Hi, and welcome to Yorkie Talk!
It sounds like you're doing all the right things for Abbie. It's very important that she sees her vet as soon as she can, so it's good that she's already scheduled for blood work tomorrow.
We have a handy reference book for Yorkies. There's a section on seizures that says they can be triggered for many reasons, including epilepsy, diseases (including liver shunt), hypoglycemia, bad reaction to a vaccine, very low thyroid, poisoning or organ failure. Only your vet can figure out what caused it, and he will be able to do tests for liver shunt, too.
Since young yorkies are so prone to hypoglycemia, a lot of yorkie owners here give our babies a nutritional supplement called Nutrical a few times a day when they are young. It's essentially a nutrient packed sugar paste. If you can't get out to a pet store to find some today, go ahead and give Abbie a fingertip amount of honey or Karo syrup every few hours today, and if she gets up in the middle of the night tonight, give her one then, too. This will help keep her blood sugar levels up.
If she has another seizure, stay close to her to comfort her while it's happening, and make sure she doesn't run into anything that can hurt her. Keep your fingers away from her mouth - our book says that dogs won't swallow their tongues during a seizure, so there's no need to put your fingers in her mouth to prevent that.
I'd say that it probably wasn't related to eating the mushroom, since that was a couple of days ago, but again, only the vet can really tell. Our little guys have eaten mushrooms from the yard before, too. I think some of them are slightly poisonous, and some aren't.
If she starts to act strange again, don't be afraid to call your vet or the emergency vet. These little guys are very delicate when they're young. We woke up one morning to find our 13 week old in a coma, and he was perfectly fine up until that point. He's fine now, but it was definitely a scary time!
Well - I hope this helps. We're glad to have you here on Yorkie Talk, and please let us know how Abbie is tomorrow!
