Feline infectious peritonitis (FIP) is a fatal disease caused by feline 
coronavirus (FCoV) infection. FCoV can be divided into serotypes I and II. The 
virus that causes FIP (FIPV) is believed to occur sporadically and spread 
infrequently from cat to cat. Recently, an FIP outbreak from an animal shelter 
was confirmed in Taiwan. FCoV from all the cats in this shelter were analyzed to 
determine the epidemiology of this outbreak. Thirteen of 46 (28.2%) cats with 
typical signs of FIP were identified. Among them, seven cats were confirmed by 
necropsy and/or histopathological examinations. Despite the fact that more than 
one FCoV was identified in this multi-cat environment, the eight FIP cats were 
invariably found to be infected with a type II FCoV. Sequence analysis revealed 
that the type II FIPV detected from fecal samples, body effusions and 
granulomatous tissue homogenates from the cats that succumbed to FIP all 
harbored an identical recombination site in their S gene. Two of the cats that 
succumbed to FIP were found to harbor an identical nonsense mutation in the 3c 
gene. Fecal shedding of this type II virus in the effusive form of FIP can be 
detected up to six days before death. Taken together, our data demonstrate that 
horizontal transmission of FIPV is possible and that FIP cats can pose a 
potential risk to other cats living in the same environment.