DEMODECTIC MANGE IN DOGS
Mange is a parasitic skin disease
caused by microscopic mites. Two different mange mites cause skin disease in dogs. One
lives just under the surface of the skin ,while the other resides in the hair follicles.
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.
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 immune systems.
Yes. Since the mite is found on
virtually all dogs, exposure of a normal dog to one with demodectic mange is not
dangerous.
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 due to a genetic defect, affected dogs should not be bred. Also,
parents of the affected dog should not be bred again.
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.
The localized form is usually
treated with topical medication. The generalized form requires shampoo therapy and a
special dip or oral medication. Shampooing with special cleansing shampoos helps to flush
out the hair follicles prior to dipping.
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 mange."
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.
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 re-treatment 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 commonly used for demodectic
mange contains the insecticide amitraz. Its use requires some caution because it is a
strong insecticide that can have some side effects to your dog and to you if it is not
used properly. Your dog may experience vomiting and sedation for 24-36 hours following
each application. If so, those problems will usually be self-limiting. If this occurs, the
dip should be diluted with 25% more water the next time it is used. Since each dipping
results in the development of tolerance to the dip, your dog is less likely to have side
effects with each subsequent treatment. Your dog should be dipped 3 times at 14 day
intervals, then examined 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.