Proceeding of Veterinary and Animal Science Days 2018, 6th- 8th June, Milan, Italy HAF © 2013 Vol. V, No. 1s ISSN: 2283-3927 l Feline infectious peritonitis (FIP) is a fatal disease in which the definitive diagnosis is achieved by immunohistochemistry (IHC) on post-mortem biopsies (Pedersen, 2007). The clinical suspicion is aroused by signalment, clinical signs and several laboratory tests, including alpha-1- acid glycoprotein measurement for which the only validated kit is no longer available (Paltrinieri et al., 2007). Paraoxonase-1 (PON-1) is a serum enzyme with antioxidant activity, considered as a negative acute phase protein in several species (Novak et al., 2010). Since inflammation plays a major role in FIP, and due to the high susceptibility of cats to oxidation, it could be of great interest the evaluation of this enzyme as a diagnostic marker for FIP (Tecles et al., 2015). The aim of this study was to measure paraoxonase-1 in healthy cats and cats with clinical signs consistent with FIP (both wet or dry form), in order to evaluate the utility of this parameter in the diagnosis of FIP. Sixty-two cats were enrolled and divided into three groups: healthy (n=16), IHC-confirmed FIP (n=22) and NON FIP with similar clinical signs (n=24). PON-1 was measured on one sample of serum, using an enzymatic method, already validated in cats (Rossi et al., 2014). Results showed significantly lower PON-1 activity in FIP cats (mean ± SD: 29.1 ± 16.3 U/mL; median: 24.4; IQR: 16.6- 38.3), compared with healthy cats (90.1 ± 24.1 U/mL; median: 86.0; IQR: 76.7-105.7; P<0.001) and with “non-FIP” cats (55.9 ± 28.3 U/mL; median: 51.9; IQR: 35.7-68.8, P<0.001). A significant difference was also found between healthy and “non-FIP” cats (P<0.001). The receiver operating characteristic (ROC) curve demonstrated that PON-1 may discriminate cats with and without FIP (AUC 0.88; CI 95%, Figure 1). At the cut-off that maximizes the diagnostic power of the test (40,70 U/mL), sensitivity and specificity for FIP were 77% each, suggesting that PON-1 may be a reliable marker in association with other confirmatory tests and with signs consistent with the disease. Keywords Paraoxonase-1, Feline Infectious Peritonitis, Diagnostic marker, Cut-off, Cat. CORRESPONDING AUTHOR Sara Meazzi sara.meazzi@unimi.it JOURNAL HOME PAGE riviste.unimi.it/index.php/haf Preliminary data about Paraoxonase-1 (PON-1) as a marker for Feline Infectious Peritonitis (FIP). S. Meazzi1,*, R. Ferriani3, S. Paltrinieri1,2, A. Giordano1,2 1 Department of Veterinary Medicine, Università degli Studi di Milano, Via Celoria, 10 – 20133 Milan, Italy. 2 Veterinary Teaching Hospital, Via dell’Università, 6 – 26900 Lodi, Italy. 3 Ospedale Veterinario San Francesco, Via Newton 2 – 20148, Milan, Italy. http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en Proceeding of Veterinary and Animal Science Days 2018, 6th- 8th June, Milan, Italy 48 HAF © 2013 Vol. V, No. 1s ISSN: 2283-3927 References Novak F., Vavrova L., Kodydkova J., Novak F.Sr., Hynkova M., Zak A., Novakova O., 2010. Decreased paraoxonase activity in critically ill patients with sepsis. Clinical and Experimental Medicine. 10(1), 21-25. Paltrinieri S., Giordano A., Tranquillo V., Guazzetti S., 2007. Critical assessment of the diagnostic value of feline alpha1- acid glycoprotein for feline infectious peritonitis using the likelihood ratios approach. Journal of Veterinary Diagnostic Investigation. 19(3), 266-272. Pedersen N.C. , 2014. An update on feline infectious peritonitis: Diagnostics and therapeutics. The Veterinary Journal. 201, 133-141. Rossi G., Giordano A., Costarelli E., Moretti P., Paltrinieri S., 2014. Analytical validation of a paraoxon-based method to measure the activity of paraoxonase-1 in feline serum. 2014. ACVP and ASVCP annual meeting, Atlanta, Nov 8th-12th, 2014. Published in: Veterinary Clinical Pathology, 43:E18. Tecles F., Caldín M., Tvarijonaviciute A., Escribano D., Martínez-Subiela S., Cerón J.J., 2015. Serum biomarkers of oxidative stress in cats with feline infectious peritonitis. Research in Veterinary Science. 100, 12-17. 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 T P F ( S e n si ti vi ty ) FPF (1 - Specificity) No discrimination PON-1 (0,883) Figure 1: ROC curve for Paraoxonase-1. The furthest point from the no-discrimination curve is the one that maximizes the diagnostic power of the test, where sensitivity and specificity for FIP were 77% each. http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en