Abstract

Isoflurane is to date the most common volatile anaesthetic in laboratory rodents
whereas the modern sevoflurane is usual for inhalation anaesthesia in human medicine.
In this study it was aimed to characterize and compare the clinical properties
and safety of both anaesthetics for anaesthetizing mice.
In an approach that mirrors the laboratory routine (spontaneous breathing, gas supply
via nose mask, preventing hypothermia by a warming mat) a 50-minutes anaesthesia
was performed. Anaesthetics were administered at standardized dosages of
1.5 X minimum alveolar concentrations (1.85% for isoflurane, 3.25% for sevoflurane)
in 100% oxygen.
Induction and recovery from anaesthesia proceeded quickly, within 1 and 2 minutes
respectively. During anaesthesia, all reflex testing were negative and no serious impairment
of vital functions was found; all animals survived. Most prominent side effect
during anaesthesia was the respiratory depression with marked decrease of respiration
rate, hypercapnia and acidosis. Under anaesthesia, heart rate and core body
temperature remained stable and within normal range, but were significantly increased
for 12 hours after anaesthesia. Locomotor activity, food and water consumption
and body weight progression showed no abnormalities after anaesthesia. No
relevant differences between the two anaesthetics were found.
In conclusion, both anaesthetics equally provide high safety margin with acceptable
side effects and are therefore recommended for anaesthesia in laboratory mice.