Evaluating postoperative analgesics in mice using telemetry

The study examined the efficacy of preemptive or postoperative analgesia on surgical pain in the mouse. Radiotelemetry transmitters were surgically implanted in 28 female ICR mice. A mock ova implantation surgery was then performed. Mice were treated with a single dose of buprenorphine or flunixin meglumine prior to or after surgery, three doses of buprenorphine, or were untreated. Heart rate, blood pressure, home cage activity, food and water consumption, and body weight were measured. The no-analgesia group showed no significant differences between any parameters collected prior to surgery and those collected at similar times during the day of surgery. Significant increases in mouse activity on the day of surgery occurred with all analgesic treatments, compared with pre-surgical activity. There were no consistent significant changes in any other telemetry parameter after treatment with analgesics compared with no analgesia. Food consumption and body weight the day after surgery were reduced significantly in the animals treated with three doses of buprenorphine compared with untreated mice and mice given a single dose of buprenorphine. We conclude that the mock ova implant procedure does not induce sufficient pain to cause alterations in heart rate and blood pressure in the mouse. Activity was significantly reduced in the first 6 h after surgery in mice without analgesia, compared with activity prior to surgery. There were no significant differences between pre-emptive and postoperative analgesia. Body weight and food and water consumption were poor measures of pain because analgesia alone affected these parameters.