Karen Purcell's book _ Essentials of Ferrets..._ is the most recent
reference and she writes that "Thyroid disorders are uncommon in the
ferret ... There are anecdotal reports of hypothyroidism...".  She goes on
to mention thyroiditis in conjunction with Aleutian Disease, and two cases
of thyroid adenocarcinoma, referring back to Fox's book for both of them.
Thyroid values are in her text on page 151.
 
Karen Rosenthal had not at the point where she wrote chapter 10 of
_Ferrets, Rabbits and Rodents..._ encountered any articles on thyroid
problems in ferrets and had not run into a case of either in ferrets.  This
Hillyer and Quesenberry text (F, R., and R..._) gives mean levels per
genders in Table 9.1 on page 88.
 
In Fox's most recent text the mention in relation to Aleutian was from
unpublished observations in 1986.  In the case of thyroid involvement in
adenocarcinoma there was a survey of 4,774 ferrets, with a total of 639
tumors of assorted types, and only ONE was of this type and location but
clinical data on that ferret was not available ( Li, Fox, Padrid,
"Neoplastic Diseases in Ferrets, 574 Cases" (1968 - 1997) JAVMA 1998;
212:1402).  A second case later appeared in a zoo male presenting with
dysphagia (problems swallowing) with the clinical signs being weight loss
and a thin coat for two years, and the ferret had first been tried with a
diet change which helped on both scores until he was one day found
semi-conscious a year later.  He did not survive corrective surgery which
was attempted at that point, and he had further illnesses present (chronic
respiratory disease, insulinomae, and bilateral adrenal hyperplasia) on
necropsy.  You will find a photo of the very large throat lump seen when he
was shaved, and radiograph in _Biology and Diseases of the Ferret_.
Thyroid values are given on page 137 of Fox's book, and further information
on other aspects else in the text.
 
I seem to recall Bruce Williams once mentioning that while he knew of a
very few hyperthyroid cases that hypothyroid in ferrets was not seen by
him.  That's from memory and could be wrong.  It was from back when a few
people were actively pushing that hypothyroidism was in their ferrets but
when push came to shove they wouldn't test the thyroid values or didn't
report the results when they finally did test.
 
While thyroid problems certainly can happen my own personal inclination at
this level in the information matrix is that a number of people take the
human tendency toward such difficulties and try to project that onto
ferrets.  If more testing were done they might be proven right but right
now the current results do not back that hypothesis and until these people
put their money where their mouths are by actually testing and then making
sure that the results get to publishing researchers through vet-to-vet
contacts there will be no hard data supporting their premise.  It may be
that such testing is actually underway somewhere now or that there are
some individual very interesting cases lying away in files; without
communication and publications of hard data the suppositions remain only
that.
[Posted in FML issue 2818]