A comparison of two combinations of xylazine-ketamine administered intramuscularly to alpacas and of reversal with tolazoline

ObjectiveTo evaluate the anesthetic and cardiorespiratory effects of two doses of intramuscular (IM) xylazine/ketamine in alpacas, and to determine if tolazoline would reduce the anesthetic recovery time.Study designProspective randomized crossover study.AnimalsSix castrated male alpacas.MethodsEach alpaca received a low dose (LD) (0.8 mg kg⁻¹ xylazine and 8 mg kg⁻¹ ketamine IM) and high dose (HD) (1.2 mg kg⁻¹ xylazine and 12 mg kg⁻¹ ketamine IM) with a minimum of one week between trials. Time to sedation, duration of lateral recumbency and analgesia, pulse rate, respiratory rate, hemoglobin oxygen saturation, arterial blood pressure, blood-gases, and the electrocardiogram were monitored and recorded during anesthesia. With each treatment three alpacas were randomly selected to receive tolazoline (2 mg kg⁻¹ IM) after 30 minutes of lateral recumbency.ResultsOnset of sedation, lateral recumbency and analgesia was rapid with both treatments. The HD was able to provide ≥30 minutes of anesthesia in five of six alpacas. The LD provided ≥30 minutes of anesthesia in three of six alpacas. Respiratory depression and hypoxemia occurred with the HD treatment during the first 10 minutes of lateral recumbency: two animals were severely hypoxemic and received nasal oxygen for 5 minutes. Heart rate decreased, but there were no significant changes in arterial blood pressure. Tolazoline significantly shortened the duration of recumbency with the HD.ConclusionsThe HD provided more consistent clinical effects in alpacas than the LD. Intramuscular tolazoline shortened the duration of lateral recumbency in alpacas anesthetized with the HD combination.Clinical relevanceBoth doses of the combination were effective in providing restraint in alpacas and the duration of restraint was dose dependent. Supplemental oxygen should be available if using the HD and IM administration of tolazoline will shorten the recovery time.     

A comparison of two intramuscular doses of xylazine-ketamine combination and tolazoline reversal in llamas

OBJECTIVE: To evaluate the anesthetic and cardiorespiratory effects of two doses of intramuscular xylazine/ketamine in llamas, and to determine if an intramuscular injection of tolazoline would shorten the anesthesia recovery time. STUDY DESIGN: Prospective randomized study. ANIMALS: Six castrated male llamas. METHODS: Each llama received a low dose (LD) (0.4 mg kg(-1) xylazine and 4 mg kg(-1) ketamine) and high dose (HD) (0.8 mg kg(-1) xylazine and 8 mg kg(-1) ketamine). Time to sedation, duration of lateral recumbency and analgesia, pulse, respiratory rate, hemoglobin oxygen saturation, arterial blood pressure, blood gases, and the electrocardiogram were monitored and recorded during anesthesia. Three llamas in each treatment were randomized to receive intramuscular tolazoline (2 mg kg(-1)) after 30 minutes of lateral recumbency. RESULTS: Onset of sedation, lateral recumbency, and analgesia was rapid with both treatments. The HD was able to provide at least 30 minutes of anesthesia in all six llamas. The LD provided only 30 minutes of anesthesia in two out of six llamas. Respiratory depression and hypoxemia were seen in the HD treatment during the first 10 minutes of lateral recumbency. Two llamas were severely hypoxemic during this period and were given nasal oxygen for five minutes. Heart rate decreased, but there were no significant changes in blood pressure. Tolazoline significantly shortened the duration of recumbency in the HD treatment. CONCLUSIONS: The HD provided more consistent clinical effects in llamas than did the LD. Intramuscular tolazoline shortens the duration of lateral recumbency in llamas anesthetized with this combination. CLINICAL RELEVANCE: Both doses appear to be very effective in providing restraint in llamas. The LD may be used for procedures requiring a short period of anesthesia or restraint. The HD could be used when a longer duration of anesthesia is desired. Supplemental oxygen should be available if using the HD. Tolazoline (IM) shortened the recovery time with this combination in llamas.     

Behavioral responses following eight anesthetic induction protocols in horses

Objective To compare behavioral characteristics of induction and recovery in horses anesthetized with eight anesthetic drug protocols. Study design Randomized prospective experimental study. Animals Eight horses, 5.5 ± 2.4 years (mean ± SD) of age, and weighing 505 ± 31 kg. Methods After xylazine pre‐medication, each of eight horses was anesthetized on four occasions using one of eight different anesthetic induction protocols which incorporated various combinations of ketamine (KET), propofol (PRO), and thiopental (THIO): THIO 8 mg kg^?1; THIO 6 mg kg^?1 + PRO 0.5 mg kg^?1; THIO 4 mg kg^?1 + PRO 1 mg kg^?1; THIO 2 mg kg^?1 + PRO 1.5 mg kg^?1; KET 2 mg kg^?1; KET 1.5 mg kg^?1 + PRO 0.5 mg kg^?1; KET 1 mg kg^?1 + PRO 1 mg kg^?1; KET 0.5 mg kg^?1 + PRO 1.5 mg kg^?1. Quality of induction and recovery were scored from 1 (poor) to 5 (excellent), and time taken to achieve lateral recumbency, first movement, sternal recumbency, and standing were evaluated. Results Time taken to achieve lateral recumbency after drug administration differed significantly (p < 0.0001) among the various combinations, being shortest in horses receiving THIO‐8 (mean ± SD, 0.5 ± 0.3 minutes) and longest in horses receiving KET‐2 (1.4 ± 0.2 minutes). The best scores for induction quality were associated with KET‐1.5 + PRO‐0.5, and the worst scores for induction quality were associated with KET‐2, although the difference was not significant. Time to first movement varied significantly among drug protocols (p = 0.0133), being shortest in horses receiving KET‐2 (12.7 ± 3.6 minutes) and longest in horses receiving THIO‐8 (29.9 ± 1.5 minutes). Horses receiving THIO‐8 made the greatest number of attempts to attain sternal posture (6.5 ± 4.7) and to stand (1.6 ± 0.8). Horses in the THIO‐8 treatment also received the poorest recovery scores (3.3 ± 1.0 and 3.0 ± 0.7 for sternal and standing postures, respectively). The best recovery scores were associated with combinations comprised mainly of propofol. Conclusions Combining propofol with either ketamine or thiopental modifies behaviors associated with use of the individual drugs. Clinical relevance Quality of early anesthesia recovery in horses may be improved by some combinations of propofol with either thiopental or ketamine.     

Comparison of lidocaine, xylazine, and lidocaine−xylazine for caudal epidural analgesia in cattle

Objective To directly compare the time to onset and duration of analgesia produced by a lidocaine/xylazine combination with that produced by lidocaine and xylazine administered alone in the caudal epidural space of dairy cattle. Design Prospective randomized experimental study. Animals Nine adult (> 4 years of age) dairy cows (520–613 kg). Methods Caudal epidural analgesia was produced in all cows with 2% lidocaine (0.22 mg kg^?1; 5.5 mL 500 kg^?1), 10% xylazine (0.05 mg kg^?1 diluted to 5.5 mL 500 kg^?1 with sterile water), and 2% lidocaine/10% xylazine (0.22 mg kg^?1/0.05 mg kg^?1; total volume of 5.7 mL 500 kg^?1), at no earlier than weekly intervals in a Latin square design. Time to onset, duration and cranial spread of analgesia were recorded, as were degree of sedation, ataxia and ptyalism. Results No significant difference (p > 0.05) was noted for time (mean ± SEM) of onset of analgesia between lidocaine (4.8 ± 1.0 minutes) and the lidocaine/xylazine combination (5.1 ± 0.9 minutes) but onset of analgesia following xylazine was significantly longer (11.7 ± 1.0 minutes) than either of the other two treatments. Lidocaine/xylazine (302.8 ± 11.0 minutes) produced analgesia of significantly longer duration than that of xylazine (252.9 ± 18.9 minutes) and both the lidocaine/xylazine combination and xylazine alone produced analgesia of significantly longer duration than that produced by lidocaine (81.8 ± 11.8 minutes). In all cattle, xylazine, administered either alone or with lidocaine, induced mild to moderate sedation and ataxia and cutaneous analgesia from the coccyx to T13. Mild ataxia was also present in those cattle receiving lidocaine alone. Conclusion The combination of xylazine and lidocaine produces analgesia of quicker onset and longer duration than xylazine administered alone and of longer duration than lidocaine administered alone. Clinical relevance Utilizing this combination, long‐duration obstetrical and surgical procedures could commence relatively soon after epidural injection and could be completed without re‐administration of anesthetic agents.     

Comparison of two injectable anesthetic regimes in feral cats at a large-volume spay clinic

Same‐day mass sterilization of feral cats requires rapid onset, short‐duration anesthesia. The purpose of this study was to compare our current anesthetic protocol, Telazol–ketamine–xylazine (TKX) with medetomidine–ketamine–buprenorphine (MKB). Feral female cats received either IM TKX (n = 68; 0.25 mL cat^?1; tiletamine 12.5 mg, zolazepam 12.5 mg, K 20 mg, and X 5 mg per 0.25 mL) or MKB (n = 17; M 40 µg kg^?1, K 15 mg kg^?1, and B 10 µg kg^?1). Intervals measured included time from injection to recumbency, time to surgery, duration of surgery, and time from reversal of anesthesia (TKX: yohimbine 0.50 mg cat^?1 IV; MKB: atipamezole 0.50 mg cat^?1 IM) to sternal recumbency. Following instrumentation (Vet/Ox 4403 and Vet/BP Plus 6500), physiological measurements were recorded at 5‐minute intervals, and included rectal temperature, heart rate (HR), respiratory rate (RR), SpO₂ (lingual or rectal probes), and indirect mean arterial blood pressure (MAP) (oscillometric method). Nonparametric means were compared using Mann–Whitney U‐tests. Parametric means were compared using a two‐factorial anova with Bonferroni's t‐tests. The alpha‐priori significance level was p < 0.05. Values were mean ± SD. Body weight (TKX: 2.9 ± 0.5 kg, MKB: 2.7 ± 0.7 kg), time to recumbency (TKX: 4 ± 1 minutes, MKB: 3 ± 1 minutes), time to surgery (TKX: 28 ± 7 minutes, MKB: 28 ± 5 minutes), and duration of surgery (TKX: 11 ± 7 minutes, MKB: 8 ± 5 minutes) did not differ between groups. In contrast, MKB cats required less time from reversal to sternal recumbency (TKX: 68 ± 41 minutes, MKB: 7 ± 2 minutes) and were recumbent for shorter duration (TKX: 114 ± 39 minutes, MKB: 53 ± 6 minutes). Temperature decreased during the study in both groups, but overall temperature was higher in MKB cats (38.0 ± 0.95 °C) than in TKX cats (37.5 ± 0.95 °C). RR, HR, and SpO₂ did not change during the study in either group. However, overall HR and RR were higher in TKX cats (RR: 18 ± 8 breaths minute^?1, HR: 153 ± 30 beats minute^?1) compared to MKB cats (RR: 15 ± 7 breaths minute^?1, HR: 128 ± 19 beats minute^?1). In contrast, overall SpO₂ was lower in the TKX group (90 ± 6%) compared to the MKB group (94 ± 4%). MAP was also lower in the TKX group (112 ± 29 mm Hg) compared to that in the MKB group (122 ± 20 mm Hg). However, MAP increased in the TKX group during surgery compared to pre‐surgical values, but did not change in the MKB group. The results of this study suggested that MKB might be more suitable as an anesthetic for the purpose of mass sterilization of feral female cats.     

Evaluation of different doses of propofol in xylazine pre-medicated horses

Objective To characterize responses to different doses of propofol in horses pre‐medicated with xylazine. Animals Six adult horses (five females and one male). Methods Each horse was anaesthetized four times with either ketamine or propofol in random order at 1‐week intervals. Horses were pre‐medicated with xylazine (1.1 mg kg^?1 IV over a minute), and 5 minutes later anaesthesia was induced with either ketamine (2.2 mg kg^?1 IV) or propofol (1, 2 and 4 mg kg^?1 IV; low, medium and high doses, respectively). Data were collected continuously (electrocardiogram) or after xylazine administration and at 5, 10 and 15 minutes after anaesthetic induction (arterial pressure, respiratory rate, pH, PaO₂, PaCO₂ and O₂ saturation). Anaesthetic induction and recovery were qualitatively and quantitatively assessed. Results Differences in the quality of anaesthesia were observed; the low dose of propofol resulted in a poorer anaesthetic induction that was insufficient to allow intubation, whereas the high dose produced an excellent quality of induction, free of excitement. Recorded anaesthesia times were similar between propofol at 2 mg kg^?1 and ketamine with prolonged and shorter recovery times after the high and low dose of propofol, respectively (p < 0.05; ketamine, 38 ± 7 minutes; propofol 1 mg kg^?1, 29 ± 4 minutes; propofol 2 mg kg^?1, 37 ± 5 minutes; propofol 4 mg kg^?1, 50 ± 7 minutes). Times to regain sternal and standing position were longest with the highest dose of propofol (32 ± 5 and 39 ± 7 minutes, respectively). Both ketamine and propofol reversed bradycardia, sinoatrial, and atrioventricular blocks produced by xylazine. There were no significant alterations in blood pressure but respiratory rate, and PaO₂ and O₂ saturation were significantly decreased in all groups (p < 0.05). Conclusion The anaesthetic quality produced by the three propofol doses varied; the most desirable effects, which were comparable to those of ketamine, were produced by 2 mg kg^?1 propofol.     

Tramadol improved the efficacy of ketamine–xylazine anaesthesia in young pigs

ObjectiveTo evaluate the influence of premedication with tramadol on xylazine–ketamine anaesthesia in young pigs.Study designProspective, randomized, blinded cross-over study.AnimalsTen young Niger hybrid pigs: mean weight 6.1 ± 0.6 kg.MethodsPigs were anaesthetized twice. Xylazine (2.5 mg kg^?1), ketamine (25 mg kg^?1) and atropine (0.04 mg kg^?1) were administered by intramuscular (IM) injection, 5 minutes after either tramadol (5 mg kg^?1)) (treatment XKT) or saline (treatment XKS). Time to loss of righting reflex (TLRR), duration of antinociception, duration of recumbency (DR) and recovery times (RCT) were recorded. Quality of induction of anaesthesia including ease of endotracheal intubation was assessed using a subjective ordinal rating score of 1 (worst) to 4 (best). Heart, pulse and respiratory rates, arterial oxygen saturations and rectal temperatures were determined over 60 minutes. Antinociception was assessed by the pigs’ response to artery forceps applied at the interdigital space. Data were compared with Student's t-test, Mann–Whitney's test or analysis of variance (anova) for repeated measures as appropriate and are presented as mean ± standard deviation.ResultsThe quality of anaesthetic induction was significantly better and duration of antinociception significantly longer (p < 0.05) in treatment XKT (3.1 ± 0.7 score; 43.7 ± 15.5 minutes) than in treatment XKS (2.8 ± 0.6 score; 32.0 ± 13.3 minutes). TLRR, DR and RCT did not differ significantly (p > 0.05) between treatment XKT (2.1 ± 0.8, 65.8 ± 17.0 and 13.2 ± 6.7 minutes) and treatment XKS (2.1 ± 1.3, 58.0 ± 14.8 and 10.3 ± 5.6 minutes). Physiological measurements did not differ between the treatments.Conclusion and clinical relevanceTramadol improved the quality of anaesthetic induction and increased the duration of antinociception in xylazine–ketamine anaesthetized young pigs without increasing duration of anaesthesia, nor causing additional depression of the physiological parameters measured.     

Comparison of isoflurane inhalation anaesthesia, injection anaesthesia and high volume caudal epidural anaesthesia for umbilical surgery in calves; metabolic, endocrine and cardiopulmonary effects

ObjectiveTo compare three anaesthetic protocols for umbilical surgery in calves regarding adequacy of analgesia, and cardiopulmonary and hormonal responses.Study designProspective, randomised experimental study.AnimalsThirty healthy German Holstein calves (7 female, 23 male) aged 45.9 ± 6.4 days.MethodsAll calves underwent umbilical surgery in dorsal recumbency. The anaesthetic protocols were as follows: group INH (n = 10), induction 0.1 mg kg^?1 xylazine IM and 2.0 mg kg^?1 ketamine IV, maintenance isoflurane in oxygen; Group INJ (n = 10), induction 0.2 mg kg^?1 xylazine IM and 5.0 mg kg^?1 ketamine IV, maintenance 2.5 mg kg^?1 ketamine IV every 15 minutes or as required; group EPI (n = 10), high volume caudal epidural anaesthesia with 0.2 mg kg^?1 xylazine diluted to 0.6 mL kg^?1 with procaine 2%. All calves received peri-umbilical infiltration of procaine and pre-operative IV flunixin (2.2 mg kg^?1). Cardiopulmonary variables were measured at preset intervals for up to 2 hours after surgery. The endocrine stress response was determined. Intra-operative nociception was assessed using a VAS scale. Data were compared between groups using appropriate statistical tests. A value of p < 0.05 was considered significant.ResultsAll three protocols provided adequate anaesthesia for surgery although, as judged by the VAS scale, intra-operative response was greatest with INJ. Lowest mean cortisol levels during surgery occurred in EPI. Heart rate and cardiac output did not differ between groups, but mean arterial blood pressure, systemic vascular resistance, and partial pressure of carbon dioxide were higher and arterial pH lower in groups INH and INJ than in Group EPI. Group INJ became hypoxaemic and had a significantly greater vascular shunt than did the other groups.Conclusion and clinical relevanceGroups INH and EPI both proved acceptable protocols for calves undergoing umbilical surgery, whilst INJ resulted in variable anti-nociception and in hypoxaemia. High volume caudal epidural anaesthesia provides a practical inexpensive method of anaesthesia for umbilical surgery.     

A comparison of sedative effects of xylazine alone or combined with levomethadone or ketamine in calves prior to disbudding

ObjectiveTo compare the sedative effects of intramuscular xylazine alone or combined with levomethadone or ketamine in calves before cautery disbudding.Study designRandomized, blinded, clinical trial.AnimalsA total of 28 dairy calves, aged 21 ± 5 days and weighing 61.0 ± 9.3 kg (mean ± standard deviation).MethodsCalves were randomly allocated to three groups: xylazine (0.1 mg kg^–1) and levomethadone (0.05 mg kg^–1; group XL), xylazine (0.1 mg kg^–1) and ketamine (1 mg kg^–1; group XK) and xylazine alone (0.2 mg kg^–1; group X). Local anaesthesia (procaine hydrochloride) and meloxicam were administered subcutaneously 15 minutes after sedation and 15 minutes before disbudding. The calves’ responses to the administration of local anaesthesia and disbudding were recorded. Sedation was assessed at baseline and at intervals up to 240 minutes postsedation. Times of recumbency, first head lift and first standing were recorded. Drug plasma concentrations were measured.ResultsData were obtained from 27 animals. All protocols resulted in sedation sufficient to administer local anaesthesia and to perform disbudding. Sedation scores significantly correlated with drug plasma concentrations (p ≤ 0.002). Times to recumbency did not differ among protocols (2.8 ± 0.3, 3.1 ± 1.1 and 2.1 ± 0.8 minutes for groups XL, XK and X, respectively), whereas interval from drug(s) administration until first head lift was significantly shorter in group XK than X (47.3 ± 14.1, 34.4 ± 5.3 and 62.6 ± 31.9 minutes for groups XL, XK and X, respectively). The area under the time-sedation curve was significantly greater in group X than XK or XL (754 ± 215, 665 ± 118 and 1005 ± 258 minutes for groups XL, XK and X, respectively).Conclusions and clinical relevanceLevomethadone or ketamine with a low dose of xylazine produced short but sufficient sedation for local anaesthesia and disbudding with minimum resistance.     

Induction of anesthesia and recovery in donkeys sedated with xylazine: a comparison of midazolam–alfaxalone and midazolam–ketamine

Objective

To compare the induction and recovery characteristics and selected cardiopulmonary variables of midazolam–alfaxalone or midazolam–ketamine in donkeys sedated with xylazine.

Sedative-hypnotic effects of midazolam in goats after intravenous and intramuscular administration

Objective To examine the effect of dose and route of administration on the sedative‐hypnotic effects of midazolam. Design Prospective randomized controlled study Animals Six indigenous, African bred goats. Methods Pilot studies indicated that the optimum dose of midazolam for producing sedation was 0.6 mg kg^?1 for intramuscular (IM) injection, while the optimum intravenous (IV) doses causing hypnosis without, and with loss of palpebral reflexes were 0.6 mg kg^?1 and 1.2 mg kg^?1, respectively. These doses and routes of administration were compared with a saline placebo in a randomized block design in the main experiment, and the sedative‐hypnotic effects evaluated according to pre‐determined scales. Results Intramuscular midazolam produced sedation with or without sternal recumbency in all animals with the peak effect occurring 20 minutes after administration. The scores for IM sedation with midazolam were significantly different (p < 0.05) from placebo. Intravenous midazolam at 0.6 mg kg^?1 resulted in hypnosis, and at 1.2 mg kg^?1 increased reflex suppression was observed. The maximum scores for hypnosis at both doses were obtained 5 minutes after IV injection. The mean (± SD) duration of lateral recumbency was 10.8 (± 3.8) minutes after IV midazolam (0.6 mg kg^?1) compared to 20 (± 5.2) minutes after midazolam at 1.2 mg kg^?1. Compared to baseline, the heart rate increased significantly (p < 0.05) after high dose IV midazolam. Conclusion Intramuscular midazolam (0.6 mg kg^?1) produced maximum sedation 20 minutes after injection. Intravenous injection produced maximum hypnosis within 5 minutes. Increasing the IV dose from 0.6 to 1.2 mg kg^?1 resulted in increased reflex suppression and duration of hypnosis. Clinical relevance For a profound effect with rapid onset midazolam should be given IV in doses between 0.6 and 1.2 mg kg^?1.     

Antinociceptive and selected physiological effects of morphine and xylazine on tiletamine‐zolazepam anesthesia in llamas

ObjectiveEvaluate antinociception, anesthesia, and recovery in llamas given tiletamine-zolazepam (TZ) with either morphine, xylazine, morphine and xylazine, or saline.Study designRandomized crossover experimental study.AnimalsSix healthy, adult intact male llamas.MethodsLlamas were given each of four treatments intramuscularly with a 1-week washout: TZ (2 mg kg^?1) combined with either morphine (0.5 mg kg^?1; M), xylazine (0.15 mg kg^?1; X), morphine (0.5 mg kg^?1) and xylazine (0.15mg kg^?1) (MX), or saline (C). Llamas breathed room air during the experiment. Characteristics of anesthesia, recovery, and selected cardiopulmonary variables were recorded. Antinociception was assessed by clamping a claw at 5-minute intervals. Data were analyzed using a mixed-model anova and Tukey-Kramer test, and are expressed as least squares mean ± SEM. Significance was set at p < 0.05.ResultsNo llama in the control group demonstrated antinociception. Antinociception was longest with treatment MX, followed by treatments X and M, respectively. Heart rates in llamas given treatments X and MX were significantly lower than with other treatments. The respiratory rate in llamas given treatment C was greater (p < 0.05) than for all other treatments, however, the respiratory rate was not significantly different among treatments X, M and MX. The PaO₂ for llamas given MX remained <60 mmHg throughout the 20 minute period of blood gas analysis. Mean arterial blood pressure in llamas in treatment MX was less than for treatments M or C.Conclusion and clinical relevanceThe combination of morphine (0.5 mg kg^?1) and xylazine (0.15 mg kg^?1) increased the duration of antinociception compared with xylazine alone, in TZ-anesthetized llamas. Treatments X, M and MX were associated with hypoxemia (PaO₂ < 60 mmHg).     

Anaesthesia with medetomidine,midazolam and ketamine in six gorillas after premedication with oral zuclopenthixol dihydrochloride

ObjectiveTo evaluate the effects of medetomidine, midazolam and ketamine (MMK) in captive gorillas after premedication with oral zuclopenthixol.Study designCase series.AnimalsSix gorillas, two males and four females, aged 9–52 years and weighing 63–155 kg.MethodsThe gorillas were given zuclopenthixol dihydrochloride 0.2 ± 0.05 mg kg^?1 per os twice daily for 3 days for premedication. On the day of anaesthesia the dose of zuclopenthixol was increased to 0.27 mg kg^?1 and given once early in the morning. Anaesthesia was induced with medetomidine 0.04 ± 0.004 mg kg^?1, midazolam 0.048 ± 0.003 mg kg^?1 and ketamine 4.9 ± 0.4 mg kg^?1 intramuscularly (IM). Upon recumbency, the trachea was intubated and anaesthesia was maintained on 1–2% isoflurane in oxygen. Physiological parameters were monitored every 10 minutes and arterial blood gas analysis was performed once 30–50 minutes after initial darting. At the end of the procedure, 42–115 minutes after initial darting, immobilisation was antagonized with atipamezole 0.21 ± 0.03 mg kg^?1 and sarmazenil 5 ± 0.4 μg kg^?1 IM.ResultsRecumbency was reached within 10 minutes in five out of six animals. One animal required two additional darts before intubation was feasible. Heart rate ranged from 60 to 85 beats minute^?1, respiratory rate from 17 to 46 breaths minute^?1 and temperature from 36.9 to 38.3 °C. No spontaneous recoveries were observed and anaesthetic level was stable. Blood gas analyses revealed mild respiratory acidosis, and mean PaO₂ was 24.87 ± 17.16 kPa (187 ± 129 mmHg) with all values being above 13.4 kPa (101 mmHg). Recovery was smooth and gorillas were sitting within 25 minutes.Conclusion and clinical relevanceThe drug combination proved to be effective in anaesthetizing captive gorillas of various ages and both sexes, with minimal cardio-respiratory changes.     

Evaluation of intramuscular anesthetic protocols in healthy domestic horses

ObjectiveTo assess anesthetic induction, recovery quality and cardiopulmonary variables after intramuscular (IM) injection of three drug combinations for immobilization of horses.Study designRandomized, blinded, three-way crossover prospective design.AnimalsA total of eight healthy adult horses weighing 470–575 kg.MethodsHorses were administered three treatments IM separated by ≥1 week. Combinations were tiletamine–zolazepam (1.2 mg kg⁻¹), ketamine (1 mg kg⁻¹) and detomidine (0.04 mg kg⁻¹) (treatment TKD); ketamine (3 mg kg⁻¹) and detomidine (0.04 mg kg⁻¹) (treatment KD); and tiletamine–zolazepam (2.4 mg kg⁻¹) and detomidine (0.04 mg kg⁻¹) (treatment TD). Parametric data were analyzed using mixed model linear regression. Nonparametric data were compared using Skillings–Mack test. A p value <0.05 was considered statistically significant.ResultsAll horses in treatment TD became recumbent. In treatments KD and TKD, one horse remained standing. PaO₂ 15 minutes after recumbency was significantly lower in treatments TD (p < 0.0005) and TKD (p = 0.001) than in treatment KD. Times to first movement (25 ± 15 minutes) and sternal recumbency (55 ± 11 minutes) in treatment KD were faster than in treatments TD (57 ± 17 and 76 ± 19 minutes; p < 0.0005, p = 0.001) and TKD (45 ± 18 and 73 ± 31 minutes; p = 0.005, p = 0.021). There were no differences in induction quality, muscle relaxation score, number of attempts to stand or recovery quality.Conclusions and clinical relevanceIn domestic horses, IM injections of tiletamine–zolazepam–detomidine resulted in more reliable recumbency with a longer duration when compared with ketamine–detomidine and tiletamine–zolazepam–ketamine–detomidine. Recoveries were comparable among protocols.     

Comparison between S(+) ketamine–diazepam and S(+) ketamine–midazolam on anesthetic induction and recovery in dogs

S(+) ketamine, one of the two enantiomers of racemic ketamine, is a phencyclidine derivative that induces amnesia and analgesia. Its activity is related to blockade of NMDA receptors and some opioid action. We compared anesthetic induction and recovery quality with S(+) ketamine in combination with diazepam or midazolam in 10 dogs (ASA 1) admitted for elective surgery. After all clinical examinations, the dogs were separated into two groups (G I and G II). All animals received acepromazine (0.1 mg kg^?1) and fentanyl (5 µg kg^?1) IM, 20 minutes before induction with S(+) ketamine (6 mg kg^?1) and diazepam (0.5 mg kg^?1) IV (G I) or midazolam 0.2 mg kg^?1 (G II) IV. The doses of diazepam and midazolam were chosen according to the literature. All dogs were intubated and then maintained with halothane in oxygen at a vaporizer setting sufficient to maintain surgical anesthesia. Quality of induction, time needed for intubation, heart rate, respiratory rate, SpO₂, time to extubation, and quality of recovery were evaluated. The results were analyzed by Student's t‐test. Smooth induction and recovery were observed in all animals. The time to intubation was 45 ± 20 (GI) and 25 ± 6 seconds (GII), HR was 122 ± 12 (GI) and 125 ± 7 beats minute^?1 (GII), RR was 17 ± 2 (GI) and 21 ± 3 breaths minute^?1 (GII), SpO₂ was 96 ± 2 (GI) and 94 ± 1% (GII), time to extubation was 7 ± 3 (GI) and 4 ± 1 minutes (GII). No statistical differences were found in analyses, although time to intubation was less in GII. The results suggested that both combinations could be used safely for anesthetic induction in healthy dogs.     

Effects of Carbon Dioxide Insufflation Combined With Changes in Body Position on Blood Gas and Acid-Base Status in Anesthetized Llamas (Llama glama)

Objective— To study the combined effects of intra-abdominal CO₂ insufflation with changes in body position during laparoscopy in xylazine-ketamine-halothane anesthetized llamas. Study Design— Prospective, controlled study. Animals— Nine castrated, male llamas weighing 114 ± 23 kg, 3 to 13 years old. Methods— Three llamas (preliminary study [PS] group) were used to study the effect of right lateral, dorsal, and left lateral recumbency on gas exchange and acid-base status. The other six (experimental study [ES] group) were used to study the combined effects of changes in body position and CO₂ insufflation to an intraabdominal pressure of 10 to 12 mm Hg. Heart rate, respiratory rate, and indirect arterial blood pressures (systolic [SAP], mean [MAP], and diastolic [DAP]) were recorded every 5 minutes during anesthesia. Arterial blood gases (PaO₂ and PaCO₂) and acid-base status (pHa and HCO₃) were measured immediately after induction of anesthesia and before each change of position. Results— In the PS group, significant decreases in SAP, MAP and PaCO₂ and increases in PaO₂ and pHa were observed when the llamas were turned from right lateral to dorsal recumbency. Values for HCO_-3 were lower than the postinduction values, but they remained unaffected by the changes in position. In the ES group, values for MAP were significantly lower when the llamas were placed in dorsal and left lateral recumbency than those observed during right lateral recumbency. Arterial O₂ tension during right lateral recumbency was lower but returned to preinsufflation values when the llamas were placed in the dorsal position. All llamas recovered uneventfully within 30 minutes after termination of anesthesia. Conclusions— Insufflation of CO₂ and changing body position induce minor and transient changes in cardiovascular and respiratory function. Clinical Relevance— Laparoscopy with mild intra-abdominal CO₂ insufflation (10 to 12 mm Hg) can be used safely in spontaneously breathing llamas anesthetized with xylazine, ketamine, and halothane.     

Chemical immobilization of chimpanzees (Pan troglodytes) using a combination of detomidine and ketamine

Objective To determine if a combination of detomidine and ketamine can be used for effective chemical immobilization of chimpanzees. Study design Observational study. Animals Twenty‐one adult captive chimpanzees (12 males, nine females), age 8–46 years, weighing 40.4–68.4 kg. Methods The chimpanzees were immobilized with intramuscular (IM) detomidine and ketamine by a darting system. Based on estimated weights, doses administered were 50 μg kg^?1 detomidine and 4 mg kg^?1 ketamine in groups 1 and 2, and 60 μg kg^?1 and 5 mg kg^?1 respectively in group 3. Eight minutes in group 1 and 15 minutes in groups 2 and 3 were allowed from the time of apparent immobilization before removing the animals from their enclosures. Body temperature, arterial haemoglobin saturation and pulse rate were measured. The time from injection to induction (recumbency and absence of voluntary movement), total anaesthetic and recovery times (with or without atipamezole) were recorded. Results Immobilization occurred within 5 minutes after darting in most animals. Early handling of the chimpanzees often resulted in arousal and required further doses of ketamine IM. Most animals were hypoxaemic and hypothermic. Occasionally, bradycardia was observed. Atipamezole resulted in an acceptable quality of recovery 10 minutes after IM injection. The duration of immobilization varied widely when no antagonist was administered. Conclusions and clinical relevance The combination detomidine (60 μg kg^?1) and ketamine (5–6 mg kg^?1) can be used for the immobilization of chimpanzees for non‐ to minimally invasive procedures. A period of 15 minutes should be allowed before handling to avoid unwanted arousal. Oxygen administration is recommended to reduce hypoxaemia. Administration of atipamezole is justified to hasten recovery.     

The pharmacokinetics and pharmacodynamics of the injectable anaesthetic alfaxalone in the horse

ObjectiveTo determine the pharmacokinetics and pharmacodynamics of the neurosteroidal anaesthetic, alfaxalone, in horses after a single intravenous (IV) injection of alfaxalone, following premedication with acepromazine, xylazine and guaiphenesin.Study designProspective experimental study.AnimalsTen (five male and five female), adult, healthy, Standardbred horses.MethodsHorses were premedicated with acepromazine (0.03 mg kg^?1 IV). Twenty minutes later they received xylazine (1 mg kg^?1 IV), then after 5 minutes, guaiphenesin (35 mg kg^?1 IV) followed immediately by IV induction of anaesthesia with alfaxalone (1 mg kg^?1). Cardiorespiratory variables (pulse rate, respiratory rate, pulse oximetry) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Venous blood samples were collected at strategic time points and plasma concentrations of alfaxalone were assayed using liquid chromatography-mass spectrometry (LC/MS) and analysed by noncompartmental pharmacokinetic analysis. The quality of anaesthetic induction and recovery was scored on a scale of 1–5 (1 very poor, 5 excellent).ResultsThe median (range) induction and recovery scores were 4 (3–5) (good: horse slowly and moderately gently attained recumbency with minimal or no rigidity or paddling) and 4 (1–5) (good: horse stood on first attempt with some knuckling and ataxia) respectively. The monitored cardiopulmonary variables were within the range expected for clinical equine anaesthesia. The mean ± SD durations of anaesthesia from induction to sternal recumbency and from induction to standing were 42.7 ± 8.4 and 47 ± 9.6 minutes, respectively. The mean ± SD plasma elimination half life (t_1/2), plasma clearance (Clp) and volume of distribution (V_d) for alfaxalone were 33.4 minutes, 37.1 ± 11.1 mL minute^?1 kg^?1 and 1.6 ± 0.4 L kg^?1, respectively.Conclusions and clinical relevanceAlfaxalone, in a 2-hydroxypropyl-beta-cyclodextrin formulation, provides anaesthesia with a short duration of recumbency that is characterised by a smooth induction and satisfactory recovery in the horse. As in other species, alfaxalone is rapidly cleared from the plasma in the horse.