Tramadol minimizes potential pain during post-oophorectomy in Wistar rats

The use of analgesic to prevent or treat post-operative pain in rodents is increasingly encouraged as a refinement method. Limited date is regarding the use of opioids in laparatomy-induced abdominal pain of laboratory animals. Thirty-three Wistar rats (219.3±16.6g) underwent bilateral oophorectomy under xylazine- ketamin anesthesia (25mg/kg and 100mg/kg i.m. respectively). The analgesic effect of tramadol (5mg/kg i.m.) was evaluated on post-surgery recovery in one group (n=13) and compared to the non-tramadol group (n=20) during 30 days. Tramadol was injected in sedated animals 1-2 minutes before the surgical incision. Recovery was determined by changes in body weight (BW) assessed every 7 days. At the first week, less BW loss was noticed in the tramadol-treated group (-0.2%) compared to the non-tramadol group (-2.4%) (T test p=0.05). BW gain started at the second week and no significant difference was noticed between the groups. However, lower BW was detected all the time in the non-tramadol group compared to the tramadol-treated, reaching respectively 244±21.9g and 259±16.7g in 30 days. Tramadol administration minimizes BW loss during post-oophorectomy and did not cause any adverse effects under this anesthetic regimen. The preoperative analgesic protocol with the opioid tramadol was effective in order to reduce post-operative pain and improve post-surgery recovery.