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.