Two doses of dexmedetomidine in combination with buprenorphine for premedication in dogs; a comparison with acepromazine and buprenorphine

<b>Objective</b>: To assess as premedicants, the sedative, cardiorespiratory and propofol-sparing effects in dogs of dexmedetomidine and buprenorphine compared to acepromazine and buprenorphine. <b>Study design</b>: Prospective, randomised, blinded clinical study <b>Animals</b>: Sixty healthy dogs (ASA grades I/II). Mean (SD) body mass 28.0 ± 9.1 kg, and mean age 3.4 ± 2.3 years. <b>Methods</b>: Dogs were allocated randomly to receive 15 μg kg<sup>−1</sup> buprenorphine combined with either 30 μg kg<sup>−1</sup> acepromazine (group 1), 62.5 μg m<sup>−2</sup> dexmedetomidine (group 2), or 125 μg m<sup>−2</sup> dexmedetomidine (group 3) intramuscularly. After 30 minutes, anaesthesia was induced using a propofol target controlled infusion. Heart rate, respiratory rate, and oscillometric arterial blood pressure were recorded prior to induction, at endotracheal intubation and at 3 and 5 minutes post-intubation. Induction quality and pre-induction sedation were scored on 4 point scales. Propofol target required for endotracheal intubation was recorded. Data were analysed using Chi-squared tests, Kruskal-Wallis, one way and general linear model anova (p < 0.05). <b>Results</b>: Age was significantly lower in group 1 (1.0 (1.0–3.8) years) than group 2 (5.0 (2.0–7.0) years), (median, (IQR)). There were no significant differences in sedation or quality of induction between groups. After premedication, heart rate was significantly lower and arterial blood pressures higher in groups 2 and 3 than group 1, but there was no significant difference between groups 2 and 3. Propofol targets were significantly lower in group 3 (1.5 (1.0–2.5) μg mL<sup>−1</sup>) than group 1 (2.5 (2.0–3.0) μg mL<sup>−1</sup>); no significant differences existed between group 2 (2.0 (1.5–2.5) μg mL<sup>−1</sup>) and the other groups (median, (interquartile range)). <b>Conclusions and Clinical relevance</b>: When administered with buprenorphine, at these doses, dexmedetomidine had no advantages in terms of sedation and induction quality over acepromazine. Both doses of dexmedetomidine produced characteristic cardiovascular and respiratory effects of a similar magnitude