Effect of an anaesthetic protocol administered by two routes on physiological parameters in guinea pigs undergoing orchiectomy

The aim of the present investigation was to evaluate the effect of a combined anaesthetic protocol of Medetomidine, Midazolam and Fentanyl administered intravenously and compare it with its standard intramuscular administration, on physiological constants, glucose levels and induction, surgical and recovery times. Fourteen guinea pigs with a mean weight of 1250.0 ± 155.66 g; body condition: 2.5 ± 0.64 were used. The animals underwent orchiectomy and were evaluated for the following: capillary refill time; mucosal colour; heart rate; respiratory rate; rectal temperature; oxygen saturation; blood glucose levels; and induction, surgical and recovery times. These measurements were taken in four phases: reception, preparation, the operating theatre, and recovery. All physiological constants showed significant variations at different measurement times (P<0.05), irrespective of the route of administration. Glucose levels during the preparation and recovery phases were affected by time (P=0.018) rather than the route of administration (P=0.166); however, the intravenous route produced a weaker hyperglycaemic effect. Similarly, there were no significant differences in the recorded times according to the route of administration (induction: P=0.93; surgery: P=1.00; recovery: P=0.56). However, the intravenous route had a numerically lower recovery time than the intramuscular group (125.7 ± 39.5 vs. 137.2 ± 32.5 min). In conclusion, the intravenous route is a viable alternative for anaesthetic management in guinea pigs, as it maintains physiological parameters within adequate ranges and shows favourable responses in terms of glycaemia and post-surgical recovery.