Effects of intramuscular alfaxalone alone or in combination with diazepam in swine

Objective To describe the use of intramuscular (IM) premedication with alfaxalone alone or in combination with diazepam in pigs. Study design Randomised-controlled trial. Animals Twelve healthy 2month-old Landrace x Large White pigs weighing 21.3 +/- 2.4kg. Methods Animals were distributed randomly into two groups: group A (n=6) 5mgkg-1 of IM alfaxalone; and group AD (n=6) 5mgkg-1 of IM alfaxalone+0.5mgkg-1 of IM diazepam mixed in the same syringe. The total volume of injectate was standardized at 14mL by dilution in 0.9% sodium chloride. Pain on injection, the degree of sedation and the quality of and time to induction of recumbency were evaluated. Once pigs were recumbent, reflexes were evaluated. Pulse and respiratory rates and arterial oxygen saturation were recorded at 5 and 10minutes after drug administration. Pigs were then moved to another room for subsequent anaesthesia. Results Two animals of group A and one of group AD showed slight pain on drug injection. Time to lateral recumbency (in seconds) was shorter in group AD (mean 203 +/- SD 45 range 140-260) than group A (302 +/- 75, range 220-420; p<0.05). In group AD sedation was deeper, and on recumbency there was better muscle relaxation. When moved for anaesthesia, two pigs in Group A showed slight resistance but did not vocalize. There were no differences in physiologic measurements between groups, although in both groups, respiratory rate was significantly lower at ten compared with five minutes post drug injection. There was no apneoa. Conclusions and clinical relevance IM administration of alfaxalone combined with diazepam resulted in a rapid onset of recumbency and deep sedation, with minimal side effects. The combination might be useful for premedication, but volume of injectate will limit its use to small pigs.