CPD ACCREDITED ARTICLE
The FIP Jigsaw-Puzzle
Dr Emma Hooijberg BVSc GPCert (SAP) DipECVCP
Department of Companion Animal Clinical Studies,
University of Pretoria Email: [email protected]
Feline infectious peritonitis is a systemic disease caused by a mutated form of the feline
enteric coronavirus (FCoV). Although the prevalence of enteric coronavirus infection is high,
around 90% in catteries, only 5% of these cats, at the most, will go on to develop FIP.1
The pathogenesis of FIP is related to an aberrant immunological and inflammatory response to this virulent mutated virus (FIPV). There are two forms of FIP.
The “wet” form occurs as a result of inflammation of
serosal surfaces (e.g. pleura, peritoneum) and is associated with the presence of body cavity effusions.
The “dry” form is characterised by granulomatous lesions in organs like the kidney, intestines, abdominal
lymph nodes, liver, eyes and CNS.2 The wet form is
more common, with ascites usually present.3 The wet
and dry forms represent two extremes of one disease,
and patients may present with clinical signs and lesions anywhere on the continuum between them. FIP
is invariably fatal.
There is unfortunately no simple definitive test for FIP.
The diagnosis of FIP can be compared to making a
jigsaw puzzle, where various puzzle pieces need to be
fitted together to complete the picture.
The important corner pieces
Signalment: Although FIP can occur in cats in of
any age, 50-70% of FIP cases occur in cats under one
year of age.
Cats from multi-cat households, catteries or rescue
centres with high population densities are exposed to
high viral loads of FCoV in faeces and easily become
infected. Stressors occurring during this time, like rehoming or neutering, decrease the chance that the
animal will eliminate the virus. Cats with immune-suppression are also predisposed. Purebred cats appear
to be more susceptible, however the at-risk breeds
vary in different studies in different regions and susceptibility may in fact be related to specific bloodlines
within a breed rather than the breed itself.2 Male cats
and intact individuals are predisposed.4
Effusion: Ascites, thoracic and/or pericardial effusion
characterise the wet form of FIP. It should be kept in
mind however that less than half of effusions in cats
are caused by FIP, and it is the characteristics of the
effusion, not the mere presence, that make up this important piece of the FIP puzzle.1
Results from effusion analysis, in particular total protein, albumin:globulin (A/G) ratio and PCR, have
a higher diagnostic value than tests performed on
blood.3 The following are typical for an FIP effusion:
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