Evaluation of Relationship between Serum Thyroid Hormones and Lipids (cholesterol, triglyceride, HDL-cholesterol and LDL- cholesterol) in Darehshori, Arabian and Mixed Horses

To study the concentration of thyroid hormones (T3, T4) and serum lipids and lipoproteins of apparently healthy horses in different breeds and to find a possible relationship between the concentrations of thyroid hormones and lipids and lipoproteins the present study was carried out on 50 horses including 15 Dareshoori, 15 Arab, and 20 mixed breeds (foreign, Kurdish and Turkmen). These horses were divided in two age categories including 26 adults and 24 under three years old. Based on the results, significant differences were observed in the concentration of triiodothyronine between horses with a body score higher than 7 and less. Based on this result, it can be pointed out that the horses studied in this study with lower body scores have higher levels of serum triiodothyronine. Also, there was a significant difference in the concentration of serum thyroxine hormone in horses at different ages, which could indicate the effect of age on the concentration of thyroid hormones in horses. Among other breeds, there was a significant difference in the serum LDL concentration and means the difference in LDL levels in other breeds; Significant correlations between total cholesterol and triglyceride (r=0.600), total cholesterol and LDL (r=0.853), total cholesterol and VLDL (r=0.600), triglyceride and LDL (r=0.521), triglyceride and VLDL (r=1.000) LDL and VLDL (r=0.521), triiodothyronine and thyroxine (r=0.599) were observed. No significant correlation was observed between the concentrations of thyroid hormones and serum lipids and lipoproteins of the studied horses.