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Please note: I am not a ferret expert, and I did not write, nor did I
independently verify, all the information in this file. I have done
my best to include only accurate and useful information, but I cannot
guarantee that what is contained in this file, whether written by me
or by one of the contributors, is correct, or even that following the
advice herein won't be harmful to you or your ferret in some way. For
advice from an expert, you may wish to consult one of several books
available, or, especially in the case of a suspected medical problem,
a veterinarian who is familiar with the treatment of ferrets.
FERRET MEDICAL FAQ -- INSULINOMA
Last modified: 16 Jan 96
Version: 1.4
------------------------------
Subject: CONTENTS
*** Insulinomas, or islet cell tumors ***
(1) Islet Cell Tumor in the Ferret (Dr. Williams)
(2) Insulinoma (Dr. Brown)
(3) Ferret Medical FAQ copyright and redistribution information
------------------------------
Subject: (1) Islet Cell Tumor in the Ferret (Dr. Williams)
Written by Dr. Bruce Williams, DVM:
The following article may be reprinted by anyone desiring to
disseminate this information in a newsletter or non-commercial
publication. This material may not be altered or changed in any way.
Under Title 17 of the U.S. Code, Section 105, copyright protection is
not available for any work of the United States Government.
Islet cell tumors, also known as insulinomas, are the most
common neoplasm in the ferret, based on the frequency of surgical and
autopsy submissions at the Armed Forces Institute of Pathology. Over
a period of two and a half years, this neoplasm alone has accounted
for almost 15% of all ferret submissions.
Islet cell tumors derive their name from their cell of origin.
These neoplasms arise in the "islets of Langerhans" - a group of
special cells in the pancreas which produce insulin (also giving rise
to the term insulinoma). Insulin is a hormone which allows most of
the cells in the body to utilize the glucose in the blood. The excess
levels of insulin produced by these tumors drive the glucose in the
blood into the cells of the body, causing a dangerously low blood
glucose level, known as hypoglycemia. (In diabetes, the opposite is
true - low levels of insulin production render the animal's cells
unable to use glucose, and dangerous hyperglycemia results).
Not all islet cell tumors appear to be functional, however.
Islet cell tumors are often found as incidental findings at autopsy of
animals dying of unrelated causes. Finally, a small percentage of
animals fail to show characteristic signs of hypoglycemia, or show
signs that are so subtle that they are not noticed by the owner and
picked up on routine blood screening for other conditions.
Hypoglycemic ferrets may exhibit a wide range of clinical
signs. Weight loss appears to be a common finding in affected
animals, and is occasionally the only sign. This is an excellent
reason why you should periodically weigh your pet as part of a good
preventive health program. Signs that are more diagnostic of islet
cell tumors are episodic depression and lethargy, which in some
animals manifests as stupor (apparent loss of touch with its
surroundings), salivation, difficulty in using the hind legs,
vocalization, and in cases of severe hypoglycemia, seizures.
Diagnosis of islet cell tumors is fairly simple and consists
primarily of measuring the blood glucose levels in the ferret, which
your vet can do if you suspected this problem. (Some vets additionally
measure insulin levels, but in most cases, this is unnecessary and
wastes valuable time.) Animals with blood glucose levels less than 60
mg/dl should be strongly suspect of having one or more of these
tumors. Exploratory surgery in hypoglycemic but otherwise healthy
ferrets should be scheduled at the earliest possible time.
In animals where surgery is not an option, or until such a
time as surgery is possible, medical management may be attempted by
using a combination of prednisone (which raises blood glucose levels
by mobilizing carbohydrate stores) and diazoxide (Proglycem) an
antihypertensive drug which appears to decrease islet cell secretion
of insulin. It is important to realize that this is only a temporary
measure and rarely is effective in controlling the animal's
hypoglycemia for a long period..
It is also important to note that in a large number of cases
(5/6 in one study), ferrets that had islet cell tumors surgically
removed developed a second or more tumors at a later
date. (Additionally, make sure that your veterinarian, if surgery is
performed, takes a moment to check the adrenal glands for those
extremely common proliferative lesions we so often see in ferrets.)
If you have a several ferrets, it is extremely likely that one
of them, sometime during its life, will develop an islet cell tumor;
it's the "nature of the beast". Just watch them closely for the
clinical signs that I have described, and have your vet check them if
you have even the slightest indication of a problem.
Happy ferreting!!!
Bruce Williams, DVM
williamb@email.afip.osd.mil
1. Marini, RP et al. Functional islet cell tumor in six ferrets.
JAVMA 202(3) 430-432, 1993.
2. Kawasaki, TA Personal communication.
In a different article, Dr. Williams cautions:
The largest number of insulinomas that I have ever seen is four.
Ferrets get an age-related finding which is also seen in older
cats known as pancreatic acinar hyperplasia. This is a
non-neoplastic proliferation of small nodules in the pancreas,
which are very normal. The problem is that while this nodular
change is perfectly normal and doesn't hurt anything, many vets
interpret it as a proliferation of islet cell tumors, and start
taking them out. Now the ferret pancreas is fairly forgiving for
surgery, but when you take out this many nodules, you stand a good
chance of causing a rip-roaring pancreatitis.
------------------------------
Subject: (2) Insulinoma (Dr. Brown)
Written by Dr. Susan Brown, DVM:
Insulinoma [is] a cancer of the pancreatic beta (insulin producing)
cells. It is extremely common in ferrets of her age and the signs are
right on. The tumors are very tiny, but produce an excessive amount
of insulin which has the effect of driving the blood sugar (glucose)
into the bodies cells at too rapid of a rate.
Some of the common signs that you might see are: Stopping and staring
blankly into space (acting out of it) for a few minutes, then snapping
out of it, or foaming and pawing at the mouth as if something is in it
(caused by a feeling of nausea....this can also be caused by stomach
problems like foreign bodies and ulcers, but those cases are usually
not eating well on top of things...insulinoma generally does not
interfere with eating habits), or just being weak in the hind end as
was described in this case and then coming out of it, or going into a
comatose state or even seizures. The more advanced the disease is the
more frequent the signs and the more severe. As long as the body is
able to it will keep counteracting the low glucose by producing more
through the liver primarily...but eventually it will be unable to do
so and the ferret may go into a permanent coma and pass away.
The disease is easily diagnosed with a FASTING blood sugar test. You
need to withhold food for 4 to NO MORE THAN 6 hours prior to the test.
This will show if the sugar is too low. Normal fasting sugar should
be between 90-120. Your vet can also run an insulin level at the same
time, but that is usually (in my experience) unnecessary.
Treatment may be a combination of surgery and medical therapy. The
worst thing that you can do is give a lot of sugary snacks and treats.
All this does is aggravate the condition by stimulating insulin
production each time you give them a sugary snack which then results
in insulin overload and hypoglycemia later. Use