Anticoagulant rodenticide accumulation in the liver and plasma of pigeons (Columba livia) in Thailand.

Background: Anticoagulant rodenticides (ARs) are widely used worldwide to control rodents. Currently, many countries are considering the use of ARs, which results in widespread accumulation and poisoning of nontarget animals. Nontarget pigeons (Columba livia) typically live near human communities and agricultural areas. These birds are at high risk of accidental daily exposure to ARs. Aim: This study aimed to evaluate ARs in the liver and plasma of pigeons living in rural and urban areas of Thailand. Methods: Bird samples were characterized by sampling location, age, body weight (BW), and body condition score. Liver and plasma samples were extracted using liquid-liquid extraction with diethyl ether and analyzed for coumatetralyl and warfarin by liquid chromatography-mass spectrometry. Results: Coumatetralyl and warfarin were detected in pigeons from both rural and urban areas. Both subadult and adult birds showed the presence of these two compounds, which were mainly detected in rural areas. The increase in BW was compared with the accumulation of coumatetralyl and warfarin, and a significant difference was observed. In addition, the concentration of coumatetralyl was significantly higher in the liver than in the plasma. The plasma concentrations of coumatetralyl and warfarin were 0.19-0.50 and 0.12-2.41 ng/ml, respectively. In the liver, coumatetralyl levels were higher than those of warfarin, with concentrations ranging from 0.07- to 3.33-ng/g wet weight and from 0.12- to 0.50-ng/g wet weight. Conclusion: AR use in human settlements and agricultural areas poses a high risk of accumulation in nontarget animals, such as pigeons. The findings of this study indicate coumatetralyl and warfarin in various concentrations in pigeon hepatic and plasma samples.