Thank you for the input, everyone. I had to do something, so I went out and bought a couple of mesh muzzles as a stop gap measure for the time being, and after introducing them to their muzzles separately during the afternoon, I had them both uncrated for a few hours in the evening. I didn't go with the basket muzzles because I saw them at only one place, and they looked pretty cheap/flimsy and hard to get a good fit, and cost twice as much as the mesh. I realize that when the weather heats up, or if I need to muzzle them while they're physically active, I'll need to invest in basket muzzles so they can pant effectively. But, for just sitting around the house in the evenings, the mesh ones work fine.

It's pretty easy to read them when they're thinking of fighting; the older one has "the stare" down to an art form, and the younger one stiffens and raises her hackles. If I see either the stare or the stiff posture with hackles, I give them a verbal reprimand and move them away from one another. If the younger one stands still and permits the older one to sniff her parts, then I leave them alone.

They'll continue to be separated when I'm not there, at night when I'm sleeping, and anytime that I can't keep an eye on them, and muzzled when I am there and able to supervise them.

LC, I agree and disagree about the "why". I do think that *sometimes*, knowing the root cause *can* lead to a more appropriate solution. But I have a lot to learn, so I could be wrong.