UPDATE: she's fine. out of surgery, groggy, and still here. :-)
i just got a call from the vet. i'd brought isabel in this morning for a relatively normal procedure (the butt-dragging was an indication, and i'll leave it at that). it turns out she needs emergency surgery. now. as in, she's in surgery as i write this.
the doc, whom i like very much, said she should be ok.
my baby girl.