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.Journal of Vete… This challenges the long-held assumption that FCoV is non-pathogenic in its enteric form.Journal of Vete…

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.MSD Vet Manuals 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.Journal of Feli…

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.Journal of Vete… Positivity also peaks seasonally in February and March.Journal of Vete…

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%.Journal of Vete… A comprehensive RT-PCR/PCR diarrheal panel is the appropriate diagnostic tool to identify co-pathogens.Journal of Vete…

Persistent FCoV shedding is documented in a meaningful subset of cats with chronic diarrhea. Among cats with repeat sampling, 72.2% of FCoV-positive cats remained persistently positive across multiple samples.Journal of Vete… The majority of infected cats shed virus in feces for some months before spontaneously ceasing, though recovered cats are susceptible to reinfection with the same or a different FCoV strain.Journal of Feli…

The veterinary literature does not currently describe a specific antiviral treatment protocol for FCoV-associated chronic diarrhea without FIP. The clinical significance of enteric FCoV as a primary pathogen is only now being formally recognized, and the authors of the largest prevalence study note that if FCoV is pathogenic and overlooked, key diagnostic and therapeutic opportunities are being missed.Journal of Vete… Management at this time is directed at identifying and treating co-pathogens detected on the diarrheal panel, as co-infections are present in the majority of affected cats.Journal of Vete…

The risk of FIP development from enteric FCoV infection is approximately 5–12%. Mutations in the spike (S) gene expand viral tropism from enterocytes to macrophages, driving systemic dissemination and the immune-mediated perivasculitis that defines FIP.Journal of Feli… Higher viral load in multi-cat environments is associated with increased likelihood of FIP emergence within a household.Journal of Feli… Approximately 20% of cats in private households and 87% of purebred cats in catteries are seropositive for FCoV.Journal of Feli…

Would you like guidance on interpreting a positive FCoV RT-PCR result in a cat with chronic diarrhea — specifically how to differentiate enteric shedding from early systemic disease?