I know the conventional wisdom says to wait about 30 minutes for a reaction. 2 years ago Tipper had her first and (with pretreatment, knock wood) only reaction 6 hours later. It only took about half an hour for her to go from retching to comatose. Naturally it was during rush hour so 20 minutes of that was spent driving to the vets. Several times I thought she was dead in the car. Fortunately, she recovered as quickly as she went down. Unfortunately, I no longer feel they're safe just because 30 minutes have passed with no reaction. Martha [Posted in FML issue 2677]