Here are three useful places with fine health info.  They also will lead
you to others.  Additionally, there are lists for some illnesses, so learn
from those, too.
 
1.  http://www.ferretcentral.org
2.  http://www.afip.org/ferrets/index.html
3.  http://www.miamiferret.org/fhc
 
I am sure there are people who know of other excellent health pages that
don't some to me off the top of my head.  (Tired.  Up late watching a
CNBC show with home raised river otters in Missouri playing the same games
that ferrets play while still young enough to be friendly.  They were
ambassadors to help promote river health and reinstate otters which had
been almost gone in MO but now number about 10,000 according to the closing
if I wasn't too asleep to get it right.)
[Posted in FML issue 3032]