Glyphosate detection in the duodenal fluid of horses with gastric ulcer syndrome

Abstract

The hay producing plants, concentrate, straw and meadows could be contaminated by the aerosols of glyphosate based herbicide during spraying process of crops and pre-harvest desiccation treatment of cereals. The aim of this study is to investigate the concentration of glyphosate in the duodenal fluid of horses with gastric ulcer syndrome. The stomach and duodenum of referred untreated horse patients (n=92) with colic, weight loss, diarrhoea, anemia or performance intolerance were endoscopically examined right after the admission. Duodenal fluid (40 ml) was collected from the duodenal region where the papilla duodeni major is located. Hematology and clinical chemistry data were examined. The concentration of glyphosate in serum and duodenal fluid samples were analysed using a competitive ELISA and control analysis had also been done with HPLC. Statistical differences between groups were determined by the non-parametric Mann-Whitney-test using a significant level of p≤0,05. Glyphosate was detected in all duodenal fluid (median 12,2 ng/ml; 1st quartile 4,0 ng/ml; 3rd quartile 19,3 ng/ml; min 0,6 ng/ml; max. 192,9 ng/ml) and blood samples (1,79 ng/ml; 1,0 ng/ml; 2,8 ng/ml; 0,2 ng/ml; 3,7 ng/ml) of all horses. Glyphosate concentrations of duodenal fluid samples are significantly higher than in blood samples (Mann Whitney U-test, p≤0,05). The concentration of glyphosate in the duodenal fluid was significantly higher in horses with squamous gastric disease (grade 4/4; n=11/92) compared to horses with normal squamous mucosa (grade 0/4, n=10/92) (median: 19,8 ng/ml versus 8,4 ng/ml). Horses with glandular gastric disease and a grade 4/4 (n=9/92) had higher concentrations of glyphosate in the duodenal fluid than horses with normal glandular mucosa (grade 0/4; n=9/92) (median: 19,2 versus 11,1). The Gamma-Glutamyltransferase (GGT) enzyme activity is significantly higher in the group of horses with lower concentration of glyphosate in the duodenal fluid (≤12,2 ng/ml) compared with the group with higher concentration of glyphosate (>12,2 ng/ml) (median 279,5 versus 101,9 U/L). During autumn the horses had higher concentrations of glyphosate in duodenal fluid (n=18; median 14,3) compared with lower concentrations in spring time (n=34; median 8,1 ng/ml). Horses kept around big cities had significantly higher concentrations of glyphosate in the duodenal fluid in comparison to horses living in the countryside (medians 17,8 ng/ml versus 7,5 ng/ml).