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Feline Coronavirus
Yvonne Drechsler, PhD

College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA, USA

Etiology/Pathophysiology husbandry practices that reduce exposure to feces and
contaminated environments have a tremendous influence
Feline coronavirus (FCoV) is a highly contagious virus on the number of cats exposed to the virus. Although
that exists as two bioforms. Feline enteric coronavirus transmission of the pathogenic FIP virus occurs is contro-
(FECV) is ubiquitous in multicat environments. This versial outbreaks in shelters have been reported. Therefore,
virus commonly causes an asymptomatic infection, quarantine of suspected FIP‐infected cats is advisable.
which can persist in certain individuals. Sporadically and
unpredictably, the infection turns pathogenic, in which
case the virus is referred to as feline infectious peritonitis Signalment
virus (FIPV), causing the highly fatal, systemic immune‐
mediated disease feline infectious peritonitis (FIP). The Although typically a disease of young cats and kittens,
current hypothesis is that FIPV arises from the FECV by the age distribution of affected cats appears to be
mutation, replicates in monocytes and disseminates, bimodal. Cats younger than 2 years of age or geriatric
resulting in vasculitis and pyogranulomatous inflamma- cats are most commonly diagnosed with FIP. In addition,
tion. However, our understanding of the pathophysiol- certain pure breeds, most notably Persians and Burmese,
ogy of FIPV is very limited due to difficulties in replicating appear to be more susceptible. Male and female cats are
the virus in laboratory settings. affected equally in some studies while others show a male
predisposition. Immune‐compromised animals, such as
cats infected with feline leukemia virus (FeLV) or feline
Epidemiology immunodeficiency virus (FIV), are also at increased risk.

Feline coronavirus is distributed worldwide and is ubiq-
uitous in virtually all cat populations. There is great vari- History and Clinical Signs
ability in prevalence among different cat populations.
Two serotypes exist, I and II, with most epidemiologic Typically, cats from shelters, catteries, and multicat
studies indicating that serotype I is more common. households are at higher risk of exposure and develop-
However, most studies have been conducted in countries ment of FIP due to the ubiquitous nature of the enteric
outside the United States so further study on serotype virus in these settings. Stress due to overcrowding may
prevalence in the United States is needed. also contribute to immune compromise and increased
The enteric virus, FECV, is readily transmitted via the susceptibility to infection. Genetic predisposition has
fecal–oral route herefore, the prevalence of FCoV infection also been hypothesized to play a role in increased sus-
is generally associated with the number and density of cats ceptibility in certain breeds.
housed together. The length of time spent in multicat envi- Clinical signs associated with the benign enteric virus
ronments also increases the risk of exposure. For example, are typically gastrointestinal, manifesting as mild vomiting
the risk of exposure was estimated to be five times higher and/or persistent or intermittent diarrhea. In cases of FIP,
for cats living in shelters for longer than 60 days than for cats may be asymptomatic or present with different levels
cats staying for shorter periods of time. Housing and of lethargy and anorexia. Other common findings include

Clinical Small Animal Internal Medicine Volume II, First Edition. Edited by David S. Bruyette.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/bruyette/clinical