By: Rob Avery D.V.M.
Mange is an infection of skin mites that often is confusing to clients. The issue arises because there are two conditions called mange, and while both involve mites they affect dogs very differently. Fortunately, it is easy to clarify the diseases and recent innovations in treatment make solving the problem much simpler than in the past.
Demodex mites live in hair follicles within the skin. They are found normally in many species including cats and humans as well as dogs, and cause no problems or disease. These mites are not infectious at all. Sometimes, especially in puppies when the immune system is developing, an overgrowth of mites occurs and hair loss, greasy skin, and odor can develop. This is often located around the eyes, on ears and other areas of the face, but can occur in other locations as well. These lesions are usually not itchy unless secondary bacterial infections occur. Disease can occur in older animals as well especially in those that have some other underlying disease that disrupts immune defenses. Diagnosis is based on appearance, age of the dog and a skin scraping test; easily done at most veterinarians at very low cost.
Sarcoptic mites live on the surface of the skin and behave very differently. They are very infectious, and extremely itchy. Infection is often acquired from wild animals, in particular foxes but can be caught from other dogs. There are sarcoptic mites that affect most species, including humans, and cross infection can occur but is self-limiting, resolving without treatment. Diagnosis is more difficult as the mites are fewer and harder to find with scraping. Fortunately, sarcoptes is rare.
In the past, a variety of treatments existed for both conditions. Amitraz dips, oral ivermectin and oral milbemycin were used to varying success, but often these diseases were frustrating and could be difficult to eliminate. A new class of drugs was developed a few years ago, the isoxazolines. These are sold under the names Nexgard, Bravecto, Simperico and others. They are given orally, at intervals that vary with each drug from monthly to every three months. They are effective in eliminating fleas, ticks and most mite species. These drugs have essentially eliminated the need for any other approach to treatment for both demodex and sarcoptic mite infections. Since these medications are extensively used for routine prophylactic parasite control in dogs, veterinarians are seeing far fewer cases of mites in our clinics.