Background: Experimental investigations on laboratory animals usually requi
re sufficient anesthesia with adequate analgesia and sedation. The techniqu
e used should be reliable and easily controllable by the investigator. Here
, we present a technique for anesthesia to facilitate invasive and noninvas
ive investigations in newborn rats and mice. Methods: Using a custom made b
reathing mask, anesthesia was induced in these animals with inhalation of g
aseous nitrous oxide-oxygen (equal volume at 1 l/min) and halothane (3 % by
volume). To maintain anesthesia, halothane insufflation was reduced to 1-1
.5% by volume. After completion of the experimental procedure, the applicat
ion of the inhalative gases was determined and substituted by oxygen at 2 l
/min. Anesthesia was performed in spontaneously breathing animals. Heart fr
equency and oxygenation were monitored using a commercially available pulse
oximeter. Results: Using the above described technique in neonatal rodents
, microsurgery of the ear was performed without signs of pain or major blee
ding. Auditory brain stem responses were recorded clearly and reproducible.
Conclusions: This method represents a noninvasive, well tolerated and easy
controllable anesthetic procedure which has proven to provide a sufficient
and reliable sedation in neonatal rodents for surgical and nonsurgical inv
estigations.