Evaluation of several drug combinations for intraperitoneal anaesthesia in adult male rats

The objective of this study was to evaluate several drug combinations for intraperitoneal anaesthesia in laboratory rats. Following dose determination of anaesthetics in a pilot study, 45 healthy adult male rats were randomly assigned in 9 treatment groups and received propofol (alone or in combination with xylazine, midazolam, or ketamine) or ketamine (in combination with xylazine, midazolam, acepromazine, acepromazine-xylazine, or midazolam-xylazine). Heart and respiratory rate, induction and total sleep times, duration of surgical anaesthesia and walking time were measured. Complete immobility and loss of righting reflex were observed within 12 min in all groups. Induction of anaesthesia was significantly longer following XP compared to other groups. Surgical anaesthesia was induced in all rats receiving XK, AXK and MXK, while propofol alone, MK and KP were associated with surgical anaesthesia in 2, 3 and 4 rats, respectively. Other combinations did not produce surgical anaesthesia. Duration of surgical anaesthesia was longest with MXK and shortest with MK. In conclusion, the most effective drug combinations, which result in longer duration of surgical anaesthesia, were AXK and MXK. Although the degree of analgesia produced by IP propofol is sufficient for restraint and non-painful procedures, the combination of ketamine-propofol can produce surgical anaesthesia in the rat.