A comparison of epidural analgesic efficacy of tramadol-bupivacaine and morphine-bupivacaine combinations in dogs subjected to stifle surgery

Abstract

To compare the analgesic efficacy of epidural bupivacaine, the combination of bupivacaine with either tramadol or morphine in 36 healthy dogs undergoing surgical correction of patellar luxation grades 2 and 3. All dogs were randomly allocated into 3 treatment groups of 12 each and received epidural drug administration as follow. Negative control group (Group B) received 0.5% bupivacaine 0.16 ml/kg added with NSS to a total volume of 0.2 ml/kg; positive control group (Group MB) received 0.1 mg/kg morphine (morphine 2.5 mg/ml) added with 0.5% bupivacaine to a total volume of 0.2 ml/kg, and experimental group (Group TB) received 2mg/kg tramadol (tramadol 50 mg/ml) added with 0.5% bupivacaine to a total volume of 0.2 ml/kg. There were no significant differences (p>0.05) of average heart rate, ETCO2, ETiso, systolic blood pressure and SPO2 during surgery. All measured parameters were also within the normal reference ranges throughout surgery. Average duration of postoperative analgesia was significantly longer in dogs of group MB(21.75±0.84 h) than in those of groups TB(14±0.42 h) and B(6.3±0.47 h). Dogs in all groups showed sign of postoperative ataxia. The transient sign of hypersalivation was observed in 1, 3 and 6 dogs in group B, MB and TB, respectively. One dog in the MB group showed sign of urine retention. In conclusion, epidural administration of tramadol-bupivacaine provides adequate postoperative analgesia and can be used as alternative to morphine but the duration of analgesia is shorter.