They did tests, but FIP (Feline Infectious Peritonitis) is very hard to detect. It masks itself according to what I've been reading about it. His symptoms are classic though, variable fever, not eating, etc. Belly is full of infectious fluid.(They found that tonight when they pulled fluid from his belly.) The vet is not too concerned about the other cat getting it, although I am washing everything and trying to disinfect. She's already exposed if he has it and I will definitely follow up with the vet for more information on keeping her healthy. FIP is most common in settings like the humane society where Harry was not caged most of the time because he was so friendly and sweet. He apparently has been carrying it for a while. I am heartbroken and praying for a miracle that Dr. Kit can make him better. We will find out in a couple of days. Thanks for your thoughts, Jo..