Mange is a parasitic skin disease caused by microscopic mites. Two different
mange mites cause skin disease in dogs. One (the demodectic mite) resides in
the hair follicles, while the other (the sarcoptic mite) lives just under the
surface of the skin. Although both mites share some similar characteristics,
there are also important differences. It is important not to confuse the two
types of mange because they have different causes, treatments, and prognoses.
What causes demodectic mange?
Demodectic mange, sometimes just called "demodex", is the most common form
of mange in dogs. It is caused by the demodectic mange mite, a parasite which
lives in the hair follicles of affected dogs. Under the microscope, this mite
appears shaped like an alligator with 8 legs. All dogs (and many humans) have
a few of these mites on their skin. As long as the body's immune system is functioning,
these mites cause no harm.
Demodectic mange most often occurs when a dog has an immature immune system,
allowing the mites to grow rapidly. Therefore, this disease occurs primarily
in dogs less than 12-18 months of age. In most cases, as a dog matures, the
immune system also matures. Adult dogs which have the disease usually have defective
Does this mean that demodectic mange is not contagious?
Yes. Since the mite is found on virtually all dogs, exposure of a normal dog
to one with demodectic mange is not dangerous.
Why doesn't the immune system mature correctly in some dogs?
Development of the immune system is under genetic control. Thus, an affected
dog usually comes from a litter containing other affected puppies. Owners of
litter mates should be put on the alert to watch for it. Because the disease
is often due to a genetic defect, affected dogs should not be bred. Also, parents
of the affected dog should not be bred again.
Sometimes the disease can occur as a result of treatment of the dog with immunosuppressant
drugs including corticosteroids.
What does demodectic mange do to the dog?
Surprisingly, a dog with demodectic mange does not itch severely, even though
it loses hair in patches. Areas of bare skin will be seen. The hair loss usually
begins on the face, especially around the eyes. When there are only a few patches
of hair loss, it is termed localized demodectic mange. If the disease spreads
to many areas of the skin, it becomes generalized demodectic mange.
How is demodectic mange treated?
The localized form is usually treated with topical medication. The generalized
form requires special shampoo and dips and sometimes medication either by injection
or by mouth. Shampooing with special cleansing shampoos helps to flush out the
hair follicles prior to dipping or rinsing techniques. Dipping is described
For dogs with generalized demodectic mange, secondary skin infections may
represent a complicating factor requiring antibiotic therapy. Dogs with skin
infections have very red, inflamed skin. This is the source of the term "red
What is the prognosis for my dog?
Treatment of the localized form is generally successful. Treatment of the
generalized form is also usually successful. However, if the immune system is
defective, neither the mites nor the infection may respond to treatment.
Following successful treatment, is it likely to recur?
Because the immune system does not mature until 12-18 months of age, a dog
with demodectic mange may have relapses until that age. It is important for
retreatment to begin promptly to minimize the possibility of developing uncontrollable
problems. Demodectic mange may also occur in very old dogs because function
of the immune system often declines with age. Dogs who have immune suppression
due to illness or medication are also candidates for demodectic mange.
The dip or shampoo commonly used for demodectic mange contains the insecticide
amitraz. The manufacturer's instructions must be carefully followed. The product
can have side effects both to your dog and yourself if not properly used. If
in doubt consult your veterinary surgeon. After the treatment it will be necessary
to examine your dog for the presence of live mites or mite eggs. Further treatment
will be determined by the results. If you do the dipping yourself, be sure to
wear rubber gloves to prevent getting it on your hands.
Sometimes treatment will involve the use of products that are not licensed
for specific use in the dog. Your veterinary surgeon will discuss these with
you and the implications involved. It is sometimes necessary to use these products
since the risk surrounding their use is less than the risk of untreated demodectic
What causes sarcoptic mange?
Sarcoptic mange is caused by a mite that burrows just beneath the surface
of the skin. It may also crawl around on the skin surface. The mite feeds on
material in and on the skin.
What does it do to the dog?
The presence of the sarcoptic mite causes severe itching. The dog will chew
and scratch its skin constantly. This leads to the loss of large amounts of
hair, especially on the legs and belly. Eventually, the skin will become thickened
and will darken due to pigmentation.
Is it contagious?
Sarcoptic mange is highly contagious to other dogs; it is also contagious
to humans, and is known as scabies. The dog's bedding should be discarded or
if this is not possible, it should be regularly washed in hot water with bleach
or one of the specific anti-scabies shampoos. Although the mites are not able
to complete their life cycle on humans, they will cause quite a bit of itching
before they finally die.
How is sarcoptic mange diagnosed?
Diagnosis is made by a skin scraping that is examined under the microscope.
However if only a small number of mites are present on the dog all skin scrapings
may be negative. A presumptive diagnosis is then made because the signs are
so suspicious and treatment is commenced without the confirmation of a skin
scraping. Age is not a significant factor in sarcoptic mange. Although most
common in puppies, it affects dogs of all ages.
How is it treated?
There are several insecticides which are effective against this mite. Various
dips and shampoos are available. Bathing should occur weekly for at least 4
weeks, at which time your dog should be reexamined to determine if further treatment
is needed. Should bathing not prove effective injections with a preparation
called ivermectin may be successful. Your veterinary surgeon will discuss the
implications prior to its use.
to Canine Information Index