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Objective: To evaluate cardiovascular effects of oral tasipimidine on propofol-isoflurane anaesthesia with or without methadone and dexmedetomidine at equianaesthetic levels., Study Design: Prospective, placebo-controlled, blinded, experimental trial., Animals: A group of seven adult Beagle dogs weighing (mean ± standard deviation) 12.4 ± 2.6 kg and a mean age of 20.6 ± 1 months., Methods: The dogs underwent four treatments 60 minutes before induction of anaesthesia with propofol. PP: placebo orally and placebo (NaCl 0.9%) intravenously (IV); TP: tasipimidine 30 μg kg -1 orally and placebo IV; TMP: tasipimidine 30 μg kg -1 orally and methadone 0.2 mg kg -1 IV; and TMPD: tasipimidine 30 μg kg -1 orally with methadone 0.2 mg kg -1 and dexmedetomidine 1 μg kg -1 IV followed by 1 μg kg -1 hour -1 . Isoflurane in oxygen was maintained for 120 minutes at 1.2 individual minimum alveolar concentration preventing motor movement. Cardiac output (CO), tissue blood flow (tbf), tissue oxygen saturation (stO 2 ) and relative haemoglobin content were determined. Arterial and mixed venous blood gases, arterial and pulmonary artery pressures and heart rate (HR) were measured at baseline; 60 minutes after oral premedication; 5 minutes after IV premedication; 15, 30, 60, 90 and 120 minutes after propofol injection; and 30 minutes after switching the vaporiser off. Data were analysed by two-way anova for repeated measures; p < 0.05., Results: Tasipimidine induced a significant 20-30% reduction in HR and CO with decreases in MAP (10-15%), tbf (40%) and stO 2 (43%). Blood pressure and oxygenation variables were mainly influenced by propofol-isoflurane-oxygen anaesthesia, preceded by short-lived alterations related to IV methadone and dexmedetomidine., Conclusions and Clinical Relevance: Tasipimidine induced mild to moderate cardiovascular depression. It can be incorporated into a common anaesthetic protocol without detrimental effects in healthy dogs, when anaesthetics are administered to effect and cardiorespiratory function is monitored., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Objective: To evaluate the effect of oral tasipimidine on dog handling, ease of catheter placement and propofol and isoflurane requirements for anaesthesia., Study Design: Placebo-controlled, randomized, blinded, experimental trial., Animals: A group of seven adult Beagle dogs weighing (mean ± standard deviation) 13.1 ± 2.7 kg with a mean age of 18.6 ± 1 months., Methods: The dogs underwent four treatments before induction of anaesthesia with propofol. PP: placebo orally (PO) 60 minutes before induction of anaesthesia followed by placebo (NaCl 0.9%) intravenously (IV). TP: tasipimidine 30 μg kg -1 (PO) 60 minutes before induction of anaesthesia followed by placebo (NaCl 0.9%) IV. TMP: tasipimidine 30 μg kg -1 PO 60 minutes before induction of anaesthesia followed by methadone 0.2 mg kg -1 IV. TMPD: tasipimidine 30 μg kg -1 PO 60 minutes before induction of anaesthesia followed by methadone 0.2 mg kg -1 and dexmedetomidine 1 μg kg -1 IV followed by a dexmedetomidine constant rate infusion of 1 μg kg -1 hour -1 . Sedation, response to catheter placement, intubation quality, time to loss of consciousness, time to intubation, required dose of propofol and minimum alveolar isoflurane concentration preventing motor movement (MAC NM ) were determined. A mixed-model analysis or the Friedman and Mann-Whitney test were used; p-value < 0.05., Results: Response to catheter placement did not differ between treatments. Tasipimidine alone reduced the propofol dose by 30%. Addition of methadone or methadone and dexmedetomidine reduced the propofol dose by 48% and 50%, respectively. Isoflurane MAC NM was reduced by 19% in tasipimidine-medicated dogs, whereas in combination with methadone or methadone and dexmedetomidine, isoflurane MAC NM was reduced by 35%., Conclusions and Clinical Relevance: An anxiolytic dose of tasipimidine induced mild signs of sedation in dogs and reduced propofol and isoflurane requirements to induce and maintain anaesthesia, which needs to be considered in an anaesthetic plan., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

To study the antinociceptive properties of epidural magnesium sulphate (MgSO 4 ) in standing horses Experimental, placebo-controlled, masked, cross-over A group of six healthy horses Through an epidural catheter, 1 mg kg -1 MgSO 4 (treatment Mg) diluted to a volume of 15 mL or the same volume of saline (treatment S) was administered over 15 minutes. Electrical, thermal and mechanical nociceptive thresholds were determined on the pelvic limb before and 20, 40, 60, 80, 100, 120, 140, 160 and 180 minutes after the start of the injection. Heart rate (HR) and respiratory frequency (f R ) were recorded every 10 minutes. Blood samples were collected before treatment and every 30 minutes throughout the study period. Data were assessed for normality using a Shapiro-Wilk test. A linear mixed model with horse as random effect and time, treatment and their interaction as fixed effects was used. Treatments were compared at 20, 60, 120 and 180 minutes using the Wilcoxon rank sum test stratified for horse (global α = 0.05, with Bonferroni correction α = 0.0125). Epidural MgSO 4 caused a significant increase in the electrical threshold (mA) (P = .0001), but no significant differences in thermal and mechanical nociceptive thresholds. During the injection of MgSO 4, two horses collapsed. One stood up within 20 minutes and was able to continue the study, the second one was excluded. A significant difference was found for HR at T180 (Mg 44 ± 23 beats minute -1 ; S 32 ± 9 beats minute -1 ) (P = .0090). Epidural administration of MgSO 4 caused an increase in the electrical threshold of the pelvic limbs of horses. Caution is warranted however, as with the current dose, 2 horses collapsed., (Copyright © 2022 Elsevier Inc. All rights reserved.)

A bolus of 50 mg kg -1 MgSO 4 (treatment Mg) or the same volume of saline (treatment S) was infused over 15 minutes in 5 adult healthy horses. T0 was the end of the infusion. Physiological parameters were recorded throughout the study period. Measurements of electrical, thermal, and mechanical nociceptive thresholds were performed at the pelvic limbs at baseline (before T0), and at specific timepoints. Blood samples were taken at fixed timepoints before, during and until 12 hours after the infusion. For statistical analysis, the 95% confidence intervals (CI's) for the differences in nociceptive thresholds between treatments were calculated. Physiological parameters were compared using a linear mixed model (global α = 0.05, with Bonferroni correction α = 0.0125). The concentrations of ions were also compared with the baseline values at specific timepoints, using a linear mixed model. The Pearson's correlation coefficient was derived between the ion concentrations. The 95% CI's of thermal, mechanical and electrical thresholds were [-1; +2]°C, [0; +3] N and [-1; +1] mA (positive differences indicate higher thresholds for treatment Mg), respectively. Heart rate was significantly higher (P < .0001) and non-invasive systolic arterial pressure (P < .0001) and respiratory rate (P = .0002) significantly lower after treatment Mg compared to treatment S. Additionally, non-invasive systolic arterial pressure was significantly different at T45 (P < .001). Although mild changes in cardiovascular parameters and plasma concentrations were seen with intravenous administration of MgSO 4 , no changes in nociceptive thresholds were detected in standing non-sedated horses., (Copyright © 2022. Published by Elsevier Inc.)

Objective: To compare the effects of MK-467 during isoflurane anaesthesia combined with xylazine or dexmedetomidine on global and gastrointestinal perfusion parameters., Study Design: Prospective, randomized experimental trial., Animals: A total of 15 warmblood horses., Methods: Horses were divided into two groups for administration of either dexmedetomidine (D) or xylazine (X) for premedication (D: 3.5 μg kg -1 ; X: 0.5 mg kg -1 ) and as constant rate infusion during isoflurane anaesthesia (D: 7 μg kg -1 hour -1 ; X: 1 mg kg -1 hour -1 ). During anaesthesia, heart rate, mean arterial blood pressure (MAP), systemic vascular resistance index (SVRI) and cardiac index (CI) were measured. Microperfusion of the colon, jejunum and stomach was measured using laser Doppler flowmetry. After 2 hours of stabilization, MK-467 (250 μg kg -1 ) was administered, and measurements were continued for another 90 minutes. For statistical analysis, the permutation test and Wilcoxon rank-sum test were used (p < 0.05)., Results: There were no differences in baseline measurements between groups. The MK-467 bolus resulted in a significant decrease in MAP (D: -58%; X: -48%) and SVRI (D: -68%; X: -65%) lasting longer in group D (90 minutes) compared to group X (60 minutes). While CI increased (D: +31%; X: +35%), microperfusion was reduced in the colon (D: -44%; X: -34%), jejunum (D: -26%; X: -33%) and stomach (D: -37%; X: -35%)., Conclusions and Clinical Relevance: Alpha-2-agonist induced vasoconstriction was reversed by the MK-467 dose used, resulting in hypotension and rise in CI. Gastrointestinal microperfusion decreased, probably as a result of insufficient perfusion pressure. An infusion rate for MK-467 as well as an ideal agonist/antagonist ratio should be determined., (Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Objective: To evaluate the transdermal local anaesthetic effect of lidocaine or lidocaine combined with prilocaine or tetracaine in horses., Study Design: Experimental, randomized study., Animals: A total of five healthy adult warmblood horses., Methods: Horses were clipped bilaterally at the withers, cranial saddle area and caudal saddle area. Baseline measurements for mechanical superficial sensation via von Frey filaments and nociceptive thermal thresholds were performed. A 5% lidocaine patch (12 hour exposure, treatment L), a lidocaine/prilocaine cream (each 2.5%, treatment LP) and a lidocaine/tetracaine cream (each 7%, treatment LT) were applied (both 2 hour exposure). The same product was applied at the same location bilaterally, but on the right side an epidermal micro-perforation (dermaroller, 1200 needles) was performed prior to application. A total of five more measurements were performed at each location, immediately at the end of exposure time followed by hourly measurements. Thermal thresholds normalized to thermal excursion were analysed. One- or two-way anova and the Wilcoxon signed-rank test were used for statistical analysis with p<0.05 considered significant., Results: Epidermal micro-perforation had no enhancing effect. Treatments L, LP, and LT resulted in increased thermal excursion (%) immediately (84.7±12.9; 100.0±0.0; 100.0±0.0) and 1 hour (81.7±66; 86.0±17.7; 87.7±14.4) after the removal of the respective product compared to baseline (66.1±9.3; 69.9±8.3; 76.5±7.8). Superficial mechanical sensation was decreased by the lidocaine-and-tetracaine cream at all time points, and by the lidocaine patch and lidocaine-and-prilocaine cream for three measurements., Conclusions and Clinical Relevance: Eutectic mixtures of lidocaine with either prilocaine or tetracaine led to a reduction in thermal nociception and mechanical sensation for up to 2 hours., (Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Objective: To compare alteration in intestinal blood flow in anaesthetized horses with changes in oral mucosa blood flow., Study Design: Prospective, randomized clinical study., Animals: Eight warmblood horses., Methods: After induction with guaifenesin and ketamine, anaesthesia was maintained with isoflurane at 1.5 vol% in oxygen. The tissue blood flow was measured using laser Doppler flowmetry at the jejunum, colon, rectal mucosa, oesophageal mucosa and the oral mucosa. After three baseline measurements, blood flow was first increased by dobutamine infusion and thereafter decreased by increasing isoflurane concentration and all measurements repeated twice. anova was used for comparing the measured parameters to baseline and correlation between the different measurement localizations was examined using Pearson correlation (p < 0.05)., Results: Microperfusion at all measurement sites increased significantly during dobutamine infusion and decreased significantly during high isoflurane concentration. There was a significant correlation between flow at the oral mucosa and flow at the jejunum (r 2  = 0.77, p = 0.002), colon (r 2  = 0.76, p < 0.001), rectal mucosa (r 2  = 0.88, p < 0.001) and oesophageal mucosa (r 2  = 0.83, p <0.001)., Conclusions and Clinical Relevance: Oral mucosa blood flow can be used in isoflurane anaesthetized horses to reflect changes of intestinal microcirculation., (Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Objective: To determine the acute anti-nociceptive and the minimal alveolar concentration (MAC) sparing effects of metamizole sodiummonohydrate (dipyrone) in dogs for possible perioperative analgesia., Study Design: Two groups of seven adult dogs were used in two separate randomised, blinded, controlled, cross-over studies. In each study, each dog received metamizole 50 mg kg(-1) intravenously (IV) and placebo (saline 0.9%) IV., Methods: Sevoflurane MAC was determined using the bracketing technique and electrical stimulation (50 V, 50 Hz, 10 milliseconds) at a thoracic limb, before treatment and 1 and 4 hours post treatment. In conscious dogs, thermal thresholds were determined by ramped contact heat at the thoracic wall. Mechanical thresholds (MTs) were measured by constantly rising force pressing against the radial bone. Thresholds were determined pre and 45, 75, 105, 135, 165, 195, 225, 255, 285, 315, 345, 375, 435, 495, 555, 615, 675, 735 minutes and 24 hours post treatment. Parametric data were analyzed by analysis of variance for repeated measurements and paired t-tests. Friedman test was used for nonparametric data. Level of significance was set to <5%., Results: Metamizole did not change MAC of sevoflurane significantly compared to baseline values [mean ± SD Vol%; 2.7 ± 0.5 (BL); 2.8 ± 0.6 (1 hour); 2.8 ± 0.4 (4 hours)] and placebo [2.8 ± 0.5 (BL); 2.9 ± 0.5 (1 hour); 2.9 ± 0.4 (4 hour)]. Metamizole caused a significant rise in % TE up to 105 minutes (66.5 ± 12.1%) and in MT up to 75 minutes (12.7 ± 5.0 N) compared to baseline (55 ± 10%; 7.9 ± 1.8 N). There were no significant differences between treatments., Conclusion and Clinical Relevance: Metamizole did not induce an anaesthetic sparing effect. In awake dogs metamizole induced only mild and short cutaneous anti-nociception. Metamizole as the sole analgesic drug in the perioperative periode is not recommended., (© 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.)

Objective: To determine the agreement of high definition oscillometry (HDO) with direct arterial blood pressure measurements in normotensive, hypotensive and hypertensive horses during general anaesthesia., Study Design: Experimental study., Animals: Seven healthy warmblood horses, aged 3-11 years, weighing 470-565 kg., Methods: Measurements from a HDO device with the cuff placed around the base of the tail were compared with pressures measured invasively from the facial artery. High blood pressures were induced by intravenous (IV) administration of dobutamine (5 μg kg(-1) minute(-1)) over ten minutes followed by norepinephrine (0.1 mg kg(-1) IV) and low pressures by increasing the inspired fraction of isoflurane and administration of nitroglycerine (0.05 mg kg(-1) IV). For analysis three pressure levels were determined: high (MAP>110 mmHg), normal (60 mmHg

Objective: Previous studies showed an influence of xylazine on the LiDCO sensor in vitro and in standing horses, but did not prove that this interaction caused error in LiDCO measurements. Therefore, agreement of cardiac output (CO) measurements by LiDCO and bolus-thermodilution (BTD) was determined in horses receiving xylazine infusions., Study Design: Prospective, experimental study., Animals: Eight Warmblood horses., Methods: All horses were premedicated with xylazine. Anaesthesia was induced with midazolam and ketamine and was maintained with isoflurane in oxygen. During six hours of anaesthesia CO measurements and blood samples were taken before, during and after a 60 minute period of xylazine infusion. Pairs of LiDCO and bolus thermo-dilution (BTD) measurements of CO were performed. Sensor voltages exposed to blood and saline were measured before, during and after xylazine infusion and compared using Bland-Altman method of agreement with corrections for repeated measures., Results: The CO values (mean ± SD) before xylazine were 34.8 ± 7.3 and 36.4 ± 8.1 L minute(-1) for BTD and LiDCO, respectively. After starting the xylazine infusion, the CO values for BTD decreased to 27.5 ± 6.1 L minute(-1) whereas CO values measured by LiDCO increased to 54.7 ± 18.4 L minute(-1) . One hour after discontinuing xylazine infusion, CO values were 33 ± 6.7 and 36.5 ±11.9 L minute(-1) for BTD and LiDCO, respectively. The difference between saline and blood exposed sensor voltages decreased during xylazine infusion and these differences were positive numbers before but negative during the infusion. There were correlations between xylazine plasma concentrations, CO differences and sensor voltage differences (saline - blood)., Conclusions and Clinical Relevance: This study proved that xylazine infusion caused concentration dependent bias in LiDCO measurements leading to an overestimation of readings. Sensor voltage differences (saline - blood) may become valuable clinical tool to predict drug-sensor interactions., (© 2014 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.)

Objective: To assess the effect of adjunctive gabapentin (GBP) on pain after thoracolumbar intervertebral disc surgery in dogs., Study Design: Prospective, randomized, controlled, clinical, 'blinded' trial., Animals: Sixty-three client owned dogs undergoing hemilaminectomy, Methods: Dogs were assigned to two treatment groups. The GBP group received gabapentin 10 mg kg(-1) orally every 12 hours starting before anaesthesia; the placebo (P) group received empty gelatin capsules. Background analgesia was initiated with intravenous levomethadone 0.6 mg kg(-1) (as the combination 'L-Polamivet) at anaesthesia induction, followed by a fentanyl patch and levomethadone 0.2 mg kg(-1) subcutaneously every 8 hours for 24 hours. Pain was assessed by the short form of the Glasgow Composite Measure Pain Score (CMPS-SF) without the gait category, and by a Visual Analogue Scale (VAS). Serum GBP concentrations and cortisol concentrations were measured. Statistical analyses utilized chi square test, Kolmogorov-Smirnov test, two-way analysis of variances for repeated measurements, Wilcoxon test and Friedmann test as relevant. Correlations were tested by Spearman's and Pearson's correlation coefficient. p < 0.05 was considered significant., Results: Median CMPS-SF was lower in group GBP than in group P on days 0.5, 1, 4 and 5. However, CMPS-SF and VAS were not significantly different between groups. Both pain scores decreased significantly over time. Cortisol concentrations were not significantly different between groups. Minimum serum concentrations of GBP fell below the detection limit of 1 μg mL(-1) in 6 of 29 and 7 of 28 dogs at 24 and 72 hours, respectively., Conclusions and Clinical Relevance: 10 mg kg(-1) GBP orally twice a day did not result in a detectable reduction in pain behaviour compared to background opioid analgesia alone, although a trend to lower pain levels (p < 0.1) was present. Further studies are needed to determine if this is related to effective background analgesia or an ineffective dose of GBP., (© 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)

Objective: To determine the cardiovascular effects of a proprietary l-methadone/fenpipramide combination (Polamivet) alone and in addition to acepromazine in dogs., Study Design: Prospective, randomized, experimental crossover study., Animals: Five adult healthy Beagle dogs (one male and four females, weighing 12.8-16.4 kg)., Methods: Dogs were instrumented for haemodynamic measurements whilst anaesthetized with isoflurane. Three hours after recovery dogs received 0.025 mg kg(-1) acepromazine (AP) or saline (SP) IM followed by 0.5 mg kg(-1) L-methadone/ 0.025 mg kg(-1) fenpipramide IV after 30 minutes. Cardiac output using thermodilution, heart rate, mean arterial pressure (MAP), central venous pressure (CVP), mean pulmonary artery pressure (MPAP), pulmonary artery occlusion pressure (PAOP), haemoglobin concentration, arterial and mixed-venous blood gas analysis were measured and sedation evaluated at baseline (BL), 30 minutes after acepromazine or saline IM (A/S), 5 minutes after L-methadone/fenpipramide IV application (35), every 15 minutes for 1 hour (50, 65, 80, 95 minutes) and every hour until baseline cardiac output was regained. Standard cardiovascular parameters were calculated. Data were analyzed by repeated measures anova and paired t-tests with p < 0.05 considered significant., Results: Baseline measurements did not differ. Cardiac index decreased after acepromazine administration in treatment AP (p = 0.027), but was not significantly influenced after l-methadone/fenpipramide injection in either treatment. In both treatments heart rate did not change significantly over time. Stroke volume index increased after A/S in both treatments (p = 0.049). Systemic vascular resistance index, MAP, CVP, MPAP, and pulmonary vascular resistance index did not change significantly after either treatment and did not differ between treatments. Dogs were deeply sedated in both treatments with a longer duration in treatment AP., Conclusions and Clinical Relevance: In healthy dogs the dose of l-methadone/fenpipramide used in this study alone and in combination with acepromazine induced deep sedation without significant cardiovascular changes., (© 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)

Objective: To compare three anaesthetic protocols for umbilical surgery in calves regarding adequacy of analgesia, and cardiopulmonary and hormonal responses., Study Design: Prospective, randomised experimental study., Animals: Thirty healthy German Holstein calves (7 female, 23 male) aged 45.9 ± 6.4 days., Methods: All 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., Results: All 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 Relevance: Groups 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., (© 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)

Objective: To compare effects of four drug combinations on sedation, echocardiographic, haematologic and biochemical variables and recovery in cats., Study Design: Experimental randomized 'blinded' cross-over study., Animals: Six healthy cats., Materials and Methods: Treatments were administered intramuscularly: midazolam 0.4 mg kg(-1) and butorphanol 0.4 mg kg(-1) (MB); midazolam 0.4 mg kg(-1), butorphanol 0.4 mg kg(-1) and ketamine 3 mg kg(-1) (MBK); midazolam 0.4 mg kg(-1), butorphanol 0.4 mg kg(-1) and dexmedetomidine 5 μg kg(-1) (MBD); ketamine 3 mg kg(-1) and dexmedetomidine 5 μg kg(-1) (KD). Sedation was evaluated at time-points over 10 minutes post injection. Echocardiography, systolic arterial blood pressure (SAP) measurement and blood sampling were performed at baseline and from 10 minutes after treatment. Quality of recovery was scored. Data were analysed by anova for repeated measures. p < 0.05 was considered significant., Results: The lowest sedation score was obtained by MB, (median 10.5 [7; 20]), highest by KD (36.5 [32; 38]). Quality of recovery was best with KD (0.5 [0; 2]), and worst with MB (7.5 [4; 11]). Relative to baseline measurements, treatments decreased SAP by 17%, 25%, 13%, 5% in MB, MBK, MBD and KD, respectively. Heart rate decreased (p < 0.05) after MBD (44%) and KD (34%). All treatments decreased stroke volume by 24%, 21%, 24%, 36%, and cardiac output by 23%, 34%, 54%, 53% in MB, MBK, MBD and KD, respectively. Packed cell volume was decreased (p < 0.05) by 20%, 31%, 29% in MBK, MBD and KD, respectively. Plasma glucose was increased after MBD (31%) and KD (52%) and lactate concentration was decreased (p < 0.05) after MBK (58%), MBD (72%) and KD (65%)., Conclusions and Clinical Relevance: The MB combination did not produce sedation in healthy cats. Treatment MBK led to acceptable sedation and minimal cardiovascular changes. Both treatments with dexmedetomidine produced excellent sedation and recovery but induced more cardiovascular depression and haematologic changes., (© 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)

Objective: To compare, ventilation using intermittent positive pressure ventilation (IPPV) with constant positive end-expiratory pressure (PEEP) and alveolar recruitment manoeuvres (RM) to classical IPPV without PEEP on gas exchange during anaesthesia and early recovery., Study Design: Prospective randomized study., Animals: Twenty-four warm-blood horses, weight mean 548 ± SD 49 kg undergoing surgery for colic., Methods: Premedication, induction and maintenance (isoflurane in oxygen) were identical in all horses. Group C (n = 12) was ventilated using conventional IPPV, inspiratory pressure (PIP) 35-45 cmH2O; group RM (n = 12) using similar IPPV with constant PEEP (10 cmH2O) and intermittent RMs (three consecutive breaths PIP 60, 80 then 60 cmH2O, held for 10-12 seconds). RMs were applied as required to maintain arterial oxygen tension (PaO2) at >400 mmHg (53.3 kPa). Physiological parameters were recorded intraoperatively. Arterial blood gases were measured intra- and postoperatively. Recovery times and quality of recovery were measured or scored., Results: Statistically significant findings were that horses in group RM had an overall higher PaO2 (432 ± 101 mmHg) than those in group C (187 ± 112 mmHg) at all time points including during the early recovery period. Recovery time to standing position was significantly shorter in group RM (49.6 ± 20.7 minutes) than group C (70.7 ± 24.9). Other measured parameters did not differ significantly. The median (range) of number of RMs required to maintain PaO2 above 400 mmHg per anaesthetic was 3 (1-8)., Conclusion: Ventilation using IPPV with constant PEEP and RM improved arterial oxygenation lasting into the early recovery period in conjunction with faster recovery of similar quality. However this ventilation mode was not able to open up the lung completely and to keep it open without repeated recruitment., Clinical Relevance: This mode of ventilation may provide a clinically practicable method of improving oxygenation in anaesthetized horses., (© 2011 The Authors. Veterinary Anaesthesia and Analgesia © 2011 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)

Objective: To review the use and adverse effects of alpha(2)-agonists in sheep., Study Design: Literature review., Material and Methods: 'Pubmed' of the United States National Library of Medicine and 'Veterinary Science' of CAB International were searched for references relating sheep to alpha(2)-agonists. The bibliographies of retrieved articles were further scrutinized for pertinent references, and relevant articles were selected manually., Results: Reports on the use of clonidine, xylazine, detomidine, romifidine, medetomidine and dexmedetomidine, MPV-2426 and ST-91 in sheep were found in the literature. Most of the studies described xylazine followed by medetomidine and clonidine. The literature on detomidine and romifidine in sheep was sparse. Reports included pharmacokinetic studies, evaluation of sedative, analgesic, and anaesthetic techniques with or without cardiovascular effects, and experimental investigations of adverse effects (mainly hypoxaemia) including the mechanisms of pulmonary oedema and impaired oxygenation after alpha(2)-agonist administration., Conclusions: A(2)-agonists are potent and effective analgesics in sheep. In combination with ketamine, they are frequently used for the induction and maintenance of anaesthesia, in this case analgesia is satisfactory. The degree of hypoxaemia which occurs with all commercially available alpha(2)-agonists is highly variable and depends on individual or breed-related factors; the most severe reactions occur after intravenous (IV) injection and during general anaesthesia. Clinical relevance Subclinical respiratory disease is common in sheep. Rapid IV injection of alpha(2)-agonists without supplementary oxygen should be avoided whenever hypoxaemia may be critical.

Objective: To compare the sedative, anaesthetic-sparing and arterial blood-gas effects of two medetomidine (MED) doses used as pre-anaesthetic medication in sheep undergoing experimental orthopaedic surgery., Study Design: Randomized, prospective, controlled experimental trial., Animals: Twenty-four adult, non-pregnant, female sheep of various breeds, weighing 53.9 +/- 7.3 kg (mean +/- SD)., Methods: All animals underwent experimental tibial osteotomy. Group 0 (n = 8) received 0.9% NaCl, group L (low dose) (n = 8) received 5 microg kg(-1) MED and group H (high dose) (n = 8) received 10 microg kg(-1) MED by intramuscular (IM) injection 30 minutes before induction of anaesthesia with intravenous (IV) propofol 1% and maintenance with isoflurane delivered in oxygen. The propofol doses required for induction and endtidal isoflurane concentrations (F(E')ISO) required to maintain anaesthesia were recorded. Heart and respiratory rates and rectal temperature were determined before and 30 minutes after administration of the test substance. The degree of sedation before induction of anaesthesia was assessed using a numerical rating scale. Arterial blood pressure, heart rate, respiratory rate, FE'ISO, end-tidal CO2 (FE'CO2) and inspired O2 (FIO2) concentration were recorded every 10 minutes during anaesthesia. Arterial blood gas values were determined 10 minutes after induction of anaesthesia and every 30 minutes thereafter. Changes over time and differences between groups were examined by analysis of variance (anova) for repeated measures followed by Bonferroni-adjusted t-tests for effects over time., Results: Both MED doses produced mild sedation. The dose of propofol for induction of anaesthesia decreased in a dose-dependent manner: mean (+/-SE) values for group 0 were 4.7 (+/-0.4) mg kg(-1), for group L, 3.2 (+/-0.4) mg kg(-1) and for group H, 2.3 (+/-0.3) mg kg(-1)). The mean (+/-SE) FE'ISO required to maintain anaesthesia was 30% lower in both MED groups [group L: 0.96 (+/-0.07) %; group H: 1.06 (+/-0.09) %] compared with control group values [(1.54 +/- 0.17) %]. Heart rates were constantly higher in the control group with a tendency towards lower arterial blood pressures when compared with the MED groups. Respiratory rates and PaCO2 were similar in all groups while PaO2 increased during anaesthesia with no significant difference between groups. In group H, one animal developed a transient hypoxaemia: PaO2 was 7.4 kPa (55.7 mmHg) 40 minutes after induction of anaesthesia. Arterial pH values and bicarbonate concentrations were higher in the MED groups at all time points., Conclusion and Clinical Relevance: Intramuscular MED doses of 5 and 10 microg kg(-1) reduced the propofol and isoflurane requirements for induction and maintenance of anaesthesia respectively. Cardiovascular variables and blood gas measurements remained stable over the course of anaesthesia but hypoxaemia developed in one of 16 sheep receiving MED.

Objective: To determine whether predictable alveolar concentrations of sevoflurane are reliably produced in dogs when liquid sevoflurane is injected into closed circuit breathing systems, as calculated by Lowe's square-root-of-time anaesthetic uptake model, and to confirm the validity of the model using soda lime and calcium hydroxide lime., Study Design: Prospective clinical study., Animals: Eleven healthy dogs with a mean body mass of 34 +/- 9 kg scheduled for pelvic limb orthopaedic surgery., Materials and Methods: Following pre-anaesthetic medication, anaesthesia was induced with propofol and maintained with sevoflurane in a closed circle system. Epidural anaesthesia was performed with morphine and bupivacaine. Liquid sevoflurane was injected into the circuit by syringe, using dosages and time intervals derived from Lowe's square-root-of-time anaesthetic uptake model. The target alveolar concentration chosen was 1.1 x MAC (2.6% end-tidal sevoflurane). Either soda lime (group S; n = 6) or calcium hydroxide lime (Amsorb; group A; n = 5) were used for CO(2) absorption. Sevoflurane concentration and the respiratory gas composition were measured with an infrared gas analyser., Results: End-tidal sevoflurane concentrations were close to the predicted value of 2.6% at 9 minutes (2.53 +/- 0.1% group S; 2.60 +/- 0.26% group A) and 16 minutes (2.55 +/- 0.30 group S; 2.52 +/- 0.28% group A) but declined thereafter to reach 50% (group S) and 64% (group A) of the predicted value at 121 minutes. There was a constant trend towards higher end-tidal sevoflurane concentrations in group A but the difference was not statistically significant., Conclusions: The square-root-of-time model leads to significantly lower alveolar concentrations than expected, suggesting that the rate of sevoflurane uptake in dogs declines less rapidly than predicted. The use of Amsorb tends to reduce the deviation from predicted concentrations., Clinical Relevance: The model used in this study provided only an approximate guide to the volume of liquid sevoflurane required. Consequently, the definitive dose schedule must be based on measured anaesthetic concentrations and clinical monitoring.

A peri-carinal tracheal laceration was produced in a 11-year-old cat during tracheal intubation. Before reconstructive surgery began, the leak was bypassed with an endobronchial tube positioned using endoscopy and direct vision. However, single-lung ventilation could not be sustained because the tube became dislodged and could not be repositioned. Consequently, surgery was completed with periods of intermittent apnoea interspersed with manually controlled hyperventilation. Cardiovascular variables were stable during anaesthesia and no signs of hypoxia were detected. The difficulties in maintaining endobronchial tube position resulted from the animal's small size relative to the dimensions of the endotracheal tube.