Anaesthetic-sparing effect of the anxiolytic drug tasipimidine in Beagle dogs

Abstract

Objective: To evaluate the effect of oral tasipimidine on dog handling, ease of catheter placement and propofol and isoflurane requirements for anaesthesia.

Study design: Placebo-controlled, randomized, blinded, experimental trial.

Animals: A group of seven adult Beagle dogs weighing (mean ± standard deviation) 13.1 ± 2.7 kg with a mean age of 18.6 ± 1 months.

Methods: The dogs underwent four treatments before induction of anaesthesia with propofol. PP: placebo orally (PO) 60 minutes before induction of anaesthesia followed by placebo (NaCl 0.9%) intravenously (IV). TP: tasipimidine 30 μg kg^-1 (PO) 60 minutes before induction of anaesthesia followed by placebo (NaCl 0.9%) IV. TMP: tasipimidine 30 μg kg^-1 PO 60 minutes before induction of anaesthesia followed by methadone 0.2 mg kg^-1 IV. TMPD: tasipimidine 30 μg kg^-1 PO 60 minutes before induction of anaesthesia followed by methadone 0.2 mg kg^-1 and dexmedetomidine 1 μg kg^-1 IV followed by a dexmedetomidine constant rate infusion of 1 μg kg^-1 hour^-1. Sedation, response to catheter placement, intubation quality, time to loss of consciousness, time to intubation, required dose of propofol and minimum alveolar isoflurane concentration preventing motor movement (MAC_NM) were determined. A mixed-model analysis or the Friedman and Mann-Whitney test were used; p-value < 0.05.

Results: Response to catheter placement did not differ between treatments. Tasipimidine alone reduced the propofol dose by 30%. Addition of methadone or methadone and dexmedetomidine reduced the propofol dose by 48% and 50%, respectively. Isoflurane MAC_NM was reduced by 19% in tasipimidine-medicated dogs, whereas in combination with methadone or methadone and dexmedetomidine, isoflurane MAC_NM was reduced by 35%.

Conclusions and clinical relevance: An anxiolytic dose of tasipimidine induced mild signs of sedation in dogs and reduced propofol and isoflurane requirements to induce and maintain anaesthesia, which needs to be considered in an anaesthetic plan.

Keywords: MAC; dog; isoflurane; propofol; tasipimidine; α(2)-adrenoceptor agonist.