FIP Symptoms -- What Else Could It Be?

One very kind breeder gave me a list of several medical issues that can cause a build-up of abdominal fluid. I'm also interested in knowing, though, what, if any, medical conditions can mimic *all* of the other symptoms of ("wet") FIP (lethargy, decreased appetite, weight loss, fever).

The list given to me includes the following conditions:

Bacterial Peritonitis
Chemical Peritonitis (pancreatitis, bile/urine Peritonitis)
Chylous effusions
some abdominal neoplasms
Liver desease (but this is more common in dogs than cats)

I strongly suspect that my kitten has FIP (she has the symptoms of "wet" FIP, and two vets confirmed her as having it). In any case, she's lethargic and quite weak. My adult cat, however, still wants to play. Tonight, I found him pinning her down; she, being in her current condition, could not easily get away and got roughed up, until I stepped in to stop it.

I didn't want to separate them due to the stress that separation could cause (and I didn't want to stress my kitten's overtaxed immune system anymore). But I'm wondering if separating them while I'm gone is the lesser of two evils.

What do you think?

I might be a bit out of line here but if you even suspect your kitten has FIP I really think she needs to be at a vet to recieve proper treatment otherwise she could die. How have the vets confirmed it is FIP? The only definite way is via blood sample for analysis and a special FIP test. I cant believe a vet would send you home with an FIP kitten until she was fully recovered. What treatment has she received? At my vet she would be on constant fluid therapy, plus a vairty of meds until her symptoms stopped if she was lucky and didnt die from it as so many do. If she does not recieve the proper veterinary care she may die. Can you take her to a vet for another opinion, I find this really strange or maybe I just dont know all the facts so can you please explain to me as I am really concerned.

PLEASE separate your cats - FIP is highly contagious and is a life threatening disease. Do not let them share litter trays under any circumstances. Your vet should have told you this. I am surprised to hear that she is still interested in playing though, FIP kitties are way too sick for this so maybe she doesnt have FIP and to be honest for a vet to send her home while she is still displaying symptoms of FIP (if this is what it is) is just wrong. If she is sick then she is way too weak to fend for herself and it is up to you to make sure she is pounced on by your other cat as this can only make things worse. I would call your vet or another immediately for further advice.