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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 -- SKIN TUMORS
Last modified: 16 Mar 95
Version: 1.2
------------------------------
Subject: CONTENTS
*** Skin and mast cell tumors ***
(1) Skin Tumors (Midwest Hospital)
(2) Skin Tumors in the Ferret (Dr. Williams)
(3) Mast Cell Tumors (Dr. Brown)
(4) Ferret Medical FAQ copyright and redistribution information
------------------------------
Subject: (1) Skin Tumors (Midwest Hospital)
from Ferret Senior Citizens and their Special Needs
Midwest Bird and Exotic Animal Hospital
Skin tumors
Most skin tumors in older ferrets should be removed because they
are generally irritating to the pet and some may become malignant.
The most common type is the mast cell tumor which appears as a round,
raised, button-like lump. It is usually quite itchy and there may be
a bloody crust on top due to the pet scratching the area. These
tumors produce histamines, which are very irritating and can even lead
to hair loss. The other most common tumor seen on the skin is the
sebaceous gland adenoma or adenocarcinoma. These tumors have the
appearance of an irregular, "wart-like" growth and bleed easily.
These tumors may become malignant easily, so it is best to remove
them.
------------------------------
Subject: (2) Skin Tumors in the Ferret (Dr. Williams)
Dr. Bruce Williams, DVM, writes:
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.
SKIN TUMORS IN THE FERRET
In previous articles, we have discussed the two most common
neoplasms of the ferret, islet cell tumors [insulinomas] and adrenal
tumors. Now lets look at the third most common group, the various
tumors of the skin.
Ferret skin tumors are very common, and increase in frequency
with age. Let's get one point straight right away - the VAST majority
of skin tumors in ferrets are benign. Malignant tumors, or tumors
that will grow rapidly, invade and destroy adjacent tissues, and
metastasize to distant sites where they can continue their destructive
processes, are very rare in ferret skin.
The most common skin tumor in ferrets, both at the AFIP and in a
recent retrospective study by Parker et al (Veterinary Pathology, Jan
1994) is a tumor composed of undifferentiated epithelial cells, known
as a basal cell tumor. This cell has the ability to differentiate
into several different components of normal skin, including glands (at
which time it is called a sebaceous epithelioma), hair follicles, or
just simple sheets of epidermal cells. Most tumors show at least two,
if not more of these structures, a feature which has caused some
pathologists in the past to consider them malignant; however, now we
know that this is not the case.
Basal tumors appear as small warty growths that may have a
depressed centers. They grow slowly, and are freely movable, as they
do not involve structures underneath the skin. They are easily
removed, and do not recur (unless the surgeon fails to remove all of
the tumor at the time of surgery. They are most common on ferrets
over the age of four. While they should be removed, as they may
become traumatized and infected, owners should be reassured by the
good outlook (or prognosis) with which they are associated.
The second most common skin tumor in the ferret is the mast cell
tumor. Mast cells are a population of cells in the skin which are
closely associated with blood cells. Normally, they mediate allergic
reactions, liberating certain chemicals which cause vascular dilation,
causing the redness associated with hives and other allergic
conditions. Mast cell tumors, although they are associated with a
high rate of malignancy in the dog and cat, are generally benign in
the ferret. There are no reports of malignant mast cell tumors in the
ferret medical literature.
Mast cell tumors usually appear as flat, often hairless, small
plaques on the ferret's body. They are also freely movable and do not
involve underlying structures. They may be somewhat crusty, as
ferrets will often chew or scratch at these sites, as some of these
tumors itch. In rare cases, animals may have multiple mast cell
tumors at once. Excision of these tumors is considered curative.
Another very common skin tumor is not actually a tumor, but a
cyst, or a dilated sweat gland, known as an apocrine cyst. Apocrine
glands may also form benign, or rarely, malignant tumors, but by far,
the most common lesion associated with these glands is a simple cyst.
These cysts appear as small, round, hard "bubbles" just underneath the
skin surface. If squeezed, they may rupture and spill their contents
into the surrounding tissue. This causes a marked inflammatory
response and gives the appearance of rapid growth. Once again,
surgical excision is curative. These cysts may occur anywhere on the
body, but the prepuce, or penile sheath of males, is the most common
site, in my experience. There is a higher concentration of apocrine
glands here that at anywhere else in the ferrets skin, so, logically,
there would be an increased incidence of cysts at this site as well.
Well, then, where are the bad tumors? There are actually very
few of them. In the last three years, I have seen less than five.
All of these skin tumors arose from those apocrine sweat glands that
we just talked about. This malignant tumor, or carcinoma, generally
grows rapidly, and in contrast to most other skin tumors, often
becomes firmly anchored to underlying muscle. It rapidly invades and
destroys adjacent skin and may metastasize to the local lymph nodes,
or in the case of two the five cases, the lungs, resulting in the
death of the animal. While excision may be curative if caught early,
masses of this type that have reached any size are associated with a
much poorer outlook.
Of course, malignant tumors arising internally, such as
lymphosarcoma, may metastasize to the skin, as they may metastasize to
any other site. I have not discussed these neoplasms, as they are
generally uncommon and do not originate in the skin.
One final note - while excision of the vast majority of the
tumors that we have discussed is curative, there is nothing to prevent
a second basal cell tumor, or mast cell tumor, from arising in another
site at a later date. This does not worsen the prognosis for that
animal, just requires a second trip to the vet for removal. And
remember, always have your vet get those tumors analyzed - while most
skin tumors are benign, you and your pet will sleep better knowing
about that tumor for sure.
Bruce Williams, DVM
williamb@email.afip.osd.mil
References:
1. Parker, GA et al. Histopathogic features and post-surgical
sequelae of 57 cutaneous neoplasms in ferrets (Mustela putorius furo).
Veterinary Pathology, 30(6) 499-504, 1993.
2. Fox, JL. Biology and Diseases of the Ferret. Lea and Febiger,
Philadelphia, 1988.
------------------------------
Subject: (3) Mast Cell Tumors (Dr. Brown)
The following article is from the Jan/Feb 1994 issue of "Off The Paw", the
Official Newsletter of the Greater Chicago Ferret Association. [IFNS]
MAST CELL TUMORS
by Dr. Susan A. Brown, DVM - Midwes