September 20th, 2023

An insight into Feline Infectious Peritonitis

Content provided from Vetstream's Vetlexicon Felis -


Feline coronavirus (FCoV) is a highly infectious enteric virus which causes subclinical infection or diarrhoea in the majority of infected cats. However it can cause a lethal monocyte-associated immune-mediated granulomatous perivasculitis, known as feline infectious peritonitis (FIP), in around 5-10% of infected cats. Infection with FCoV is very common, particularly in cats from rescue shelters, breeding catteries and other large multi-cat households.

Clinical signs

Feline infectious peritonitis has two different forms. The more common form is called 'wet' or 'effusive' FIP, where blood vessels leak protein-rich fluid into body cavities. Most commonly this fluid accumulates in the abdomen (ascites), causing it to swell leading to a 'pregnant' appearance. Fluid accumulations may also occur in the chest (pleural effusion) leading to dyspnoea. Fever, anorexia and wasting may also be seen.

© Waltham Centre for Pet Nutrition

The less common form of the disease is 'dry' or 'non-effusive' FIP in which inflammatory nodules develop in the cat's internal organs and can cause a wide variety of clinical signs, eg neurological signs, fever, renal and hepatic failure, uveitis, anorexia and wasting.


FIP is difficult to diagnose - there is no simple blood test to confirm a diagnosis. The Rivalta’s test on an effusion sample is an inexpensive and simple test to rule out FIP.

If history, clinical signs, haematology and biochemistry are consistent with FIP, FCoV RT-PCR tests on effusions and fine needle aspirates can be used to confirm diagnosis. Specificity is around 96% with sensitivity depending on the laboratory used.

A definite diagnosis of FIP can be made by detecting the virus by FCoV antigen staining of histopathology samples.


FIP treatment includes supportive treatment, antiviral agents, immunosuppression, and immunomodulation.

Antiviral agents are effective in curing 70-80% of cats with effusive disease and a smaller percentage of cats with non-effusive disease.


The prognosis for cats with FIP is poor. A few cats can maintain a reasonable quality of life for some weeks, rarely months.


·       Feline coronavirus: FIP

·       Feline infectious peritonitis

·       FIP / FCoV tests

·       Feline Infectious Peritonitis (FIP) Client Factsheet

·       Feline infectious peritonitis Table 1

·       Feline infectious peritonitis Table 2

·       Feline infectious peritonitis Table 3


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