Effects of intramuscular dexmedetomidine in combination with ketamine or alfaxalone in swine.

OBJECTIVE: To evaluate and compare the use of intramuscular (IM) premedication with dexmedetomidine in combination with ketamine or alfaxalone in pigs. STUDY
DESIGN: Prospective, randomized, 'blinded' trial. ANIMALS: Fourteen healthy 2-month-old Landrace × Large White pigs weighing 21.5 ± 0.6 kg.
METHODS: Animals were distributed randomly into two groups: group KD (n = 7) was given 10 mg kg(-1) IM ketamine + 10 μg kg(-1) IM dexmedetomidine; and group AD (n = 7) was given 5 mg kg(-1) IM alfaxalone + 10 μg kg(-1) IM dexmedetomidine mixed in the same syringe. Pain on injection, degree of sedation and quality of induction were scored. The time from induction of anaesthesia to recumbency was recorded. Once pigs were recumbent, reflexes were evaluated. Pulse and respiratory rates, end-tidal carbon dioxide and arterial oxygen saturation were recorded at 5 and 10 minutes after drug administration. Data were compared using a two-way anova or a t-test for unpaired data as relevant. Data are presented as the mean ± standard deviation (range).
RESULTS: Two animals in both groups showed slight pain on drug injection. The time to lateral recumbency in group KD [187 ± 34 seconds (153-230)] was similar to group AD [206 ± 36 seconds (150-248)]. In group AD, sedation was deeper, and the quality of anaesthetic induction was smoother. When moved for anaesthesia, five pigs in group KD vocalized. There were no differences between groups in pulse rates, arterial oxygen saturation and end-tidal carbon dioxide; however, the respiratory rate at 10 minutes was significantly higher in group KD than in group AD. CONCLUSIONS AND CLINICAL RELEVANCE: IM dexmedetomidine in combination with ketamine in pigs induced moderate to deep sedation and fair to smooth induction of anaesthesia. When dexmedetomidine was combined with alfaxalone, sedation was deeper, and induction was of a better quality.