Subcutaneous Administration of Tramadol after Elective Surgery Is as Effective as Intravenous Administration in Relieving Acute Pain and Inflammation in Dogs

Subcutaneous (SC) administration of tramadol was compared with intravenous (IV) administration to evaluate analgesia following canine ovariohysterectomy (OHE). Healthy female dogs (n = 12) between 1 and 3 years of age (1.95 ± 0.65 years), weighing between 10.5 and 17.1 kg (13.12 ± 1.95 kg), were used. Pain was assessed at baseline before surgery and then hourly for 8 hr after surgery. Tramadol was administered both SC and IV at a dose of 3 mg/kg and provided significant postoperative analgesia, as indicated by analgesiometry, β-endorphin levels, and interleukin 6 (IL-6) levels. The respiratory rates and rectal temperatures remained normal and were not significantly different between or within the groups. A significant increase in heart rate was observed at 4 hr for dogs in both groups relative to the baseline, but there was no significant difference in heart rates between the groups at any time point. A significant decrease in mechanical pain threshold was observed within each group after surgery, but both groups responded similarly, suggesting that SC administration of tramadol is as effective as IV administration. Increased serum levels of both IL-6 and β-endorphin 3 hr postoperatively further indicate that both routes of administration achieve similar pain control. Thus, the relative analgesic efficacy of SC tramadol is comparable to that of IV administration and can be used to achieve similar effects for postsurgical pain management in dogs undergoing OHE.