All animals must be evaluated immediately prior to anesthesia to assure that they are healthy and capable of tolerating a general anesthetic event. Animals that are showing signs of disease should be evaluated by a veterinary staff member prior to administration of anesthesia. Animals that are hunched and scruffy, have reduced activity, or any changes in respiratory status (increased rate or effort) are particularly susceptible to anesthetic complications.

If inhalant anesthetics (isoflurane) are used, it should be administered in oxygen via a precision vaporizer. In certain instances, a drop jar method of anesthesia may be appropriate. It should only be used for non-surgical procedures requiring short anesthetic episodes. Specific requirements regarding the safe use of gas anesthetics can be found in the IACUC SOP, Vaporize Equipment Monitoring and Maintenance.

All anesthetized animals undergoing a procedure that will take >5 minutes must receive heat support to prevent the development of hypothermia, one of the most common causes of anesthetic complications in rodents. Circulating hot water blankets and rodent specific electric heating pads are the preferred methods of heat support. Re-warmable heating pads (SnuggleSafe pads) can be used but require regular assessment and reheating. Use of heat lamps and electric pads that are not intended for veterinary use are discouraged as they can result in animals overheating or inadvertent burns.

Prior to a procedure that will take >5 minutes, eye lubricant must be applied to both eyes to prevent drying of the corneas and subsequent ocular inflammation. The lubricant should be re-applied every 30-60 minutes until recovery.

For surgical procedures longer than 30 minutes and/or where fluid loss due to hemorrhage or evaporation is anticipated, fluid support should be provided. Warmed subcutaneous, intravenous, or intraperitoneal fluids (Lactated Ringer's or normal saline) are given at the rate of 10-20 ml/kg every 2 - 4 hours.

During anesthesia, animals must never be left unattended and should be monitored throughout the procedure to ensure that anesthetic depth is adequate to the procedure being performed.

General indicators of adequate anesthetic depth include regular respirations, lack of response to toe or tail pinch, and lack of palpebral (eyelid) or whisker reflexes. Excessive anesthetic depth will most often manifest as a slowing respiratory rate that progresses to irregular, deep, forced breaths (i.e. abdominal respiration with effort).

Researcher must stay in the room to monitor anesthetized animals until they are fully recovered from anesthesia. Animals should be visually/physically assessed at least every 10 minutes.

The animal is placed in a clean dry cage without bedding, as it may be ingested or inhaled during recovery. Place the animal in sternal recumbency on a paper towel to allow absorption of expelled urine, replace when soiled. To prevent possible injury to the anesthetized animal, recovering animals must be singly housed until they return to their home cage.

Supplemental heating must be continued through the immediate recovery period. The heat source (water circulating heating pad or electric heating pad) should be placed under half of the cage with the animal placed on heated side. Preferably, research should drape half the cage during recovery to help decrease light and exposure to movements in the environment. This provides a calmer initial recovery.

Recovery progress should be evaluated through one or more of the following methods: rate and depth of respiration color of mucous membranes, ears and/or tail and reflexes (i.e. pedal, palpebral, whisker).

Once the animal has regained normal ambulation and displays grooming behavior the animal must be returned to its normal housing cage and placed back in the DLAR vivarium, unless otherwise described in the protocol. Additional supportive care will be provided by the research team unless DLAR staff is directed to assume this responsibility.

Additional monitoring/recordkeeping may be necessary for those animals that undergo any invasive survival procedures such as surgery or injury. These requirements are outline in the Principles of Rodent Surgery policy.