EXPRESS: Agreement between point-of-care and external reference laboratory RT-qPCR testing for feline coronavirus in cats with suspected feline infectious peritonitis.

POC FCoV RT-qPCR shows substantial agreement with reference labs, especially in effusion samples.

This prospective study evaluated the diagnostic agreement between a commercially available point-of-care (POC) feline coronavirus (FCoV) RT-qPCR assay and external reference laboratory RT-qPCR testing in 100 client-owned cats suspected of feline infectious peritonitis (FIP). Sample types included effusions (n=62) and ultrasound-guided fine-needle aspirates (FNAs) from liver, spleen, or mesenteric lymph nodes (n=38). FIP diagnosis was established per AAFP/EveryCat guidelines. Overall agreement between the two assays was substantial (Cohen's κ=0.73), with near-perfect concordance for effusion samples (κ=0.81) and moderate agreement for FNAs (κ=0.61). Relative sensitivity was markedly higher in effusions (POC: 98.1%; external lab: 92.3%) compared to FNAs (63.3–64.5% for both platforms), indicating that sample type significantly influences diagnostic yield regardless of platform. Negative predictive values followed similar trends, with effusions outperforming FNAs. Crossing point (Cp) values were moderately correlated between assays with a mean difference of approximately one cycle, suggesting comparable quantitative performance. False negatives from FNAs were attributed to low viral loads and heterogeneous viral distribution within solid tissues. The POC assay demonstrated practical utility through rapid turnaround times, supporting timely clinical decision-making. Authors conclude that POC FCoV RT-qPCR is a reliable alternative to external laboratory testing, particularly when effusion is present, but emphasize that results must always be interpreted in the context of clinical signs and complementary diagnostics, especially when FNAs are the only available sample type.

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