10/02/2022
Freezing is a natural state of paralysis (Tonic Immobility) where the whole body doesn't move at all.
Quite often with big cats, when the prey animal does not react and run, the killing instinct is not stimulated. Also, big cats suffocate their prey by putting their mouths over the prey's mouth or grabbing its throat and shutting down its breathing and when it no longer reacts, they let go. So freezing is a really good adaptation to dupe the predator into thinking to let go and the prey can suddenly leap up and run off.
So why does a domesticated horse freeze when we are riding it?
Quite often they freeze for similar reasons. When they are subjected to high levels of fear and confusion, for instance, using a whip and they can't give a reaction to cease it, or they don't have the correct reaction in their array of responses, because it has not been reinforced in the past. Freezing is an option to high levels of sympathetic nervous activity. The real freeze where they stop and go rigid is more common in the hotter breeds. You can also get a Tonic Immobility reaction and consequent violent reaction from a nose-twitched horse. It can suddenly panic and react violently to free itself.
This is an excerpt of the article series 'Conversations with Dr Andrew McLean', available to purchase here: https://esi-education.com/product/conversations-with-dr-andrew-mclean/.