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Mange: A common — but ugly, painful problem in Am Samoa

Compiled by Dr. Jo Olver

Pago Pago, AMERICAN SAMOA — Mange is a common term people use for any dog with skin disease, especially the ones with hair loss and itchiness. However, mange refers to specific skin diseases caused by mites. Mange is caused by different kinds of mites, and affects many kinds of animals, including humans.

In dogs, there are two major forms of mange, each caused by different mites:

            •  Sarcoptic Mange (also known as scabies) 

            •  Demodectic Mange (also known as red mange or demodex) 

In cats we commonly find feline scabies caused by Notoedres cati.


This mange is caused by a circular-shaped, eight-legged mite called the Sarcoptes scabiei. This form of mange is highly contagious. The parasite can be transmitted from dog to dog and can pass from dogs to humans, although it doesn’t thrive on people. Female mites burrow into the skin to lay their eggs. The eggs hatch in about three weeks, and the young feed on the host’s skin. 


Sarcoptic mange is diagnosed by signs of the disease and a lab test called a skin scrape. 
Signs generally appear about 10 days after contact with a dog carrying scabies (but can take up to 8 weeks). The first signs of the infection are often on the margins of the ears, chest, lower legs and tummy. The most common symptoms of sarcoptic mange include: extreme itchiness, red skin, crusty skin, and hair loss; which can quickly spread. As the disease progresses untreated there will be severe hair loss, thickened skin and thin body condition. 

Demodectic mange, or demodex, is caused by a cigar-shaped mite called Demodex canis. As different from sarcoptes mites, demodex appear to be a normal part of the skin flora, always present, and usually harmless in normally extremely small numbers. They are passed to pups from their mothers in the first few days after birth. The mites take up residence deep in hair follicles and stay there usually causing no problems for the dog. A normal immune system keeps their numbers in check. But in a dog with a weakened immune system (young puppies, older dogs who might be sick or neglected and strays) they can grow out of control. Young healthy dogs can have patches of demodex, which is often spot treated locally with success.

Demodex mites are not contagious to humans.


Similarly to any mange by signs on the dog and by a microscope exam after a skin scrape.

Symptoms of Demodectic Mange

            •  In localized cases, it shows up as patches of hair loss and red, scaling skin. 

            •  In generalized cases, the entire body may be covered with redness, infections, scaling, swelling, and crusts. As the disease advances the dog loses most, if not all, hair and is very painful for the animal infected.