I had/have a similar situation when I brought a 7-week old female pup into my home and my 5-year-old male attacked her a few times over her insolence. He was great with her until she did something that REALLY challenged him, then he nailed her. Well, I guess he saw something in her that I didn't at the time. She has grown into a very scrappy girl, and I have to keep them separated at all times so SHE doesn't start fights now with him. It's not a way to live that I'd recommend, though. I manage it with a lot of "herding" and crating & such, but really, it's no way to live. And, you have to be constantly vigilant to make sure the dogs never get loose with each other. Unless you want a future of dead/bloody Akitas and horrendous fights (which, by the way, are quite dangerous to humans, too), I think you should try to rehome the pup now. Your female is clearly telling you that she won't tolerate another dog in the house...and believe me, when a female dog is intolerant of other dogs, it's serious business. And don't forget, when your male gets older he won't take her abuse anymore. A fight between two grown Akitas is a horrible thing, and from your female's behavior now, that is where you're headed if you keep the pup. Sorry.
