Salivary markers

Thoroughbred racehorses face significant physiological and behavioural challenges during early training, requiring rapid adaptation to novel environments and stimuli. This study investigated salivary cortisol as a marker for individual variability in acute stress responses during key training milestones in 96 yearling Flat racehorses. Saliva samples collected at rest across three timepoints showed no significant differences in cortisol levels (ANOVA, P > 0.05). However, cortisol concentrations increased significantly 30 minutes after novel training events, including long-reining, first backing by a jockey and first gallop under saddle (Paired t-test, P < 0.005). Post-event variability in cortisol levels reflected individual differences in stress responses, suggesting that salivary cortisol could be a valuable objective measure of stress in Thoroughbred training.

https://doi.org/10.1371/journal.pone.0284102