Training in behaviour-based post-operative pain scoring in rats - An evaluation based on improved recognition of analgesic requirements

The objective of the Study was to evaluate whether an objective technique based on quantitative behaviour analysis represents a methodological improvement upon a simple subjective approach for assessing post-operative pain in rats. Data were collected during three Phases from 332 treatment-blinded volunteer observers with varying prior experience of animal husbandry and care. Aside from Phase 3, initially, they each used the subjective approach (visual analogue scale, VAS) to estimate pain severity after observing four randomly presented 5 min videotaped clips of the behaviour of rats. The rats had each undergone surgery (lower abdominal laparotomy) for an unrelated Study, and the four clips corresponded to individual rats given saline or one of three dosages of meloxicam (0.5, 1, or 2 nig/kg) 1 hr prior to surgery. Following VAS assessment, the volunteers received approximately 10 min of training in behaviour scoring. They were then asked to re-observe the four clips and score the occurrence of behaviour with the clips presented in another random sequence. The data were collated for each Phase of the exercise and a measure of success was calculated for scores obtained with each assessment method (VAS and behaviour). Success or failure relied upon each volunteer's ability to differentiate between the rats according to the treatment received. Success rates with VAS scoring were considerably more varied than with behaviour scoring, and although some groups were quite accomplished with VAS scoring, success rates with behaviour scoring were even hi,,her in these groups. Irrespective or prior experience of rat or other laboratory animal husbandry, behaviour scoring was overall superior for differentiating between the effects of analgesic treatment. Overall success rate for differentiating between treatments by subjective (VAS) assessment was 54%, compared with 75% with behaviour scoring. We conclude that this technique of behaviour scoring represents a significant methodological improvement that can be rapidly learned by inexperienced staff and used to recognise and assess pain following laparotomy in rats. (c) 2005 Elsevier B.V All rights reserved.