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: A total of 20 client-owned dogs scheduled for noninvasive diagnostic procedures. METHODS: Dogs were allocated to be administered dexmedetomidine 0.02 mg kg-1 IN (IN group) or IM (IM group). Sedation was scored before and at 5 minute intervals (for 45 minutes) after drug administration using a composite simple descriptive sedation scale giving a score of 0 (not sedated) to 13 (well sedated). Respiratory frequency (fR), heart rate, haemoglobin oxygen saturation (SpO2) and noninvasive arterial blood pressure were recorded every 5 minutes for 45 minutes. Normally distributed data were analyzed using two-way ANOVA and post hoc Sidak's multiple comparison test. Non-normally distributed 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 different between groups. Dexmedetomidine onset of action after IN administration was not shorter compared to IM administration (6.3±3.3 versus 9.4±4.6 minutes, p=0.120). Sedation score in the IN group was higher [10 (0-11)] compared to the IM group [6 (0-8)] (p<0.001). At time of peak sedation, heart rate decreased 56% from baseline values in the IM group, and 18% 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 dexmedetomidine administration in dogs.