Antioxidant Status and Biomarkers of Oxidative Stress in Dogs with Congestive Heart Failure

Alterations in antioxidant status and oxidative stress have been documented in dogs with dilated cardiomyopathy (DCM). The purpose of this study was to more broadly assess this relationship in dogs with congestive heart failure (CHF). Malondialdehyde (MDA), 8-F2α-isoprostane, protein carbonyls, reduced (GSH) and oxidized (GSSG) glutathione, vitamins A, C, and E, and oxygen radical absorbance capacity (ORAC) were measured from a single venous blood sample from dogs with CHF secondary to DCM or chronic valvular disease (CVD) and in healthy controls. Nineteen dogs with CHF (14 CVD and 5 DCM) and 12 healthy controls were enrolled in the study. Concentrations of 8-F2α-isoprostane (CHF: 44.6 pg/mL [range, 27.1–98.0 pg/mL], controls: 25.3 pg/ mL [range, 11.1–80.4 pg/mL]) but not MDA (CHF: 4.11 μM [range, 1.89–6.39 μM], controls: 3.88 μM [range, 2.14-4.72 μM]) or protein carbonyls (0.69 nmol/mg protein [range, 0.37-1.67 nmol/mg protein], controls: 0.80 nmol/mg protein [range, 0.40-1.14 nmol/mg protein]) were significantly higher in the dogs with CHF than in the controls. Vitamin E concentration (CHF: 2,215 μg/ dL [range, 916–3,499 μg/dL], controls: 2,820 |xg/dL [range, 1,738-3,775 μg/dL]) and GSH:GSSG (CHF: 12.0 [range, 3.69-30.1], controls: 22.7 [range, 12.5–227]) were significantly lower, whereas ORAC (CHF: 824 μmol Trolox equivalent/L [range, 304–984], controls: 497 μmol Trolox equivalent/L [range, 258–759]) and vitamin C (CHF: 0.90 mg/dL [range, 0.55-2.02 mg/dL], controls: 0.72 mg/dL [range, 0.43-0.85 mg/dL]) concentrations were higher in dogs with CHF than in controls. Vitamin A concentrations were not different between dogs with CHF and controls. No differences in any of the parameters were detected between dogs with DCM versus those with CVD. Some antioxidant defenses are decreased in dogs with CHF, and some biomarkers of oxidative stress are increased in dogs with CHF. The effect of dietary interventions to correct this imbalance in antioxidant defenses warrants further study.