Lessons Learned from Feline Infectious Peritonitis Cases

Abstract

Feline infectious peritonitis (FIP) is a fatal disease in cats caused by a mutant form of the feline enteric coronavirus (FECoV). There are two forms of FIP, they are effusive or “wet” and non-effusive/granulomatous or “dry”. The diagnosis of FIP is still difficult, especially in dry form. The aim of this study was to describe a better test for the diagnosis approach of FIP. We performed a literature review and case study of FIP with “wet” and “dry” forms, then lessons learned from the best test used for the diagnosis of FIP. The wet form is easily recognized with ascites and/or dyspnea due to fluid accumulation. The dry form of the disease is less easily recognized as it is not associated with fluid accumulations, but instead with masses in the liver, spleen, kidney, or other organs, including the nervous system and the eye. The diagnosis of FIP is difficult because a serology test for FECoV antibodies is positive in most cats. However, it can be useful only if the serology titer is very high and the cat has the typical polyclonal gammopathy and the appropriate clinical signs. Examination of effusion fluid in the wet form for macrophages containing the coronavirus is the preferred way to confirm the diagnosis. Some laboratories offer a histopathologic examination and a reverse-transcription polymerase chain reaction (RT-PCR) test for the detection of the viral antigen in inflammatory fluids. As the clinical symptoms vary in cats infected with FIP, further diagnostic methods become a challenge in the clinic due to the complexity of the disease which often requires many laboratory tests to confirm the diagnosis of FIP.