My kitten had F.I.P. It is an uncurable and 98% fatal disease. Feline Infectious Peritonitis [F.I.P.] is a mutated form of the feline coronavirus. The symptoms include an expanding stomach, [due to liquids in the stomach] and diarrhea. It is a very sad disease because it is almost always fatal and suffering for the cat. I had to put mine down 2-3 weeks after the diarrhea symptom. The cat lies around all day just wanting to be petted.