Intranasal atomized dexmedetomidine alone or in combination with ketamine or midazolam to sedate healthy dogs

Abstract

A prospective, randomized, blinded experiment was conducted to compare the effects of intranasal (IN) dexmedetomidine (Dex, 10 µg/kg; n=12) alone or combined with midazolam (DexM, 0.3 mg/kg; n=12) or ketamine (DexK, 2 mg/kg; n=12) in healthy dogs. Ease of administration (EA1), total administration time (TAT), time for first (TA1) and second nostril administration (TA2), and adverse events during atomization were recorded. Two days later, EA2 was assessed by IN atomization of injectable water as an additional outcome variable. Onset of sedation was evaluated, along with behavioral scores and physiological parameters from T0 (baseline) to T120. Statistical analyses included Chi-square, one-way ANOVA or Kruskal-Wallis, repeated measures or Friedman’s ANOVA, and Wilcoxon’s tests. Significance was p≤0.05.

Onset of sedation was 12.9 ± 4.1, 18.2 ± 7.5, and 9.9 ± 4.3 mins (mean ± SD) for Dex, DexM, and DexK, respectively. Onset was shorter in DexK compared to DexM (p=0.002), explaining the lower behavioral scores in DexM at T15. All dogs in Dex and DexK reached adequate sedation, with peak sedation occurring at T30, while some dogs in DexM never reached adequate sedation and this group peaked at T45. Adverse events such as saliva drooling and pawing at the nose were significantly higher in DexM and DexK, explaining their differences in TA2, TAT, and EA1 comparing to Dex. EA2 was also higher in Dex compared to DexM and DexK. In conclusion, Dex was better tolerated in dogs and DexK showed faster and more profound sedative effects. Due to paradoxical excitement, unpredictable sedation, and nasal irritation, DexM is not recommended.