Variation of Physiological and Behavioural Parameters during the Oestrous Cycle in Mares.
Authors: Stachurska Anna, Kędzierski Witold, Kaczmarek Beata, Wiśniewska Anna, Żylińska Beata, Janczarek Iwona
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Understanding oestrous cycle dynamics in mares extends well beyond behavioural cues typically used for breeding management—physiological markers including cardiac variables, core and surface temperature, and locomotor patterns shift significantly across the cycle in tandem with hormonal fluctuations. This 2023 analysis tracked 15 cycling mares across six consecutive days of oestrus and five scattered days of dioestrus, measuring heart rate variables, rectal and skin temperatures alongside detailed behavioural observations (interactions with handlers and other horses, standing duration, and activity levels) both morning and evening. During oestrus, elevated sympathetic nervous system activity was evident through physiological measures, yet paradoxically mares displayed increased docility towards humans and affiliative behaviours with conspecifics, suggesting a complex dissociation between autonomic activation and behavioural presentation; notably, locomotor activity increased sharply as oestrus waned, with most physiological variables declining rapidly before the transition into dioestrus. These findings have practical significance for handlers and veterinarians managing mares, as relying solely on sexual behaviour to confirm oestrous status may miss important physiological markers, whilst also highlighting that heightened heart rate or temperature during oestrus should not be interpreted as stress or illness—rather, they represent normal cyclical variation. Nutritionists and conditioning coaches might similarly benefit from recognising that work tolerance and recovery patterns likely fluctuate across the cycle alongside these measurable physiological shifts.
Read the full abstract on PubMed
Practical Takeaways
- •Sexual behaviour alone is insufficient for accurate oestrus detection; monitor cardiac activity and temperature changes alongside behavioural signs for more reliable assessment.
- •Expect increased locomotor activity and relaxed demeanour in oestrous mares, which may affect rideability, training response, and safety management.
- •Use the transition from elevated physiological markers to decreased activity as a predictive sign of oestrus ending and approaching dioestrus for breeding timing.
Key Findings
- •Physiological variables (cardiac activity, rectal and superficial temperatures) show elevated adrenergic nervous system activity during oestrus with rapid decrease at oestrus end.
- •Behaviour towards humans and conspecifics and standing time indicate a relaxed state during oestrus despite elevated physiological markers.
- •Locomotor activity increases at the end of oestrus, followed by behavioural changes at the beginning of dioestrus.
- •Physiological and behavioural variables oscillate together during the oestrous cycle, with each phase showing distinct patterns across multiple parameters.