Demodectic mange or demodecosis is caused by a mite. While there are three species of Demodex mite that can cause mange in a dog, the most common one is Demodex canis. All dogs have this mite living on their skin, as it is transferred from the mother dog to her pups during their first few days of life. Most dogs do not have any problems with this mite unless there is an underlying disease in the affected dog.
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Localized Demodecosis
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Some dogs have a small area of their body affected by Demodex. This is a common problem in puppies, and their faces will have a few areas of small bald spots with scaly skin. In this case no treatment is necessary and as the pup's immune system kicks in the Demodex mites will be controlled by natural processes. You can spot treat affected areas with a topical insecticide such as amitraz (sold under various brand names) and anti-bacterial ointments. Amitraz should be used only under the direction of a veterinarian as it can cause serious side effects if used improperly.
Paw Demodecosis
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Demodecosis frequently affects only the dog's paws. Some cases can be quite severe and include a bacterial infection. This form of demodecosis can be very difficult to cure. Treatment requires frequent dipping of the paws in amitraz along with antibiotics.
Generalized Demodecosis
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In the generalized form, the dog's entire body is affected by the out-of-control mites. There will be large areas of bald, scaly skin and the fur falls out in patches. The skin becomes infected and itchy. The dog may acquire a bad smell due to the skin infection. In dogs younger than 1 year of age, the immune system usually will respond and control the mites. In older dogs, an underlying immune system disorder should be suspected.
Treatment of Generalized Demodecosis
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Treatment is by use of dips (amitraz) scheduled two weeks apart until skin scrapings come up negative for mites. The fur also might need to be clipped short and a pre-bath with shampoo may be needed to remove debris from the skin. Antibiotics are prescribed if there is a skin infection. It is very important for older dogs to undergo a complete medical workup to find the underlying cause for the immune disorder.
Ivermectin Treatment
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Ivermectin is a broad-spectrum antiparastic drug. This is the treatment of choice for dogs that do not have Australian shepherd, collie, Old English sheepdog, or Shetland sheepdog breeding. These breeds are very sensitive to ivermectin. In these breeds, the drug can be toxic to the nervous system. In breeds that can tolerate ivermectin, oral treatment or injections are given every other day or once a week until skin scrapings are negative for the mites.
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