Effects of vatinoxan in dogs premedicated with medetomidine and butorphanol followed by sevoflurane anaesthesia: a randomized clinical study

To investigate effects of vatinoxan in dogs, when administered as intravenous (IV) premedication with medetomidine and butorphanol before anaesthesia for surgical castration. A randomized, controlled, blinded, clinical trial. A total of 28 client-owned dogs. Dogs were premedicated with medetomidine (0.125 mg m −2 ) and butorphanol (0.2 mg kg −1 ) (group MB; n  = 14), or medetomidine (0.25 mg m −2 ), butorphanol (0.2 mg kg −1 ) and vatinoxan (5 mg m −2 ) (group MB-VATI; n  = 14). Anaesthesia was induced 15 minutes later with propofol and maintained with sevoflurane in oxygen (targeting 1.3%). Before surgical incision, lidocaine (2 mg kg −1 ) was injected intratesticularly. At the end of the procedure, meloxicam (0.2 mg kg −1 ) was administered IV. The level of sedation, the qualities of induction, intubation and recovery, and Glasgow Composite Pain Scale short form (GCPS-SF) were assessed. Heart rate (HR), respiratory rate ( f R ), mean arterial pressure (MAP), end-tidal concentration of sevoflurane (F e′ Sevo) and carbon dioxide (P e′ CO 2 ) were recorded. Blood samples were collected at 10 and 30 minutes after premedication for plasma medetomidine and butorphanol concentrations. At the beginning of surgery, HR was 61 ± 16 and 93 ± 23 beats minute −1 ( p  = 0.001), and MAP was 78 ± 7 and 56 ± 7 mmHg ( p  = 0.001) in MB and MB-VATI groups, respectively. No differences were detected in f R, P e′ CO 2, F e′ Sevo, the level of sedation, the qualities of induction, intubation and recovery, or in GCPS-SF. Plasma medetomidine concentrations were higher in group MB-VATI than in MB at 10 minutes ( p  = 0.002) and 30 minutes ( p  = 0.0001). Plasma butorphanol concentrations were not different between groups. In group MB, HR was significantly lower than in group MB-VATI. Hypotension detected in group MB-VATI during sevoflurane anaesthesia was clinically the most significant difference between groups.