Anticoagulant rodenticide toxicosis in nutria (Myocastor coypus) in Thailand

Abstract Nutria (Myocastor coypus) is a large, herbivorous rodent found in Africa, Europe, North America, and Asia. Anticoagulant rodenticide (AR) toxicosis was diagnosed in nutrias based on history taking, clinical signs and chemical analysis, marking the first confirmed case in this species in Thailand. Six out of the eight nutrias in the same herd died, showing initial clinical signs such as abnormal bleeding and abortion in pregnant individuals. The carcasses of the dead nutrias were analysed for exposure to rodenticides and insecticides. Screening tests on liver specimens, using thin-layer chromatography and spectrophotometry, confirmed the presence of AR. In contrast, the two survival nutrias were clinically observed and remained healthy during an 18-month follow-up period. To date, there have been no reports of nutrias with diagnosed AR poisoning. This case likely resulted from rodenticide contamination in agricultural settings, underscoring the importance of proper rodenticide management to protect nontarget species and prevent environment contamination.