American Bull Dog females will stay in heat for 3 weeks, and they will be in heat every 6 months (so twice a year). It is a good idea, at this time, to keep them away from any male dogs you own, and stray dogs that will be attracted to her scent, unless you want her to get pregnant. She will be anxious, and will try and get out, so you might want to tie her up to a post, or keep her in the house. There will also be some discharge, so you should be prepared to do clean up after her.
If you do want her to mate, then find a suitable dog and leave them together. They will mate a few times in these three weeks, and hopefully one of those attempts will result in puppies after 9 weeks.
If you do want her to mate, then find a suitable dog and leave them together. They will mate a few times in these three weeks, and hopefully one of those attempts will result in puppies after 9 weeks.