OH my goodness!! Poor thing.
Years ago, my friends Rottie got into poison and I helped her take her to the vet while my mom stayed with her children. They gave her the activated charcoal and sent her home. It sounds like this pup probably had a worse case, having had a seizure. But my friends dog....we later found out she was pregnant!!! She had 4 or 5 puppies, but only one made it.
I'm glad it sounds like she is going to be fine.