Veterinary Student University of Wisconsin Madison, WI, United States
Human non-Hodgkin lymphoma, which resembles canine multicentric lymphoma (CML), is associated with herbicides and volatile organic compounds (VOCs). However, it is not known whether these genotoxic chemicals are associated with CML, or early DNA damage, in dogs. We hypothesized that VOC and herbicide exposures would associate with both early DNA damage and CML in dogs. We utilized banked blood and urine from the Golden Retriever Lifetime Study, in 30 CML cases and 30 matched controls at time of CML diagnosis (T0) and one year prior (T-1y). We measured urinary concentrations of the herbicides 2,4-D and glyphosate, and metabolites of the VOCs benzene, xylene, and 1,3-butadiene in all dogs at T0 and T-1y. Whole blood DNA strand breaks and oxidized DNA bases were detected with the alkaline comet assay, with or without FpG. DNA damage was compared between cases and controls using Wilcoxon signed ranks tests and was correlated with herbicide and VOC exposures using Spearman rank order. To date, median oxidative DNA damage (as percent comet tail) at T-1y was 4.6 (0-23.2) in 10 cases and 1.4 (0-14.8) in 10 matched controls (P = 0.10). Ongoing assays will further assess oxidative DNA damage in CML prior to diagnosis and its association with herbicide and VOC exposures. If oxidative DNA damage is associated with chemical exposures in dogs that later develop CML, this could support targeted screening and environmental prevention measures in high-risk breeds.
