This article is published in this site with the special permission of END FIP®
FIP is a vasculitis and there are two main forms of FIP: effusive (wet) and non-effusive (dry). While both types are fatal, the effusive form is more common (60 -70% of all cases are wet) and progresses more rapidly than the non-effusive form.
The earliest FIP occurs is at around 28 days post-infection, and there is usually a history of stress such as having been rehomed or spayed/neutered. Effusive or wet FIP is the acute form, occurring 4-6 weeks post-stress and non-effusive or dry FIP is the chronic form and can occur months to years after infection. In effusive FIP many blood vessels are damaged, and in non-effusive FIP the immune response has been partially successful, walling off the infected vessels with pyogranulomata which can become quite large (in abdominal palpation and gross postmortem they can be mistaken for tumors).
Effusive FIP
The hallmark clinical sign of effusive FIP is the accumulation of fluid within the abdomen or chest, which can cause breathing difficulties. Other symptoms include but not limited to: lack of appetite, fever, weight loss, jaundice, and diarrhea.
Non–effusive FIP
Dry FIP also presents with lack of appetite, fever, jaundice, diarrhea and weight loss but there will not be an accumulation of fluids. Typically a cat with dry FIP will show ocular or neurological signs. The cat may develop difficulty in standing up or walking, becoming functionally paralyzed over time and loss of vision is another possible outcome of the disease.
About 80% of cats diagnosed with non-effusive FIP turn out to have some other condition. Cats with non-effusive FIP are NOT clinically well!
Cats with non-effusive FIP do NOT have a normal temperature, normal appetite, they aren’t bright and responsive.
Source: https://www.endfip.com/fip-in-depth/clinical-signs
