Kitten panleukopenia or something else

Sorry for the long text. Some cats live in the garage of my building (not in the US or Europe). A kitten, the runt of the litter has been having foul smelling diarrhea qnd a swollen stomachfor nearly 20 days and was wasting away. It's around 10 weeks old and weighed under 500 grams. We took it to the vet and they suspected panleukopenia and told us it may not live. For the past 3 days we have been treating it with subcutaneous fluids, metronidazole and ceftraxone (not sure about the spelling) injections. We are also giving it saline with prebiotics and zinc. The kitten has perked up in the past day, and is actively eating and even came running at me. From everything I Googled, it seems like the kitty shouldn't have survived this long, and should be near death. How long do kittens usually survive from the onset of symptoms if they get this disease? Do I stand a chance of saving this baby? How can I help it gain some weight? I am beside myself with worry.

Hello!  I'm afraid that its quite difficult to know how long your kitten will live, without knowing what is wrong.   What is causing the swollen stomach, for example?  If it's just worms, that can often be treated.  If it's fluid, eg due to ascites from heart disease or peritonitis, or a swollen organ, this implies some far more serious disease process in play.  Does the kitten definitely have feline Panleukopenia? - Do bloods and testing back that up? These details are quite important.  It sounds as though you and the vets have done a good job of helping the kitten to feel better in the short term, but the long-term prognosis depends on what is going on in this indivudual cat.   Good questions for your vet include, how many differential (possible) diagnoses are there for this kitten?  Is FIP a definite diagnosis?  What would you do if this was your kitten?

Panleukpenia, not FIP, sorry.

Hi, Today the vet said the swollen stomach was most probably due to a combination of severe gas and worms.

That sounds much more positive.  Best of luck