Recovery of male rats from major abdominal surgery after treatment with various analgesics.

The objective of this study was to compare the recovery of male rats after a major abdominal surgical procedure (the implantation of a radiotelemetry transmitter) when treated with buprenorphine, butorphanol, or ketoprofen and subcutaneous fluids (5% dextrose) or with subcutaneous fluids only. The parameters for assessing recovery were heart rate (HR), mean arterial blood pressure (MAP), home cage activity, food and water consumption, and body weight. HR, MAP, and activity were continuously monitored by radiotelemetry methods, food and water intakes were determined daily, and body weights were measured once or three times a week. In light of HR, nocturnal home cage activity, water consumption, and body weight gain, animals were recovered by about 7 days after surgery. MAP normalized by 1 to 2 days postsurgery, and food consumption returned to presurgical levels 5 to 12 days after surgery, depending on the analgesic treatment. On the basis of nocturnal activity, HR, and food and water intakes, buprenorphine-treated animals recovered more slowly than did the other two analgesic-treated groups. By the other parameters, all three analgesic-treated groups showed very similar responses across time. Surprisingly, when compared with the groups receiving only subcutaneous fluids, buprenorphine and butorphanol delayed or did not advance recovery, whereas ketoprofen neither retarded nor advanced recovery. Explanations for these results include: (a) the analgesics were effective in relieving pain but had pharmacological side effects that altered the measured parameters, making it difficult to determine recovery; (b) the level of pain experienced did not notably affect recovery; (c) the analgesics, at the doses and/or dosing schedules used, were not effective in the relief of pain, thereby causing both groups of animals to recover at the same rate; and (d) the analgesics interfered with recovery. Final resolution of these issues awaits further investigation.