Treatment outcomes and prognostic indicators of primary immune thrombocytopenia in 31 cats: a multicenter retrospective study (2000-2023).

Abstract

BACKGROUND: Primary immune thrombocytopenia (ITP) in cats is rare. Evidence is lacking on effective immunosuppressive protocols, prognosis, and prognostic indicators. HYPOTHESIS/OBJECTIVES: To investigate immunosuppressive treatment outcomes and prognostic indicators of cats with primary ITP. ANIMALS: Thirty-one cats with primary ITP. METHODS: Multi-institutional retrospective cohort study (2000-2023). Cats were identified by searching medical records from 12 institutions. Immunosuppressive treatments and prognostic indicators were studied in association with clinical outcomes. Indicators included age, sex, breed, bodyweight, initial platelet count and PCV, blood urea nitrogen concentration, and blood product administration. Outcomes including medical control (platelet count > 57 000/μL), relapse, remission, death, and survival to discharge were analyzed using logistic regression models. Hospitalization duration, days to medical control, remission, and death were assessed using linear regression models. Survival was assessed using the Kaplan-Meier method. RESULTS: Of the cats included, 27/31 (87%) survived to discharge, 25/31 (81%) achieved medical control, 8/25 (32%) achieved remission, 10/25 (40%) relapsed during immunosuppressive tapering, and 5/10 (50%) had a second relapse. Cats administered corticosteroids and cyclosporine had longer hospitalizations than corticosteroids alone (8.4 ± 0.9 vs 4.4 ± 0.9 days; P = .005). Median survival was not reached. Median follow-up was 315 days (95% CI, 216-1252). CONCLUSIONS AND CLINICAL IMPORTANCE: Cats with primary ITP have a fair short-term prognosis and low remission rate. The frequent relapse rate warrants close monitoring. Besides longer hospitalization durations, combination immunosuppressive treatment did not affect other outcomes, when compared to corticosteroids alone.