A structured literature review was carried out to assess recent trends in the administration of analgesics and anaesthetics to laboratory rats and mice undergoing surgical procedures. The ScienceDirect database was used to systematically identify studies published in peer-reviewed journals over two periods (2000–2001 and 2005–2006), 86 studies from each time period were included in the review. The total number of animals that underwent surgery, species used, type of procedure, anaesthetic regimen and analgesic administration were noted for each study. There was an increase in the reported administration of systemic analgesics from 10% in 2000–2001 to 20% in 2005–2006. Buprenorphine was the most commonly reported analgesic in both periods (2000–2001: 78%, 2005–2006: 35%) and reporting the use of non-steroidal anti-inflammatory drugs increased from 11% to 53%. There was also a change in reported anaesthetic practices, notably a decrease in the use of pentobarbital and an increase in the use of isoflurane and ketamine/xylazine. Although reported administration of analgesics has increased and there has been some refinement in the selection of anaesthetic agents used, the findings of this review suggest that there is still significant scope for improvement with respect to the perioperative care of laboratory rodents.

Current attitudes to the use of animals in biomedical research require that any pain or distress should be minimised. This can often be achieved by the use of appropriate anaesthetic and analgesic regimens. There, is however, little information on the peri-operative regimens used. A literature review was conducted to estimate how commonly analgesics are administered to laboratory rodents, the most widely used species of laboratory animals, and to assess the anaesthetic regimens employed. Studies describing potentially painful experimental procedures involving rodents were identified from peer-reviewed journals published from 1990 to 1992 and from 2000 to 2002. In papers published between 2000 and 2002, if analgesic administration was not specified, the institutional veterinary surgeons or authors of the papers were contacted by e-mail to obtain additional information on analgesic use. From 1992 to 2002, there was an increase in the reported prevalence of analgesic administration to laboratory rodents from 2.7% to 19.8%. Although the use of analgesics has increased over the past ten years, the overall level of post-operative pain relief for laboratory rodents is still low. Anaesthetic methodology changed markedly between the two time-periods sampled. Notably, there was an increase in the use of isoflurane and of injectable anaesthetic combinations such as ketamine/xylazine, whereas the use of ether and methoxyflurane decreased.

Background: It has become widely accepted that whenever animals are used in scientific procedures, the 3Rs principle of replacement, reduction and refinement described by William Russell and Rex Burch should be adhered to. Animals should be replaced with non-sentient alternatives if possible, the number of animals used should be reduced and experimental procedures should be refined to minimise pain, suffering and distress. Administration of analgesic agents to animals undergoing surgical procedures is a refinement used to alleviate pain. In this study, a structured literature review was carried out to examine current trends in analgesic administration to rabbits undergoing experimental surgical procedures. Results: 128 papers from 51 peer-reviewed journals were selected for inclusion in this review. Reporting administration of systemic analgesia to rabbits in peer-reviewed scientific papers increased significantly from 16% to 50% between 1995-1997 and 2005-2007 (P < 0.001). Papers that reported ethical approval were more likely than papers that did not specify approval to report systemic analgesic administration (P < 0.001). When systemic analgesics were administered, buprenorphine was the most frequently used agent and non-steroidal anti-inflammatory drugs were used less frequently than opioids in both time periods. Conclusions: Although this review provides evidence that systemic analgesic administration to rabbits undergoing surgical procedures is increasing, rabbits do not always receive analgesia when they undergo experimental surgery. Other practices in rabbit perioperative care that could be improved, highlighted by this survey include: 1) changing the timing of analgesic administration by giving systemic analgesics pre- or perioperatively rather than only postoperatively, 2) using multimodal analgesia when pain is likely to be moderate to severe and 3) increasing the use of non-steroidal anti-inflammatory drugs and use of other techniques such as epidural analgesia particularly for orthopaedic procedures.

Background: Non-invasive biomarkers of disease progression in mice with cancer are lacking making it challenging to implement appropriate humane end points. We investigated whether body temperature, food and water consumption could be used to predict tumour burden. Methods: Thirty-six male, wild-type C57Bl/6 mice were implanted with subcutaneous RFID temperature sensors and inoculated with Eμ-myc tumours that infiltrate lymphoid tissue. Results: Decrease in body temperature over the course of the study positively predicted post-mortem lymph node tumour burden (R²=0.68, F(1,22)=44.8, P<0.001). At experimental and humane end points, all mice that had a mean decrease in body temperature of 0.7 °C or greater had lymph nodes heavier than 0.5 g (100% sensitivity), whereas a mean decrease in body temperature <0.7 °C always predicted lymph nodes lighter than 0.5 g (100% specificity). The mean decrease in food consumption in each cage also predicted mean post-mortem lymph node tumour burden at 3 weeks (R²=0.89, F(1,3)=23.2, P=0.017). Conclusion: Temperature, food and water consumption were useful biomarkers of disease progression in mice with lymphoma and could potentially be used more widely to monitor mice with other forms of cancer.

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.