Separate him from his friends and he will get over it
He is in a shared paddock with 5 other horses but we can't move him. We did try bringing him in with another horse but he continued to rear.
First off, is he grazed with 1 or more how? Is it separation from the herd, 1 horse or leaving the paddock in general. You want to find out if he does the same when said horse/s leave him by himself in the paddock. If this is the case if you can move his paddock so he isn't paddocks with them. Also start with little steps if you can't move him, like bring him in with another horse etc xx