Álvarez, E. R., Solé, L. V., Mateo, A. G. de C. 2022. Comparison of subcutaneous sedation with alfaxalone or alfaxalone-midazolam in pet guinea pigs (Cavia porcellus) of three different age groups. Journal of the American Veterinary Medical Association 260(9), 1024–1030.

OBJECTIVE To compare the cardiorespiratory effects, quality and duration of sedation of 2 subcutaneous sedation protocols for noninvasive procedures in guinea pigs (GPs). ANIMALS 24 pet GPs (15 females, 9 males) of 3 different age groups: infant (n = 8), juvenile (8), and adult (8). PROCEDURES The study design was a randomized, crossover, blinded, clinical trial with a washout period of at least 7 days between protocols. Guinea pigs were sedated SC with alfaxalone (5 mg/kg; group A) or alfaxalone (5 mg/kg) and midazolam (0.5 mg/kg; group A + M) to facilitate blood sampling, radiography, or abdominal ultrasonography. Vital parameters, hemoglobin saturation (SpO2), and sedation scores were recorded every 5 minutes. RESULTS Mean heart rate was lower in group A than group A + M (P = 0.001), and respiratory rate was significantly (P = 0.001) decreased relative to baseline during sedation in both groups. The SpO2 remained above 95% in both sedation groups. Rectal temperature was significantly (P = 0.001) lower during recovery versus baseline. Onset of sedation was shorter and the duration longer in group A + M than in group A. The duration and depth of the sedation was different between age groups (P = 0.001), being longer and deeper in adults. Bruxism, hectic movements, twitching, and some degree of hyperreactivity were observed during 41 of the 48 sedations. CLINICAL RELEVANCE Subcutaneous administration of alfaxalone provided reliable sedation for nonpainful procedures in GPs. When combined with midazolam, alfaxalone provided longer and deeper sedation that was more significant in adults than in younger patients.