The Effect of a Subsequent Dose of Dexmedetomidine or Other Sedatives following an Initial Dose of Dexmedetomidine on Sedation and Quality of Recovery in Cats: Part I

TL;DR

This study examines how additional doses of sedatives like dexmedetomidine or ketamine affect sedation and recovery in cats after an initial dose of dexmedetomidine.

Contribution

The study identifies that a second dose of dexmedetomidine or ketamine improves sedation, while midazolam worsens recovery in cats.

Findings

Two doses of dexmedetomidine or ketamine after an initial dose improved sedation in cats.

Midazolam reduced sedation and caused prolonged recovery.

Recovery was generally uneventful except in the midazolam group.

Abstract

Dexmedetomidine is a frequently used sedative; however, in some cases, its administration may prove insufficient; therefore, an additional dose or another drug is required to achieve the desired sedative outcome. The present study investigated the sedative effects of commonly used anaesthetics when administered after an inadequate initial dose of dexmedetomidine. Six healthy adult cats were included in the study, and each cat participated seven times. The initial dose of dexmedetomidine was followed by the administration of a second dose of dexmedetomidine, butorphanol, buprenorphine, tramadol, ketamine, midazolam, or saline NS 0.9%. Additionally, atipamezole was administered to all animals to elicit recovery. To assess the sedative effect of each treatment, a sedation scale was used, and recovery quality was evaluated using two recovery scales. The results suggested that the two consecutive doses of dexmedetomidine produced deeper sedation compared to the administration of a single dose of dexmedetomidine. Sedation levels were also enhanced by the administration of dexmedetomidine, butorphanol, or ketamine following the administration of an initial dose of dexmedetomidine, and the recovery quality was good. On the contrary, administration of midazolam following dexmedetomidine administration resulted in inferior sedation and recovery quality.

Dexmedetomidine is an a2-agonist commonly used in veterinary practice. Occasionally, the administered dose of dexmedetomidine may result in insufficient sedation, and an additional dose or drug may be required. The sedative effects of seven different drugs administered at subsequent time points after an initial, insufficient dose of dexmedetomidine were evaluated. Seven adult cats participated in this crossover, blind, randomised study. The groups consisted of two consecutive doses of dexmedetomidine (15 + 10 μg/kg) (DD) or a dose of dexmedetomidine (15 μg/kg) followed by either NS 0.9% (DC-control group), tramadol 2 mg/kg (DT), butorphanol 0.2 mg/kg (DBT), buprenorphine 20 μg/kg (DBP), ketamine 2 mg/kg (DK), or midazolam 0.1 mg/kg (DM). Sedation was evaluated using the Grint sedation scale. In all groups, atipamezole was administered at the end of the evaluation, and recovery was assessed using the Lozano and Sams recovery scales. The DC and DM groups exhibited minimal sedative effects. The maximum sedative effect was observed in the DD and DK groups, while sedation in the DD and DK groups was significantly higher compared to the DC group. Recovery in all groups was uneventful, except in the DM group, where it was prolonged and difficult, although no statistically significant difference was detected. Therefore, insufficient sedation with dexmedetomidine can be enhanced by a subsequent dose of dexmedetomidine, ketamine, or butorphanol, whereas the addition of midazolam reduces sedation and prolongs recovery.

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