Systemic oxidative stress, selected nonenzymatic exogenous and endogenous antioxidants, and hematologic and biochemical alterations in bitches with pyometra

Objective: To evaluate oxidative stress biomarkers (malondialdehyde [MDA] and total oxidant status [TOS]), selected nonenzymatic endogenous (glutathione [GSH], albumin, and bilirubin), and, for the first time, exogenous (ascorbic acid, α-tocopherol, β-carotene, and retinol) antioxidants together with hematobiochemical alterations in canine pyometra. Methods: 33 bitches were classified into pyometra (n = 17) or control (16) groups based on clinical and hematological evaluations. Ascorbic acid was measured by the phosphotungstate method; GSH, MDA, β-carotene, and retinol spectrophotometrically; α-tocopherol by ELISA; and TOS by a colorimetric assay. Hematobiochemical variables were analyzed using automated analyzers. Results: Bitches with pyometra had higher MDA and TOS than controls (36.30 ± 13.95 µmol/L vs 24.61 ± 4.80 µmol/L and 27.78 ± 15.51 µmol H2O2 Eq/L vs 13.13 ± 1.84 µmol H2O2 Eq/L; Hedges' g = 1.08 and 1.27, respectively). Glutathione tended to increase in pyometra (12.04 ± 10.80 nmol/g Hb vs 6.40 ± 2.97 nmol/g Hb; Hedges' g = 0.68), whereas the other antioxidants were similar between groups. Pyometra was also associated with leukocytosis, neutrophilia, monocytosis, decreased erythrocyte counts and Hct, and increased ALP, ALT, and cholesterol. Conclusions: Canine pyometra is accompanied by systemic oxidative stress and hematobiochemical alterations. However, circulating nonenzymatic antioxidants remained largely unchanged, suggesting complex antioxidant regulation rather than simple depletion. Increased GSH may reflect a thiol-based compensatory response to increased oxidative burden. Clinical Relevance: Nonenzymatic antioxidant regulation in canine pyometra may be more complex than simple depletion. Further studies incorporating disease-severity stratification and tissue-level assessments of both enzymatic and nonenzymatic antioxidants are warranted.