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Description or definition:
|Demodectic mange is caused by an
external parasite (a mite, a microscopic ectoparasite) that
infects the hair follicles that is also present in low numbers on
healthy animals, including people. Whether or not a pet shows
symptoms of this disease depends primarily on their immune status.
Since there is no easy test to determine immune status, it is
impossible to predict which pets will get this disease, or how
well a pet will heal if it shows symptoms of demodex.
Fortunately, most cases of
Demodectic mites are self-limiting… that is, the animal is able
to arrest the reproduction and growth of the mites and repair the
damage they do. Once eliminated, most dogs do not
acquire another infestation; the dog’s immune defenses are
primed to eliminate any new Demodex mites that happen to find
themselves on the dog. However, there are certain
individual dogs that do not produce the specific immune factors
that will target the mites for destruction. That specific
lack of adequate immune defense against the mites is a hereditary
aspect of the disease that can predispose an infested dog to a
severe, unresponsive case of Demodex. Many veterinarians
believe that all dogs have small numbers of Demodex mites residing
in the skin and that having a few mites is normal and common.
It is when immune related, or nutritional or environmental
stresses impact the dog that visible skin lesions from mite
infestations become noticeable. Seen most commonly in young
dogs, Demodex skin lesions are usually transient, but occasionally
in certain individuals the mites will totally overwhelm the dog's
It is important to note that
the diagnosis of this skin condition, like most skin conditions,
cannot be made just by looking at a pet. Diagnostic tests are
mandatory to arrive at a correct diagnosis and achieve a
satisfactory outcome to therapy. Stating that an animal looks
"mangey" is not the same thing as making a positive
diagnosis of mange. Pets that have Ringworm or Sarcoptic mange can
look like they have demodex.
One of the most
common symptoms of this disease is small patches of hair loss
(alopecia), towards the front of the body initially, with the
ability to affect the whole body. When it is present in adult dogs
it commonly affects the feet.
If a pet has only a
few small patches of alopecia the disease is classified as
localized. If it has spread throughout the body it is classified as
generalized. Most pets that have demodectic mange are young, which
is a big aid in the diagnostic process.
The primary way to
diagnose demodectic mange is to do a skin scraping where the
patches of alopecia occur. The fortunate thing about demodex is
the ease of diagnosis in most dogs (Shar Pei's can be an
exception). In most cases the mites are easy to find under the
microscope, and if your pet is diagnosed as having this disease,
one of our staff members will show them to you. A positive skin
scraping of large numbers of demodex mites, along with alopecia
(remember demodex is naturally found in the skin also), is
verification of demodectic mange and necessitates treatment.
We are fortunate
to have several medications at our disposal to treat demodecosis.
These medications have proven to be highly effective, and have
saved many pets from suffering, and even euthanasia. Sometimes the
most we can hope for is to control the problem, not cure it.
Treatment duration needs to based on skin scrapings, not just the
appearance of the skin. A skin that looks like it is healed can
still harbor demodex mites. This is especially true for adult dogs
with feet lesions.
Unfortunately, due to
the fact that the immune system is paramount in whether or not your
pet gets this disease, no guarantee can be made that these medications
will work. No matter which form of demodex is treated, several
ancillary issues need to be addressed. Your pet needs to be on optimum
nutrition, stay current on vaccines, and be free of internal parasites
(worms). Like any disease process, the psychological needs of your pet
need to be met, which includes plenty of exercise, TLC, and access to
fresh water at all times. Other skin conditions like allergies can
occur simultaneously, and need to be treated also.
1. Localized Treatment
Bathing with an
antibacterial shampoo is the first step in therapy. This loosens up
scales, removes oily discharges, and decreases the secondary
bacterial infection that is usually present.
can be treated with a medication called Goodwinol. It is a creme
that is rubbed into the areas of alopecia once daily. This rubbing
initially causes more hair to fall out, but within 1-3 weeks the
problem usually goes away. If more areas of alopecia appear during
this time they should be treated with Goodwinol and brought to the
attention of one of our doctors during recheck exams.
for localized demodex involves the use of Mitaban mixed into olive
oil. This mixture is applied on the areas of hair loss daily. It is
possible for localized demodex to progress to generalized demodex
even if it is treated. Localized demodex might even resolve without
is treated with a combination of medications and modalities. It is
important to understand that treatment may take 2-3 months to be
effective. The hair is usually clipped to allow the topical
medication easy access to the skin, which makes it substantially
more effective. Secondary pyoderma (skin infection) is usually
present also, so your pet is put on oral antibiotics for several
weeks to months.
The main drug used
to treat generalized demodex is called Mitaban. Mitaban has to be
used precisely by label instructions. Since it is difficult for
people to do this properly in their homes, we treat most pets in our
hospital. Pets are dipped once per week, in between these dips your
pet should not be bathed. We continue dipping until successive skin
scrapings are negative for the mites.
If Mitaban does not
work there are other medications that are used with varying success
to cure the problem. These include oral Ivermectin and Milbemycin
(Interceptor). Side effects like excess salivation, incoordination,
even coma and death are possible, so they must be used judisciously.
They should not be given to Collies, Shelties, Australian shepherds,
or dogs that are positive for heartworm. There can be no guarantee
that they will work, especially in a disease that is so closely
associated with the immune system. Spaying infected females is
Pets that have this
disease should not be bred. Otherwise, it is difficult to predict
just what pets will get this problem.
There are underlying
causes that can weaken the immune system and make a pet more
susceptible to this disease. These include the chronic use of
cortisone, Cushing's disease, heartworm, cancer, and hypothyroidism.
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