My thoroughbred Jack is a total stress head when my mare goes out without him. The other way round he's not so bad eg. If i hack him on his own. I have a lovely lady who rides my mare for me but its such a pain that whenever she wants to ride she has to bring Jack in too. If he doesn't come inside he gallops round the field full pelt, slamming the breaks on at the gate, i'm worried that he's going to really injure himself or jump out. From the minute Milly goes out, he trots round the box, shouting and throwing his head about, this continues until she comes back. We have put another pony in the field with him for company, didn't work. We have put a pony in the barn next to him, makes no difference, have tried just taking Milly out for short periods and bringing her back to him, nothing seems to work, Id really like to help him with his anxiety so any suggestions would be appreciated.