Bridgid Conway asked about the risk of ferrets having toxoplasmosis.  It has
been reported in ferrets, but I'm not sure anyone knows how common it is.
Rather than give up your three ferrets you could have yourself tested to see
if you have antibodies to toxoplasmosis.  The risk for toxo mostly applies
(1) to women who have never been exposed to toxo and (2) become exposed for
the first time during pregnancy.  There would also be a risk for anyone
(women or men) who are severely immune suppressed, due to cancer treatment,
bone-marrow transplantation or AIDS.  Assuming you don't fall into the
latter category, you can be tested to see if you have a level of nutralizing
antibodies in your blood.  If you do, the fetus is protected and there
should be no risk of passing toxo along to your child.  As your obstetrician
about the test.
 
The question from Canada about hazards of eating red licorice reminds me of
a case report I saw once in a radiology journal of a kid, who was about six
or so, who ate four bags of gummi bears over a short period.  The candy
accreted into a large mass (called a bezoar) in his stomach which had to be
removed through an endoscope.  I doubt red licorice is much different from
gummi bears.  If the ferret were to drag off a bag of the stuff and gorge
itself (we all know ferrets would *never* do that, right...*sigh*) it's
possible the licorice could collect into a mass big enough to cause
obstruction and which may be *too* big to dissolve on its own.  So, be a
little careful with those gummy treats.  And it's worth pointing out that
black licorice is potentially dangerous for different reasons.  A chemical
in black licorice messes up the chemical pathway in the body that controls
blood pressure.  At least in humans, binge-eating of black licorice has
causes hypertensive crises.  I have no idea if ferrets would be as
susceptible to this, but it's worth exercising caution with black licorice.
(The red licorice does not have the same chemical that black licorice does.)
 
Pam Grant expressed the need for caution in discussing the transmissibility
of lymphosarcoma so as not to cause a panic.  Good point.  Because I analyze
infectious diseases all the time, it's possible to become detached from the
real life aspects of disease--the fear, worry, even guilt.  I don't want to
panic anyone.  So as not to be alarmist, there does *not* appear to be a
raging epidemic of adult lymphosarcoma.  It's more common than it should be,
but it is by no means the #1 cause of ferret deaths.  Also, as you stated,
ferret owners have had ferrets with lympho housed with other ferrets who
never got the disease.  So, it's not spread like chickenpox where you can be
20 feet away from an infected person and catch it.  Whatever this is, it's
not the Andromeda strain.
 
That said, Dr. Erdman's work shows that healthy ferrets develop lymphoma
after receiving extracts from ferrets with lymphoma.  Her research team at
MIT has identified a retrovirus in lymphoma tissue, and retroviruses are
known to cause these sorts of cancers in other mammals.  So, there is very
solid evidence that *some* adult lymphomas in ferrets could be caused by a
transmissible virus.  Others could be genetic or spontaneous mutations,
although the high rate of lymphoma in ferrets suggests that they can't all
be spontaneous.
 
The big mystery is unraveling how the virus (assuming it's a retrovirus for
the moment) is transmitted.  As an example, consider hepatitis C.  While
Hep-C is not a retrovirus, it is also transmitted by blood.  Throughout the
world, almost all hepatitis C occurs following blood transfusion, organ
transplant, intravenous drug abuse, or--less commonly--through sex.  BUT, in
Asia, as much as half of the people with hepatitis C have none of these risk
factors other than sharing a house with someone who is also infected.  That
transmission pattern doesn't occur outside of Asia and no one knows why Asia
is different in that regard.  That seems to be the sort of mystery that
surrounds lymphosarcoma in ferrets.  There's a higher-than-normal rate and
evidence that a virus could cause it, but, at least right now, it's not clear
how such a virus could be transmitted.  Pam's evidence that cohabitation is
not enough for other ferrets to "catch" lymphoma is wonderful and should
ease the worries of ferret owners in similar situations.  I encourage others
who have had ferrets with lymphoma to post any observations that may prove
or disprove routes by which lymphoma appears to spread among ferrets.
 
Pam also commented about the increased risk of adrenal cancers she's
observed in Marshall Farms ferrets.  Although other people have posted that
non-MF ferrets get adrenal tumors, too, it's possible MF ferrets could have
a higher incidence for a number of reasons.
 
>...there is a genetic issue here that with closed colony breeding is
>magnified by farms with this mutant in them - I have only seen MF ferrets
>and some backyard ferrets with adrenal tumors.
 
Certainly possible, but remember that adrenal tumors in ferrets are mostly
estrogenic cell cancers.  Sex hormones are potent modifiers of reproductive
cancers.  If there's a genetic cause at fault for adrenal cancers then I'd
bet that there's an interaction between the cancer gene and neutering and
perhaps with light cycles as well.  A number of people have noticed a higher
rate of adrenal cancers in females versus males, which also suggests a
hormonal influence.  So, adrenal cancers are likely to be more complicated
than lymphoma.  I'll see if I can call Dr. Rosenthal this week and ask her
about how many adrenal tumors were in MF ferrets.  I'll also ask some of the
vets around here where MF ferrets are less common and I'll ask if they've
seen a change in the age at onset of adrenal disease.  If cancers are being
seen *commonly* at 2.5 years, I agree something is very wrong.
 
Here's another wrinkle: The review of ferret cancers by Beach and Greenwood
(from Leicestershire, England: J Comp Pathol 1993;108:133) reported a high
rate of leiomyomas, which occur mostly in the smooth muscle of the uterus.
I haven't heard many reports of this cancer in North America.  Presumably,
leiomyomas occur primarily in breeding jills.  Could this be a different
genetic predisposition to a different type of cancer?  I also don't know how
old these ferrets were when the cancers were found.  Have any
backyard/hobby/private breeders had these cancers in their jills in North
America?
 
--Jeff Johnston ([log in to unmask])
[Posted in FML issue 1732]