What if you have an older Boston (5 months) with a 4 inch straight tail? Leave it be or should we do something?

We brought home a second boston (this time female) 3 months ago (feels like 3 years ago at this point) We are a week past 5 months in age and we are having a heck of a time housebreaking her. In addition to her digging and biting of our male boston ...