Ferret
Adrenal Disease
An
Overview of Ferret Adrenal Disease
WHAT IS ADRENAL DISEASE AND WHY DO
I NEED TO KNOW ABOUT IT?
The adrenal glands are located in the abdomen of the ferret.
There is one on each side of the abdomen.
The adrenal gland’s normal function in the body is to
produce hormones that help the body cope with stress (cortisol)
and also to produce other hormones that help regulate functions of
the kidneys, such as maintaining proper electrolyte balance and
the appropriate concentration of the urine.
These glands have the potential to produce sex hormones
such as estrogen, progesterone, androstrenedione and testosterone.
What we are seeing these days is that more and more ferrets
have adrenal glands that have been “turned on” and are
producing excessive amounts of these hormones.
These excessive amounts of hormone cause a wide variety of
clinical signs in your pet ferret.
The adrenal glands themselves start out as just
overproducing hormone, but they can proceed to a precancerous
state, a benign cancerous state (adenoma) and then often to a
malignant cancerous state (carcinoma).
You need to understand this disease process because it has
become so common that approximately 80% of all pet ferrets are
succumbing to this disease.
CLINICAL SIGNS
Alopecia (hair loss) - this often starts with the tail and
then progresses up the rear end and back.
It can be seen in other presentations as well.
I had one patient that just had a bald spot as bit as a
fifty-cent piece on the top of her head and that was it – she
had one of the largest tumors I have ever seen.
Pruritis – severe itching
Lethargy –
less energy than normal.
Muscle
atrophy – especially over the back and rump.
Enlarged
vulva
Male aggressive behavior – this can be seen in either
male or female ferrets.
Stranguria
(straining to urinate)—This is seen mainly in male ferrets.
It is due to the prostate becoming enlarged secondary to
excessive testosterone secreted by the adrenal gland(s).
Polyuria-
excessive urination
Polydipsia-excessive
water consumption
Vomiting-This
is often secondary to excessive hair consumption if they are
losing hair and grooming themselves.
Possible
Causes
Genetics: Our pet
ferrets are called Mustela putorius furo.
This subspecies of the original ferret never existed in
the wild. They were
derived from M. putorius (European polecat) with possibly
some M. eversmanni (Siberian polecat).
Due to overzealous breeding programs, there is not much
genetic diversity among pet ferrets in the
United States
. It is possible that
this predisposition to this form of cancer is inherently genetic.
There are some current studies being considered to
determine the cause of this disease.
One is taking a look at the human model of multiple
endocrine neoplasia (cancer).
In humans this syndrome is caused by a tumor suppressor
gene that gets turned off.
Prepubescent spaying and neutering:
Dr. Nico Schoemaker in the
Netherlands
is currently studying how this affects onset of adrenal disease.
When an animal is neutered, the negative feedback from
estrogen and testosterone on the production of GnRh (gonadotropin
releasing hormone) by the hypothalamus (an area in the brain)
doesn’t exist anymore. This
results in a continuous pulsitile production of GnRH.
GnRH stimulates the production of LH (leutenizing hormone)
and FSH (follicle stimulating hormone).
There are receptors on the adrenal glands for both LH and
FSH. The current
hypothesis is that the LH and FSH continuously stimulate the
adrenal gland. This
could be what is causing the hyperplasia formation and tumor.
Treatment Options
Surgery
Currently the one “tried and true” method for dealing with
adrenal disease is to surgically excise the affected gland(s).
It is not uncommon for both glands to be affected.
Note: Remember the adrenal glands have a very important
NORMAL
function producing cortisol, regulating electrolytes, and urine
concentration. If both
glands are taken out, your ferret may need to be on a supplement
to replace those hormones for the rest of his or her life.
This supplement can be provided in a daily liquid.
Medical
The most popular alternative to surgery is a medication called
Lupron®. This drug
acts by stopping the pulsitile secretion of GnRH.
The end effect is an inhibition of the production of FSH
and LH. There are two
different protocols for this drug.
One involves a monthly depot injection; the other involves
a depot injection once every 4 months (two different kinds of
Lupron). The cost
works out to be roughly the same.
The injections do need to be repeated for the rest of the
ferret’s life. Chicago Exotics carries just the one month
depot.
Also available through Chicago
Exotics is the Suprelorin 4.7mg implant. This implant was
originally made for reproduction control in dogs, cats, and
horses. It has been found to work in a similar way to Lupron
in ferrets. The best part is that it lasts for a whole
year. I do not recommend using it in those ferrets with
existing prostate enlargement, however. It can cause
transient enlargement of the prostate which could be fatal for
those ferrets who already have some enlargement of the prostate.
Arimidex works by inhibiting the enzyme that converts
androstenedione that is produced by the adrenal glands to
estrogen. This drug is
potentially useful if the ferret’s adrenal tumor is
over-secreting androstenedione that is being converted to
estrogen. Both males
and females can have excessive estrogen production secondary to
adrenal disease. An
assay of the ferret’s hormone levels is necessary to determine
if this alternative therapy might be helpful for your ferret.
We do not recommend this therapy.
One other alternative supplement that has been seen clinically to
help males that have stranguria secondary to an enlarged prostate
is Saw Palmetto. I
have had several clients report back to me with good results with
this herbal remedy. Keep
in mind though- this is not a cure.
It is just palliative treatment to keep a ferret
comfortable until arrangements can be made for other treatment.
The form I recommend is the alcohol-free elixir at a dose
of 3 drops orally twice daily.
It is critical that a male ferret on this supplement be
observed carefully for the straining to urinate getting worse or a
complete lack of being able to urinate. More commonly
prescribed for prostate enlargement is the drug Flutamide. I
have great success with this drug in controlling prostate
growth.
Preventing Adrenal Disease By Exams Every
January
Recent research indicates that there are annual treatments
that can significantly reduce the risk of your ferret contracting
this serious disease. We strongly recommend an
annual examination every January for all ferrets where we can
administer the prophylactic treatments and make sure your ferret
is in tip top shape!
References
Johnson-Delaney C: Ferret adrenal disease:
Alternatives to surgery.
Exotic DVM 1(4):19-22, 1999.
Johnson-Delaney C: personal communications.
Schoemaker N: New developments in research on
hyperadrenocorticism in ferrets.
Exotic DVM 2(3):81-83, 2000.
Hillyer EV, Quesenberry KE: Ferrets, Rabbits and Rodents-
Clinical Medicine and Surgery.
Philadelphia, WB Saunders Co, 1997.
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