 Thorebreds are bred for competitive racing and undergo intensive training regimens. Their physical soundness and desirable behavioral characteristics must be maintained to ensure their longevity in the sport. Yearlings begin training as they enter the racing industry and go through introductory training before being put into exercise conditioning for racing. This period requires them to quickly adapt to a new environment. Prey animals like thorebreds have a strong fight or flight response, which is highly adapted to respond to stressful situations. When exposed to stress, these animals release cortisol, which can be detected in their saliva. Researchers have found that there is a significant difference in salivary cortisol levels between thorebreds who have just experienced their first time riding with a jockey and those who haven't. To test the hypothesis that salivary cortisol levels can be used to objectively detect individual variations in the acute physiological stress response, researchers investigated individual variations in cortisol response to training milestones. Saliva samples were taken from a group of 96 thorebred yearlings at the same training yard across three time points before entering the training. This article was authored by Amy R. Hopi, Beatrice McGivney, John A. Brown and others. We are article.tv, links in the description below.