Only you can decide when to put your cat to sleep.
The fluid in her abdomen is outside of all her organs and is part of the
pain and devastation of this disease.  The disease also attacks many of her
organs too.
Personally, if my cat did not seem to be happy anymore, that is the point
where I would opt for euthanasia.
Feel comforted in the fact that there is nothing you could do to prevent
this disease.  It is not certain whether vaccinating for coronavirus even
helps.  (FIP is a variant of a coronavirus.  While most cats will carry the
coronavirus, but not all will develop FIP.)
Most cats from shelters will have a URI (upper respiratory infection) after
they have been in the shelter for more than 3 days.  The shelter I am most
familiar with (Chicago Anti-Cruelty Society) does what it can to keep the
new cats away from the older cats, but also will treat (in house, or after
you adopt) if the cat does come down with a URI.  Due to the overwhelming
abundance of URI in shelters the cats there usually get it pretty bad and
have to be treated for 30 days.
I am not trying to dissuade  anyone from adopting a cat from a shelter by
any means.  I just want all to be aware of this situation and to know to ask
their shelter representative how it will be treated if an URI occurs after a
cat is adopted.

I received this e-mail a week or so ago. It may interest you...

Corrected email contact info:Eastwood Animal Clinic, Dr. Bruce LeGallais

Email: catamnt662@adelphia.net Phone: 802-773-7711

PERMISSION GIVEN TO CROSS POST

I hope this e-mail does not offend anyone but I sure would like to see
if anyone out there can help this vet find homes for these cats.

PLEASE CROSS POST!

150 Purebred Cats Need Rescue
August 1, 2005
Below please find a desperate email from Dr. Bruce LeGallais in Vermont.
He is trying to save 150 cats alone in a house, left from a hoarding
case. These cats are slated to be destroyed soon. The local animal
rescues, humane societies and animal control refuse to get involved. Dr.
Bruce is on his own.
We hope you can help by either adopting some of these cats or by
networking with others in cat rescue to try to save as many of these
cats as possible. Please forward this email to as many animal lovers as
you know. If you can help, please contact Dr. Bruce directly.

Message from Dr. Bruce LeGallais

My name is Dr. Bruce LeGallais. I am a veterinarian working in a small
animal practice in Central Vermont. A client of mine, 4 or 5 years ago,
attempted to become an exotic cat breeder (specifically Bengals and
Abyssinians). Unfortunately she has bred a great number of cats but was
unable to part with any of the litters. As a consequence she has become
a hoarder and potentially has 100 to 150 cats in her house. Although
this woman is very nice she obviously has some problems and is finally
seeking some medical treatment. Therefore she can no longer care for her
cats. The humane societies in Vermont are at full capacity at this time
and no one can seem to help out with this problem.
I am volunteering my time and resources to help find her cats homes. If
not, they will all have to be euthanized. I personally will be going
into the house to select out the healthy individuals and make sure they
are up to date on their vaccines.
This is a very unfortunate situation but hopefully with some good old
Yankee Ingenuity (I am Canadian) some of these cats can be adopted out
to good and loving homes. The house they are currently living in has
been condemned by the Dept. of Health.
In conclusion, I am seeking help in finding an alternative to
euthanizing young, healthy cats of an unfortunate circumstance. If
anyone is interested or can help me find homes please e-mail me.
Thank-you for your time and consideration, Dr. Bruce