The use of alfaxalone for premedication, induction and maintenance of anaesthesia in pigs: a pilot study

Objective: The evaluation of alfaxalone as a premedication agent and intravenous anaesthetic in pigs.

Study design: Prospective, clinical trial.

Animals: Nine healthy, 6-8-week-old female Landrace pigs weighing 22.2 ± 1.0 kg, undergoing epidural catheter placement.

Methods: All pigs were premedicated with 4 mg kg^-1 alfaxalone, 40 μg kg^-1 medetomidine and 0.4 mg kg^-1 butorphanol administered in the cervical musculature. Sedation was subjectively scored by the same observer from 1 (no sedation) to 10 (profound sedation) prior to induction of anaesthesia with alfaxalone intravenously to effect. All pigs were maintained on alfaxalone infusions with the rate of administration adjusted to maintain appropriate anaesthetic depth. Quality of induction was scored from 1 (poor) to 3 (smooth) and basic cardiorespiratory variables were recorded every 5 minutes during anaesthesia. Results are reported as mean ± standard deviation or median (range) as appropriate.

Results: Sedation scores were 9 (7-10). Inductions were smooth in all pigs and cardiovascular variables remained within normal limits for the duration of anaesthesia. The induction dose of alfaxalone was 0.9 (0.0-2.3) mg kg^-1. Three pigs did not require additional alfaxalone after premedication to facilitate intubation.

Conclusions and clinical relevance: Intramuscular alfaxalone in combination with medetomidine and butorphanol produced moderate to deep sedation in pigs. Alfaxalone produced satisfactory induction and maintenance of anaesthesia with minimal cardiovascular side effects. Appropriate monitoring of pigs premedicated with this protocol is required as some pigs may become anaesthetized after intramuscular administration of this combination of drugs.