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Summary Reason for performing study: The recovery quality scoring systems (RQSSs) in current use have not been critically reviewed for reliability. Objective: To examine reliability (reproducibility) of 4 RQSSs when applied to a ranked series. Methods: A DVD incorporating the recordings of 9 horses recovering from general anaesthesia was evaluated by final year students over 5 days. On Day 1, each evaluator ranked recoveries from 1-9 (1 = best). Over the following 4 days, each evaluator scored the same recoveries using 4 different RQSSs (3 of them in common usage and previously published) applied in random order. The scores from each RQSS were ranked and plotted against the Day 1 ranking of each evaluator to establish the extent of agreement using generalisability theory. The same 9 recoveries were also ranked by 12 experienced equine anaesthetists and the Spearman Rank Correlation coefficient calculated to determine the agreement between experienced and inexperienced evaluators. Results: The recoveries were evaluated by 117 students. All 4 RQSSs were equally reliable with low (<4%) interobserver variability. The main (80%) source of total variation arose from differences between horses. The overall ranking within each RQSS was strongly correlated with Day 1 ranking. There was strong correlation (r = 0.983) between the students' ranking and that established by experienced anaesthetists. Interobserver reliability was similar with all 4 RQSSs. Conclusion: All 4 RQSSs studied were similarly reliable. Potential relevance: The selection of a universally acceptable RQSS from amongst the 4 examined can be based on criteria other than reliability, e.g. ease of use. This will facilitate wider scale multi-centre studies in recovery quality after anaesthesia in horses. [ABSTRACT FROM AUTHOR]

Background: In equine anaesthesia, the recovery period is a time of considerable risk and has been the focus of prolific research. Risk factors, including age, type and duration of procedure or temperament may influence recovery quality. Unfortunately, the anaesthetist is unable to control for these factors, therefore various pharmacological interventions and recovery methods have been developed with the objective of improving recovery quality. However, no consensus among anaesthetists has been reached for many of these interventions and their implications for recovery‐related mortality and morbidity. Objectives: To conduct a systematic review of the published evidence relating to risk factors and interventions in the recovery period which may influence recovery quality from equine general anaesthesia (GA). Study design: A systematic evaluation of the equine veterinary literature using the GRADE framework. Methods: A literature search was performed and studies were assessed for eligibility by both authors utilising PRISMA guidelines. Studies meeting inclusion criteria were evaluated by both authors, categorically summarised and the quality of evidence for each sub‐topic was assessed using the GRADE framework. Results: Thirty‐nine studies were identified which directly assessed the impact of risk factors and recovery interventions on recovery quality after equine GA. There was evidence to support that peri‐anaesthetic risk factors such as anaesthesia duration, American Society of Anesthesiologists (ASA) physical status and surgical procedure influenced recovery quality. We also identified sufficient evidence that administration of α‐2 adrenoreceptor agonists immediately prior to recovery, improves recovery quality. Main limitations: The validity of the results of some studies may have been compromised by missing data and small sample sizes. Conclusions: Recovery quality is influenced by factors including: anaesthesia duration, ASA physical status and surgical procedure. Recovery quality can be improved by the administration of an α‐2 adrenoreceptor agonist immediately prior to recovery. [ABSTRACT FROM AUTHOR]

Background: Flumazenil antagonises the actions of benzodiazepines. There has been no prior research specifically investigating this anaesthetic reversal agent for horses. Objectives: To determine the effects of flumazenil administration in horses on (a) ventilatory parameters after midazolam‐ketamine induction and maintenance with isoflurane in oxygen and on (b) the characteristics of recovery from general anaesthesia. Study design: Blinded, randomised, crossover experiment. Methods: Six horses were randomly assigned to receive high‐dose flumazenil (Fhigh, 20 µg/kg), low‐dose flumazenil (Flow, 10 µg/kg) and saline (control). Cardioventilatory parameters were monitored. After 90 minutes of isoflurane anaesthesia, a bolus of Fhigh, Flow or saline was administered i.v. The horses were recovered using head and tail rope assistance. The times to first movement, to achievement of sternal recumbency, to the first attempt to stand and the total recovery time were determined. The recovery quality was evaluated using a 115‐point recovery scoring system. The cardioventilatory parameters and recovery times were analysed using mixed‐effects regression analyses. Intraclass correlation (ICC) analysis was used to evaluate the recovery scores. A Mann‐Whitney U test assessed the relationship between recovery score and flumazenil administration. Results: A significant difference with flumazenil administration was found for SpO2, mean arterial pressure, I:E ratio, minute volume of ventilation (MV) and peak inspiratory pressure. There was a significant difference with flumazenil administration for the time to sternal recumbency, the time to the first attempt to rise and the total recovery time. There was no significant difference in total recovery score with flumazenil administration. Main limitations: Plasma levels of midazolam and flumazenil were not obtained. Conclusions: Flumazenil has a dose‐dependent effect on MV and recovery time, which may make it useful in cases for which a prolonged anaesthetic recovery is undesirable. [ABSTRACT FROM AUTHOR]

Summary: Background: There is no information directly comparing midazolam with guaifenesin when used in combination with an alpha‐2 agonist and ketamine to maintain anaesthesia via i.v. infusion in horses. Objectives: To compare ketamine–medetomidine–guaifenesin with ketamine–medetomidine–midazolam for total intravenous anaesthesia (TIVA) in young horses anaesthetised for computerised tomography. Study design: Prospective, randomised, blinded, crossover trial. Methods: Fourteen weanlings received medetomidine 7 μg/kg bwt i.v. and anaesthesia was induced with ketamine 2.2 mg/kg bwt i.v. On two separate occasions horses each received infusions of ketamine 3 mg/kg bwt/h, medetomidine 5 μg/kg bwt/h, guaifenesin 100 mg/kg bwt/h (KMG) or ketamine 3 mg/kg bwt/h, medetomidine 5 μg/kg bwt/h, midazolam 0.1 mg/kg bwt/h (KMM) for 50 min. Cardiorespiratory variables and anaesthetic depth were assessed every 5–10 min. Recovery times after the infusions ceased were recorded and recovery quality was assessed using a composite score system (CSS), simple descriptive scale (SDS) and visual analogue scale (VAS). Multivariable models were used to generate mean recovery scores for each treatment and each recovery score system and provide P‐values comparing treatment groups. Results: Anaesthesia was uneventful with no difference in additional anaesthetic requirements and little clinically relevant differences in cardiopulmonary variables between groups. All horses recovered without incident with no significant difference in recovery times. Quality of the anaesthetic recovery was significantly better for the KMM group compared with the KMG group using the CSS (P<0.001), SDS (P<0.001) and VAS (P<0.001). Main limitations: No surgical stimulus was applied and study animals may not represent general horse population. Conclusion: Midazolam is a suitable alternative to guaifenesin when co‐infused with ketamine and medetomidine for anaesthesia in young horses undergoing noninvasive procedures. Both infusions produce a clinically comparable quality of anaesthesia; however, recovery from anaesthesia is of a better quality following an infusion of ketamine–medetomidine–midazolam. [ABSTRACT FROM AUTHOR]

Background Although rare, 70% of equine fatalities during recovery from general anaesthesia ( GA) are due to catastrophic fractures from poor recovery quality. Objective To determine the effect of repeated GA recovery on GA recovery quality. Study design Experimental blinded trial. Methods Eight adult horses underwent six GA events on sevoflurane for distal limb MRI examination over a 14-week period. Prior to GA recovery, xylazine was administered. Randomly ordered video-recorded GA recoveries were scored by three blinded board certified veterinary anaesthesiologists, unaware of patient identity or GA event number, for nine parameters using a 100 mm visual analogue scale ( VAS) where 0 = worst and 100 = best. The number of attempts to stand, duration of lateral and sternal recumbency, total recovery duration and physiologic parameters during each GA event were recorded. Repeated measures ANOVA were used to detect differences. Agreement between observer VAS scores was determined via inter-rater reliability using an intraclass correlation. Results With GA recovery experience, VAS scores for balance and coordination, knuckling, and overall quality of recovery were improved and the duration of lateral recumbency was increased. There were no differences in total recovery duration, number of attempts to stand, physiologic parameters other than heart rate during GA, or VAS scores for activity in lateral recumbency, move to sternal, move to stand, or strength. Main limitations Each GA event was relatively short and there was no surgical stimulation. The same results may not occur if there was surgical stimulation and pain during each GA event. Conclusion Recovery from GA improves with multiple anaesthetic episodes in horses. Clinicians can advise clients that horses are likely to have better GA recovery on repeated GA recovery due to improved balance and coordination and reduced knuckling. Additionally, there is no change in anaesthetic morbidity with six repeated GA events over a 14-week period. [ABSTRACT FROM AUTHOR]

Reasons for performing study Tramadol is an analgesic agent used in man and a number of veterinary species. The pharmacokinetics and behavioural effects of tramadol and its active metabolite have been described in mature horses, but not in young foals. Objectives To characterise the pharmacokinetics, metabolism and some induced behavioural and physiological responses following i.v. tramadol administration in the same group of foals on 4 different occasions, from a few days after birth to age 43 days. Study design Experimental. Methods Tramadol was administered i.v. (3 mg/kg bwt) to a group of 8 foals on 4 separate occasions at ages 6-8, 13-15, 20-22 and 40-43 days. Blood samples were collected prior to administration and at multiple times until 48 h post administration. Blood samples were analysed for tramadol and metabolite concentrations and pharmacokinetics determined at each age. Behavioural and physiological effects were also assessed. Results The average volume of distribution was 5.10, 4.63, 4.02 and 3.84 l/kg bwt and clearance 3.44, 3.08, 3.14 and 2.69 l/h/kg bwt when foals were aged 6-8, 13-15, 20-22 and 40-43 days, respectively. There was not a significant difference in the elimination half-life between age groups (1.52, 1.73, 1.13 and 1.51 for ages 6-8, 13-15, 20-22 and 40-43 days, respectively). The metabolites produced were the same as in mature horses; however, glucuronidation capability, appeared to increase with increasing age. Tramadol administration was well tolerated at all ages studied with sedation noted in the 3 older age groups. Conclusions Tramadol appears to be consistently well tolerated following i.v. administration of 3 mg/kg bwt to foals ranging in age from 1 to 6 weeks. Although analgesic concentrations in foals have yet to be established, the results of this study support further study of tramadol for clinical use in foals. [ABSTRACT FROM AUTHOR]

Reasons for performing study A significant effect of gender, experience and background, i.e. an evaluator's relationship with horses as equine anaesthetists, orthopaedic surgeons, practitioners or owners, on perceptions of recovery quality after anaesthesia would reduce the validity of recovery quality scoring systems. Objectives To determine the effects of evaluator background, experience and gender on their perceptions of recovery quality; and questionnaire response rate as a function of background. Study design Cross-sectional survey. Methods A total of 440 potential evaluators were invited to evaluate the video-recorded recoveries of 24 horses using a visual analogue scale ( VAS) in which 0 = worst, 100 = best possible recovery. A mean score was generated for each of the 1-24 recoveries within each background group. These were compared using Spearman's rank correlation. The effect of gender and experience on VAS scores were analysed using an ordinal logistic regression after scores were categorised into 'intermediate, 'worst' and 'best' recovery categories based on median, 25th and 75th percentile VAS scores, respectively. Results The overall response rate was 35%. The greatest was from the anaesthetists (78%) followed by surgeons (43%). The response rate among owners and practitioners was 26%. Correlation among VAS scores across all background groups was high ( Spearman rank >0.90; P<0.001). Among the combined veterinarians, there was no significant gender (P = 0.551) or experience (P = 0.103) effect. Among horse owners, the effect of experience was not significant (P = 0.116) although gender was (P = 0.027). Male horse owners awarded significantly greater scores than females. Conclusions When VAS are used to grade recovery quality, neither the background nor the gender of veterinary evaluators affects quality perception. Male owners awarded greater scores than female owners, implying that they are less critical of recovery quality and a gender effect among horse owners must be considered when VAS are used to score recovery quality. [ABSTRACT FROM AUTHOR]

Reasons for performing study Both the potential analgesic effect and the conflicting reports describing tramadol disposition in the horse warrant further study of the pharmacokinetics of tramadol in this species. Objectives To describe the pharmacokinetics of tramadol and its metabolites, O-desmethyltramadol and N-desmethyltramadol, following i.v. administration of 3 doses to the horse. Methods Nine adult horses received a single i.v. dose of 0.5, 1.5 and 3 mg/kg bwt tramadol. Blood samples were collected prior to and at various times up to 72 h post administration. Plasma samples were analysed using liquid chromatography-mass spectrometry and data analysed using noncompartmental analysis. Chin-to-ground distance, heart rate and rhythm, step count and gastrointestinal activity were also assessed. Results Maximal measured plasma tramadol concentrations were 454 ± 101.6, 1086.7 ± 330.7 and 1697.9 ± 406.1 ng/ml for 0.5, 1.5 and 3 mg/kg bwt, respectively. Depending on the dose administered, the tramadol clearance, volume of distribution and half-life ranged from 24.6 to 25.0 ml/min/kg, 2.66 to 3.33 l/kg and 2.17 to 3.05 h, respectively. Following administration of 0.5, 1.5 and 3 mg/kg bwt tramadol, the maximal measured plasma concentrations of the active metabolite, O-desmethyltramadol, were 3.9 ± 1.9, 9.6 ± 4.8 and 12.9 ± 5.2 ng/ml, respectively. Muscle fasiculations and tremors were seen following administration of the 2 high doses. No significant changes in chin-to-ground distance, heart rate and rhythm, step count and gastrointestinal activity were observed. Conclusions and potential relevance This study confirms and extends previous studies describing the pharmacokinetics of tramadol following i.v. administration to the horse. Plasma tramadol concentrations exceeded those necessary for analgesia in human patients; however, further studies are necessary to determine plasma concentrations of tramadol necessary for analgesic efficacy in the horse. These results support further investigation of the analgesic efficacy of tramadol in the horse. [ABSTRACT FROM AUTHOR]