[An anesthesia technique for experimental studies and microsurgical ear interventions in newborn rodents]

Experimental investigations on laboratory animals usually require sufficient anesthesia with adequate analgesia and sedation. The technique used should be reliable and easily controllable by the investigator. Here, we present a technique for anesthesia to facilitate invasive and noninvasive investigations in newborn rats and mice.

Using a custom made breathing mask, anesthesia was induced in these animals with inhalation of gaseous 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 application of the inhalative gases was determined and substituted by oxygen at 2 l/min. Anesthesia was performed in spontaneously breathing animals. Heart frequency and oxygenation were monitored using a commercially available pulse oximeter.

Using the above described technique in neonatal rodents, microsurgery of the ear was performed without signs of pain or major bleeding. Auditory brain stem responses were recorded clearly and reproducible.

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 investigations.