AEMV FORUM TWO CASES OF SYSTEMIC CORONAVIRUS- ASSOCIATED DISEASE RESEMBLING FELINE INFECTIOUS PERITONITIS IN DOMESTIC FERRETS IN JAPAN Jin Shigemoto, Yukinori Muraoka, Annabel G. Wise, Matti Kiupel, Roger K. Maes, and Shidow Torisu Abstract A systemic disease of domestic ferrets characterized by pyogranulomatous inflammation was first recognized in Europe and the United States in 2002. The disease closely resembled feline infectious peritonitis and subsequently has been shown to be associated with ferret systemic coronavirus (FRSCV). A definitive laboratory diagnosis of this disease is typically based on a combination of immunohistochem- istry (IHC) and reverse-transcriptase polymerase chain reaction tests to detect FRSCV in granulomatous lesions. In 2010, this feline infectious peritonitis–like disease was first identified in a laboratory ferret in Japan, and laboratory confirmation of the clinical diagnosis was limited to IHC. This report describes 2 cases of systemic coronavirus-associated disease in ferrets presented to Japanese veterinary hospitals. Both presented with pyogranulomatous inflammation in the abdominal cavity, and both cases tested positive for coronavirus antigen by IHC. In 1 case, for which unfixed tissues were available, FRSCV RNA was detected by reverse-transcriptase polymerase chain reaction in the affected tissues. Copyright 2014 Published by Elsevier Inc. Key words: coronavirus disease; ferret; FIP; Japan; pyogranulomatous inflammation F eline infectious peritonitis (FIP) is a fatal, multisystemic, immune-mediated disease of cats caused by a feline coronavirus mutant, generally considered to arise spontaneously from subclinical low-pathogenic or nonpathogenic feline enteric coronavirus.1 Recently, another hypothesis was presented,2 which states that genetically distinct avirulent and virulent forms of feline coronavirus cocirculate in natural cat populations. In ferrets, epizootic catarrhal enteritis, caused by the ferret enteric coronavirus (FRECV), is widely recognized.3,4 More recently, a new ferret systemic coronavirus (FRSCV)-associated ferret disease, closely resembling the granulomatous or dry form of FIP, was reported in the United States, Europe, and Japan.5-7 Although it is unknown whether FRSCV and FRECV are genetically distinct coronaviruses of ferrets, 3 geographically distinct systemic ferret coronavirus strains were found to share a conserved spike (S) gene genotype that was distinguishable from that of 3 independent enteric coronavirus strains.8 Based on this finding, 2 S gene genotype-specific reverse-transcriptase polymerase chain reaction (RT-PCR) assays had been developed that can potentially differentiate FRSCV from FRECV.8 The authors were recently involved with 2 ferret cases that were presented to private veterinary practices with clinical signs consistent with FIP-like disease. All confirmatory testing by immunohistochemistry (IHC) and RT-PCR was conducted at the Diagnostic Center for Population and Animal Health at Michigan State University (Lansing, MI USA) using the previously described methods.3,4,8 � 2014 Published by Elsevier Inc. 1557-5063/14/2101-$30.00 http://dx.doi.org/10.1053/j.jepm.2014.02.006 From the Ouji Pet Clinic, Tokyo, Japan; the Diagnostic Center for Population and Animal Health, Michigan State University, Lansing, MI USA; the Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI USA; and the Miyazaki University Veterinary Teaching Hospital, Miyazaki-city, Japan. Address correspondence to: Jin Shigemoto, Ouji Pet Clinic, 1-15-9 Toshima Kita-ku, Tokyo 114-0003, Japan. E-mail: