There is a really great pro/pre-biotic product out there called Proviable it is made by Nutramax Labs, an excellent company. I have tried it as well as several of my co-workers on cats with watery explosive diarrhea- the stuff works overnight and if the cat has a metabolic or IBD type issue it really helps a lot. Please consider adding this great neutraceutical. Yes, we do sell it where I work, But... we didn't sell it till a few of us tried it and believed in it! It has the most types of bacteria and the most cultures of any brand out there right now. It should help with any kind of diarrhea there is.
There is another product called Duralactin which is made from Milk enzymes that is great for IBD cats as well. It works by decreasing inflammation without antibiotics, it works on the cellular level and is well tolerated by cats as long as they aren't allergic to milk products.
Beth Shelby, CVT