
I never had this problem because when our bitches were in season, they were moved away from the rest of our small pack for the entire length of their seasons. I never had more than one in at the same time (odd really because they can and often do, bring each other in). But then again once my girls reached around 7, and the end of their show/breeding career (other than the occasional outing in Veterans classes at the Club shows), they were spayed to minimise angst amongst the males.
If this is going on, apart from making the decision to spay, I'd separate them before one of them gets teed off and a fight starts and we all know that once bitches take against each other, there is often no way back.