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Animals : an open access journal from MDPI2025; 15(10); 1436; doi: 10.3390/ani15101436

The Effect of Ambient Temperature, Relative Humidity, and Temperature-Humidity Index on Stress Hormone and Inflammatory Response in Exercising Adult Standardbred Horses.

Abstract: In the present study, the changes in the markers of stress and inflammatory responses of 12 Standardbred horses were investigated before and after exercise during late spring and summer. The environmental temperature, relative humidity, and temperature-humidity index (THI) were assessed during this study. From horses, blood sampling, measurement of heart and respiratory rate (HR and RR), and measurement of rectal temperature (RT) were performed before exercise (Pre) and within 5 min following the end of the exercise (Post). THI values showed mild stress in June and high stress in July. Direct erythrocyte indices statistically increased after exercise compared to the rest condition ( < 0.05). Higher serum cortisol, α1-, α2-, and β-globulin values were found at Post than at Pre ( < 0.05), whereas lower serum albumin and A/G ratio values were found at Post than at Pre. The HR, RR, and RT statistically increased at Post than at Pre ( < 0.05). The month influenced the values of RR, platelets, cortisol, albumin, α1-, α2-, and β-globulins ( < 0.05). Overall, the results of this study confirmed the well-recognized physiological response of athletic horses to re-establish homeostasis following exercise.
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Publication Date: 2025-05-15 PubMed ID: 40427313PubMed Central: PMC12108177DOI: 10.3390/ani15101436Google 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 investigated the correlation between environmental conditions and stress and inflammation levels seen in exercise-performing Standardbred horses. Multiple parameters, like temperature, humidity, temperature-humidity index (THI), and blood, heart, and respiration data were considered, and the results confirmed that exercise impacts the physiological response of horses in an attempt to reestablish stability.

Study Overview

  • The study was conducted on 12 Standardbred horses. These horses were put through exercise routines during late spring and summer.
  • During these exercise sessions, the environmental temperature, humidity and temperature-humidity index (THI) were carefully monitored alongside several health parameters of the horses.
  • Physiological factors such as the horses’ heart and respiratory rates (HR and RR), and their rectal temperature (RT) were measured both before and after each exercise session.
  • THI values from June pointed towards mild stress in horses while those from July suggested high stress.

Bloodwork Findings

  • Bloodwork indicated an increase in direct erythrocyte indices post-exercise compared to pre-exercise levels.
  • Other significant changes in post-exercise bloodwork were higher serum cortisol, α1-, α2-, and β-globulins levels.
  • Conversely, serum albumin and a low albumin-to-globulin ratio (A/G ratio) were observed in the post-exercise measurements.

Physiological Changes

  • Other physiological changes seen after exercise included statistically higher values of HR, RR, and RT.
  • The month or season also had an influencial role on diverse parameters. Variations due to seasonal changes were seen in RR, platelets quantity, cortisol, albumin, α1-, α2-, and β-globulins levels.

Concluding Remarks

  • The conclusion was that exercise does impact the physiological response of horses, an effect that seemed correlated with the attempt of these equines to reestablish their body’s homeostasis after exercise.
  • Combined, the data suggest that varying environmental conditions do impact the stress and inflammatory response in horses in a quantifiable way.

Cite This Article

APA
(2025). The Effect of Ambient Temperature, Relative Humidity, and Temperature-Humidity Index on Stress Hormone and Inflammatory Response in Exercising Adult Standardbred Horses. Animals (Basel), 15(10), 1436. https://doi.org/10.3390/ani15101436

Publication

Animals : an open access journal from MDPI
ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 15
Issue: 10
PII: 1436

Researcher Affiliations

Conflict of Interest Statement

The authors declare no competing interests. None of the authors has any financial or personal relationships that could inappropriately influence or bias the content of the paper.

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Citations

This article has been cited 2 times.
  1. Mecocci S, Porzio E, Chiaradia E, Pepe M, Paris A, Bergagna S, Pietrucci D, Chillemi G, Beccati F, Cappelli K. Omic technology to monitoring resilience and adaptation to exercise and heat stress in endurance horses. Front Vet Sci 2025;12:1734969.
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  2. Ataallahi M, Park GW, Ghassemi Nejad J, Park KH. Evaluation of earwax and hair cortisol concentration in relation to environmental stressors in Hanwoo cattle. Vet Res Commun 2025 Sep 9;49(5):306.
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