I am leasing a 25 year old Quarter horse mare ( she acts no where near 25). Last week the owner of the stable told me that one night she had an episode of some sort. She started to whinny, and then she was circling in her stall. She was rearing and just a mess. She was shaking her head, and would tilt it to the right. The owner tranquilized her, and by the next morning she was fine. She has shown no signs since, and last night the same thing happened just not as severe, once again she was tranquilized for her safety. Today I went out to ride her, and she just seemed out of it not her normal self, which is VERY energetic and a bit of a brat at times. She has been ridden more than normal, but she is the kind of horse that is never tired. I road her that day and she showed no signs of anything of the sort. Her ears were out to the sides and her eyes glazed over and she was not very responsive. Her left side especially, I was snapping by her eye, and she was not really blinking, she was better and the right. Then after a while she would jerk and almost come out of this daze. She was still eating while not in her daze. I didn't end up riding her and ended up by just observing her. Her jaw was also clenched so tight. I did walk her a bit, and she was a bit sluggish and dragged her feet a bit, but nothing to odd. The vet and the dentist are coming out tomorrow, but if anyone has any idea of what this could be please let me know as soon as possible!