Scabies and Demodex
by Melissa Cash, CVT
Dermatology Technician
Dr. Klaus Loft leads Angell’s Dermatology service and sees many dogs and cats with itchy skin, crusty lesions, and hair loss. Many of these animals have allergies, and will have to undergo lifelong treatment to manage their symptoms. Some, however, have an infestation of microscopic mites that can cause similar symptoms but, when treated properly, can be completely cured. The two most common mites that can cause these problems are demodex and sarcoptes, or scabies. Flea and tick medications do not protect against either scabies or demodex mites, and there is no recognized prevention that owners can use to protect their pets from scabies or demodex.
Above: Bam Bam, a 10 month old Chow Chow with demodex before treatment
Above: Bam Bam after 1.5 months of treatment for demodex
Demodicosis, or demodectic mange (previously known as red mange), is caused by an overgrowth of a microscopic mite that is normally found in small numbers living in the hair follicles of any dog or cat. It is not contagious for other animals or people. Overgrowth of the mites in small localized areas is relatively common in puppies and often resolves on its own. In adult dogs demodectic mange can be caused by a stressed or weakened immune system, or in cases where immunosuppressive drugs such as steroids have been used for extended periods of time. Demodicosis is not necessarily itchy on its own, but may lead to secondary skin infections that can cause discomfort and additional skin lesions. Animals with Demodicosis often present with areas of hair loss, redness, scabbing, and crusting. A deep skin scrape and identification of the Demodex mites using a microscope is the best way to diagnose demodicosis, but it can also be seen on biopsy or occasionally in stool samples if the animal has ingested the mites while grooming itself. Demodicosis can be treated with topical medicated dips or with daily oral medication. Treatment can take several months depending on the severity of the infestation, but once the eradication of the mites has been verified by two negative skin scrapes, the patient is considered cured.
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| 5 year old Cocker spaniel, Maggie, with scabies - before |
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| Maggie after treatment |
Sarcoptic mange is caused by an infestation of the scabies mite (sarcoptes scabei var. canis). This is a contagious mite that is often found on wildlife such as coyotes, foxes, and opossums, and is passed to dogs in the woods, the dog park, or even our own backyards. Once infected, the dog becomes extremely itchy, often stopping mid-activity (walking, eating, sleeping) to scratch. The scabies mites tend to live on the lower half of the dog, especially on the elbows, hocks, and ear margins. These areas may also develop a yellow, beeswax-like crust and hair loss. Although the scabies mite that infests dogs is not able to live on humans, they will sometimes try to bite and can cause red, itchy bumps on human skin. Sarcoptic mange is diagnosed by a skin scrape and identification of the scabies mite using a microscope, but this can be difficult due to the relatively few number of mites needed to cause symptoms. Blood testing is available but rarely used in clinical practice. If a scabies mite infestation is suspected treatment may be recommended even if the mites are not found on a skin scrape. Fortunately treatment is generally a relatively easy and effective application of a topical or oral medication, although all dogs in the household need to be treated because of the highly contagious nature of the mite. The scabies mites can only live off the host for a short period of time, but all dog bedding should be thoroughly cleaned or thrown away to avoid re-infestation. Once the full course of treatment has been completed (generally 30-45 days) the animal is considered cured.
For more information or to book an appointment, please visit www.angell.org/dermatology or call 617-524-5733.
