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Journal of animal science2025; 103; doi: 10.1093/jas/skaf146

Rein tension and heart rate variability in horses: an experiment on experience.

Abstract: Studies on stress and emotions are fundamental to assessing welfare in wild and domestic animals. In this study, we experimentally investigated how different levels of rein tension affect autonomic nervous system activation and heart rate variability (HRV) in horses. We hypothesized that increased rein tension, through a learning process, would elevate sympathetic nervous system activity and HRV, and that adult horses would be less affected by stimulus administration (EXP) than young horses due to their experience. The magnitude of rein tension significantly altered the sympatho-vagal balance in horses. Both the type of equipment (bit versus halter) and the age of the horses influenced their responses. HRV frequency domain analysis showed a significant shift in sympatho-vagal balance during EXP, with values returning to baseline during the recovery period (R) (P < 0.001). Notably, during EXP, the observed increase in LF power alongside a decrease in HF power suggests a shift toward sympathetic dominance and a reduction in vagal modulation. Interestingly, the maximum rein tension did not affect the parameters used to measure these activities, suggesting the tension levels were within an acceptable range for the horses. The balance between sympathetic and parasympathetic activities improved in R with the low-frequency/high-frequency power ratio decreasing by 49.4% from EXP to the baseline condition (B) and by 37.5% from B to R, indicating stress release and increased vagal activity (P = 0.002). During EXP, we recorded an elevated heart rate, indicating heightened arousal, particularly in young horses (P = 0.005) and when using a bridle with a bit (P = 0.024). Our findings suggest that rein tension can induce mild stress, potentially enhancing the learning process. A better understanding of these effects could improve training practices for equids' welfare. This study explores how different levels of rein tension affect the stress response and heart activity in horses, focusing on the differences between younger and older horses. We aimed to understand whether the experience of older horses makes them less sensitive to rein tension compared to younger ones. Using heart rate variability (HRV) as a measure, we found that higher rein tension activated the horses’ stress response but did not overwhelm them, suggesting the tension used was within a safe range. Interestingly, older horses handled the tension better, likely due to their training experience. We also discovered that using different types of equipment, such as a bit or halter, affected how the horses responded, with the bit causing higher stress levels. Our findings suggest that while rein tension can trigger a mild stress response, it may also be part of the learning process for horses, helping them adapt. This research could inform future training methods that take into account the horses’ stress responses, potentially improving their welfare by identifying optimal training conditions.
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Publication Date: 2025-05-07 PubMed ID: 40331242PubMed Central: PMC12168203DOI: 10.1093/jas/skaf146Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article examines the impact of rein tension on the heart rate variability (HRV) of horses. The researchers suggest that an increase in rein tension alters the balance between the sympathetic and parasympathetic activities in the horses’ autonomic nervous system, thereby indicating stress level.

Objectives and Hypotheses

  • The main objective of the study was to understand how varying levels of rein tension affect the activation of the autonomic nervous system and heart rate variability in horses.
  • The researchers hypothesized that an increase in rein tension would increase activity in the sympathetic nervous system, altering HRV.
  • They also predicted that adult horses with more experience would be less affected by increased rein tension than younger, less experienced horses.

Method and Results

  • The experiment was conducted using two types of equipment – bit and halter, and horses of different ages.
  • A significant shift was observed in the sympatho-vagal balance of the horses during the experiment (EXP). The balance returned to baseline during the recovery period (R).
  • Furthermore, an increase in low-frequency power and a decrease in high-frequency power were observed during EXP. This suggests a shift towards sympathetic dominance and a reduction in vagal modulation, indicating stress in horses.
  • Interestingly, the maximum rein tension did not affect these activities, suggesting that the used tension levels were within an acceptable range for the horses.

Conclusion and Implications

  • The ratio of low-frequency to high-frequency power significantly decreased from EXP to baseline condition (B) and from B to R. This indicated release of stress and increased vagal activity.
  • An elevated heart rate was recorded during EXP, indicating heightened arousal. This was more prominent in young horses and when using a bridle with a bit.
  • The findings suggest that rein tension can induce mild stress in horses, which could potentially enhance their learning process.
  • This study provides valuable insights that can guide training practices for better horse welfare.

Cite This Article

APA
Galotti A, Eisersiö M, Yngvesson J, Lanatà A, Maglieri V, Palagi E, Baragli P. (2025). Rein tension and heart rate variability in horses: an experiment on experience. J Anim Sci, 103. https://doi.org/10.1093/jas/skaf146

Publication

Journal of animal science
ISSN: 1525-3163
NlmUniqueID: 8003002
Country: United States
Language: English
Volume: 103

Researcher Affiliations

Galotti, Alice
  • Unit of Ethology, Department of Biology, University of Pisa, via Alessandro Volta 6, 56126, Pisa, Italy.
Eisersiö, Marie
  • Department of Applied Animal Science and Welfare, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Skara, Sweden.
Yngvesson, Jenny
  • Department of Applied Animal Science and Welfare, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Skara, Sweden.
Lanatà, Antonio
  • Department of Information Engineering, University of Florence, Florence, Italy.
Maglieri, Veronica
  • Unit of Ethology, Department of Biology, University of Pisa, via Alessandro Volta 6, 56126, Pisa, Italy.
Palagi, Elisabetta
  • Unit of Ethology, Department of Biology, University of Pisa, via Alessandro Volta 6, 56126, Pisa, Italy.
  • Natural History Museum, University of Pisa, Via Roma 79, 56011, Calci, Pisa, Italy.
Baragli, Paolo
  • Department of Veterinary Sciences, University of Pisa, Viale delle Piagge 2, 56124, Pisa, Italy.
  • Bioengineering and Robotics Research Centre "E. Piaggio", University of Pisa, Largo Lucio Lazzarino 1, 56122, Pisa, Italy.

MeSH Terms

  • Animals
  • Horses / physiology
  • Horses / psychology
  • Heart Rate / physiology
  • Male
  • Female
  • Autonomic Nervous System / physiology

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