can feline coronavirus cause chronic diarrhea without progressing to FIP, and how is it managed?

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Feline coronavirus (FCoV) causes chronic diarrhea in cats without progressing to feline infectious peritonitis (FIP), and this presentation is far more common than previously recognized. FCoV was detected in 65.1% of 493 cats presenting with chronic diarrhea, and was the sole pathogen identified in 23.9% of those cats — making it the most frequently detected enteropathogen in this population.1 This challenges the long-held assumption that FCoV is non-pathogenic in its enteric form.1 The enteric biotype, feline enteric coronavirus (FECV), typically produces mild, self-limiting gastroenteritis, but chronic and treatment-unresponsive diarrhea does occur. Most FECV infections are clinically inapparent or cause transient vomiting and diarrhea; occasionally, however, diarrhea is acute and severe or chronic and unresponsive to treatment.2 Natural FCoV infections are transient in approximately 70% of cats, persistent in approximately 13%, and approximately 5–10% of cats appear resistant to infection entirely.10 FCoV-positive chronic diarrhea is most prevalent in cats under 1 year of age. Cats under 12 months were significantly more frequently FCoV-positive than older cats — 74.1% versus 58.3% of samples, respectively.1 Positivity also peaks seasonally in February and March.1 Co-infection with other enteropathogens is common and should be ruled out before attributing chronic diarrhea solely to FCoV. In the same chronic diarrhea population, Clostridium perfringens toxin DNA was detected in 54.4% of samples, Giardia spp. in 8.4%, Tritrichomonas blagburni in 8.4%, Cryptosporidium in 5.1%, Campylobacter jejuni in 3.4%, Campylobacter coli in 1.6%, Salmonella spp. in 0.8%, panleukopenia virus in 0.8%, and Toxoplasma gondii in 0.5%.1 A comprehensive RT-PCR/PCR diarrheal panel is the appropriate diagnostic tool to identify co-pathogens.1 Persistent FCoV shedding is documented in a meaningful subset of cats with chronic diarrhea. Among cats with repeat sampling, 72.2% of FCoV-positiv