We have multiple terrier bitches, so bitch fights happen every once in a blue moon at our house. Our girls are 16lbs or less, which makes their fights serious but easier to manage since they are little. I’ve had success using a collar (or my hands) on the aggressor who is “locked-on” to her opponent. You have to be very calm and rational about it so that you’re aware of what you’re doing and don’t put too much pressure on the dog’s throat and hurt it. Essentially you slowly twist their collar to choke them off the dog they are biting. Not ideal, but I find that they just release their opponent and very little skin tearing occurs like it might if you’re pulling them apart. I don’t know how this would work with a big dog fight. With the little ones, I’ve felt like a had a lot of control of the dog’s head since I had the back of the collar plus another part of the dog’s body and didn’t fear being bit. Again, if you panic and lose your calm during a fight, I’d be careful trying this because you could do permanent damage if you’re not very aware of the amount of pressure you’re putting on the dog.
My two little girls got into a squabble once and my intact male Doberman looked a little too interested in what they were doing for my comfort. I didn’t know what his plans were (he’s usually a real sweetie to everybody), but he was looking a little reactive for my liking. My plan for controlling him before he escalated the entire fight, if that’s what he was planning, was to just tackle him to the ground. I wish I had it on video. I’m not a large person, and he’s a strong guy. It was like wrestling a greased pig. He didn’t know what the heck I was doing to him!! Good thing he’s a good sport. That’s my big dog plan.