I have had my 14 year old gelding for about a year now, and its been good for the most part. Today we had a rain/thunderstorm for about an hour. I don't know if my horse was frightened by all the thunder, because when I bring him in I have to turn him around to shut the gate behind me. As I turned around he didn't rear but kind of came off his front feet and had his ears pinned and had a strange look in his eye like something was wrong. Anytime in the past my horse has tried running past me while being led I just disengaged his hind quarters until he would walk at my pace, so that's what I did because it happened so fast not knowing if he was injured or not. I looked him over didn't see any cuts or could tell if he was sore anywhere. But he has been out with a mare that is in heat and she flaunts her stuff for him and it seems like he is annoyed by this because he is always trying to get away from her. So my question is do you guys think it was the thunder that startled him or the mare in heat?