The effect of intravenous administration of variable-dose flumazenil after fixed-dose ketamine and midazolam in healthy cats

The effects of intravenous administration of variable-dose flumazenil (0, 0.001, 0.005, 0.01, and 0.1 mg/kg) after ketamine (3 mg/kg) and midazolam (0.0 and 0.5 mg/kg) were studied in 18 healthy unmedicated cats from time of administration until full recovery. End-points were chosen to determine whether flumazenil shortened the recovery period and/or modified behaviors previously identified and attributed to midazolam. Overall, flumazenil administration had little effect on recovery or behaviors. One minute after flumazenil administration, all cats were recumbent but a greater proportion of cats which received the highest dose assumed sternal recumbency with head up than any other group. Although not significant, those cats that received the highest flumazenil dose also had shorter mean times for each of the initial recovery stages (lateral recumbency with head up, sternal recumbency with head up and walking with ataxia) than any of the other treatment groups that received midazolam. For complete recovery, flumazenil did decrease the proportion of the cats that was sedated, but did not shorten the time to walking without ataxia. Based on this study, the administration of flumazenil in veterinary practice, at the doses studied, to shorten and/or improve the recovery from ketamine and midazolam in healthy cats cannot be recommended.