Long-term efficacy of cyclosporine and interferon-ω in feline chronic gingivostomatitis: insights from SDAI scores.

Abstract

BACKGROUND: Feline chronic gingivostomatitis (FCGS) is a challenging disease with unclear causes and limited treatment options. The most effective treatment for FCGS is tooth extraction. However, most cats require additional drug treatment for refractory FCGS even after undergoing extractions. We hypothesized that the combination of interferon-ω (IFN) and cyclosporine (CsA) would improve clinical outcomes. This study aimed to evaluate the long-term efficacy of IFN and CsA in FCGS using Stomatitis Disease Activity Index (SDAI) scores. In this study, the treatment process was divided into two stages: in the surgical stage (Stage 1), all cats underwent tooth extraction combined with submucosal IFN injection; in the immunomodulatory stage (Stage 2), additional IFN/CsA treatment was administered to cats with refractory FCGS. RESULTS: The therapeutic response was monitored during treatment period using SDAI scores. The patients were classified into four groups by oral examination: Group A (Surgical remission), Group B (Substantial improvement to resolution), Group C (Partial improvement), and Group D (No response). Patients achieving complete remission following surgical treatment were classified into Group A (39.2% of all cases). Patients assessed as having refractory FCGS after surgical treatment accounted for 60.8% of all patients and were divided into three groups. Groups B, C, and D accounted for 52.1%, 45.2%, and 2.7% of refractory cases, respectively. In addition, the SDAI scores showed significant differences across groups at all time points. Receiver operating characteristic curve analyses identified key SDAI thresholds for early classification: a Tscore cutoff of 6.5 and a T-Tscore change cutoff of - 14.5 effectively distinguished Group A. The long-term follow-up revealed that cats classified as "subs-resolution" at Twere significantly more likely to sustain clinical improvement for ≥ 2 years than those in the "non-partial" group. CONCLUSION: This study showed that the combination of IFN and CsA is an effective therapeutic option for refractory FCGS, with more than half of treated cats showing clinical improvement and 76.5% of those achieving subs-resolution at 6 months maintaining remission for 2-6 years. These findings further indicate that evaluating SDAI scores six months after a three-month course of immunomodulatory therapy provides prognostic value for predicting long-term outcomes.