Forensic LC-MS/MS Monitoring of Anticoagulant Rodenticide Poisoning in Cats Over a Half-Decade.

BACKGROUND: Anticoagulant rodenticides (ARs) are important toxicants in veterinary forensic investigations involving suspected poisoning in cats. OBJECTIVES: This study aimed to develop and validate a standardized LC-MS/MS-QTRAP method for the simultaneous identification and quantification of eight ARs in gastric matrices from cats and to assess its applicability to veterinary forensic toxicology. METHODS: Automated sample preparation was implemented to reduce inter-analyst variability. Dual confirmation using multiple reaction monitoring (MRM) and enhanced product ion (EPI) spectra was applied to improve identification reliability and minimize false-positive results caused by structurally related compounds. The method was applied to 747 cat forensic toxicology cases submitted between January 2020 and August 2025, in which gastric tissue or gastric contents were available for analysis. RESULTS: ARs were detected in 2.5% of cases (19/747). Coumatetralyl was the most frequently detected AR, followed by flocoumafen and bromadiolone. Flocoumafen was detected despite not being an officially registered active ingredient in Korea, highlighting the need for broad multi-analyte screening. CONCLUSIONS: The standardized LC-MS/MS-QTRAP method enabled reliable detection and quantification of ARs in gastric matrices from cats. This approach provides useful forensic evidence of recent AR exposure in suspected poisoning cases and may support improved toxicovigilance for registered and unregistered rodenticides.