Demodex Skin Condition
Written by Dr. Melissa Rotella, DVM
Lucy is a one year old spayed female who was came to Route 516 Animal Hospital for localized areas of hair loss and some mild crusting of the skin around some lesions. The lesions were approximately an inch in size and the skin underneath appeared healthy. Lucy’s owners did not notice her to be scratching at all. Remaining physical exam was unremarkable.
Demodicosis is a skin condition when there is an overpopulation of the mite Demodex canis (in dogs) or Demodex cati/Demodex gatoi (in cats). This can lead to furunculosis (infection of the hair follicle), hair loss and secondary bacterial infections. This mite is a normal inhabitant, in small numbers, of hair follicles and sebaceous glands on all dogs. Demodectic overgrowth is thought to be associated with a number of factors including genetics, stress, poor nutrition, endocrine diseases (including diabetes, Hypothyroidism, and Cushings) and immunosuppressive drug therapy. Demodex is diagnosed by a deep skin scrape, which is then looked at under a microscope. The disease is not considered to be contagious to other animals (except newborn cats and dogs) or people.
Localized Demodex on the face
There are two forms of the disease: localized and generalized.
Localized lesions tend to occur in younger, otherwise healthy animals. These animals range from having 1-5 areas of hair loss (alopecia). Occasionally, localized lesions will spontaneously recover without treatment. Topical treatments, including benozyl peroxide shampoos, help flush out the hair follicles. Oral antibiotics are often prescribed to treat any secondary bacterial infections. Prognosis is usually good with most cases resolving in 4-8 weeks. However, some cases can progress to the generalized form.
Generalized form of demodex tends to be more frustrating to owners. Generalized demodex usually starts as localized lesions that spread. Lesions can be anywhere on the body and consist of generalized areas of hair loss, crusting, red, inflamed skin. For all adult onset cases of demodex, underlying diseases should be ruled out. Your veterinarian may want to start with blood work. Treatment includes medicated baths, oral antibiotics, and medications directed at killing the mites. Prognosis is fair to good. Relapses may reoccur.