Boxer is dog aggressive

Question
I have owned Boxer "Emma" for 8 years. I have socialized her put her obedience training and even got a male Bullmastiff puppy and is psycho aggressive towards all dogs except the Bullmastiff and other adult Boxers. All her siblings are the same. Could it be hereditary? I understand they are high energy. Thanks.

Answer
No, it is not hereditary.

Boxers are great and protection of children and owners: family.

They generally social well with other dogs in the family; becomes a pack.

However, if you do not socialize a Boxer puppy when young, with other dogs, such as a dog park, etc., they can become overly protective of the family- which Emma is.

It shouldn't have taken you 8 years to break her habit of being aggressive to other dogs.

Now, you have a problem because she is older and set in her behavior.

The only things you can do is: 1) keep her away from other dogs, 2) train her as best you can at this late point in life; leash her, muzzle her, and expose her to other dogs at a public dog park in order to train her to accept other dogs under your supervision leashed.