
Is she producing milk? If so you might ask your vet for Galastop which stops lactation. I would hang on before you go down this route just in case, by some miracle, she goes on to produce a pup / puppies, wait until after her due date.
Dobes are prone to false pregnancies, mine have them practically after each season.
If she was mated she is probably having a phantom pregnancy. How old is your bitch and how many seasons has she had?
Has she been mated before with a successful outcome?
Sorry for all the questions but to offer any help a bit more info. is required.
Regards
Karen