Veterinary Help

Demodex canis mites are a normal inhabitant of canine skin. They live in the hair follicles and sebaceous glands of the skin. These mites are not contagious and in most cases cause no clinical signs. Skin problems develop when the mites multiply and become overwhelming to the immune system leading to hair loss and in some cases secondary bacterial infections. Diagnosis is confirmed with a skin scraping where a scalpel blade is used to scrape the surface of the skin. This sample is then viewed under the microscope to look for the mites.

The two types of demodex presentations are localized and generalized. Localized demodex lesions are typically mild with several patches of hair loss on the body. Sometimes these areas have some crust or scale present. Localized demodex will often resolve on its own or with topical treatment over a period of several months. This is the most common form in young dogs. It is suspected that puppies are susceptible to this form when their young immune systems are not fully functional or stressed from other issues in their environment.

Generalized demodex is more severe with lesions covering a much larger area of the body. This can be found in puppies who’s localized demodex has progressed or in adult dogs. Treatment for generalized demodex involves topical shampoos with benzoyl peroxide to flush the hair follicles and medicated dips every 2 weeks until multiple skin scrapes do not show any mites. Treatment typically takes at least 3 months. These dogs are often also placed on oral antibiotics to address secondary bacterial infections. In some refractory cases oral medications to address mites are needed. Adult onset demodex can be difficult to cure. It is necessary to evaluate the dog for possible underlying systemic disease that could be suppressing the immune system but in some cases no underlying cause is found. The mechanism for the immune system being susceptible to the mites is unknown. In some adult cases, the mites are controlled but infection is not completely cured.