[SWHouston]

cockerduchess,

Many Yorkie Females are not what you'd call "laid back". Some can really have an attitude. When one gets Her sights set on being the Alpha Female, it's Katy bar the Door for any others. But, as disturbing as She is right now, I really don't think that She wants/needs to actually do much harm to the other two, just rough enough to put them on their place, and, that's in the number two slot in Her Pack. It will be up to them, to work out who's number three.

I strongly suspect, that there has been a new Male arrival in your area, (not necessarily a Yorkie) which She senses/smells, and is setting up for possible contact. This may subside (a little) after a while, but in the interim period, keep a close eye on Her when She's outside, Her "escape artists" ability may show. This has nothing to do with Her being Spayed, if in fact she is.