GSD fighting with other dog
We adopted our GSD from the humane society last December and she was getting along great with our blue heeler (he is 12.5 and she is 4.5-5).
Unfortunately in the last month they have gotten in fights that have drawn blood and led to vet visits. I am not sure what is triggering the fights as they happen when my husband and I leave for a short period of time in the evening (around 30 minutes).
I am not sure if she is trying to play too rough and he gets mad and bites her and she keeps going. Last night she broke his jaw and he bit her eye lid.
I am looking for some advice on if I need to work with her for training or exercise her even more to prevent this behavior.
While the heeler is healing my parents will be taking care of him. Any advice is much appreciated.