I understand how scary an FIP diagnosis can be, so let me do my best to explain it. FIP progresses quickly, often over a few weeks to a few months, though it varies. It usually starts with vague signs like lethargy and a reduced appetite. Soon, you may notice weight loss, fever, and abdominal swelling if it develops into the wet form of FIP.
The illness is usually fatal if left untreated. FIP is caused by a mutation of a common virus called feline coronavirus. While most cats with the coronavirus don’t get FIP, the few that do have a poor prognosis. However, recent breakthroughs with the antiviral drug GS-441524 have made FIP a curable disease; this PIF chat website has an example of that.
The issue is that the drug won't reverse the organ damage caused by the disease. So the sooner a pet is diagnosed and treated, the better their chances of making a full recovery, as that gives FIP less time to cause damage.
