Oliver J W, Held J P
J Am Vet Med Assoc. 1985 Nov 1;187(9):931-4.
Thyrotropin (thyroid stimulating hormone; TSH) stimulus to thyroid cells of horses and dogs resulted in increased serum triiodothyronine (T3) concentrations that were detected earlier than those of thyroxine (T4). Doubling of the base-line T3 values in horses was detected 0.5 hours after injection of 5 IU of TSH IV, with peak response of 5 times base-line value detected 2 hours after injection. Doubling of T4 values in horses was noticed between 2 and 3 hours, with the peak response of 2.4 times base-line value at 4 hours after injection of TSH. Doubling of base-line T3 values in dogs in response to 0.2 IU TSH/kg of body weight (IV-5 IU maximum dose) was noticed at 1 hour, whereas T4 response doubled between 1.5 and 2 hours. Peak release of T3 and T4 in response to TSH in dogs had not developed by 4 hours; however, the percentage increase over base-line values was greater for T3 than T4 at early sampling time points, and this response has resulted in an increased T3/T4 ratio in hypothyroid dogs. Thus, in both dogs and horses, these studies indicated that T3 response to TSH could be used as a measure of thyroid function at earlier time intervals after TSH administration than one measures T4 response.
促甲状腺激素（甲状腺刺激素；TSH）对马和狗的甲状腺细胞产生刺激后，血清三碘甲状腺原氨酸（T3）浓度升高，且T3浓度升高比甲状腺素（T4）出现得更早。静脉注射5国际单位TSH后0.5小时，马的基础T3值翻倍，注射后2小时检测到峰值反应为基础值的5倍。马的T4值在2至3小时之间翻倍，注射TSH后4小时峰值反应为基础值的2.4倍。静脉注射0.2国际单位TSH/千克体重（最大剂量5国际单位）后，狗的基础T3值在1小时时翻倍，而T4反应在1.5至2小时之间翻倍。狗对TSH反应的T3和T4峰值释放到4小时时仍未出现；然而，在早期采样时间点，T3相对于基础值的增加百分比高于T4，这种反应导致甲状腺功能减退的狗的T3/T4比值升高。因此，在狗和马中，这些研究表明，与测量T4反应相比，TSH给药后更短的时间间隔内，T3对TSH的反应可作为甲状腺功能的一项指标。
