So far it seems that the news is good and I hope that it continues this way through the additional testing.
I am also glad that they had a good suggestion for a pet friendly product to take the place of the one that you were using.
As far as his system goes, you may have already thought of this but I thought I would throw it out there... some of his gastrointestinal distress could also be from the different pet food that they fed him at the ER.
Best wishes.