) mg/kg azaperone, and 0.2 (0.03) mg/kg medetomidine needed supplementary isoflurane at 5% and 5 L/min for <1 min to induce full anesthesia. In none of the beavers did BAM alone provide sufficient depth of anesthesia to drill a hole in the tail for transmitter placement, and supplementary isoflurane was administered to reach a sufficient level of analgesia for the procedure. The beavers were reversed with 5 mg of atipamezole per milligram of medetomidine and 1 mg of naltrexone per milligram of butorphanol. No adverse effects or mortalities were observed. Butorphanol-azaperone-medetomidine can be considered safe for use in American beavers for minor procedures.

Concepts: Opioid, Natural number, Beaver, Transmitter, Beavers, Fur trade, North American Beaver, Medetomidine

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OBJECTIVE To assess the effects of sedation on results of acoustoelastography of the superficial digital flexor tendons (SDFTs) in clinically normal horses. ANIMALS 27 clinically normal horses. PROCEDURES For each horse, the pathology index (PI) for the SDFT of each thoracic limb was determined by use of acoustoelastography at 4 locations (5, 10, 15, and 20 cm distal to the accessory carpal bone). Horses were evaluated before and after they were sedated with a combination of detomidine hydrochloride (0.01 mg/kg, IV) and butorphanol tartrate (0.01 mg/kg, IV). A repeated-measures ANOVA was used for statistical analysis. RESULTS Overall, the PI was lower after sedation than before sedation. In addition, the PI was lower at more distal locations than at more proximal locations. There was not a significant effect of limb (left or right). Differences among individual horses accounted for the largest variance effect. CONCLUSIONS AND CLINICAL RELEVANCE Sedation with detomidine and butorphanol facilitated acoustoelastography; however, it decreased the SDFT PI in clinically normal horses and should be used consistently in prospective studies. Variance associated with each individual horse in the sample population had the greatest effect on the PI.

Concepts: Statistics, Variance, Effectiveness, Normal distribution, Analysis of variance, Butorphanol, Medetomidine, Detomidine

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Seventeen captive Nubian ibex ( Capra nubiana ) were immobilized for transportation and/or hoof trimming, deworming, and vaccinations. Of these, 11 were immobilized with a combination of butorphanol (0.13 ± 0.03 mg/kg), midazolam (0.13 ± 0.03 mg/kg), and medetomidine (0.13 ± 0.03 mg/kg) (BMM), and 6 were immobilized with a combination of butorphanol (0.11 ± 0.03 mg/kg), azaperone (0.22 ± 0.06 mg/kg), and medetomidine (0.11 ± 0.03 mg/kg) (BAM) by intramuscular injection. Induction and recovery times were recorded. Heart rate, respiratory rate, rectal temperature, blood pressure, and oxygen saturation were measured. The quality of induction, immobilization, and recovery were scored (scale 1-5; 1 = poor, 5 = excellent). Mean induction time was significantly shorter in the BMM group versus the BAM group (8.8 ± 2.7 and 20.1 ± 7.8 min, respectively). Median induction score and median immobilization score were significantly higher (i.e., better) in the BMM group than the BAM group (5 versus 2.5 and 4 versus 3, respectively). The mean and diastolic blood pressures were significantly higher in the BMM group at the 25-min time point. Atipamezole was administered at the end of procedures, and all ibex recovered smoothly. Mean recovery time was significantly longer in the BMM group versus the BAM group (9.5 ± 4.3 and 3.3 ± 2.2, respectively). In conclusion, at the doses used, the combination of BMM was superior to BAM for short-term immobilization in captive Nubian ibex.

Concepts: Time, Blood, Blood pressure, Medical signs, Arithmetic mean, Systole, Capra, Medetomidine

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An anesthetic mixture of medetomidine (MED), midazolam (MID), and butorphanol (BUT) has been used in laboratory animals. We previously reported that this anesthetic mixture produced closely similar anesthetic effects in BALB/c and C57BL/6J strains. We also demonstrated the efficacy of atipamezole (ATI), an antagonist of MED that produced quick recovery from anesthesia in mice. Anesthetics have various anesthetic effects among animal strains. However, the differences in the effects of anesthetic mixtures in rats are unclear. In the present study, we first examined effects of the abovementioned anesthetic mixture using three different rat strains: Wistar (WST), Sprague-Dawley (SD), and Fischer 344 (F344). Second, we examined how different dosages and optimum injection timing of ATI affected recovery from anesthesia in rats. We used the anesthetic score to measure anesthetic duration and a pulse oximeter to monitor vital signs. We found no significant differences in anesthetic duration among the three different strains. However, recovery from anesthesia in the SD strain took significantly longer than in the other strains. The antagonistic effects of ATI (0.15 mg/kg and 0.75 mg/kg) were equivalent when administered at 30 mins (min) after anesthetic mixture administration. The antagonistic effects of ATI 0.75 mg/kg were stronger than those of ATI 0.15 mg/kg at 10 min after anesthetic mixture administration. This anesthetic mixture is a useful drug that can induce similar anesthetic effects in three different strains and has an antagonist, ATI, that makes rats quickly recover from anesthesia. These results may contribute to the welfare of laboratory animals.

Concepts: Anesthesia, Opioid, Difference, Receptor antagonist, Rat, Local anesthetic, Anesthetic, Medetomidine

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Selecting the appropriate anesthetic protocol for the individual animal is an essential part of laboratory animal experimentation. The present study compared the characteristics of four anesthetic protocols in mice, focusing on the vital signs. Thirty-two male ddY mice were divided into four groups and administered anesthesia as follows: pentobarbital sodium monoanaesthesia; combined ketamine and xylazine combined (K/X); medetomidine, midazolam, and butorphanol combined (M/M/B); and isoflurane. In each group, rectal temperature, heart rate, respiratory rate, and O2 saturation (SPO2) were measured, and the changes over time and instability in these signs were compared. The anesthetic depth was also evaluated in each mouse, and the percentage of mice achieving surgical anesthesia was calculated. K/X anesthesia caused remarkable bradycardia, while the respiratory rate and SPO2 were higher than for the others, suggesting a relatively strong cardiac influence and less respiratory depression. The M/M/B group showed a relatively lower heart rate and SPO2, but these abnormalities were rapidly reversed by atipamezole administration. The pentobarbital group showed a lower SPO2, and 62.5% of mice did not reach a surgical anesthetic depth. The isoflurane group showed a marked decrease in respiratory rate compared with the injectable anesthetic groups. However, it had the most stable SPO2 among the groups, suggesting a higher tidal volume. The isoflurane group also showed the highest heart rate during anesthesia. In conclusion, the present study showed the cardiorespiratory characteristics of various anesthetic protocols, providing basic information for selecting an appropriate anesthetic for individual animals during experimentation.

Concepts: Time, Medical signs, Anesthesia, Opioid, Al-Andalus, Heart rate, Anesthetic, Medetomidine

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The anesthetic mixture of medetomidine (MED), midazolam (MID) and butorphanol (BUT) produced anesthetic duration of around 40 mins (min) in ICR mice. We reported that this anesthetic mixture produced almost the same anesthetic effects in both male and female BALB/c and C57BL/6J strains. Intraperitoneal (IP) administration of drugs has been widely used in mice. However, various injectable routes of the anesthetic mixture may cause different anesthetic effects. First, we examined effects of the anesthetic mixture by subcutaneous (SC) and intravenous (IV) injection compared to IP injection. After injection of the anesthetic mixture, administration of atipamezole (ATI) induced mice recovery from anesthesia. Secondly, we examined how different dosage and optimum injection timing of ATI affected mice recovery from anesthesia. We used an anesthetic score to measure anesthetic duration and a pulse oximeter to monitor vital signs under anesthesia. Usually, drugs from SC injection work more weakly than IP or IV injection. However, we found no significant differences of anesthetic duration among the three different injection routes. Antagonistic effects of ATI (0.3 mg/kg and 1.5 mg/kg) worked equally when administered at 30 min after injection of the anesthetic mixture. Antagonistic effects of ATI (1.5 mg/kg) were stronger than ATI (0.3 mg/kg) at 10 min after injection of the anesthetic mixture. The anesthetic mixture is a useful drug to induce nearly the same anesthetic effects by different injection routes and has an antagonist of ATI which helps mice quickly recover from anesthesia. These results may contribute to the welfare of laboratory animals.

Concepts: Opioid, Receptor antagonist, Pharmaceutical drug, Hypodermic needle, Injection, Recovery, Medetomidine

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Abstract We report the clinical course and physiologic and anesthetic data for a case series of 76 free-ranging dromedary camels (Camelus dromedarius) chemically restrained, by remote injection from a helicopter, in the rangelands of Western Australia and South Australia, 2008-11, to attach satellite-tracking collars. Fifty-five camels were successfully anesthetized using medetomidine-ketamine (MK, n = 27) and medetomidine-ketamine-butorphanol (MKB, n = 28); the induction of anesthesia in 21 animals was considered unsuccessful. To produce reliable anesthesia for MK, medetomidine was administered at 0.22 mg/kg (±SD = 0.05) and ketamine at 2.54 mg/kg (±0.56), and for MKB, medetomidine was administered at 0.12 mg/kg (±0.05), ketamine at 2.3 mg/kg (±0.39), and butorphanol at 0.05 mg/kg (±0.02). Median time-to-recumbency for MKB (8.5 min) was 2.5 min shorter than for MK (11 min) (P = 0.13). For MK, the reversal atipamezole was administered at 0.24 mg/kg (±0.10), and for MKB, atipamezole was administered at 0.23 mg/kg (±0.13) and naltrexone at 0.17 mg/kg (±0.16). Median time-to-recovery was 1 min shorter for MK (5 min) than MKB (6 min; P = 0.02). Physiologic parameters during recumbency were not clinically different between the two regimes. Both regimes were suitable to safely anesthetize free-ranging camels; however, further investigation is required to find the safest, most consistent, and logistically practical combination.

Concepts: Anesthesia, Livestock, Camel, Anesthetic, Dromedary, Camelid, Australian feral camel, Medetomidine

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Three medetomidine-based protocols were evaluated for sedation in companion rats undergoing diagnostic procedures. Group Me received medetomidine at 150 μg/kg intramuscularly (IM); group Me-Bu received medetomidine 100 μg/kg IM and butorphanol 2 mg/kg IM, and group Me-Bu-Mi received medetomidine 50 μg/kg IM, butorphanol 2 mg/kg IM and midazolam 1 mg/kg IM. The righting reflex disappeared more quickly in the Me-Bu-Mi group, but recovery after atipamezole was longer. In group Me, a palpebral reflex was present throughout sedation in more rats than in the other two groups. Pulse and respiratory rates were higher when lower doses of medetomidine were used, although arterial haemoglobin O2 saturation was similar among groups. All protocols tested produced adequate sedation lasting 25 min.

Concepts: Rat, Brown rat, Medetomidine

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Abstract We compared dosages of a combination of sedatives, which included butorphanol tartrate, azaperone tartrate, and medetomidine HCl (BAM) in captive adult Rocky Mountain elk (Cervus elaphus nelsoni). All three BAM dosages (low, medium, and high) effectively immobilized elk and produced an adequate level of sedation in all subjects. Induction times were similar among the three groups (mean±SD: low = 6.9±1.1 min; medium = 6.3±0.9 min; high = 4.7±1.3 min). Most elk became hypoxemic regardless of BAM dosage, but hypoxemia tended to be most severe in the high-BAM group; regardless of BAM dosage, oxygen supplementation improved the percentage of oxygen saturation and stabilized the vital rates. Recovery after administration of antagonists (3 mg atipamezole/mg medetomidine and 2 mg/kg tolazoline) was comparable among groups (range of means = 9±1.5-11.7±1 min). Based on the findings from clinical trials and field data from free-ranging elk immobilizations, we recommend low-dose BAM (2 mL dose; equivalent to 46 mg butorphanol, 30 mg azaperone, and 18 mg medetomidine) and supplemental oxygen for adult elk; immobilization should be antagonized using 3-5 mg atipamezole/mg medetomidine and 2 mg/kg tolazoline, with tolazoline injected about 5-10 min before atipamezole to smooth out recovery.

Concepts: Oxygen, Deer, Dose, Elk, Oxygen saturation, Rocky Mountain Elk, Hypoxemia, Medetomidine

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The anesthetic effect of a combination of medetomidine, midazolam, and butorphanol (Me-Mi-Bu) was evaluated in healthy cynomolgus monkeys. The Me-Mi-Bu combination was intramuscularly administered as follows: Dose 1, Me 0.015 mg/kg-Mi 0.1 mg/kg-Bu 0.15 mg/kg; Dose 2, Me 0.02 mg/kg-Mi 0.15 mg/kg-Bu 0.2 mg/kg; and Dose 3, Me 0.04 mg/kg-Mi 0.3 mg/kg-Bu 0.4 mg/kg. The combination rapidly induced immobilization, and lateral recumbency was reached within 15 min, and the duration of anesthesia for each dose administered was follows: Dose 1, 47 ± 27 min; Dose 2, 113 ± 31 min; and Dose 3, 190 ± 24 min. The anesthetic effect of the combination was abolished by the α2-adrenoceptor antagonist atipamezole. No marked changes in the levels of hematologic or serum biochemical parameters were noted in cynomolgus monkeys administered the combination plus atipamezole. Taken together, these results suggest that the Me-Mi-Bu combination exhibits reversible anesthetic effect and may be useful for studies involving cynomolgus monkeys.

Concepts: Local anesthetic, Medetomidine