I have a male doxie and female golden retriever, who have always gotten along even though they were older when they were brought into our home. We adopted the doxie 5 years ago and then adopted the golden 2.5 years ago. This past fall we adopted a female doxie mix, not sure of her age, maybe 5-6 yrs old. At that time we had her spayed before bringing her home. During our visits to the adoption center, she never, ever showed any aggression or fear from other dogs and when we did a meet and greet with our two dogs, she was fine. Over the past 2 months, things have changed a bit and she has been aggressive twice towards our golden retriever, this last time drawing blood. I am getting nervous and feel it is something I am doing. It is obvious the female mix is the alpha female. I had allowed her to sleep in bed with us but have decided to stop that and make her sleep in her own bed. The fights took place when the golden encroached on her space, such as the car, and at the front door when returning from a walk. There have been no other altercations over food or toys either. Everything I read on the internet or trainers I've talked to at pet stores, are very different.
As far as we know, they get along fine when we are not at home. Any suggestions on what I can do or not do to help with the situation. We don't want to have to return her as she can be sweet and loves to play. She also tries to hump and poke at the golden which I am trying to discourage with a flyswatter. She knows the basic commands of sit, etc.
Any help is appreciated.