Comparison of the sedative effects of intranasal or intramuscular dexmedetomidine at low doses in healthy dogs: a randomized clinical trial.

OBJECTIVE: To compare the sedative effects of dexmedetomidine administered either intranasally or intramuscularly to healthy dogs. STUDY DESIGN: Prospective, randomized, blinded, clinical trial. ANIMALS: A group of 16 client-owned healthy dogs. METHODS: Dogs were randomly allocated to one of two groups that were administered dexmedetomidine 5 µg kg-1 via either the intranasal route (INDex), through a mucosal atomization device in one nostril, or the intramuscular route (IMDex), into the epaxial muscles. Ease of intranasal administration, sedation score, onset of sedation, cardiopulmonary variables, mechanical nociceptive thresholds (MNTs) and response to venous catheterization were recorded at 0 (baseline), 5, 10, 15, 20, 25, 30, 35, 40 and 45 minutes, following drug administration. Data were compared with the one-way anova, Mann-Whitney U test, and chi-square test, where appropriate. RESULTS: Groups were not different for age, sex, weight, body condition score or temperament. Sedation scores, MNTs and response to intravenous catheter placement were not different when dexmedetomidine was administered by either route (p = 0.691; p = 0.630 and p = 0.435, respectively). Onset of sedation was not different between groups INDex and IMDex reaching a score of 4.2 ± 0.9 and 5.5 ± 1.2 at 9 ± 5 and 8 ± 4 minutes, respectively (p = 0.467). The highest sedation score was achieved at 30 and 35 minutes and sedation scores were 9.7 ± 2.0 and 9.5 ± 2.3 in groups INDex and IMDex, respectively (p = 0.799). Respiratory rate was higher in group INDex (p = 0.014), while there were no differences between routes in heart rate (p = 0.275), systolic (p = 0.957), diastolic (p = 0.837) or mean arterial pressure (p = 0.921). CONCLUSIONS AND CLINICAL RELEVANCE: Intranasal administration of dexmedetomidine at 5 µg kg-1 provides effective sedation in healthy dogs.

Comparison of the sedative effects of medetomidine administered intranasally, by atomization or drops, and intramuscular injection in dogs.

OBJECTIVE: To compare the sedative effects of intranasal atomization (INA) of medetomidine with intranasal drops (IND) and intramuscular (IM) injection in healthy dogs. STUDY DESIGN: Prospective, blinded, randomized study. ANIMALS: A group of 18 mixed-breed shelter-owned dogs weighing 27 ± 4.3 kg (mean ± standard deviation). METHODS: The dogs were randomly assigned to equal groups of six dogs for administration of medetomidine (40 µg kg-1) by INA, IND and IM routes. Ease of administration was evaluated using a resistance scale. Composite sedation score (CSS), heart rate (HR) and respiratory frequency (fR) were measured immediately before (T0, baseline) and after drug administration at time points 15, 45, 75 and 120 minutes. The time of onset of sedation was recorded. Ease of administration and onset of sedation were analysed by the Kruskal-Wallis and post hoc Dunn's tests. Repeated measures analysis of anova and least significant difference tests were used to analyse CSS, HR and fR over time. Tukey's post hoc test was used for time point comparisons among groups. Significance was set at p < 0.05. RESULTS: No differences were detected among groups for ease of administration (p = 0.346). CSS increased in all groups from baseline values. Onset of sedation in IM was 6.3 ± 2.0 minutes, in INA was 7.2 ± 2.5 minutes and in IND was 20.7 ± 5.4 minutes. CSS in IND was lower than in the other groups at T15 and lower than in INA at T45. CSS was not different between IM and INA. HR and fR decreased in all groups compared with respective baseline values. HR in IND was lower than in IM at T45-T120. CONCLUSIONS AND CLINICAL RELEVANCE: INA medetomidine (40 µg kg-1) can be an alternative and noninvasive route to IM injections for sedating healthy dogs. IND resulted in a slow onset of sedation.