As a group, autoimmune diseases of the skin
are uncommon to rare in frequency. Diagnosis is often difficult, especially for
the general practitioner who may see one or two cases during a career. Skin
biopsy and immunofluorescent staining are generally required to diagnose one of
these diseases, and the prognosis for recovery may vary. Our old friends the
corticosteroids are the primary mode of therapy.
"Discoid lupus erythematosis" is
thought to be a benign form of systemic lupus (to be discussed next month) and
is an autoimmune dermatitis of the face. It is most common in Collies and
Shelties; more than 60 percent of affected dogs are female. The lesion is often
described as a "butterfly pattern" over the bridge of the nose and
must be differentiated from nasal solar dermatitis and pemphigus erythematosis.
As in other autoimmune diseases previously
discussed, the primary goal of therapy is to suppress the body's immune
response with large doses of systemic glucorticoids. More potent drugs like
Cytoxan or Imuran are used if steroids fail. Gold therapy has been advocated
for the pemphigus group or pemphigoid. In cases where nasal depigmentation has
occurred, tattooing the affected area helps prevent the sunburn and squamous
cell carcinoma that may follow. The prognosis for discoid lupus is usually
good, but it is variable in the other diseases. Many dogs with VKH are
euthanized due to blindness. Breeding affected dogs is not recommended.
Currently, little information exists on the heritability of autoimmune skin
diseases.
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