I have a 9 yr old OTTB who has been off the track since 2008. She is a pretty easy going mare but is a little high strung. I have only owned her for just under 2 months and she has been at the new barn about a month. I have been lungeing her daily and I ride her a few days a week. She reared the first time I got on her after I moved her, I pushed her forward and our session My sister rides as well and is there with me everyday of training. My horse has reared on her 3 times (does it every time my sister mounts). She did it to my husband as well. I will reiterate that SHE DID IT TO ME ONE TIME AND STANDS FINE WHEN I MOUNT HER!! I have checked her back and she is showing no signs of soreness. I have also checked saddle fit and seems fine. I think if it was saddle fit or soreness she would do it all the time not just everyone but me. Does anyone have any helpful hints to try to figure out the issue? I have trained horses but never had an issue like this before. I love that she is great for me but I also want others to be able to ride her.