I thought you were describing my dog! Minus the surgery, etc. I swear she barks at air all the way up the road till we get to the woods. Then, she's either tired or trees don't bother her. I've tried just about everything, nothing has worked.
I've decided that it is not fear, nor agression, but that she feels the need to 'announce' herself to the world (even if no one else is around). Sorry I'm no help... just didn't want you to feel alone....
