Dear Shira Taragin

Core body temperature decreases suddenly after induction and continues to diminish during the course of prolonged general anesthesia, especially in small rodents. Therefore hypothermia (which is potentially lethal) must be prevented by providing heat through warming pads and infrared lamps.

I hope this helps.

Can only give info from humans, hope this may help

1. Maintain normal temperature

2. Oxygenation, lungs start to collapse with GA and need ventilatory support, also lying in one position leads to alveolar collapse in dependent lung

3. Fluid balance need to be maintained

4. keep top up drugs to a minimum, dose needed may decrease over time, depending on tissue storage, metabolism and excretion, repeat anaesthetics need much smaller doses as earlier drugs not yet excreted.

5. We dose each individual depending on the response, some need more other less.

not sure of any of this human info is transferable to mice.

finally, is there a vetinary Anaesthetist you can discuss this with.

good luck

Do not use inhalation drugs only ketamine and xylazine

How are you monitoring their core temp, pulse ox, tidal volume and CO2 levels? You can't have them under for a long time without monitoring those parameters.

I agree for the temperature regulation. Make sure they are kept warm and you can also inject ~0.5-0.8cc of warm saline SC every hour (especially if you get loss of blood). I would also try to use inhalants only. Isoflurane is easier to maintain depth of anesthesia and you can find the "sweet spot" to keep him/her at the ideal depth without having the vitals crash. Labs I work with who use injectables for long procedures had the same problem. Since they have changed to iso only the problem has been fixed.