Multiplex fluorescent immunocytochemistry is a complementary test for the diagnosis of feline infectious peritonitis: a diagnostic clinical trial.

The study included 84 cats with known FIP outcome status, comprising 58 FIP-positive cats and 26 non-FIP control cats.

Excerpt verified in the source — verbatim, in the source's own language“Of these 84 included cases, 58 cats had FIP (n = 35 diagnosed via histopathology/IHC and n = 23 diagnosed via clinical data + positive response to antiviral therapy) and 26 did not have FIP (control cases), according to the criteria described above.”

This establishes the analyzed clinical cohort composition for the diagnostic trial. It does not establish anything about FeLV prevalence or FeLV outcomes.

MF-ICC analysis was available for 85 samples representing 69 cats after exclusions for unrecorded and non-diagnostic samples.

Excerpt verified in the source — verbatim, in the source's own language“Thus, a total of 85 MF-ICC samples representing 69 cats (50 FIP cats and 19 control cats; 16 repeat samples) were available for analysis.”

This defines the sample basis for the MF-ICC diagnostic performance analysis. It also shows that not every enrolled cat contributed an interpretable MF-ICC result.

At a threshold of at least one positive cell, MF-ICC had 77.7% diagnostic accuracy, 76.6% sensitivity, 81.0% specificity, 92.4% PPV and 53.1% NPV in the study cohort.

Excerpt verified in the source — verbatim, in the source's own language“Test MF-ICC (n = 85) Serology (n = 28) RT-PCR (n = 34) Serum A:G <0.6 (n = 68) Diagnostic accuracy (%) 77.7 (67.3–85.9) 75.0 (55.1–89.3) 69.4 (51.9–83.7) 76.5 (64.6–85.9) Sensitivity (%) 76.6 (64.3–86.3) 94.4 (72.7–99.9) 58.3 (36.6–77.9) 79.6 (64.7–90.2) Specificity (%) 81.0 (58.1–94.6) 40.0 (12.2–73.8) 91.7 (61.5–99.8) 71 (64.7–90.2) PPV (%) 92.4 (83.4–96.8) 73.9 (62.8–82.6) 93.3 (67.5–99.0) 83.3 (72.5–90.5) NPV (%) 53.1 (41.0–64.9) 80.0 (34.0–96.9) 52.4 (39.9–64.5) 65.4 (52.2–75.9)”

This supports MF-ICC as a moderately sensitive and specific diagnostic assay for FIP in this selected feline clinical cohort. It does not establish MF-ICC as definitive or sufficient as a standalone diagnostic test.

On a per-cat basis, considering any positive MF-ICC sample as positive for that cat, MF-ICC diagnostic accuracy was 81.1%, sensitivity 80.0% and specificity 84.2%.

Excerpt verified in the source — verbatim, in the source's own language“Table 7 Diagnostic performance of the multiplex fluorescent immunocytochemistry (MF-ICC) assay at a threshold of ⩾1 positive cell reported on a per-cat basis (n = 69 cats) Parameter FIP Non-FIP MF-ICC positive 40 3 MF-ICC negative 10 16 Diagnostic accuracy (%) 81.1 (69.9–89.6) Sensitivity (%) 80.0 (66.3–90.0) Specificity (%) 84.2 (60.4–96.6) PPV (%) 93.0 (80.9–98.5) NPV (%) 61.5 (40.6–79.8)”

This indicates that per-cat interpretation with multiple possible sample sites produced slightly higher diagnostic accuracy than the per-sample comparison. It does not prove that sampling multiple sites will always improve diagnosis in all clinical settings.

The authors concluded that MF-ICC should be considered complementary to other ante-mortem diagnostic assays for FIP rather than a perfect standalone test.

Excerpt verified in the source — verbatim, in the source's own language“MF-ICC is an imperfect test but is considered complementary to other commonly used ante-mortem diagnostic assays for FIP. It can be used alongside RT-PCR and other minimally invasive tests to build a case for FIP in an individual patient.”

This captures the authors' clinical interpretation of the diagnostic assay. It is not a treatment recommendation and does not relate directly to FeLV.

The study's diagnostic performance estimates may be affected by a high prevalence of FIP-positive cats and relatively low numbers of FIP-negative control cats.

Excerpt verified in the source — verbatim, in the source's own language“Limitations of this study include relatively low numbers of FIP-negative cases, which is likely a result of the clinical trial recruitment design.”

This is an author-stated limitation affecting confidence in diagnostic specificity, PPV and NPV estimates. It does not invalidate the findings, but it limits how broadly the reported metrics should be generalized.

The source does not provide evidence about FeLV treatment, FeLV diagnosis, or FeLV clinical outcomes.

FeLV is mentioned only as part of point-of-care testing in the diagnostic workup for suspected FIP cases. Applying this study's FIP/FCoV diagnostic findings to FeLV would not be supported by the document.