Morris D D, Garcia M
Am J Vet Res. 1983 Mar;44(3):503-7.
Adult horses showed a mild diurnal variation in equine plasma thyroxine (T4) concentrations, but not triiodothyronine (T3). Plasma T4 concentrations tended to be higher between 5 PM and 8 PM than at 8 AM. Increases in plasma T4 and T3 were similar in adult healthy horses given 5, 10, or 20 IU of thyroid-stimulating hormone (TSH). The T4 peaked at approximately twice (2.0 +/- 0.4 times) as high as the base line at 6 to 12 hours after the TSH was given. The greatest change from base line T3 occurred at 1 to 3 hours after the TSH was given, but the magnitude of increase was widely variable (4.36 +/- 2.49 times as high as base line). The following method for doing the equine TSH-response test was suggested: (i) prepare plasma or serum sample for determining base line T4 and T3, (ii) inject 5 IU of TSH IM, (iii) prepare plasma or serum samples at 3 and 6 hours after the TSH was injected, and (iv) freeze samples at -20 C until T4 and T3 determination by radioimmunoassay. Treatment of horses with phenylbutazone for 5 days caused a significant decrease in base line T4 and T3 in horses (P less than 0.05). However, phenylbutazone-treated horses responded to the injection of TSH, and the increase in T4 at 6 hours was greater than in the controls (not given phenylbutazone) (P less than 0.02).
成年马的血浆甲状腺素（T4）浓度呈现轻微的昼夜变化，但三碘甲状腺原氨酸（T3）浓度则无此变化。下午5点至8点之间的血浆T4浓度往往高于上午8点。给予5、10或20国际单位促甲状腺激素（TSH）的成年健康马，其血浆T4和T3的升高情况相似。给予TSH后6至12小时，T4达到峰值，约为基线的两倍（2.0±0.4倍）。给予TSH后1至3小时，T3相对于基线的变化最大，但升高幅度差异很大（为基线的4.36±2.49倍）。建议采用以下方法进行马的TSH反应试验：（i）准备用于测定基线T4和T3的血浆或血清样本；（ii）肌肉注射5国际单位TSH；（iii）注射TSH后3小时和6小时准备血浆或血清样本；（iv）将样本在-20℃冷冻，直至通过放射免疫测定法测定T4和T3。用保泰松治疗马5天，会导致马的基线T4和T3显著降低（P<0.05）。然而，用保泰松治疗的马对注射TSH有反应，且6小时时T4的升高幅度大于对照组（未给予保泰松）（P<0.02）。
