Demodicosis or red mange

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Demodicosis or red mange, is a common disease caused by Demodex mites. Demodicosis is caused when the immune, or protective, systems in dogs allows mites to proliferate unchecked. These mites are part of the normal flora of the skin and are present in small numbers. For this reason this disease is not contagious.

It is not understood why some dogs develop demodicosis and others do not.

There are two forms of this disease: localized and generalized.

Localized
The localized form usually occurs in younger dogs (less than one year of age). Affected dogs are usually healthy with breed or sex not being a predilection. Some believe the localized form can be a result of a temporary illness or stressful event however that has not be totally proven yet.

The first sign might be thinning hair, usually around eyelids, lips, mouth or front legs. These bear spots may appear as a moth-eaten section. It's common for 90% of dogs to recover spontaneously with 10% becoming generalized.

Generalized
Generalized demodicosis can start out as a localized case. It usually is categorized according to the age of the dog during the initial onset. Usually classified as juvenile or adult, the main distinction is the result of differences in predisposing factors and prognosis.

Juvenile
With juvenile demodicosis most cases will "self cure" as their immune system matures. This usually happens around 8 months and 3 years

Adult
Adult demodcosis occurs as a result of another illness or immunosuppressive therapy. Conditions associated with adult demodicosis include, but not always cancer, endocrine disease, metabolic disease or steroid therapy.

Signs to Watch For
Bold patches appears on the head, legs, and trunk. This areas usually will grow in size resulting in crusty sores.

Figure 1

Figure 2

Figure 1 is a close up of Zoey's back end. This spot is about the size of a dime.
Figure 2 is a shot of Zoey's left front paw. Again, this spot is about the size of a dime.

Treatment

Localized
Initially you may be asked to just monitor your dog. If things do not improve you may need to bathe your dog using an antibacterial shampoo and apply a medicated lotion to the affected areas.

Generalized
Treatment is always necessary when the disease is generalized. This includes the treatment of secondary bacterial infections and eradication of the mites. The eradication process can be accomplished by using an amitraz based dip.

Although not technically contagious, it is highly recommended that dogs with demodicosis not be breed. Vets will usually suggest that an infected dog be spayed or neutered.

Figure 3

Figure 3 shows what one of these mites looks like under a microscope.