I've only had 2 situations in my house where serious fights occurred.
The first was in college before I ever thought about behavior work or training. I had a 6ish female GSD mix and then adopted a 2ish female chow mix. They were fine for about 6 months, then they wanted each other dead. I learned ALOT during that time and almost lost my thumb. I ultimately placed the chow. There really were no known stimulus and the figths were very serious.
Much, much later I happily had multiple dogs in and out of my care and did a ton of rescue. I got a rescue DS (well....he wasn't REALLY, but that's what he was sold as) and he was a 95 pound boy. I also had a 14 month intact male who was about 75. Everyone was fine and we all went for nightly walks to and in the pond. One day, they decided that they didn't like each other anymore and got into it. But it wasn't really serious and I was able to break them up. So I decided to not let them hang out together.
A month or more later, Ike and I came in from doing some narc work and Rocco (the big rescue) had broken out of his crate and was waiting at the door. That fight was NASTY! My only recourse (and what I swear by now) was looping a leash around Rocco and tying him to the door. Then looping a leash around Ike and choking him off. In reality I was choking both dogs out. Worked and Ike had a very swollen head. The 2 leash method just now seems like my go-to if I had to. They can't fight if they can't breathe and I have a physical way of keeping them (hopefully) from coming back at me.
Sorry - long, but kinda funny story. We were at training one day and an officer had his K9 in his cruiser, but left the window down....and Savvy could be a BITCH. I pulled Ike out to work and Savvy jumped out and immediately started posturing over him. He wasn't much for letting dogs have a chance any more, and they started to throw down. I was PISSED. Here I was, with 6 cops - all over 6 feet and huge - all with hands covering their faces in shock.
I grabbed Ike by his collar and flank (thank God that dog never dreamed of coming back at me), picked him up and threw him to the ground, pinning him. I back handed Savvy and just said, in my meanest big girl voice "Will someone grab this f--king dog before they get hurt." THAT broke the silence and a few guys came in to subdue the already subdued female.
One of the guys just sheepishly said "Um Matt? I don't want to fight with Christie. She just body slammed that dog."
I don't know if I could do it again. It was an adrenaline thing. But really? I was the only one with adrenaline at that moment????
Incidently, Ike wasn't traumatized by the body slam. He found all of his hides right after