Antioxidant status and biomarkers of oxidative stress in dogs with lymphoma.

Background: Oxidative stress might play a role in carcinogenesis, as well as impacting morbidity and mortality of veterinary cancer patients. The purpose of this study was to evaluate antioxidant concentrations and biomarkers of oxidative stress in dogs with newly diagnosed lymphoma before treatment and once in remission, with comparison with healthy controls. Hypothesis: Dogs with lymphoma have increased oxidant and reduced antioxidant concentrations compared with healthy controls, and that these abnormalities normalize once remission is achieved. Animals: Seventeen dogs with lymphoma and 10 healthy controls. Methods: Prospective, observational study. Measures of oxidative stress [malondialdehyde and total isoprostanes (isoP)] and antioxidants [α-tocopherol, γ-tocopherol, oxygen radical absorbance capacity (ORAC), and glutathione peroxidase (GSHPx)] were assessed in dogs with newly diagnosed lymphoma before treatment compared with healthy control dogs. The same parameters were measured in the dogs with lymphoma on week 7 of the chemotherapy protocol when all dogs were in remission. Results: At baseline, dogs with lymphoma had significantly lower α-tocopherol (P <.001) and γ-tocopherol (P= .003) but higher GSHPx (P= .05), ORAC (P= .001), and isoP (P < .001) compared with healthy controls. In the dogs with lymphoma, α-tocopherol concentrations were higher (P= .005) and ascorbic acid were lower (P= .04) after treatment. Conclusions and Clinical Importance: Results suggest that dogs with lymphoma have alterations in oxidant and antioxidant concentrations and that the status of some of these biomarkers normalize after remission. Further studies are warranted to determine whether antioxidant interventions to correct these are beneficial in the treatment of canine lymphoma.