03-02-2025 | Original Article
A study on the correlation between serum thyroid hormone levels and oxidative stress parameters in clinically healthy and sick dogs
Published in: Comparative Clinical Pathology
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Thyroid hormones and oxidative status are both affected by the health condition of the dog. The association between thyroid hormones and oxidative stress (OS) in different health conditions of dogs is not fully elucidated. This study was conducted to evaluate the possible relationship between serum concentration of total and free thyroid hormones (T4, fT4, T3, and fT3) and two OS parameters including malondialdehyde (MDA) and total anti-oxidant capacity (TAC) in clinically healthy dogs as well as dogs with different diseases. Sixty-seven clinically healthy dogs without a history of thyroid disorders and 17 dogs with different health complaints that were referred to the clinics were included in this study. Serum T4, fT4, T3, and fT4 concentrations were assayed by a competitive ELISA method. Serum MDA concentration and TAC were determined by a spectrophotometric method. While all thyroid hormones showed statistically the same levels between healthy and sick dogs (p > 0.05), serum MDA concentration in sick dogs was significantly higher than healthy animals. Moreover, healthy dogs showed appreciably higher TAC as compared to sick animals. Serum T4 concentration demonstrated a direct correlation with serum TAC and an inverse correlation with serum MDA in healthy dogs. The correlation was absent in sick animals. Higher serum levels of T4 (but not fT4, T3, and fT3) are associated with better oxidative status in healthy dogs. In mild to moderately sick dogs without non-thyroidal illness syndrome, no correlation is present between serum thyroid hormones and OS parameters.