Anesthesia dose for adult male T-Rex

Question

This question is a follow up on How to do dental surgery on a T-Rex tooth?

I need to give an adult male T-Rex dental surgery and I don't want to risk any unexpected jaw movements while I climb inside its cave to do the dirty work. What kind of anesthesia and how much do I need to give my T-Rex to completely paralyze it for the duration of the orthodontic operation?

I treat my pet humanely so tranquilization is not an option as discussed in How to estimate size of ketamin dose to sedate a T. rex.?

Answer 1

Paralytics.

1. You will use neuromuscular blocking drugs to paralyze the T.Rex. You can administer these with darts. Use a lot. Tetrapod neuromuscular junctions are all similar so drugs will work, eventually.

2. You will use an electrical peripheral nerve stimulator to determine depth of nerve blockade.

https://emedicine.medscape.com/article/2009530-overview

NMBAs are used to decrease the work of breathing and facilitate mechanical ventilation in the most critically ill patients. Peripheral nerve stimulation monitoring during NMBA administration results in use of less medication, which can allow for quicker recovery of spontaneous ventilation and accelerated neuromuscular transmission recovery when the NMBA is discontinued

If electrical stimulation of a nerve results in contraction, it is possible the jaw might close. More drugs are needed. You can use the peripheral nerve stimulator on a robot, or a long stick.

3. Once there is no peripheral nerve motion on stimulation you have paralyzed the animal deeply enough. You quickly need to establish an airway and mechanically ventilate the animal, because it is not breathing. You can go thru the nose, or the mouth, or the neck.

4. Animal is paralyzed and you have established it cannot move. Airway and breathing is established and working. Now work on teeth. A hood or blinders might reduce distress, because the animal is awake.

5. Once tooth is fixed, administer antidote if you have it or let paralysis wear off. When T Rex removes intubation tube itself, it is awake enough to not need mechanical ventilation. Tube is long and ventilator is in another room so the machine itself will not be damaged.

Answer 2

Simple answer is we can't be sure.

First, T. Rex are neither the large mammals (either herbivores like elephants and rhinos or carnivores like bears and tigers) most commonly given this kind of treatment, nor are they closely related to large modern reptiles like crocodilians or monitor lizards. Their nearest living relatives are birds, but the largest of those (ostriches, emus, cassowaries, condors) have enough differences from what we think we know about T. Rex that there isn't any way to know ahead of time either what anesthetic will work, or how much you'll need (never mind how fast the big guy will metabolize it).

Your best bet would be to choose drugs that work on both large mammals and large reptiles -- bonus points if they're also safe and effective on birds -- and have them administered by an experienced anesthesiologist, with continual monitoring of pulse, respiration, blood pressure, etc. In other words, more or less the same way you'd anesthetize a human for surgery.