Sedative and Recovery Effects of Intramuscular Alfaxalone-Butorphanol-Midazolam Compared with Medetomidine-Butorphanol-Midazolam in Cats: A Randomized, Blinded Clinical Study

The goals of this study were to evaluate the effectiveness and physiological effects of alfaxalone-butorphanol-midazolam sedation in cats compared with the common sedation protocol used at our institution; medetomidine-butorphanol-midazolam. Thirty-one cats requiring sedation for various procedures were recruited randomly to receive intramuscular butorphanol (0.4 mg/kg) and midazolam (0.3 mg/kg) combined with alfaxalone (2 mg/kg) (ABM; n=16) or medetomidine (0.02 mg/kg) (MBM; n=15). Physiological variables and sedation quality (scale 7-28; 7=awake, 28=deeply sedated) were collected every 10 minutes until recovery. For medetomidine antagonism, the MBM cats received atipamezole intramuscularly. Induction and recovery times were recorded, and recovery quality was scored (1-4 scale: 1=poor, 4=excellent). Evaluations were performed by one blinded observer. Mann-Whitney U test, Fischer’s exact and repeated measures mixed-effects were used for analysis, and p<0.05 was set for significance. Six cats (ABM) and three cats (MBM) required an additional dose. At 10-40 minutes sedation scores were significantly better in the MBM (21-24) compared with ABM group (19-20). Significant lower heart rate, higher blood pressure and respiratory frequency were recorded in the MBM group. Time to recovery was significantly faster (9±7 versus 26±21 minutes) and recovery of better quality (4 [1-4] versus 3 [1-4]) in the MBM compared with the ABM group. During recovery, cats in the ABM group showed opisthotonos, twitching, and paddling, which resolved within an hour. In conclusion, at the doses used, ABM was a viable alternative to MBM with less cardiovascular effects, however, sedation plane was inferior and recovery, longer, accompanied by adverse behaviors.