Table 1.

Categorisation of diagnostic parameters as consistent, doubtful and not consistent with FIP

	Consistent (C)	Doubtful (D)	Not consistent (NC)
History	Cattery with previous cases of FIP or high prevalence of positive serology	—	Households or pet cats without contacts with potential shedders of FCoV
Clinical signs	Fever, effusion, ocular lesions, jaundice, masses, neurological signs	Masses, fever or neurological signs	None of the findings reported for group C or D
Effusion	Macroscopic and cytological pattern consistent with FIP, high protein content, low A/G	Only some of the changes reported for group C	Macroscopic and cytological pattern not consistent with FIP, low protein content, normal A/G
SPE	Hyperproteinemia, increased α2‐ and γ‐globulin, low A/G ratio	One or few electrophoretic abnormalities	Normal electrophoretic pattern
AGP	>1·5 (mg/mL)	0·5 to 1·5 (mg/mL)	<0·5 (mg/mL)
Serology and/or PCR	Positive serology and/or PCR in blood and/or effusions	Positive serology and negative PCR (or vice versa)	Negative serology and/or PCR in blood and/or effusions
Postmortem examination and/or histology	Fibrinous serositis and/or nodular lesions in one or more organs, histology consistent with fibrinous serositis and/or pyogranulomatous foci	Lesions as in group C but atypical localisation or presence of additional potential pathogens (e.g. fungi and bacteria)	Absence of lesions described in group C; presence of lesions consistent with diseases other than FIP (e.g. fibrosis)

SPE serum protein electrophoresis, AGP α1‐acid glycoprotein