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Thermographic assessment of surface temperature distribution and agreement between a thermographic camera, infrared thermometer, and rectal temperature in exercising horses under tropical climate conditions.
Abstract: Infrared thermography has become an increasingly valuable non-invasive imaging technique for monitoring physiological status and detecting abnormalities in horses. However, its application under tropical environmental conditions remains insufficiently investigated, particularly regarding the influence of ambient conditions on measurement accuracy and agreement with conventional temperature assessment methods. This study aimed to evaluate the agreement among a thermographic camera (TC), infrared thermometer (IR), and rectal temperature (RT), characterize body surface temperature distribution before and after exercise, and determine the effects of environmental conditions on temperature measurements in exercising horses under tropical climate conditions. Unassigned: Thirty-one clinically healthy horses performing schooling, training, or lunging exercises were enrolled in this prospective repeated-measures observational study. Temperature measurements were obtained using RT, IR at the medial canthus, and TC across the eye, neck, shoulder, back, trunk, and hindquarters regions before exercise, immediately before and after exercise, and during recovery. Environmental variables, including ambient temperature and relative humidity, were simultaneously recorded. Temperature differences among anatomical regions, exercise stages, and measurement methods were analyzed using linear mixed-effects models. Agreement between methods was assessed using Bland-Altman analysis, whereas environmental influences were evaluated using Kendall's rank correlation. Unassigned: No significant differences were observed between the left and right body sides or among exercise activities. RT consistently recorded the highest temperatures, followed by IR and TC. Thermographic assessment demonstrated that the eye exhibited the highest surface temperature under resting conditions, whereas the back, trunk, and hindquarters showed the greatest post-exercise temperature increases (p < 0.001). Outdoor measurements produced significantly higher TC temperatures than indoor assessments (p < 0.001). IR demonstrated closer agreement with RT, with a mean difference of 1.02°C, whereas TC underestimated RT by 2.88°C and exhibited wider limits of agreement. Ambient temperature showed a strong positive correlation with TC measurements (r = 0.52, p < 0.001) but had minimal influence on IR measurements, indicating superior environmental stability of IR. Surface temperatures generally returned to baseline during the recovery period. Unassigned: Thermographic imaging provides comprehensive visualization of regional surface heat distribution and effectively identifies exercise-induced thermal changes in horses under tropical conditions. However, its measurements are substantially influenced by environmental temperature and should not be used as a surrogate for core body temperature. In contrast, IR demonstrated greater agreement with RT and superior resistance to environmental variation, making it a practical alternative for rapid estimation of body temperature when rectal measurement is impractical. These findings provide valuable guidance for selecting appropriate temperature monitoring techniques for equine health assessment, exercise monitoring, and welfare management in tropical climates.
Copyright: © Pongsumpun, et al.
Publication Date: 2026-09-07 PubMed ID: 42857287PubMed Central: PMC13650291DOI: 10.14202/vetworld.2026.3899-3914Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
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.
Objective Overview
- This study evaluated the accuracy and agreement between thermal imaging devices (thermographic camera and infrared thermometer) and traditional rectal temperature measurements in horses exercising under tropical climate conditions.
- It also analyzed body surface temperature distribution before and after exercise and assessed how environmental factors affect temperature readings.
Study Purpose and Background
- Infrared thermography is a non-invasive technique increasingly used to monitor horse physiology and detect abnormalities.
- The study explored its effectiveness under tropical environmental conditions, where high ambient temperatures and humidity could influence measurement accuracy.
- The research aimed to:
- Characterize surface temperature distribution on different body regions of exercising horses.
- Compare thermographic camera (TC) and infrared thermometer (IR) readings with standard rectal temperature (RT).
- Determine the environmental impacts, such as ambient temperature and humidity, on measurement reliability.
Methods
- Participants: 31 clinically healthy horses involved in schooling, training, or lunging exercises.
- Measurement Times:
- Before exercise
- Immediately before and after exercise
- During recovery period
- Temperature Measurement Techniques:
- Rectal temperature (RT) – used as the reference/core temperature measure.
- Infrared thermometer (IR) – applied to the medial canthus (eye corner).
- Thermographic camera (TC) – images captured over the eye, neck, shoulder, back, trunk, and hindquarters.
- Environmental variables such as ambient temperature and relative humidity were recorded simultaneously.
- Data Analysis:
- Linear mixed-effects models analyzed temperature differences between:
- Body sides (left vs. right)
- Exercise activities
- Measurement methods
- Bland-Altman analysis assessed the agreement between temperature measurement methods.
- Kendall’s rank correlation evaluated the effect of environmental factors on temperature readings.
- Linear mixed-effects models analyzed temperature differences between:
Key Findings
- No significant temperature differences were observed between:
- The left and right sides of the horse’s body.
- Different exercise activities performed.
- Temperature Recording Trends:
- Rectal temperature (RT) consistently showed the highest temperature values.
- Infrared thermometer (IR) readings were slightly lower than RT.
- Thermographic camera (TC) readings were the lowest among the three methods.
- Surface Temperature Distribution:
- At rest, the eye region showed the highest temperature on the horse’s surface.
- Post-exercise, the back, trunk, and hindquarters regions experienced the largest temperature increases.
- Differences in temperature due to exercise were statistically significant (p < 0.001).
- Environmental Effects:
- Thermographic camera temperatures were significantly higher when measured outdoors compared to indoors (p < 0.001).
- Ambient temperature strongly correlated with TC measurements (correlation coefficient r = 0.52, p < 0.001).
- IR measurements were minimally affected by environmental temperature, demonstrating superior stability.
- Agreement Between Methods:
- Infrared thermometer showed close agreement with rectal temperature, with a mean difference of 1.02°C.
- Thermographic camera underestimated rectal temperature by an average of 2.88°C and showed broader limits of agreement, indicating less precision.
- Post-exercise, surface temperatures detected by these methods generally returned to baseline during recovery.
Conclusions and Practical Implications
- Thermographic imaging is valuable for:
- Visualizing regional surface heat distribution across the horse’s body.
- Detecting thermal changes caused by exercise in tropical environments.
- Limitations of Thermographic Camera:
- Substantially influenced by ambient temperature, which can skew measurements.
- Not suitable as a substitute for core body temperature measurement.
- Infrared Thermometer Advantages:
- Better agreement with rectal temperature and less affected by environmental conditions.
- Offers a practical and rapid alternative to rectal measurement when rectal access is impractical.
- Recommendations:
- Select temperature monitoring techniques based on specific needs and environmental conditions, especially in tropical climates.
- Use thermographic imaging primarily for assessing surface temperature distribution and exercise-induced changes rather than absolute core temperature monitoring.
- Consider infrared thermometer measurements for quick, non-invasive core temperature estimation when rectal measurement is not possible or practical.
- Overall, the findings enhance equine health assessment, exercise monitoring, and welfare management under challenging tropical climatic conditions.
Cite This Article
APA
Pongsumpun J, Isawirodom A, Sangsasithorn P, Wong-Aree K, Satumay N, Yamsakul P, Pongkan W, Rungsri P, Lampang KN.
(2026).
Thermographic assessment of surface temperature distribution and agreement between a thermographic camera, infrared thermometer, and rectal temperature in exercising horses under tropical climate conditions.
Vet World, 19(9), 3899-3914.
https://doi.org/10.14202/vetworld.2026.3899-3914 Publication
Researcher Affiliations
- Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
- Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
- Royal Stable Unit Equine Medical and Rehabilitation Service Centre, Bangkok 10400, Thailand.
- Royal Stable Unit Equine Medical and Rehabilitation Service Centre, Bangkok 10400, Thailand.
- Royal Stable Unit Equine Medical and Rehabilitation Service Centre, Bangkok 10400, Thailand.
- Department of Veterinary Medicine, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
- Department of Veterinary Medicine, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
- Department of Veterinary Medicine, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
- Department of Veterinary Medicine, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
- Research Center for Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
Conflict of Interest Statement
The authors declare that they have no competing interests.
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