Demodicosis (Demodectic Mange) in Dogs
Demodicosis (aka demodectic mange) is caused by a microscopic mite (Demodex spp.) that lives in the hair follicles. All species, even humans, have their own species of mites that are considered part of the normal flora. As long as the immune system is functioning properly, these mites do not cause any clinical issues. However, when these tiny mites take over, they can cause some mite-y big skin issues.
Symptoms of Demodicosis
This condition was originally known as red mange, due to a marked redness of the skin being a key symptom.
Other common clinical signs include:
- Hair loss (alopecia)
- Black heads (comedones)
Since mites overpopulate the hair follicle, it can lead to a rupture, known as furunculosis. Mites that live in the ear follicles can also cause infections. Dogs with demodectic mange are generally not itchy, unless they have a secondary bacterial infection. Unlike other parasites, Demodex spp. are not contagious to other dogs, other pets, or humans.
Diagnosis of Demodectic Mange
Demodicosis can mimic the clinical signs of many other skin diseases, but requires very different treatment. Although you cannot see these mites with the naked eye, it is generally simple to diagnose with a deep skin scrape. This procedure can be performed by your veterinarian, who will use a dull scalpel blade to gently scrape the skin. Although there will be a little bleeding, it is usually painless. The mites are diagnosed via microscopic evaluation of the samples from the skin scrape.
After a diagnosis is made, further workup and treatment will depend on the classification of demodicosis. Demodicosis is generally classified as juvenile onset (onset prior to 2 years of age) vs. adult onset (first occurrence after 2 years of age). Young dogs are more prone because their immune systems are not fully developed, while common underlying causes that may predispose older animals to development of demodicosis include hypothyroidism (low thyroid), Cushing’s disease, cancer, and other chronic immunosuppressive diseases.
Demodicosis is also classified by how many lesions are present: localized (less than five lesions) vs. generalized (five or more lesions, on two or more paws or on the face). Many localized cases will self-resolve and not require treatment, while generalized disease almost always requires treatment. In older dogs, diagnosis includes full blood work, chest radiographs, and abdominal ultrasound based on clinical suspicion of underlying disease.
Treatment for demodicosis is fairly straightforward, as many of the common antiparasitic medications can be used to treat this skin condition. Recommendations will be made based on the age, overall health, and breed of your pet. Certain breeds, like Australian Shepherds, collies, and Shetland Sheepdogs, are more sensitive to antiparasitic medications, so different treatment options or genetic testing may be recommended.
Overall, demodicosis is a very treatable condition in most cases. Deep skin scrapes should be performed at 4 and 8 weeks after starting antiparasitic therapy to ensure clearance of the mites.