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 (f _R ), heart rate, haemoglobin oxygen saturation (SpO ₂ ) 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 SpO ₂ and f _R 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.
(Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)