Jacqueline C Brearley

The sedative effects of low-dose medetomidine and butorphanol alone and in combination intravenously in dogs

OBJECTIVE To evaluate the sedative effects of intravenous (IV) medetomidine (1 μg kg-1) and butorphanol (0.1 mg kg-1) alone and in combination in dogs. STUDY DESIGN Prospective, blinded, randomized clinical trial. ANIMALS Sixty healthy (American Society of Anesthesiologists I) dogs, aged 6.2 ± 3.2 years and body mass 26 ± 12.5 kg. METHODS Dogs were assigned to four groups: Group S (sodium chloride 0.9% IV), Group B (butorphanol IV), Group M (medetomidine IV) and Group MB (medetomidine and butorphanol IV). The same clinician assessed sedation before and 12 minutes after administration using a numerical scoring system in which 19 represented maximum sedation. Heart rate (HR), respiratory rate, pulse quality, capillary refill time and rectal temperature were recorded after each sedation score assessment. Sedation scores, sedation score difference (score after minus score before administration) and patient variables were compared using one-way anova for normally distributed variables and Kruskal-Wallis test for variables with skewed distributions and/or unequal variances. Where significance was found, further evaluation used Bonferroni multiple comparisons for pair-wise testing. RESULTS Breed, sex, neuter status, age and body mass did not differ between groups. Sedation scores before substance administration were similar between groups (p = 0.2). Sedation scores after sedation were significantly higher in Group MB (mean 9.5 ± SD 5.5) than in group S (2.5 ± 1.8) (p < 0.001), group M (3.1 ± 2.5) (p < 0.001) and group B (3.7 ± 2.0) (p = 0.003). Sedation score difference was significantly higher in Group MB [7 (0-13)] than in Group S [0 (-1 to 4)] (p < 0.001) and Group M [0 (0-6)] (p < 0.001). HR decreased significantly in Groups M and MB compared with Group S (p < 0.05). CONCLUSION AND CLINICAL RELEVANCE Low-dose medetomidine 1 μg kg-1 IV combined with butorphanol 0.1 mg kg-1 IV produced more sedation than medetomidine or butorphanol alone. HR was significantly decreased in both medetomidine groups.

The effect of omeprazole on oesophageal pH in dogs during anaesthesia

OBJECTIVES Intra-operative, gastro-oesophageal reflux may be associated with post-anaesthestic complications such as oesophagitis and oesophageal stricture in dogs. The aim of this study was to investigate the effect of preoperative administration of omeprazole, a proton pump inhibitor, on oesophageal pH in anaesthetised dogs. METHODS Forty-seven dogs undergoing elective pelvic limb orthopaedic surgery were enrolled into the study. These were randomly allocated to treatment group (n=22) or control group (n=25). The treatment group received one dose of omeprazole (1 mg/kg po) at least 4 h before anaesthesia. All dogs were anaesthetised by the same standardised protocol. A pH probe was inserted into the distal oesophagus after induction of anaesthesia and oesophageal pH was continuously monitored. RESULTS In the treatment group, four animals (18 per cent) showed a sudden decrease in oesophageal pH (<4). In the control group the same phenomenon was detected in 13 animals (52 per cent). Gastro-oesophageal reflux occurred more frequently in the control group compared with the omeprazole group (odds ratio 4.7, 95 per cent C.I. 1.1 to 24.7, P=0.032). CLINICAL SIGNIFICANCE This study suggests that the preoperative administration of omeprazole is effective in reducing the incidence of gastro-oesophageal reflux during anaesthesia in dogs.

A comparison of recovery times and characteristics with sevoflurane and isoflurane anaesthesia in horses undergoing magnetic resonance imaging

OBJECTIVE To compare recovery times and quality following maintenance of anaesthesia with sevoflurane or isoflurane after a standard intravenous induction technique in horses undergoing magnetic resonance imaging (MRI). STUDY DESIGN Prospective, randomised, blinded clinical study. Animals One hundred ASA I/II horses undergoing MRI. MATERIALS AND METHODS Pre-anaesthetic medication with intravenous acepromazine and romifidine was followed by induction of anaesthesia with diazepam and ketamine. The animals were randomised into two groups to receive either sevoflurane or isoflurane in oxygen. Horses were subjectively scored (0-5) for temperament before sedation, for quality of sedation, induction and maintenance and anaesthetic depth on entering the recovery area. Recoveries were videotaped and scored by an observer, unaware of the treatment, using two scoring systems. Times to the first movement, head lift, sternal recumbency and standing were recorded along with the number of attempts to achieve sternal and standing positions. Variables were compared using a Student t-test or Mann-Whitney U-test (p < 0.05), while the correlation between subjective recovery score and other relevant variables was tested calculating the Spearman Rank correlation coefficient and linear regression modelling performed when significant. RESULTS Seventy-seven horses entered the final analysis, 38 received isoflurane and 39 sevoflurane. Body mass, age and duration of anaesthesia were similar for both groups. There were no differences in recovery times, scoring or number of attempts to achieve sternal recumbency and standing between groups. Weak, but significant, correlations were found between the subjective recovery score for the pooled data from both groups and both temperament and time in sternal recumbency. CONCLUSIONS No differences in recovery times or quality were detected following isoflurane or sevoflurane anaesthesia after intravenous induction. Clinical relevance Sevoflurane affords no obvious advantage in recovery over isoflurane following a standard intravenous induction technique in horses not undergoing surgery.

Comparison of pain on injection during induction of anaesthesia with alfaxalone and two formulations of propofol in dogs

OBJECTIVE To compare the incidence of pain during injection of three intravenous induction agents in dogs. STUDY DESIGN Prospective, crossover, randomized, blinded, clinical study. ANIMALS Thirty dogs requiring anaesthesia for radiotherapy. METHODS Dogs were anaesthetized on three occasions at weekly intervals. An IV cephalic catheter was placed, flushed with saline and alfentanil 0.01 mg kg(-1) and atropine 0.02 mg kg(-1) administered. After 30 seconds either: propofol lipid macroemulsion (Drug(P) ), propofol lipid-free microemulsion (Drug(PC) ) or alfaxalone (Drug(A)) was administered over 60 seconds. Each induction agent was administered once to each dog. Induction was recorded by video and reviewed by an assessor, unaware of treatment. Catheter placement (number of attempts, site, size and recent vein use) were recorded. Behavioural changes associated with pain or excitation, were recorded. Severity of pain on injection was recorded (mild, moderate or severe pain). Incidence of pain was analysed using logistic regression, excitation using McNemars test (p < 0.05) and association of pain with induction agent and catheter placement using the Akaike Information Criterion (AIC). RESULTS No dogs reacted to saline or Drug(A,) thus Drug(A) was excluded from analysis. Pain on injection occurred in six dogs (20%) with Drug(PC) and one dog (3.3%) with Drug(P). Pain was severe in four dogs with Drug(PC). Drug(P) resulted in a trend for reduced risk of pain compared to Drug(PC) (p = 0.076, odds ratio [confidence intervals] 0.14 [0.027-0.86]). Both propofol formulations resulted in greater risk of excitation than Drug(A) (p = 0.0003, odds ratio 4.5 [1.86-10.90]). Induction agent was associated with pain, whilst catheter placement was not. One dog developed facial oedema and one other dog skin necrosis adjacent to the catheter site following Drug(PC.) The study was terminated early due to ethical concerns about the severity of reactions with Drug(PC). conclusions and clinical relevance: Drug(PC) was associated with clinically relevant moderate to severe pain behaviour whilst Drug(A) and Drug(P) were not.

Assessment of the variation in American Society of Anaesthesiologists Physical Status Classification assignment in small animal anaesthesia

OBJECTIVE To evaluate the interobserver variability in the assignment of the American Society of Anesthesiologists Physical Status Classification (ASA-PSC) to compromised small animal patients amongst a group of veterinary anaesthetists. STUDY DESIGN Anonymous internet survey. ANIMALS Hypothetical case presentations. METHODS Sixteen hypothetical small animal cases with differing degrees of physiological or patho-physiological compromise were presented as part of an internet survey. Respondents were asked to assign a single ASA-PSC to each case and also to answer a number of demographic questions. ASA-PSC scores were considered separately and then grouped as scores of I-II and III-V. Agreement was analysed using the modified kappa statistic for multiple observers. Data were then sorted into various demographic groups for further analysis. RESULTS There were 144 respondents of which 60 (~42%) were anaesthesia diplomates, 24 (~17%) were post-residency (nondiploma holders), 24 (~17%) were current anaesthesia residents, 21 (~15%) were general practitioners, 12 (~8%) were veterinary nurses or technicians, and 3 (~2%) were interns. Although there was a majority agreement (>50% in a single category) in 15 of the 16 cases, ASA-PSC were spread over at least three ASA-PS classifications for every case. Overall agreement was considered only fair (κ = 0.24, mean ± SD agreement 46 ± 7%). When comparing grouped data (ASA-PSC I-II versus III-V) overall agreement remained fair (κ = 0.36, mean ± SD agreement 69 ± 19%). There was no difference in ASA-PSC assignment between any of the demographic groups investigated. CONCLUSIONS AND CLINICAL RELEVANCE This study suggests major discrepancies can occur between observers given identical information when using the ASA-PSC to categorise health status in compromised small animal patients. The significant potential for interobserver variability in classification allocation should be borne in mind when the ASA-PSC is used for clinical, scientific and statistical purposes.

Effect of intratesticular lidocaine on isoflurane requirements in dogs undergoing routine castration

OBJECTIVES To evaluate the isoflurane sparing effect of intratesticular lidocaine administration in dogs undergoing castration. METHODS Thirty dogs received a standardised anaesthetic regimen including systemic analgesia with intramuscular buprenorphine at a dose of 0·02 mg/kg and intravenous carprofen at a dose of 4 mg/kg. Dogs were randomly assigned to a lidocaine group receiving 1 mg/kg lidocaine into each testis or a control group receiving no lidocaine. Baseline physiological parameters were measured after 10 minutes at an end-tidal isoflurane concentration of 1·3%. End-tidal isoflurane concentration was altered throughout surgery to maintain these parameters within 10% of baseline and recorded at five time points. T0 was baseline, T1 was the start of surgery, T2 to T3 were clamping of the testicular pedicles and T4 was skin closure. End-tidal isoflurane concentrations were compared using analysis of variance and Bonferroni tests. RESULTS Fifteen healthy dogs were included in each study group. End-tidal isoflurane concentration was significantly lower in the lidocaine group compared to the control group at T2 (P<0·01), T3 (P<0·01) and T4 (P<0·01). CLINICAL SIGNIFICANCE Intratesticular lidocaine reduces isoflurane requirements in dogs undergoing castration.

Ease of intravenous catheterisation in dogs and cats: a comparative study of two peripheral catheters

OBJECTIVES To evaluate animal comfort and ease of placement of a veterinary-specific intravenous catheter compared with a catheter manufactured for human use. METHODS Fifty-nine veterinary undergraduates were recruited to perform intravenous catheterisations with two brands of over-the-needle catheter [Smiths Medical Jelco® (human use) and Abbott Animal Health catheter® (veterinary use)] in 69 healthy cats (n = 28) and dogs (n = 41) requiring general anaesthesia. After a standardised pre-anaesthetic medication, each animal was randomly allocated to have one of the two brands of catheter placed. Each student was allowed a maximum of three attempts to achieve cephalic vein catheterisation. The student and a single experienced observer evaluated each attempt. Observations related to ease of placement and to the animals reaction were recorded. RESULTS Human use catheters were placed in 34 and veterinary use in 35 animals. There was no difference in weight, sex or sedation score between the two groups. The number of failed attempts was similar between the two groups. There was no difference between groups for the number of animals reacting to catheter insertion. CLINICAL SIGNIFICANCE The two types of catheters evaluated are equally suitable for intravenous catheterisation of sedated animals by veterinary undergraduate students.

Use of xylocaine spray in cats.

ON behalf of the Association of Veterinary Anaesthetists (AVA), I am writing to draw attention to the potential for fatal adverse effects from using a non-veterinary-licensed product for the desensitisation of the feline larynx for intubation. This has become a matter for concern in the light of the

The challenge of teaching undergraduates evidence-based veterinary medicine

The Royal College of Veterinary Surgeons now lists ‘How to evaluate evidence’ as a day one competence for newly qualified vets. In this article, representatives from each of the veterinary schools in the UK discuss how the challenge of delivering and assessing the concepts of evidence-based veterinary medicine in a crowded undergraduate curriculum can be met.