Comparison of tramadol and buprenorphine analgesia for continuous intravenous propofol anaesthesia in dogs undergoing dental prophylaxis

The objective of this study was to compare, in client-owned patients, the analgesic effects of the centrally acting analgesics tramadol and buprenorphine in continuous intravenous anaesthesia (TIVA) with propofol. The study included forty dogs aged two to seven years and weighing 6-27 kg undergoing prophylactic dental treatment. The animals were classified into ASA (American Society of Anaesthesiologists) I. and II. risk groups. One group of dogs received intravenous administration of tramadol (2 mg/kg) and the second one buprenorphine (0.02 mg/kg) 30 min prior to sedation induced by midazolam (0.3 mg/kg) and xylazine (0.5 mg/kg) i.v. General anaesthesia was induced by propofol (2 mg/kg) and maintained by a 120-minute propofol infusion (0.2 mg/kg min). Arterial blood pressure, heart rate, respiratory rate, saturation of haemoglobin with oxygen, body temperature and deep pain sensation elicited by haemostat forceps pressure on the fingers were recorded at ten minute intervals. The tramadol group of dogs showed significantly better blood pressure values (P < 0.001), minimal tendency to bradycardia (P < 0.05) and respiratory rate (P < 0.001), without any negative effects on oxygen saturation. Significantly better deep pain sensation was achieved in the tramadol group (P < 0.001). Blood gas/acid base profile analysis showed a non-significant increase in the tramadol group of dogs. In conclusion, in comparison with buprenorphine, tramadol provided significantly better results with respect to degree of analgesia, as well as the tendency towards cardiopulmonary complications arising during anaesthesia. Significantly better analgesia and a lower depressive effect of tramadol on vital functions allows better control and management of the continuous intravenous propofol anaesthesia.