Was just supposed to be a routine spay surgery and we got the terrifying call that they had "messed up" and my dog has accidentally been administered penicillin through her intravenous. She has yet to have a reaction (Thank goodness!) and the vet said to be on the lookout for signs of anaphylactic shock. Has anyone else ever had this happen? How serious is this "mess up"? And what signs should I look out for other than vomiting, diarrhea and seizures?