ed, if your wife could separate them with a broom, they have not gotten into a fight to the death yet. An e-collar to correct them before they think about trying to eat each other may work so long as you are right there holding the control. If you leave them alone or with someone else, it can be a different story. It can also be that your bitches had a normal dog-scrimage that would have been fine. Hard to say. But a bitch who is seriously fighting with another bitch will not stop because someone beats them apart with a broom stick, that or working dogs aren't as tough/drivy as show dogs that I have experience with.
Also, if they are in the middle of the fight, the e-collar isn't going to stop them.
Babs and Jenna are littermates. They shared a kennel until they were 15 months old. Also loose in the house/yard, etc. No problems, no fights. I did notice that Jenna was doing a lot of posturing and Babs would be very submissive so I separated them. Fast forward 5.5 years. Jenna is in with Hepzibah her daughter, she has the puppy pen so its in/out and has a baby gate separating it from the living room. Babs is lying on my bed. I opened the gate to let Hepsi in, and Jenna squeezed through the gate, through the shower board barrier separating the living room from the hall to the bedroom and was up on my bed posturing over Babs.
There was not a fight. But there could have been a fight.
When Arwen and Jasmine went at it, they wanted to kill each other. I have separated males fighting. Separating females, should be easier because they are smaller, but it isn't. It's kind of like saying you would rather face a Malinois than a GSD because the GSD is bigger.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC