Long hair dachshunds never have to be cut or shaved! Their hair will grow a nice length and silky but should not get extremely long. They do need daily brushing, but it shouldn't take more than a few minutes if it's maintained. As far as shampoo, I use an oatmeal based doggy shampoo on mine. The oatmeal helps to soothe any itchy spots on them. For long hairs, you can also use a small amount of doggy conditioner too. This will help maintain the silkiness of their hair.