Abstract
One of the major challenges for individuals working with laboratory animals is the recognition and alleviation of pain. The Pain Gauge® is marketed as a pain assessment device that measures electrodermal activity. To establish whether the Pain Gauge® is effective in assessing postoperative pain in laboratory rats, preoperative and postoperative pain gauge scores ('pain scores') were obtained from 67 rats. Rats were randomly assigned to one of three experimental groups (laparotomy, craniotomy or control) and to one of four analgesic groups (meloxicam [2 mg/kg s.c.] or parecoxib [1, 5 or 20 mg/kg i.v.]). Five consecutive 'pain scores' were obtained from each animal at each of five time points (preprocedure, and at 1, 2, 3 and 4 h postoperatively). Overall there was a significant difference between 'pain scores' at different time points; mainly a decrease at 1 h postoperatively compared with the preoperative scores. There was no overall increase in postoperative 'pain scores' in the rats that were most likely to suffer from postoperative pain (rats given a lower dose of analgesic that underwent a surgical procedure) compared with rats that did not undergo a potentially painful procedure (rats in anaesthesia-only/control group). Therefore it was concluded that the Pain Gauge® is ineffective in assessing postoperative pain in rats in this study.