Feline coronavirus (FCoV) is a positive-stranded RNA virus that infects cats worldwide. It is a coronavirus of the species Alphacoronavirus 1 which includes canine coronavirus (CCoV) and porcine transmissible gastroenteritis coronavirus (TGEV). It has two different forms: feline enteric coronavirus (FECV) that infects the intestines and feline infectious peritonitis virus (FIPV) that causes the disease feline infectious peritonitis (FIP). Feline coronavirus is typically shed in feces by healthy cats and transmitted by the fecal-oral route to other cats. In environments with multiple cats, the transmission rate is much higher compared to single-cat environments. The virus is insignificant until mutations cause the virus to be transformed from FECV to FIPV. FIPV causes feline infectious peritonitis, for which treatment is generally symptomatic and palliative only. The drug GS-441524 shows promise as an antiviral treatment for FIP, but at the moment it still requires further research. The drug GC376 is also being studied and developed. Prevalence Feline coronavirus is found in cat populations around the world. The only known exceptions are on the Falkland Islands and the Galapagos, where studies found no occurrences of FCoV antibodies in cats tested. Virology Feline enteric coronavirus (FECV) Feline enteric coronavirus is responsible for an infection of the mature gastrointestinal epithelial cells (see also enterocytes, brush border, microvilli, villi). This intestinal infection has few outward signs, and is usually chronic. The virus is excreted in the feces of the healthy carrier, and can be detected by polymerase chain reaction (PCR) of feces or by PCR testing of rectal samples. Cats living in groups can infect each other with different strains of the virus during visits to a communal litter tray. Some cats are resistant to the virus and can avoid infection or even becoming carriers, while others may become FECV carriers. Carriers may heal spontaneously, but acquired immunity may be short, and they may go on to reinfect, usually within a few weeks, if they are living in a group with healthy, but persistent, excretory carriers. Some cats never heal, and the excretory phase remains permanently. Feline infectious peritonitis virus (FIPV) and Feline infectious peritonitis The virus becomes feline infectious peritonitis virus (FIPV) when random errors occur in the virus infecting an enterocyte, causing the virus to mutate from FECV to FIPV. FIPV causes a lethal, incurable disease: feline infectious peritonitis (FIP). In their pre-domestication natural state, cats are solitary animals and do not share space (hunting