ANALGESIA WITH ORAL TRAMADOL AS AN ALTERNATIVE TO SUBCUTANEOUS BUPRENORPHINE IN THE POST-OPERATIVE PERIOD

Postoperative pain management is a critical welfare consideration in laboratory animal research, as inadequate analgesia leads to stress, suffering, and compromised scientific outcomes. In line with the 3Rs principle of refinement, this pilot study evaluated oral tramadol as a potential alternative to repeated injectable analgesia following surgery in rats, comparing its effectiveness with subcutaneous buprenorphine.
Post-surgical rats (approximately 300 g; n = 7 per group) undergoing stereotactic injection and electrode implantation were assigned to two analgesic protocols. Group A received subcutaneous buprenorphine (0.05 mg/kg, QID) on post-operative days 1-4. Group B received subcutaneous buprenorphine (0.05 mg/kg, QID) on days 1-2 followed by oral tramadol (10 mg/kg, BID, administered in condensed milk) on days 3-4. Rats had been habituated to ingesting condensed milk before any surgical procedure. Animal welfare and pain were assessed using standardized score sheets evaluating appearance, weight, behaviour, and mobility, alongside the Rat Grimace Scale.
Welfare scores and rat grimace scale assessments indicated comparable recovery and analgesic effectiveness between groups. Oral tramadol was well tolerated, with no adverse effects observed. Animals receiving tramadol showed sustained post-operative analgesia during later recovery phases while avoiding repeated injections, thereby reducing handling-associated stress. Buprenorphine proved to be effective but with shorter-acting analgesia, requiring repeated administration.
These findings suggest that oral tramadol administered during post-operative days 3-4 can replace subcutaneously injected buprenorphine with similar analgesic effect. This represents a promising refinement to existing analgesic protocols. Expanding the use of oral tramadol beyond these time points will require additional research.