- Type Disease
Demodicosis/ Demodectic mange
Demodex canis is a mite that is present in small numbers in the skin of most healthy dogs. Nursing puppies acquire the mite from their mothers during the first few days of life, and in most dogs there will never be any associated problems.\nIn some dogs however, the normal balance is disrupted due to an immune defect. The mites multiply by the thousands in the hair follicles causing inflammation, in a condition called demodicosis. Demodicosis may be localized - that is, confined to 1 or more small discrete scaly reddened areas of hair loss, most commonly on the face or front legs. This is usually seen in pups of 3 to 6 months of age, and most cases resolve spontaneously. Alternately, generalized demodicosis may develop, at anywhere from 3 to 12 months of age. This is a severe skin condition.\nThe defect in the cell-mediated immune system which allows the development of generalized demodicosis is believed to be inherited.
- How Transferred
- What to Look for
It is important to note that demodicosis is not infectious, to other pets or to people. The mite is present in small numbers in the skin of healthy dogs, but the condition of demodicosis only develops in some animals, who are believed to have a defect in their immune system.\nDemodicosis may be localized - a mild disorder confined to 1 or more small scaly reddened areas of hair loss, most commonly on the face or front legs. This is usually seen in pups of 3 to 6 months of age, and most cases resolve spontaneously.\nGeneralized demodicosis on the other hand can be one of the most severe skin diseases in dogs. It starts out with local lesions that instead of disappearing, get worse and spread, generally on the head, legs and body. Secondary infections of the hair follicles occur, and large scaly crusted patches form which may eventually cover most of the dog. The deep skin infections can be complicated by resistant bacteria.\nSome dogs only develop demodicosis on the feet (demodectic pododermatitis). These lesions commonly become infected, are painful, and can be quite difficult to treat successfully.
Your veterinarian will do a simple procedure called a skin scraping to find the mites on your dog's skin. In the shar pei, because of the thick skin, a skin biopsy is often needed to make the diagnosis. This is a simple procedure done with local anesthetic, in which your veterinarian removes a small sample of your dog's skin for examination by a veterinary pathologist.
Localized demodicosis: This is a mild disease that usually heals on its on within a few weeks, with or without treatment. Your veterinarian may suggest a mild parasitidal ointment or lotion to rub on the affected area. Whether or not your veterinarian recommends treatment, s/he will want to recheck your dog in about 4 weeks to make sure that the condition is not spreading.\nGeneralized demodicosis: In most cases this serious disease can be treated successfully. Treatment can be lengthy and expensive but the majority of dogs recover completely. In most of the rest, the disorder can be well-controlled with monthly treatment.\nMost dogs recover after 4 to 8 treatments at bi-weekly intervals. Treatment for generalized demodicosis consists of clipping the dog's entire hair coat to allow better contact of the medication with the skin, removal of all crusts (which may require sedation or anesthesia depending on the extent), bathing with medicated shampoo to kill bacteria and remove debris, and application of a solution called Amitraz (Mitaban) to kill the mites. This regimen works in the majority of dogs.\nAnother option is a course of oral medication, given daily for several months.\nUnderlying skin infections and seborrhea (scaliness) must also be treated.\nFor the veterinarian: In comparison to the initial scraping, a recheck skin scraping should reveal fewer mites, and fewer immature forms. If the lesions are spreading, there are more mites, and the ratio of immature forms to adults is high, than the dog should be treated for generalized demodicosis. Regional or generalized lymphadenopathy is another indicator of generalized demodicosis.\nSee references below for detailed discussion of treatment, including of refractory cases.
- Veterinarian Information
A skin scraping for demodectic mites should be done in all skin diseases of the feet, pyodermas, and seborrhea. Remember that an occasional adult mite seen on skin scraping is consistent with normal skin.\nOver 50% of dogs with generalized demodicosis have a normocytic, normochromic, nonresponsive anemia, consistent with chronic infection. Many also have low thyroid hormone levels but they are not hypothyroid.
- Breeding Considerations
Dogs that have required treatment for generalized demodicosis should not be used for breeding, and neither should their parents. Another good reason to spay females with generalized demodicosis is that during estrous, the condition worsens.
- Known Breeds Affected
American Staffordshire terrier\nShar-pei (Chinese shar-pei)\nAfghan hound\nAmerican pit bull terrier\nBeagle\nBoston terrier\nBoxer\nBull terrier\nChihuahua\nCollie (rough and smooth)\nDachshund\nDalmatian\nDoberman pinscher\nEnglish (British) bulldog\nGerman shepherd\nGreat Dane\nOld English sheepdog\nPointer (English pointer)\nPug\nRottweiler\nStaffordshire bull terrier\nLhasa apso\nPharaoh hound