No there isn't a scientific medical test for deafness so to speak.
I've heard that its "possible" but it would be extremely invasive and
stressful to the ferret (and expensive for you), and that only one or two
places would even be equiped to do that.  And I dont' have that on good
authority.  I'd say that there are reliable tests that you, yourself, can
do.  Home tests that may even be better than testing at a vets office.  I
say that because in a vets office a ferret is far too overwelmed with the
new odors, sounds, sights, etc, to get reliable results from any tests
there.  Here is an addie to a site that tells you step by step how to
test your ferret.  http://www.geocities.com/wolfysluv/test.html
 
If you find that your ferret is deaf, then go on to my deaf page.  You
may even want to join Amy Flemmings deaf ferret egroup for further info
and some fun.  The link to that group is on the main deaf site.
 
Deafness can come not only from breeding with the Waardenburg gene that
expresses itself in those sterotypical markings, but it can come from
medication (Gentacin, Gentamycin), infection, and severe prolonged ear
mite infestation also.  Make sure you're little guy has no ongoing ear
infection, or ear mite infestation if you find that he is deaf.
 
I notice recently too, that I"m seeing more and more dilute colors with
deafness in stores from the major farms.  I'm seeing champaynes and light
chocolates with none of the tell tail markings that are stone deaf.  Very
odd.  On the other hand, I'm seeing more and more "fanciful" marked
ferrets that are NOT deaf in stores.  Which is good.  I think maybe the
Waardenburg gene is getting so washed out that the deafness factor is
getting eliminated in some cases.  The bad part is when the few that have
that gene, but don't have the obvious markings, get the deafness because
people don't think to look for it or consider it.
 
Wolfy
 
Please visit:
http://www.geocities.com/wolfysluv/
for information on ferret deafness:
http://www.geocities.com/wolfysluv/deaf.html
[Posted in FML issue 3905]