The scent of a female dog in heat travels; any unneutered male in the area who can scent her will be interested in getting to know her. You cannot completely get rid of the scent, but you can reduce it to deter male dogs from trying to get to her. Bathe her back half, including inner legs and tail, to wash off the discharge regularly and avoid leaving her outside alone.
Topical Products
When trying to mask the smell of your dog's heat, you have a variety of products to consider. Menthol, camphor, eucalyptus and wintergreen are popular choices. Dab a little on the coat around the base of the tail.
Chlorophyll
You can give your female dog chlorophyll tablets or liquid chlorophyll daily to help reduce the smell. It will not get rid of the smell completely, but it can help, especially if you are living with an unnuetered male or have one in a neighboring yard. You want to consult your vet to get the exact dosage before giving it to your dog.