ECE - treat same as ulcers, just watch out for dehydration. If the ferret just paws at his mouth, this is one of the warning signs of insulinoma. It would be a good idea to take you ferret to the vet to have its glucose level checked. There are two reasons ferrets loose their fur. If it is an overall shedding, clumps of fur will come out when you pet the ferret or pinch some hair.
Ferrets shed twice a year and do so in about two weeks time.
The other reason ferrets loose their fur is because of adrenal disease. This fur pattern is even from side to side, and usually starts at the rump and moves up the back. New fur does not grow back in. It is a slow process and can leave the ferret bald in less than a year. The resolve to this is removal of the affected adrenal gland, which has become enlarged and is producing too many hormones for the ferret's body to handle.