Canine Cushing syndrome elevates oxidative stress that is attenuated by trilostane.

Objective: To evaluate oxidant-antioxidant status in hyperadrenocorticism (HAC) dogs at diagnosis and after trilostane (Adrestan).

Methods: This study, conducted from June 2024 through March 2025, enrolled 25 dogs with HAC and 21 healthy control dogs. Serum malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, total oxidant status (TOS), total antioxidant capacity (TAC), and oxidative stress index (OSI) were analyzed before and after treatment.

Results: The study included 25 dogs with HAC (14 treated with trilostane, 1 mg/kg, twice daily for 45 days) and 21 healthy controls. At baseline, HAC dogs had significantly elevated oxidative stress markers (MDA, 10.28 μmol/L; TOS, 35.68 μmol H2O2 equivalent (Equiv)/L; OSI, 4.60 arbitrary units (AU)) compared to controls, whereas SOD (44.77 U/mL) and TAC (0.96 mmol/L) remained similar. After trilostane treatment, oxidative stress significantly improved, including decreases in MDA (7.91 → 4.28 μmol/L), TOS (30.82 → 17.85 μmol H2O2 Equiv/L), and OSI (3.61 → 2.14 AU); increased SOD (46.25 → 56.06 U/mL nonsignificant); but no change in TAC (0.97 → 0.94 mmol/L).

Conclusions: These findings demonstrated elevated oxidative stress in HAC dogs that was effectively ameliorated by trilostane.

Clinical relevance: This study first provides comprehensive documentation of oxidative stress in dogs with HAC and its mitigation after trilostane treatment. Significant oxidative imbalance in canine HAC supports monitoring redox parameters as part of disease management.