Hello! I have a 8month old female boxer who has been absolutely wonderful so far however she has been showing some worrying aggression lately to some other dogs. She has been socialised from a young age and daily plays with other dogs on the beach with no issues, however, lately she has been showing agression to one of our other dogs when it barks. At first we assumed this was a learned behaviour since when our sausage dog barks my brother often trys to call him in or tells him 'no/naughty'. Usually ellie ignores this, but the last month or so she approaches the other dog and pushes him directly under her. He used to growl and bark at her which she never responded to, but now this causes her to growl back and wrestle him until he is pinned on the floor. We have tried breaking them up and seperating them when they bark or people are coming into the house however this seemed to make it worse. Talking calmly and calling ellie back while keeping a distance when she shows this behaviour seems to stop her and she simply walks back, however if the other dog continues growling or nipping at her she will pin him. Once they start she tries to go back and once calm will go and check on the other dog. Outside of barking they both play together with various toys that she normally takes over to him. They both sleep on the same couch and eat in the same area. I feel this is getting worse the last week due to a dog running straight across the beach to her and biting her to switch she fell over but got back up and tryed to bite back, but again once seperated she was fine and continued her walk. But today another small dog approached her and started to growl which she responded by pining to the floor! Luckily neither dog was hurt. In addition to these incidents she is now growling / lunging for our other dog if it has any of her raw hide bones which she previously has never done or if it stares at her while sitting on the couch. Does anyone know how to stop this behaviour or possible causes of this? She is a really friendly dog and of the 100's of dogs she has played with and met this has only happened with our other dog and 2 others that showed aggresion first. I feel like its not a socialisation issue, and since it happens so quickly and out of character its hard to place why she is doing it We have a 3rd very small elderly dog she leaves alone and doesnt react to when it barks or growls, which my family are now worried leaving alone with ellie incase she starts doing the same thing to. Its bizzare she only reacts to franky. Ona side note: she has never bit or injured/been injured in these incidents, she just kind of climbs on top of the other dog while holding her head up barking. Sorry for the ultra long post. I just would really love any help or tips anyone can offer to help with the situation! Thanks in advance!