LAUSR

OBJECTIVE To characterize alfaxalone administered subcutaneously (SC) in guinea pigs, both alone and in combination with dexmedetomidine and buprenorphine. STUDY DESIGN Prospective, blinded, crossover study. ANIMALS A total of 15 healthy female guinea pigs weighing 400-600 g. METHODS Alfaxalone (10, 20 and 40 mg kg-1) was administered SC to three guinea pigs as a pilot dose-finding study. Alfaxalone (20 mg kg-1; A20) was selected for comparison against combination protocols of alfaxalone (15 and 20 mg kg-1) with dexmedetomidine (0.25 mg kg-1) and buprenorphine (0.05 mg kg-1; A15DB, A20DB). Each protocol was randomly administered to 12 guinea pigs separated by ≥7 days. Time and quality of induction and recovery, heart rate, respiratory rate, peripheral hemoglobin oxygen saturation, rectal temperature, pedal withdrawal reflex and adverse effects were recorded. RESULTS The median time to induction for A20, A15DB and A20DB was 6.8-8.0 minutes with no significant difference between treatments. Mean duration of recumbency for A20 was 73.6 ± 19.6 minutes. Recumbency duration for A15DB and A20DB extended to 90 minutes, at which time dexmedetomidine was antagonized using atipamezole (0.025 mg kg-1 SC). Physiological variables were within normal limits with the exception of one animal that died 45 minutes following treatment with A20DB. Pedal withdrawal reflex remained intact with all treatments. Minor side effects such as twitching or bruxism occurred sporadically with treatment A20 but not with A15DB and A20DB. CONCLUSIONS AND CLINICAL RELEVANCE SC alfaxalone produced uncomplicated sedation that may be recommended for nonpainful procedures that do not require complete immobility. The addition of dexmedetomidine and buprenorphine increased the duration of sedation and immobility, but did not result in general anesthesia. This combination sedation protocol may be useful for nonpainful procedures requiring extended immobility.