Has the vet done a chest tap? This will give Polkadots some relief, even if
temporary, and he can analyze the fluid or maybe even tell just by looking at
it whether it is characteristic of FIP or of thymic/mediastinal lymphoma, as
you are probably looking at one or the other, although there could be a small
chance of a bacterial infection like Joe and Michelle's kitty had, which can
be successfully treated. The character of the fluid will tell the vet which
it is. Perhaps not FIP since other bloodwork was normal. My Kit-Kat had
thymic lymphoma - a huge tumor in the chest (yet it didn't show on X-ray).
The first chest tap brought 3 good months of relief, but the fluid eventually
came back and despite tapping again couldn't win the battle. But I'm glad we
had that 3 months. Some chest tumors regress with chemotherapy - there are
some kitties on the lymphoma list who have had a year and more, and even a
couple who are in total remission, but I don't believe any of them are
leukemia positive. Will be saying prayersfor Polkadots.