Changes in saliva biomarkers during a standardized increasing intensity field exercise test in endurance horses

• Published in: Animal (Cambridge, England) England), 2021-06, Vol.15 (6), p.100236-100236, Article 100236
• Main Authors: Contreras-Aguilar, M.D., Cerón, J.J., Muñoz, A., Ayala, I.
• Format: Article
• Language: English
• Subjects: Heart rate variability; Horses; Physical effort; Salivary analytes; Stress
• ISSN: 1751-7311; 1751-732X
• DOI: 10.1016/j.animal.2021.100236

Salivary biomarkers could be useful to evaluate stress, fitness level, and skeletal muscle damage associated to exercise in horses in an easy and non-painful way. Therefore, this study aims to evaluate if cortisol in saliva (sCor), salivary alpha-amylase (sAMY) and butyrylcholinesterase (sBChE) and lactate (sLA) and creatine kinase (sCK) in saliva of horses can show changes during a standardized exercise test, and if they are related to heart rate variability (HRV) parameters related to sympathetic and parasympathetic tone, fitness level or skeletal muscle damage. For this purpose, ten endurance horses were submitted to a standardized exercise test in field conditions. Saliva and blood were obtained at basal time (TB), after the seven bouts of velocity (T + 01 to T + 07), and 5, 15, 30, and 45 min later (T + 5, T + 15, T + 30, and T + 45). Five endurance horses in resting condition (control group) were also enrolled. HRV and fitness level parameters, and plasma CK as a marker of muscle damage were also evaluated. Salivaryalpha-amylase increased at T + 30 (P = 0.03), sBChE at T + 5 (P = 008), and sCK at T + 07 (P = 0.009) after the exercise test, with significant differences between the exercise and control groups’ results. The sCor did not show significant changes during the exercise test in the exercise group but higher concentration compared to the control horses (P