There are 2 kinds of Mange.

One kind of Mange is hereditary and will NEVER go away. The dog will have it it's whole life. This problem arises from inbreeding to make pure-bred dogs. However it is treatable with medicine which will reduce flareups. Also keeping the dog groomed well will help a TON.

The second form of Mange is a bacterial infection of the skin that can be treated and will eventually go away.