In Cats

Feline infectious peritonitis - FIP

FIP is a fatal immune-mediated disease of wild and domesticated cats caused by mutant strains of Feline coronavirus (FCoV). The disease was first described in the U.S. in 1963. The first reported appearance in Australia was in 1974

FIP is reported to occur more frequently in cats from catteries, boarding facilities and multi cat households. The incidence of FIP in purebred catteries increases in proportion to the number of animals kept in that facility. 93% of cats within catteries are infected with FCoV


The most common method of FCoV transmission is via virus-infected faeces although in the first few hours to days of infection it can be shed in the saliva and respiratory droplets. Kittens are usually infected from their mother at the age of 6-8 weeks when their maternal antibodies wane. Healthy cats that are consistently infected with FCoV are thought to play an important role in recycling FCoV in multi cat environments. FCoV is a fairly fragile virus that is destroyed by most household disinfectants and detergents. It can however survive up to 7 weeks in dry conditions eg. dried faeces, carpet etc

There is considerable debate over how a persistently FCoV infected cat develops FIP. One theory is that a mutation of the virus occurs within an individual cat. To date the mutant forms of the virus have NOT been found in the secretion s of faeces from cats with FIP. Therefore transmission of mutated FCoV from one cat to the next is considered unlikely under natural conditions. Another idea is that the cat itself is immunocompromised in some way, allowing a normally benign virus to evade the bodies natural defenses

Clinical presentation

This is variable and often complex reflecting variations in the virus itself, the nature of the cat’s immune response and the influences of environmental stress. Affected cats are clinically very unwell with often more than one body system involved. Some will develop thoracic or abdominal effusions (fluid accumulation) in addition to fever, inappetence, weight loss, anaemia and jaundice


This is a complicated and controversial issue due to the similarity between FIP and many other feline diseases. Many of the tests available are not-specific being unable to differentiate between the harmless and mutant forms of the virus

The only conclusive test for FIP is the detection of characteristic microscopic changes in virus by immunohistochemistry of affected tissues from the sick cat


No therapies have been proven to effectively treat FIP. Many immunosuppressive drug combinations have been tried with limited success

In summary FIP is a relatively rare disease occurring mostly in multi-cat households with breeding catteries containing large numbers of cats being the most susceptible


There are FIP vaccines on the market but efficacy is dubious and you are unlikely to find a specialist who would recommend its use