First, a big thank you to Sukie for the excellent discussion of prolapses.
The only additional note (based on my own experience) is to be extremely
careful that the prolapsed ferret stays out of clay litter -- the pieces
stick to the prolapse, and as the moisture from the skin is absorbed into
the litter, the litter adheres very strongly to the delicate tissue.  This
is extremely painful for the ferret and removal is also painful.  My
solution was to use the paper from my paper shredder as litter but just an
empty litter box is also a good temporary solution until the prolapse is
corrected.
 
Second, my ferrets love the taste of petroleum jelly, so that is what we
use as a hairball remedy/preventative.  My understanding is that
ferretone/linatone are more oil supplements, and not especially effective
as hairball remedies.
[Posted in FML issue 2448]