Biomarkers of oxidative stress as an assessment of the redox status of the liver in dogs

Abstract

Background: Oxidative stress is associated with a diverse group of liver disorders across species. Objectives: Determine whether glutathione (GSH) concentration in plasma and red blood cells correlates with liver GSH concentration in dogs and evaluate whether other markers of systemic oxidative stress, plasma vitamin E and urine 8-isoprostanes/creatinine (F 2 -IsoPs/Cr) concentrations, correlate with liver GSH. Animals: Thirty-four client-owned dogs undergoing clinically indicated liver biopsy and 15 healthy control dogs. Methods: Prospective, observational cross-sectional study. Urine and blood were collected before liver biopsy. Plasma, erythrocyte, and liver GSH were measured using high performance liquid chromatography (HPLC); vitamin E was measured by HPLC, and F 2 -IsoPs/Cr was measured by gas chromatography/mass spectrometry. Results: All dogs were treated at the discretion of the attending clinician (24/34 received antioxidants; 4/34 fed therapeutic liver diet), which included dogs with primary or secondary liver disease (inflammatory (n = 21), metabolic (n = 9), vascular (n = 2), and neoplastic (n = 2)). Median GSH concentrations in plasma, erythrocyte, and liver were 0.18 mg/dL (range 0.14 to 0.56 mg/dL), 56.7 mg/dL (18.3 to 79.2 mg/dL), and 181 mg/dL (39.9 to 527 mg/dL), respectively. No significant correlations were found between liver GSH and erythrocyte GSH, plasma GSH, vitamin E, or F 2 -IsoPs/Cr. Dogs undergoing clinically indicated liver biopsy had significantly higher urine F 2 -IsoPs/Cr than did healthy controls (5.89 vs 2.98 ng/mg; P