Hi X,
 
Yes it is the hormones (estrogens) that causes the swollen vulva, just
like an intact female in heat.  Quite often you will get a bacterial
vaginal/vulva infection.  Usually you see a mucoid discharge.  Most of
these do not progress to a bladder infection but that is possible.
Usually keeping the vulva clean prevents further problems, but a topical
antibiotic ointment (neosporin) and an oral antibiotic (amoxi drops,
clavamox drops, or Baytril) may be necessary in some cases.  Yes,
melatonin may cause sleepiness during the first 7-10 days.  After the
ferret gets used to it the activity level increases again.  You are not
the only one who has trouble giving a tablet daily, that is why we are
looking into the melatonin implants.  Plus the constant release may work
better than the once a day tablet.
 
Good luck with Sassy,
Jerry Murray, DVM
[Posted in FML issue 3702]