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1996-05-27
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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 -- ADRENAL DISEASE
Last modified: 3 May 96
Version: 1.7.1
------------------------------
Subject: CONTENTS
*** Adrenal disease ***
(1) Adrenal Disease in the Ferret (Dr. Williams)
(2) Adrenal Adenoma or Adenocarcinoma (Midwest Hospital)
(3) Diagnosing adrenal disease (Drs. Weiss and Williams)
(4) Blood tests for adrenal disease
(5) Statistics about adrenal tumors
(6) Options for ferrets with problems in both adrenals
(7) Hair growth after adrenal gland removal
(8) Ferret Medical FAQ copyright and redistribution information
------------------------------
Subject: (1) Adrenal Disease 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.
"My ferret is losing its hair."
While hair loss in the ferret can occur from many causes, I would
like to concentrate on what is the most common and what is becoming
the most commonly talked about reason for serious hair loss --
proliferative lesions of the ferret adrenal gland.
Ferrets with adrenal lesions - including areas of hyperplasia as
well as both benign and malignant neoplasms of the adrenal cortex -
typically all show the same clinical signs regardless of which type of
growth is present. These signs are fairly diagnostic, and in the
majority of cases, are so characteristic that no other diagnostic
tests are required before therapy is instituted.
The signs of adrenal disease in the ferret are well documented
(Fox et al., 1987, Lawrence et al. 1993, Rosenthal et al., 1993,
Lipman et al, 1993) although the cause of these signs is still
somewhat unclear. Adrenal lesions may be seen in animals ranging from
one to seven years of age, with the average being around 3.5 years. In
one study (Rosenthal, 1993), 70% of affected ferrets were female.
Hair loss, or alopecia, is by far the most common clinical sign in
affected ferrets. Hair loss often begins at the tail, and progresses
forward over the trunk, flanks, and abdomen, until hair is only
present on the neck, head, and the extremities. Additionally, in
spayed females, the vulva will often become swollen to the extent that
the owner may erroneously believe that the animal is in estrus. A watery
mucus discharge from the vulva may also be seen in this animal.
(Vulvar swelling in a spayed female on its own is sufficient cause to
warrant abdominal exploratory surgery). Other clinical signs that may
be seen in ferrets with adrenal lesions include increased scratching,
excessive drinking and urination, anemia, weight loss, and in
long-standing cases, difficulty in using the hind legs.
The cause of the hair loss and vulvar swelling is not currently
known. In other species with hyperadrenocorticism, high circulating
levels of adrenal corticosteroids cause the hair follicles to atrophy
and the skin itself to become thin, resulting in hair loss. But since
we know that these ferrets do not have these high levels of cortisone,
this explanation does not suffice for what we see clinically. A
plausible theory has been advanced by specialists at the Animal
Medical Center in New York City. (Rosenthal, 1993). Citing the fact
that 36% of affected ferrets have high blood levels of estrogen, the
believe that early neutering (most ferrets in the U.S. are neutered
before six weeks of age) cause a population of cells in the adrenal
gland which have retained the ability to secrete gonadal hormones to
grow, in essence "filling the void". High levels of estrogen are well
known to also cause hair follicle atrophy, and would also cause vulvar
swelling in females, as is seen in estrus. In fact, Dr. Rosenthal has
demonstrated that serum estrogen levels are indeed higher in ferrets
with adrenal disease.
The treatment for adrenal disease in ferrets primarily involves
removal of the affected adrenal gland. [If money is an object,
Dr. Tom Kawasaki in Woodbridge VA, will probably do it for less than
$300 (and he has done many more than most vets).] In most cases,
adrenalectomy is performed based solely on clinical signs. Routine
pre-surgical blood work should be performed in all animals over 4
years of age, as would be done for any other type of surgical
procedure. Special diagnostic tests which are used in other species
to diagnose adrenal disease are rarely of use in the ferret. Specific
testing for estrogen levels in the ferrets is not commonly available,
even at diagnostic labs, and in most cases is not necessary to confirm
the diagnosis.
In most cases, one gland is noticeably larger than the other and
is removed. For unknown reasons, the left adrenal gland accounts for
the majority of lesions (64%), with the right adrenal gland accounting
for 26%, and 8% of ferrets having disease in both adrenals. Removal
of one adrenal gland is generally well tolerated in ferrets and in
most of these cases, if disease is confined to that gland, clinical
signs will cease (i.e., the hair will grow back and the swollen vulva
will diminish to its previous size). In animals with bilateral disease,
removal of one gland and part of another has been done, but carries a
more significant risk of post-operative complications. (If a vet goes
in on an animal with classic signs of adrenal disease, he shouldn't
come out empty-handed. If you can't tell, then take the left
one. [from another article by Dr. Williams]) Ferrets require at least
a portion of one adrenal gland to live. (Just because both of the
adrenals are enlarged doesn't necessarily mean that both are involved.
I commonly see cysts in the right adrenal, which don't cause any
problem at all, but just make the adrenal larger. ... Just make sure
you get the adrenal looked at by a pathologist.
[from another article by Dr. Williams])
The surgery itself is not excessively difficult. Removal of the
left adrenal is fairly easy and has a low risk of complication. Due
to the position of the right adrenal near several large blood vessels,
it is a more difficult surgery and requires considerably more
expertise on the part of the surgeon. As always, if your veterinarian
has little expertise in performing this surgery, it is wise to ask for
a referral to a more experienced surgeon. In cases in which surgical
excision of the offending adrenal gland is not an option, medical
treatment with certain drugs that kill off a large portion of the
cells of the adrenal cortex may be tried. Unfortunately, this
medication is not specific for estrogen-secreting cells, and affect
all of the other cortical cells as well. For this reason, this form
of treatment should be reserved only for those animals who are poor
surgical candidates.
Unfortunately, not all adrenal surgeries end happily.
Postoperative mortality averages from 10% (Tom Kawasaki, personal
communication) to 12.5% (Rosenthal, 1993). The cause of the
post-surgical mortality is not known; most theories center on the
inability of the other, unaffected adrenal gland to produce enough
cortisol on short notice, i.e., the hyperfunctioning gland has caused
it to atrophy.
On a personal note - while some owners believe that hair l