The following list includes only the commonly used anesthetic agents in mice.  A list of other anesthetics suitable for specific procedures and additional information about the effects, mode of action, metabolism, and side effects of these agents are available in the CMU office, extension 6555.  The use of an anticholinergic (atropine, 0.04 mg/kg, intramuscularly, subcutaneously, or intraperitoneally) may help reduce salivation and maintain heart rate.

INJECTABLE AGENTS:

Note:  The doses of injectable anesthetic agents can vary depending upon the genetic background of the mouse.  In some mice, the therapeutic dose is very close to the lethal dose.  The doses provided here are intended as a guide, and they may have to be adjusted for different strains or stocks of mice.

Ketamine - 100-200 mg/kg by intraperitoneal injection. COMMENTS: Poor muscle relaxation, incomplete analgesia, not suitable for procedures requiring deep anesthesia, lasts about 30 minutes or less, time to recovery is longer.

Ketamine + acetylpromazine - 100 mg/kg ketamine + 2.5 mg/kg acetylpromazine by intramuscular injection (can be mixed together in the same syringe). COMMENTS: More muscle relaxation than #1, incomplete analgesia, not suitable for procedures requiring deep anesthesia, lasts less than 30 minutes, time to recovery is longer.

Ketamine + xylazine - 100 mg/kg ketamine + 5 mg/kg xylazine by intramuscular injection. COMMENTS: Good analgesia and muscle relaxation, suitable for more invasive procedures than #1 or #2, up to 80 minutes of surgical anesthesia, causes hypothermia, bradycardia and hypotension, can be reversed at least partially with 1.0-2.1 mg/kg yohimbine by intraperitoneal injection.

Ketamine + xylazine + acetylpromazine - Mix 1.5 ml of ketamine (100 mg/ml) with 1.5 ml of xylazine (20 mg/ml) and 0.5 ml of acetylpromazine (10 mg/ml), give 0.5 - 0.7 ml/kg by intramuscular or subcutaneous injection.  Intraperitoneal injection MAY also be suitable. COMMENTS: Suitable for most surgical procedures, good muscle relaxation and analgesia.

Pentobarbital - 40-80 mg/kg by intraperitoneal injection. COMMENTS: Highly variable effect in mice depending on numerous factors including genetic background, sex, diet, environmental temperature, and type of bedding used for housing; poor analgesia; suitable for mildly invasive procedures at higher dose range; can last 20-30 minutes.

Tribromoethanol (Avertin) - 0.2 ml/10 g (approximately 250 mg/kg) of a 1.25% w/v solution by intraperitoneal injection. COMMENTS: Produces anesthesia for about 16 minutes with full recovery in 40-90 minutes; commonly used in embryo transfer, vasectomy and distal tail amputation for Southern blot analysis; high mortality associated with toxic breakdown products if stored improperly - must be protected from light and kept at 4EC; contact the CMU for instructions on mixing.

INHALANT AGENTS:

Carbon dioxide – Administer in an enclosed container such as a bell jar using bottled CO2, given to effect, optimal concentration is 70% CO2 + 30% O2.  COMMENTS: Generally safe so long as not overdosed, suitable only for very brief procedures - 1 minute or less.

Halothane – Halothane should be administered with a vaporizer.  Anesthesia can be induced with 3 – 5% Halothane and maintained at 1.0 – 1.5% of inspired gas. Mice are usually maintained with a face mask.   COMMENTS:  Rapid induction and changes in levels of anesthesia make Halothane dangerous when used without a vaporizer; waste gases should be scavenged for personal safety reasons; microsomal enzymes are induced to a greater degree than with methoxyflurane; suitable for prolonged procedures when administered with a vaporizer; rapid recovery.

Isoflurane – Administer with a vaporizer. Anesthesia can be induced with 3 – 5% isoflurane and maintained at 1 – 2% of inspired gas. Mice are usually maintained with a face mask.  COMMENTS:  Rapid induction and changes in levels of anesthesia make isoflurane dangerous when used without a vaporizer, waste gases should be scavenged for personal safety reasons; suitable for prolonged procedures when administered with a vaporizer; rapid recovery; can be cardioprotective in some species.