Mange (demodicosis) is an inflammatory disease in dogs caused by the Demodex mite. When the number of mites inhabiting the hair follicles and skin of a dog rapidly increase, it can lead to skin lesions, skin infections and hair loss (alopecia). The severity of symptoms depends upon the type of mite inhabiting the dog.
Symptoms and Types of Demodectic Mange in Dogs
Demodectic mange in dogs may either be localized, meaning that it affects only specific areas of the body, or generalized, where it affects the entire body.
If localized, symptoms are usually mild, with lesions occurring in patches, especially on the face, torso or legs. If generalized, symptoms will be more widespread and appear across the body. These symptoms include alopecia, a redness of the skin (erythema) and the appearance of scales and lesions.
The demodex mite is a normal inhabitant of your dog’s skin. In low numbers, these mites cause no symptoms and may serve an important role as part of your dog’s normal skin microfauna (similar to the way healthy bacteria is important in digestive health).
Three species of mites have been identified to cause mange in dogs. The species of mite most commonly associated with demodicosis is the Demodex canis, which inhabits the skin and hair follicles and may transfer from mother to newborn during nursing. This means that nearly all dogs carry these mites, and very few suffer symptoms.
However, when dogs have a compromised immune system, the mites can start to multiply unchecked, which leads to demodectic mange and itchy skin.
Skin scrapings are used to find and diagnose demodicosis in dogs. Plucking hairs may also help identify the mite responsible for the condition.
Alternative diagnoses may include bacterial infection in the hair follicle, other types of mange, autoimmune disease of the skin or other metabolic diseases that can affect the skin.
Treatment of Demodectic Mange in Dogs
If localized, the problem is likely to resolve itself and disappear spontaneously, which happens in approximately 90 percent of cases. For severe generalized cases, long-term dog medications may be necessary to control the condition. Females should be spayed, as fluctuations in hormones can exacerbate the disease. High-quality dog food and a low-stress home environment may also help reduce future flare-ups.
There are now several treatments available for dog demodectic mange. The easiest are the isoxazoline flea and tick medicine for dogs.
The frequency of dosing will depend on which brand is chosen, but it’s typically one chewable tablet every 2-6 weeks for mange. An older type of medication, ivermectin, is very effective but requires daily dosing until the infection is controlled.
While these medications are labeled for use against mites in other countries, the FDA considers this use “off-label” and therefore carries warnings, so you should discuss treatment with your veterinarian.
WARNING: Though you may read about the use of motor oil in treating mange, it is HIGHLY TOXIC to dogs and should never be applied to their skin or fed to them.
Living and Management of Demodectic Mange
Follow-up care should include skin scrapings to continually monitor the presence of mites and check the treatment’s progress. With chronic long-term cases, regular medication may be necessary.
Your veterinarian will continue treatment for several weeks after there is no longer evidence of mites. Year-round dog flea and tick treatments with a product that is effective against mites is highly recommended for dogs with a history of mange.
Most dogs recover completely, especially if they are under 18 months, when they are diagnosed with demodectic mange.
The mites are not contagious to humans or cats. There is controversy about whether mites may transfer between dogs after the first few weeks of life. However, evidence supporting such transmission is rare.
Prevention of Demodex in Dogs
General good health may help prevent some cases.
Dogs with generalized chronic mange should not be bred, as the condition is likely to be passed to offspring.