Raw data for: Albumin-to-Globulin Ratio Outperforms Other Acute Phase Proteins in Predicting Treatment Response in Feline Infectious Peritonitis

Objectives This study aimed to: (1) characterize the behaviour of α1-acid glycoprotein (AGP), serum amyloid A (SAA), and haptoglobin at diagnosis, during treatment and post-recovery; (2) evaluate predictive utility of AGP, SAA, haptoglobin, albumin, globulin and albumin-to-globulin ratio (A:G) for distinguishing simple versus challenging remission; and (3) determine reference intervals for AGP, SAA and haptoglobin in recovered cats. Methods Twenty-eight client-owned cats with confirmed FIP received antiviral therapy using remdesivir or GS-441524-based protocols. Serum was collected during treatment and retrospectively analysed for AGP, SAA, and haptoglobin, with albumin, globulin and albumin:globulin (A:G) ratio concentrations included as comparator biomarkers. Linear models assessed the effects of time (Week) and remission type (Simple vs Challenging) on each analyte. Logistic regression assessed associations between biomarker thresholds and remission type. Relapses and APP trends were summarised descriptively. Results A:G ratio was the strongest prognostic marker: >0.4 at week 1 (Odds Ratio [OR] 6.7) and >0.5 at week 4 (OR 20.25) predicted simple remission. APPs showed inconsistent predictive value for remission type and relapse. Persistent APP elevation did not reliably indicate viral activity or justify extended therapy. Within 2-13 days of treatment cessation, three cats relapsed despite normal or equivocal APP and A:G values. Conclusions and relevance The A:G ratio is a simple biomarker with potential to guide treatment duration and predict outcomes in this cohort of cats. Individual APPs may reflect non-viral inflammation and should be interpreted cautiously. Larger, prospective studies are needed to validate A:G thresholds, clarify APP kinetics, and establish standardised reference intervals.