At my shelter we have taken in over 1200 ferrets in eight years.  I have
NEVER seen a scar from a spay operation on a pet shop ferret, and very
rarely on a late spay ferret.
 
If you ferret has a tattoo in the ear (any ear, any tattoo), that is a good
sign that the ferret has been spayed.  I've told this to the local vets who
didn't know, and the only time a tattooed female's vulva swells is when the
spay operation was incomplete (2% of the time) or she has an adrenal (the
rest of the time).
 
BTW, all of my ferrets are "home growns" or retired breeders (ie all altered
late in life) except one - Bear is an albino who belonged to a friend that
moved to Florida nad could not take Bear with them.  He was 5ish when he
came to us.  If his former owner's given birthdate is accurate, Bear will be
7 in May.  He has never had an operation for any disorders or health
concerns.  He is just now slowing down and becoming a little thready.  He
has the MF tattoo.  I consider him to be the last of his kind.  Most MF
ferrets don't live that long.
 
Pam
[Posted in FML issue 1475]