The freeze response
It is used for survival in a confrontation with an overpowering opponent. In this reaction, part of the parasympathetic system takes over the control of the highly excited system and a “shutdown” occurs where the entire organism is brought down to a state similar to death.
When animals emerge from this freezing reaction, they usually go through a distinct tremor for a short period of time. The high level of excitation that was blocked by the shutdown is released.
This is the reason why wild animals do not experience trauma.