Efficacy, Dosing, And Duration Of Antiviral Therapy In Feline Infectious Peritonitis: A Systematic Review Protocol To Support Iscaid Fip Treatment Guidelines

Abstract

Rationale Feline infectious peritonitis (FIP) is a progressive, systemic disease caused by feline coronavirus (FCoV) and characterised by pyogranulomatous inflammation, vasculitis, and variable clinical manifestations. Historically, FIP was considered uniformly fatal, but the emergence of antiviral therapies in recent years has transformed the therapeutic landscape and created an urgent need for rigorous, evidence‑based evaluation of available treatment strategies. Despite increasing research interest, published studies remain highly variable in diagnostic criteria, case definitions, treatment protocols, outcome measures, and methodological quality, making interpretation and comparison challenging.

To ensure that the forthcoming treatment guideline addresses the most relevant and clinically meaningful questions, a panel of 16 stakeholders from 10 countries across six continents was formed. Panel members represent a deliberately broad range of perspectives, including general practitioners, specialist clinicians, virologists, cat owners, and breeders. This diverse group collaboratively drafted, refined, and prioritised the key clinical questions using the PICO (Population, Intervention, Comparator, Outcome) framework.

This systematic review will support the ISCAID (International Society for Companion Animal Infectious Diseases) guideline and will apply the GRADE framework to rate the certainty of evidence and support trustworthy, actionable recommendations.

Objectives

• To compare the efficacy of antiviral therapies for FIP on patient-important outcomes, using GS-441524 as the standard-of-care comparator where applicable. • To evaluate how dose category (very low to very high, in mg/kg/day) and treatment duration (short vs long) affect efficacy and safety. • To explore effect modifiers (e.g., FIP form, diagnostic certainty, route and frequency of administration, baseline severity) on response to treatment, as data allow.