I am not one of those people that say poor thing she's crazy bc she was abused, I KNOW she was. Her whole body was shaking around my dad and neighbor, everytime you raise your arm above your shoulder she jerks back, and if someone is walking behind you carrying ANYTHING she's constantly looking back NERVOUS.
I have a three year old mare who is the same way. I raised this mare and she has NEVER been beaten. Her attitude in new situations is to be very aware (some might call it nervous)- especially when she is alone or in heat.
9 year old training horse - same thing. He shakes when he is in a new situation. He has been owned and handled by the same person his whole life. SPOILED.
Heck - I shake when I anxious about a new situation.