Frequency of anticholinesterase insecticide positive samples in non-target animals in Thailand

Abstract Background Anticholinesterase insecticides (antiChE), including organophosphates and carbamates, are widely used to control crop pests in agriculture, household pests, and animal parasites, making them a potential source of poisoning in both humans and animals. This retrospective study aimed to document the frequency of antiChE positive samples in animal specimens analysed at the Department of Veterinary Pharmacology, Faculty of Veterinary Science, Chulalongkorn University from January 1, 2019, to December 31, 2024 using a cholinesterase kit based on Ellman’s method, to raise awareness and mitigate the risk to non-target animals. Results During the study period, specimens from 61 animal cases involving accidental or environmental exposure were submitted for antiChE detection. Of these, 16 cases (26.2%) tested positive. Dogs accounted for the majority of positive cases (11/16; 68.75%), followed by chickens (2/16; 12.5%), cats (2/16; 12.5%), and one duck (1/16; 6.25%). Stomach ingesta were the most frequently submitted specimens and consistently yielded antiChE positive results in confirmed cases. Conclusion This study underscores the ongoing risk of cholinesterase inhibitors in domestic animals and avian species, which are non-target of these compounds. The cholinesterase kit proved to be a useful screening tool, particularly when ingestion was not directly observed. Stomach ingesta specimens were the most reliable sample type for detecting antiChE poisoning. This study provided reference data for future research on antiChE toxicosis among non-target species.