Antemortem diagnosis of feline infectious peritonitis (FIP) is particularly difficult in cats without effusions, of which about 40% have neurological signs indicative of central nervous system (CNS) manifestation.

Aim of this study was to evaluate sensitivity and specificity of a realtime reverse transcription polymerase chain reaction (RT-qPCR) able to distinguish the two feline coronavirus (FCoV) pathotypes (feline infectious peritonitis virus [FIPV] and feline enteric coronavirus [FECV]) in cerebrospinal fluid (CSF) of cats suspected of having FIP.

The study population consisted of 31 cats with confirmed FIP (six with neurological signs) and a control group of 29 cats (ten with neurological signs) for which FIP was considered a differential diagnosis, but which were definitively diagnosed with other diseases. CSF of these cats was tested for presence of feline coronavirus (FCoV) RNA by RT-qPCR and in positive cases, the pathotype was determined according to the S gene sequence. Sensitivity and specificity including 95% confidence intervals (95% CI) were calculated.

FIPV was detected in the CSF of three cats with FIP. In six cats with FIP, FCoV RNA was detected, but virus load was too low to allow pathotyping. FCoV was not detected in any of the control cats.

Specificity of the RT-qPCR was 100% (95% CI 88.1–100.0); sensitivity for detection of any FCoV was 29.0%; sensitivity of detection of the FIPV pathotypes in all cats was 9.7% (95% CI 2.0–25.8), 16.7% in cats with neurological signs.

Specificity of the RT-qPCR was excellent, but a negative test result cannot rule out FIP.

Disclosures

Disclosures to report
Dr. Christian Leutenegger is the Head of Molecular Diagnostics at IDEXX Laboratories, Inc. Dr. Hans-Jörg Balzer and Dr. Nikola Pantchev are employed at IDEXX Laboratories, Ludwigsburg. This laboratory offers the FCoV and FIP virus realtime RT-PCR on a commercial basis and performed the testing in this study. IDEXX played no role in the study design, in the collection and interpretation of data, or in the decision to submit the manuscript for publication. There is no commercial conflict of interest, as the information generated here is solely for scientific dissemination. The authors declare that they have no competing interests.