Mange In Dogs

Hello there! I've two dogs, one is a german shepherd and other is labrador retriever, both of them are very fond of each other and love to play with each other whenever they are set free, but recently my lab is detected with Mange and also it has lost some hair, since then I've kept my german shepherd away from the labrador but both of them have became very aggressive since I've kept both of them isolated. Please tell me whether Mange in dogs is contagious or not and also when will the lost hair of my lab will grow back. If it is not contagious then I can again allow then to play together. Thanks!