Demodectic Mange

The term “mange” is used to describe skin disease caused by a variety of microscopic mites. This article will briefly describe the two most common mite infestations of dogs and their treatment.

Demodex canis is the scientific name for the mite that causes “demodectic mange”. This follicular mite lives in the hair follicle where it occupies the space between the hair shaft and the lining of the hair follicle.

It is believed to feed on fluids present in the hair follicle. It causes inflammation in the hair follicle. This inflammation damages the hair follicle and the surrounding skin causing the hair to fall out.

As the infestation progresses, secondary bacterial infection occurs which results in formation of pus and drainage from the skin surface. It is believed that all puppies acquire a small number of mites during nursing and dogs normally have a small number of mites in their skin.

The immune system normally keeps the number of mites in check and most dogs never develop disease from the mite. However if the immune system is weakened by disease or medications that are immunosuppressive, the mites may multiply and cause disease.

It is believed that susceptibility to mange can also be inherited. This is the reason some veterinarians do not recommend breeding dogs that have ever gotten demodectic mange.

The most common finding in dogs with this type of mange is hair loss that starts on the face and/or legs. This type of mange does not cause itchiness unless a secondary bacterial infection occurs.

This type of mange is not considered to be contagious to other dogs and isolation from unaffected dogs is not believed to be necessary. This type of mange is not contagious to people.

Diagnosis is by multiple skin scrapings and examination of the material with a microscope. The only approved treatment is MitabanTM (amitraz) a dip that is applied to the skin. For some difficult cases 1% ivermectin, used to treat parasites in cattle and horses, has been used.

This drug is not approved for treatment of demodicosis in dogs and has significant possibly fatal side effects if used improperly. Advice from a veterinarian familiar with your dog is needed.