Heart rate and salivary cortisol concentrations in foals at birth.
Authors: Nagel C, Erber R, Ille N, Wulf M, Aurich J, Möstl E, Aurich C
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Nagel et al. (2015) examined cardiovascular and endocrine stress responses in 13 foals during the transition from fetal to neonatal life, measuring heart rate, heart rate variability, and salivary cortisol from 120 minutes before birth through five months of age. Contrary to conventional assumptions about birth-related stress, fetal heart rate actually decreased steadily in the final two hours before delivery (from 77 to 60 beats/min), then spiked dramatically to 160 beats/min within 30 minutes of birth; salivary cortisol similarly remained relatively modest immediately post-partum (11.9 ng/mL) but nearly quadrupled to peak levels of 52.5 ng/mL within two hours. These findings suggest that the physiological stress response in foals is not triggered by the mechanical and chemical demands of parturition itself, but rather by the environmental and respiratory challenges encountered immediately after delivery. For practitioners assessing neonatal foal health and stress status, this distinction has practical implications: elevated cortisol and tachycardia in the first hours of life represent normal adaptive responses rather than indicators of labour-related compromise, though understanding these baseline patterns is essential for identifying genuinely pathological presentations that warrant intervention.
Read the full abstract on PubMed
Practical Takeaways
- •Elevated heart rate and cortisol in newborn foals within 2 hours of birth are normal physiological responses to birth rather than indicators of distress during parturition
- •These stress markers can be used to distinguish birth-related physiological responses from complications occurring during labor
- •Baseline understanding of normal perinatal cardiac and endocrine changes helps practitioners identify genuine neonatal problems requiring intervention
Key Findings
- •Fetal heart rate decreased from 77±3 to 60±1 beats/min in the 120 minutes before birth
- •Heart rate increased to 160±9 beats/min within 30 minutes after birth (P<0.01)
- •Salivary cortisol concentrations increased from 11.9±3.6 ng/mL immediately after birth to a maximum of 52.5±12.3 ng/mL within 2 hours (P<0.01)
- •Increases in heart rate and cortisol are triggered by birth itself, not by the birthing process