Hi,
 
To clear up blackheads on ferret tails, we've had good luck with
Neutrogena's T/Gel shampoo.  It's dark brown, a little smelly, and kind
of expensive, but it cleared up Grendel's blackheads in about two baths
(one a week), and more recently, has helped Boomer's acne in about three
baths.  We also carefully groom their tails to remove the blackheads at
the same time that we clip their nails.  They don't approve of either the
grooming or the clipping, but when they're distracted with a little
ferretone on the tummy, they're too busy licking to protest much.
 
I don't know if it's the shampoo or the grooming or just time that
helped, but both our guys cleared up pretty quickly.  I don't expect
Boomer to get his tail fur back until autumn shedding, but at least
it's not getting worse.
 
I've also seen generic brands of "Tar shampoo" which look and smell
very similar for less money; maybe one of those would work as well.
 
Happy Ferreting!
Dennis
[Posted in FML issue 1268]