Thirteen seems more like herself this evening. She barked for me when I opened the door, went right to her food and ate about half of it, and is alert now.
I think it's unlikely that she'll eat the whole day's food portion tonight, but if she eats all of this morning's food I'll be okay with that. We have her acupuncture in the morning so I'll be able to talk to the vet about her appetite. And I hope the blood tests will be back by then. In the meantime I withheld tonight's antihistamine. If she gets really itchy I can always give it to her later. If not, then maybe we can cut her back to one a day as the vet suggested.
that's wonderful!