- Trainer: Alex C.T. Horton
- Career earnings: $885,780
- Running Style: Drunken Leader
- Brief Interesting History: HyperLoop is the epitome of the stereotypical high-strung Thoroughbred. She breaks from the start gate and sprints to the lead just as quick as a people run away from their problems. She has held a respectable career based on earnings alone. The ability to cope with her self-induced stress is closely controlled by use of sugar cubes to keep the blood sugar up and ACTH injections to encourage cortisol production. Trainer Alex C. T. Horton takes pride in his ability to closely monitor the well-being of his filly, but it has raised concern when grooms are often seen sticking the filly every half hour retrieving vials of blood. After intensive investigation determining no foul play, illegal drug use, or colony of vampires seeking refuge in the tack stalls, HyperLoop is certainly one to watch. Despite hormonal assistance and white blocks of sugar, race day has this filly running on pure adrenaline for an easy lead of 3 furlongs and a memorable sporadic leading style weaving from the inside position to the outside and back the whole way. Without the stress of race day, this filly would likely not be able to produce cortisol to calm herself anyway so she uses it to her advantage.
by Dr. Emily Taylor
An article published in the January 2018 issue of the Journal of Animal Science conducted a study to evaluate the proportional changes of free cortisol levels in both dairy cows and horses. Specifically, the contribution of blood free cortisol to saliva cortisol and the relation to overall plasma total cortisol concentrations with activation of the hypothalamic-pituitary-adrenocortical axis (HPA) was studied.
The HPA axis activation has long been assessed by using cortisol as a marker. While the majority of plasma cortisol is bound, only free cortisol can actively regulate metabolic and immunological processes. The author identifies an absence of knowledge pertaining to the investigation of changes in free cortisol and further cortisol fractions during HPA axis activation within both dairy cattle and horses. Therefore, this study used 8 dairy cows and 5 horses which were intravenously administered dosages of ACTH, previously described in the literature. \
For the duration of the study, 180 minutes post ACTH injection, blood and saliva were collected every 30 minutes and analyzed for total cortisol and saliva cortisol, the ratio of free cortisol and the concentration of free cortisol in plasma. Results from the study show that plasma total cortisol was paralleled by blood concentration free cortisol, ratio free cortisol and saliva cortisol in both cows and horses. Because the ration of saliva cortisol to concentration free cortisol in horses remained similar during the ACTH challenge, the author suggests that saliva cortisol is being recruited from plasma free cortisol. However, the same is not true for cattle.
Overall, the activation of the HPA axis increased both total cortisol and ratio free cortisol similarly in both species, with saliva cortisol reflecting changes of free cortisol in horses but not cattle. The author suggests that the evaluation of these changes in cortisol factions could give further indications of the adaptive mechanisms in glucocorticoid regulation. In addition, these results could be used to differentiate cortisol-related health disorders.