Mange in Dogs: Causes of Mange

Mange is a generic term for hair loss caused by a mite infection of the skin in dogs. It is caused by one of two mites which infect dogs, either Demodex or Sarcoptes. While dogs with mange might appear similar, the two diseases are very different.

Mange in Dogs: Demodex

Demodecosis in dogs is caused by the Demodex canis mite. This cigar-shaped mite lives in the hair follicles of all dogs and normally does not cause a problem. However, in young dogs and dogs with poor immune systems, it can cause mange. There are different types of demodex mange depending on the severity of the disease. Causes of Mange in Dogs
Localized demodex causes patchy hair loss on the face and sometimes limbs. These patches are usually less than 2 inches in diameter.  Localized demodex is usually seen in dogs less than 1 year of age. Almost all dogs with localized demodex do not require treatment as the disease spontaneously resolves. Goodwinol ointment, which is an insecticide, can be used on these spots if treatment is desired. About 10% of dogs with localized demodex will progress to generalized demodex.
Generalized demodex results in hair loss over large parts of the body, and is often accompanied by secondary bacterial or yeast infections of the skin. These dogs are often itchy. In young dogs, generalized demodex is due to an immature immune system, but in older dogs, it is often related to underlying diseases like cancer. Oral ivermectin isDogs and Mange used to treat generalized demodex, but cannot be used in Collies, Shelties, or other herding breeds as it will cause a toxicity. In these patients, daily dosing with Interceptor can be used but it is costly. Treatment may continue for months. Generalized demodex can be cured but in older patients it carries a guarded prognosis.

Mange in Dogs: Sarcoptes (Scabies)

Scabies is caused by the mite Sarcoptes scabiei. These mites can infect any dog and are contagious between dogs.  Humans and cats can also become infected but the mites don’t live on them so the disease is transient. Humans with scabies usually have small red bites on their arms, belly and neck, which are very itchy. The female mites burrow into the skin to lay their eggs which results in extreme itchiness for the dog. Hair loss usually begins on the ears, elbows and belly areas. Eventually it progresses to generalized hair loss and secondary bacterial infections of the skin.Causes of Mange and Dogs
Diagnosis of scabies infection can be difficult. A skin scraping is used but the mites are only seen about 20% of the time. Often your veterinarian will treat for scabies if there is a suspicion as treatment is relatively cheap and easy. Scabies can be treated with either oral, injectable, or topical medication, including Ivermectin (except for Collies, Shelties, and other herding breeds), Revolution, and Interceptor.  All dogs living in the household must be treated even if they don’t exhibit clinical signs of mange. Treatment lasts for two to four weeks and dogs with scabies mange have an excellent prognosis for recovery after treatment.

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Dr Jill Christofferson

Jill Christofferson, DVM is an experienced veterinary general practitioner. Her professional interests include ophthalmology, dentistry, and reproduction.

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