Problem with my boxer

Question
Hi,
I have a 11 year old female boxer named drew who has never had pups and has not been spaded and a 7 month old female American bulldog/ boxer cross named messy. Messy has been with drew since she was 4 weeks old. Messy and drew play, feed, sleep together. On Sunday 6th February had a fight which was caused over next doors dog barking we split them up straight away and told them off. After the fight we tried putting them together Messy wanted be with drew but drew just wants to fight all the time now drew's hair is always up on her back. Its now Tuesday and we cant place drew were she can see messy. Is there any advice you can give me please and have you any idea why this is.
Thank You

Answer
The Boxer is the aggressor always? Drew?

Something isn't right for Drew to want to fight Messy all of a sudden.

Maybe Messy is challenging Drew for the "alpha" position in their "pack" and Drew is not allowing it, while fighting to keep it.

You must maintain control-- you are suppose to be the "alpha" not them.

You can try this trick:

Place their food dishes on the kitchen counter or table, full of their food. Place crackers, cookies or chips on the table behind the food dishes. Stand before them while they are watching you, and eat the crackers, cookies, or chips while NOT looking at them.

When you are finished, place their food dishes on the floor in front of them and tell them they can eat.

Do this at every meal for a month.

In the wild, the alpha always eat first while the pack waits and watches. When the alpha is finished eating, he or she allows the pack to eat if there is anything left.

This establishes you as the alpha.

Also, when Drew becomes aggressive, immediately put her down to the floor and hold her there for 3 minutes in the submissive position. When she calms and submits to you, hold her a moment longer then walk away. The alpha does this to chastise the misbehaved pack member.

They know they are doing something wrong when the alpha makes them submit. Be consistent. Do not waiver.