This study aimed to identify behaviours that could be used to assess post-operative pain and analgesic efficacy in male rabbits. In consideration of the ‘Three Rs’, behavioural data were collected on seven male New Zealand White rabbits in an ethically approved experiment requiring abdominal implantation of a telemetric device for purposes other than behavioural assessment. Prior to surgery, rabbits were anaesthetised using an isoflurane/oxygen mix and given Carprofen (2 mg kg−1) as a peri-operative analgesic. Rabbits were housed individually in standard laboratory cages throughout. Data were collected at three time periods: 24-21 h prior to surgery (T1) and, post-surgery, 0-3 h (T2) and 3-6 h (T3). Behavioural changes were identified using Observer XT, significance of which was assessed using a Friedman's test for several related samples. The frequency or duration of numerous pre-operative behaviours was significantly reduced in T2 and T3, as compared to T1. Conversely, novel or rare behaviours had either first occurrence or significant increase in T2 into T3 as compared to T1, these include ‘full-body-flexing’, ‘tight-huddling’, ‘hind-leg-shuffling’. We conclude that reduced expression of common pre-operative behaviours and the appearance of certain novel post-operative behaviours may be indicative of pain in rabbits. Behaviours identified as increased in T2 as compared to T1 but not consistently elevated into T3 were considered separately due to the potentially confounding effect of anaesthesia recovery. These included lateral lying, ‘drawing-back’, ‘staggering’ and ‘closed eyes’. We postulate that for effective application of best-practice post-operative care, informed behavioural observation can provide routes by which carers may identify requirements for additional post-operative analgesia. Additionally, improvement of the peri-operative pain management regimen may be required to ameliorate the immediate effects of abdominal surgery. Comparisons with other studies into post-operative pain expression in rabbits suggest behavioural indicators of pain may differ, depending on housing and surgical procedure.

Concerns about the over-prescription of peri-operative fluids, particularly normal saline, culminated in the recent publication of UK national guidelines on fluid prescription during and after surgery. A working group comprising members of the nutrition support team, surgeons, anaesthetists and pharmacists therefore sought to reduce the overall levels of fluid prescription and to limit normal saline usage in our large Teaching Hospital by producing written local fluid prescribing guidelines and holding a series of fluid prescription education sessions for consultants and junior staff. Ideally, the success of such measures would have been determined by studies on fluid balance, body weight and/or measured body water in large numbers of individual patients in a large cluster-randomised controlled trial. However, this would have proved logistically difficult and very costly especially as it is notoriously difficult to rely on the accuracy of daily fluid balance charts in large numbers of patients on busy post-operative surgical wards. We therefore undertook a pragmatic study, comparing historical data on fluid type/volume prescribed (from both individual and ward level pharmacy records), oedema status and clinical outcomes from 2002 with two prospective audits of similar data carried out during 2008 and 2009. Our data showed that in the comparable, elective surgical patients within each audit, there was a decline in total intravenous fluids prescribed over the first 5 post-operative days from 21·1 litres per patient in 2002 to 14·2 litres per patient in 2009 (P<0·05), while pharmacy records showed that the proportion of 0·9% saline supplied declined from 60% to 35% of all fluids supplied to the surgical wards involved, with a concomitant increase in the use of 4%/0·18% dextrose-saline and Hartmann's solution. Alongside these changes in fluid prescribing, the number of patients with clinically apparent oedema declined from 53% in 2002 to 36% in 2009; gut function returned more quickly (6 d in 2002 v. 4 d in 2009, P<0·05) and the length of stay improved from 13 d in 2002 to 10 d in 2009, P<0·05). Although we accept that other factors might have contributed to the observed changes in these clinical parameters, we believe that the measures to reduce fluid and saline administration were the major contributors to these improved clinical outcomes.

The terminology used for describing intervention groups in randomised controlled trials (RCT) on the effect of intravenous fluid on outcome in abdominal surgery has been imprecise, and the lack of standardised definitions of the terms ‘standard’, ‘restricted’ and ‘liberal’ has led to some confusion and difficulty in interpreting the literature. The aims of this paper were to clarify these definitions and to use them to perform a meta-analysis of nine RCT on primarily crystalloid-based peri-operative intravenous fluid therapy in 801 patients undergoing elective open abdominal surgery. Patients who received more or less fluids than those who received a ‘balanced’ amount were considered to be in a state of ‘fluid imbalance’. When ‘restricted’ fluid regimens were compared with ‘standard or liberal’ fluid regimens, there was no difference in post-operative complication rates (risk ratio 0·96 (95% CI 0·56, 1·65), P=0·89) or length of hospital stay (weighted mean difference (WMD) −1·77 (95% CI −4·36, 0·81) d, P=0·18). However, when the fluid regimens were reclassified and patients were grouped into those who were managed in a state of fluid ‘balance’ or ‘imbalance’, the former group had significantly fewer complications (risk ratio 0·59 (95% CI 0·44, 0·81), P=0·0008) and a shorter length of stay (WMD −3·44 (95% CI −6·33, −0·54) d, P=0·02) than the latter. Using imprecise terminology, there was no apparent difference between the effects of fluid-restricted and standard or liberal fluid regimens on outcome in patients undergoing elective open abdominal surgery. However, patients managed in a state of fluid balance fared better than those managed in a state of fluid imbalance.