My dog at a whole sweet bread and now she is sick?

She is in a 24hour animal hospital getting fluids and plasma transfusions because her liver level is 4 thousand... it should be 100... with those results the vet feels it wasn't the sweet bread that made her sick, they feel she was exposed to a toxin..... well after researching online i found out yeast can be toxic to dogs...especially the amount she had! the vet has seen animals exposed to toxins before make a full recovery... has anyone ever experienced something similar to this? shes like my baby so i keep praying she gets better. they are also giving her vitamin K to help her coagulation level