Sedative and cardiovascular effects of intranasal or intramuscular dexmedetomidine in healthy dogs

Objective: To compare the clinical effects and sedation scores following either intranasal (IN) or intramuscular (IM) administration of dexmedetomidine in dogs. Study design: Prospective, ‘blinded’, randomized, clinical study. Animals: Twenty client-owned dogs scheduled for non-invasive diagnostic procedures. Methods: Dogs were allocated to receive dexmedetomidine 0.02 mg kg-1 IN (group IN) or IM (group IM). Sedation was scored before and every 5 minutes after drug administration using a composite simple descriptive sedation scale giving a score of 0 to 13. Respiratory frequency, heart rate, haemoglobin oxygen saturation and non-invasive arterial blood pressure were recorded every 5 minutes. Parametric data were analysed using the 2-way ANOVA and post-hoc Sidak’s multiple comparison test. Non-parametric data were compared using the Scheier Ray Hare test and post-hoc Mann-Whitney U-test. Statistical significance was set at p < 0.05. Results: Weight, age and sex were not significantly different between groups. Dexmedetomidine onset of action after IN administration was not significantly shorter compared to IM administration. Sedation score in the IN group was significantly higher (p < 0.001) compared to the IM group. At peak sedative time, a 56% HR decrease from baseline values was recorded in the IM group, while an 18% decrease was present in the IN group. No significant differences in SpO2 and fR were found between the two groups at any time point. No undesirable effects were observed. Conclusions and clinical relevance: Intranasal dexmedetomidine 0.02 mg kg-1 produced effective sedation with less bradycardia and more profound sedation compared to IM administration in healthy dogs and may be considered as an alternative route for DEX administration in dogs.