I have a one year old female cat and a two year old male. The male has always been overly aggressive (he would attack me before we even got here). He was a sweet side, but he enjoys hiding and swiping at anyone that may walk by. When we first got our female we tried to intorduce them slowly and in our old apartment would keep them separated whenever we left. When wemoved they seemed to be getting along better, however lately he has gotten aggressive with her to the point I am scared. A couple times now I have come home to her with a scratch on her nose. Nothing too bad, but it still drew blood. Also, she has been going to the bathroom under the couch and even relieved herself all over the kitchen floor. I am not sure if she is so scared that she can't hold it in or if he is completely preventing her from using the litter box. We have decided to try to keep them separate from now on when we are not home and to get a second litter box. We have a squirt bottle that we use to break up their fights already. I just want to know if there is anything else I can do to stop this behavior? I cannot imagine having to get rid of one of them, however he is so much larger than her (hes over 20 lbs and she was the runt of her litter and does not even like to play rough) and I am terrified he is going to seriously hurt her or she is going to develop some sort of anxiety or depression. Please help!

I would have to say take the high road and have him neutered. That will put him on the same page as her!

He is neutered, he was actually already neutered when I got him at 8 weeks old. And she was spayed when she was 4 or 5 months old. He has always been very large for his age and very aggressive. I'm not so sure he is purely a domestic short hair based on his size. Everyone that sees him comments on his size which is part of the problem. He is not overweight, just very long/tall and solid (over 20 lbs). She was the runt of her litter and is tiny, about 10-12 lbs, she's a little chubby :), and does not like to even play fight.