My doggie is on her cycle and I think she may be pregnant. She started on her cycle on June 15th and on June?

19th she ran outside. She's an in house dog and when someone opened the door she ran out. my husband ran after her and notice she was running towards something in the distance. Another dog. They ran off into the night. As we search for hours and no sign of her she finally came home. Learning the next day it was a boy dog she was out with it's a strong possibility she may be pregnant. Is there something we can do to stop the pregnancy in case she is?