Hi Joe-Joe! Thank you for your response. To clarify some things, my trainer has been with Cappy for a little over 4 months at this point- Cappy has been at the barn for three years (going on four), and this is the beginning of my second year. I leased him from Jan-June last year, and renewed the lease this September. I completely agree that time with him is important- from the beginning he has gotten much better, but is still aggressive. He’s also turned out from about 8-3 every day with an sweet old pony, then ridden (so out of stall for 3 hours including grooming), so I think he’s getting an ample amount of outside time. On the weekends he’s out for the whole day as well. Also, when I or anyone else gives him food he doesn’t have a problem with people entering his stall, it’s when I don’t have food or treats to give him that he turns aggressive.