Dogs are in heat for 3 weeks! You need to keep her separated from all male dogs, that are not Neutered for 3 weeks. If you have a male dog in the house that is not Neutered, then you need to keep them separated in different rooms. The male will go nuts, stop eating, lose weight, cry and want to get to her, but when you have an unspayed female in heat, that's normal. An unneutered male can smell a female in heat from miles away and will do anything it takes to get to her, mate with her and get her pregnant. Never leave your female outside on her own, when she is in heat! Go out there with her and bring her back inside when she's done going potty. Doggie Diapers will help with keeping her from getting blood on things, but will Not stop a male from mating with her. You need to be very careful! Once she finishes her heat cycle, have her Spayed. You can have her Spayed while she's in heat, but it will be more expensive because they bleed more during surgery.
They usually keep themselves pretty clean, they do have sanitary diapers for them at the pet store. I suggest you get her spayed, then you don't have to worry about anything:)