In your post you asked me:
<<Does your horse by any chance scrub his belly as well so that the area from
girth line to his sheath is all scabby and itchy? If so, he may have a fly
(gnat) allergy.>>
He has only a slight scabby spot on his belly. It's never gotten too bad.
But I believe that the mane & tail rubbing are connected to the scabby
belly. And they are all connected to the fly (gnat) allergy. I was told
that the gnats are active from one hour before to one hour after dawn and
dusk. It was suggested (by a friend) that I keep a fly mask on my horse
between those hours and the itchy mane and tail problem would go away. It
did!! :-) There is supose to be some connection between the gnats around the
eyes that set up an allergic reaction that cause the horse to itch in the
mane, tail & belly areas. It didn't make a lot of sense to me, but I figured
that I had $12 to spend on a fly mask and would give it a try. I'm so glad I
did. Maybe it would work for your horse too. I just leave the fly mask on
my horse all the time (except when I ride him) during the warm months of the
year.
Thanks for you suggestion of the garlic & Vaseline.
~Nora