Department for Small Animals and Horses, Artificial Insemination and Embryo Transfer, Vetmeduni Vienna, Veterinärplatz 1, 1210, Vienna, Austria.
Graf Lehndorff Institute for Equine Science, Vetmeduni Vienna, Hauptgestüt 10, 16845, Neustadt (Dosse), Germany.
Domest Anim Endocrinol. 2022 Jul;80:106728. doi: 10.1016/j.domaniend.2022.106728. Epub 2022 Mar 20.
Horse mares are frequently treated with the progestin altrenogest with the aim to suppress estrous behavior and its negative impact on equestrian performance. Progestogens, however, also have sedative effects in males, and females of different species. The aim of our study was therefore to investigate altrenogest-induced changes in the stress response of female horses during initial equestrian training. Three-yr-old Warmblood mares were randomly assigned to treatment with altrenogest (ALT; 0.044 mg/kg once daily; n = 6) or sunflower oil (CON; n = 5) for 12 wk during training. At predefined steps of the training program (free movement, lunging without and with side reins, lunging with saddle, mounting of a rider, free riding, riding by an unfamiliar rider) salivary cortisol concentration, and heart rate were determined from 60 min before to 120 min after training. The same procedures were performed during repeated gynecologic examinations and 2 novel object tests. Bodyweight and body condition scores (BCS) were assessed at 4-wk intervals. During all training units, salivary cortisol concentration and heart rate increased (P < 0.001), but the increase was smaller in group ALT mares (time x treatment P < 0.001). Gynecologic examinations and novel object tests induced a much smaller increase in cortisol and heart rate (P < 0.001) than equestrian training with no difference between groups ALT and CON. Initially, bodyweight, and BCS decreased during training. The subsequent increase was larger in group ALT vs CON (time x treatment P < 0.05). In conclusion, altrenogest reduced the stress response of 3-yr-old mares to equestrian training. The use of altrenogest during equestrian competitions should therefore be reconsidered.
母马经常接受孕激素阿尔特龙（altrenogest）治疗，目的是抑制发情行为及其对马术表现的负面影响。然而，孕激素在雄性和不同物种的雌性中也具有镇静作用。因此，我们的研究目的是调查在初始马术训练期间，阿尔特龙对雌性马应激反应的影响。将 3 岁的温血母马随机分配接受阿尔特龙（ALT；0.044mg/kg，每日一次；n=6）或葵花籽油（CON；n=5）治疗 12 周，同时接受训练。在训练计划的预定步骤（自由移动、无侧缰和有侧缰的快步、带鞍的快步、骑手上马、自由骑行、由不熟悉的骑手骑行）之前 60 分钟到之后 120 分钟，从唾液中测定皮质醇浓度和心率。同样的程序在重复的妇科检查和 2 项新物体测试中进行。每隔 4 周评估体重和身体状况评分（BCS）。在所有训练单元中，唾液皮质醇浓度和心率均增加（P < 0.001），但 ALT 组母马的增加较小（时间×处理 P < 0.001）。妇科检查和新物体测试引起的皮质醇和心率增加较小（P < 0.001），与 ALT 和 CON 组之间无差异。最初，体重和 BCS 在训练期间下降。随后，ALT 组的增加大于 CON 组（时间×处理 P < 0.05）。总之，阿尔特龙降低了 3 岁母马对马术训练的应激反应。因此，在马术比赛中使用阿尔特龙应该重新考虑。
