FCoV

Feline coronavirus (FCoV) is a coronavirus that infects cats. It is a single-stranded, positive-sense RNA virus in the genus Alphacoronavirus, family Coronaviridae. FCoV primarily causes enteric infection and is transmitted mainly via the fecal-oral route. In cats, the infection spectrum ranges from subclinical or mild gastrointestinal disease to feline infectious peritonitis (FIP), a fatal systemic disease that can arise when the virus mutates within the host.

Two serotypes have been described in cats, FCoV type I and type II, with type I being more common in natural infections. Transmission occurs through contact with infected feces and contaminated environments, making crowded households, shelters, and multi-cat facilities high-risk settings. Most infections are mild or asymptomatic, with occasional diarrhea or transient fever; many cats clear the virus, while others become intermittent or persistent shedders of FCoV.

FIP develops in a minority of FCoV-infected cats and is thought to result from viral mutation within the host that enables macrophage tropism, leading to granulomatous inflammation in various organs. Clinically, FIP presents as an effusive (wet) form with fluid accumulation in body cavities or a non-effusive (dry) form with organ involvement. Diagnosis is challenging; FCoV RNA detection in feces confirms exposure but does not diagnose FIP. Clinicians use clinical signs, imaging, cytology of effusions, and sometimes tissue biopsy; no single test definitively confirms FIP.

Treatment options are limited; there is no universally approved cure. Antiviral agents such as GS-441524 have shown high efficacy in some settings, but availability and regulatory status vary by country. Prevention focuses on hygiene, minimizing cat crowding, and isolating new animals; vaccination against FCoV/FIP exists in some regions but has variable efficacy and is not universally recommended.