15 mo. old female boxer

Question
This is our first boxer. We have a 12 yr old female aussie and 6 yr old silky. Everything has been perfect until about 3 wks ago. My female boxer has been socialized with others and gets exercise on a regular basis and free play with other dogs of all sizes and sexes. The first incidence occurred at doggy daycare with my boxer and my 12 yr old aussie. My aussie had been resting off by herself and got up to come across the yard to me when my boxer came out of nowhere and jumped her attacking her without provocation. I was shocked and horrified. I had never observed any power struggle at home and the boxer had always displayed "puppy" behavior with her by licking her mouth. Since then, the boxer has on 3 different occasions at home jumped on her. Last night I watched her posturing when my 6 yr old silky was coming upstairs to bed. The silky would turn her head away, but the boxer would continue until the silky went back downstairs, and she would follow and posture some more. I am really at a loss. I have been feeding the older 2 dogs first while she lays and waits to be fed. I am having her "work" for attention. I'm really worried that this is just the tip of the ice berg. I never wanted to believe that you couldn't have 2 females in the same household. Is this just a coming of age thing that will pass? She is so sweet and loving, and this is just crushing me. I would love any insight on what we might be dealing with, and really need some advice on how to handle it.
thank you,
Jennifer

Answer
Hi Jennifer. It sounds like your girl is having some dominance issues, maybe. It's really hard to say for sure without seeing it myself. Is she spayed? Some Boxer girls can be same sex dog agressive, so can some Boxer boys. My best advice here would be to keep your Boxer girl seperated from the older dog until you can a fix on this. If they're together, you need to be with them at all times. Then, I'd get some help, a trainer. Find one that has experience with Boxers. This really isn't something that someone can tell you how to fix over the internet, you need to be able to see exactly what's going on, what's triggering her. It's not much help, I know, but that's the best advice that I can give you. If you need help finding a trainer close by, let me know and I'll try to help. Good luck!