C.B.
Ok, don't know if it will help either, but I would probably do a timeout with my child if they were doing that at 3 1/2. I use the timeout method when they are misbehaving and put them in the corner (3 min or a 3 yr. old, 4 min. for a 4 yr. old, etc.) I would let him know that he is hurting the dog and that is not ok, put him timeout and then get down to his heigth, eye to eye and talk with him about why he was in time out, and then he has to apologize for what he did and say he isn't going to do that anymore. I like the idea of having him say he's sorry to the dog too and make him give the dog a hug.
I believe that even the little ones need to know that when they do something wrong, they will be punished (timeout) and that it's a NO-NO.
C.