There are two types of mange, Demodectic and Sarcoptic. Demodectic mange is cause by the mite Demodex, and is not passed from dog to dog and it's not contagious to humans. Usually dogs have the mites in their skin and if they get sick with another thing, or if they are stressed or weak, they flare up. Sarcoptic mange is caused by the mite Sarcoptex and is contagious to both other dogs and humans. Even though each type of mange have certain characteristic patterns, to know exactly which one is, a skin scrapping is needed.