Demodectic mange (a.k.a. demodex or red mange), is the most common form of mange that lives in the hair follicles of affected dogs. Under the microscope, this mite appears shaped like a cigar with eight 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 properly, these mites cause no harm.
Click here to see a live demodectic mite under the microscope
Surprisingly, a dog with demodectic mange does not itch severely, but loses hair in patches. The hair loss usually begins on the face, especially around the eyes. Dogs with skin infections often have very red, inflamed skin. This is the source of the term “red mange.”
Demodex most often occurs when a dog has an immature immune system, allowing the skin mites to grow rapidly. As a result, this disease occurs primarily in dogs less than twelve to eighteen months of age. In most cases, as a dog matures, the immune system also matures. Adult dogs that have the disease usually have defective immune systems.
Demodex is not contagious to other animals or humans. Treatment of demodectic mange is generally successful. However, if the immune system is defective, neither the mites nor the infection may respond to treatment.