First report on the occurrence of anticoagulant rodenticides toxicosis in nontarget animals in Thailand.

Background: Anticoagulant rodenticides (ARs) are widely used worldwide to control rodent populations, yet their toxicity to nontarget animal species, such as dogs and cats, raises significant concerns. Until now, there has been no information about the occurrence status of ARs toxicosis in Thailand. This study presents occurrence data on ARs poisoning in animal specimens analysed at the Department of Veterinary Pharmacology, Faculty of Veterinary Science, Chulalongkorn University, Thailand. Data from January 1, 2018, to December 31, 2023, was collected retrospectively, focusing on confirmed ARs intoxication cases identified through chemical analysis using thin-layer chromatography (TLC) and spectrophotometry methods. Detailed information on animal species, ages, sex, and types of animal specimens analysed was included.

Results: During the study period, 35 cases (63.6%) out of 55 tested positive for ARs. Dogs accounted for 77.1% of the ARs-positive cases. Notably, specimens from wild animals and exotic pets, including a turkey, a wild boar, a goose, and three Patagonian mara, were also tested positive for ARs poisoning. Both liver and stomach content specimens showed high agreement in ARs detection, suggesting the potential utility of stomach content analysis alongside liver specimens, which has not been previously reported.

Conclusions: This retrospective study underscores the risk of ARs toxicosis in nontarget species. TLC and spectrophotometry methods serve as reliable screening tools for confirming ARs intoxication diagnosis. This study provided a reference for future research on the epidemiology on ARs toxicosis among nontarget species.