I went through that.. and ughhh! I hate to say it but sometime this just happens, and it is not always about socialization.
Our Bridget and Monroe started the same this over a year ago, the fights became so vicious that we had to keep one dog in an xpen at all times, otherwise there were some serious injuries, they even got us once or twice as we tried to separate them. We tried everything from trying to let them have it out ( vets advice) to the Cesare milan books, to dog training, and nothing changed even after we spayed monroe. The last fight they had Monroe bit off a portion of Bridgets ear...I finally could not take it, they were fine with other dogs, just not each other. I ended up finding a new pet home for Monroe as I could not see keeping one dog locked up at all times for the rest of their lives, I hated it, and even though we changed out them a lot, it just seemed unfair to both of them.
Sometimes there is just a personality conflict. I would try everything you can, but if it does not work, you need to protect them both and re home one of them. Perhaps a friend or family member would take one in if you needed???
I wish you luck, and I pray your outcome is better than mine!!!
__________________ Marlee Bridget's Mommy 
Bridget  's Romeo |