An investigation into factors influencing basal eye temperature in the domestic horse (Equus caballus) when measured using infrared thermography in field conditions.
Abstract: Infrared thermography (IRT) is a popular technology used for the detection of thermal changes given its non-invasive nature and lack of direct contact with the individual. Accordingly, the maximal eye temperature (MaxET) measured with IRT has been extensively applied in equine research. However, there is little information available about the potential limitations of the MaxET in field studies. Thus, the aims of this study were to 1) quantify the individual variation of MaxET in field conditions and the effects of individual, breed, body size (height at withers), eye side, sex and age, 2) determine the effects of environment and operator, and 3) explore the relationship between MaxET and rectal temperature (RT) at rest. To accomplish these aims, 791 MaxET measures from 32 horses were collected in Sweden in five different months and five farms over a period of 12 months. There was an effect of individual on IRT (P < .05) and individual MaxET varied from 29.4 to 37.6 °C. IRT was also affected (P < .05) by breed and sex (maximal difference 1.1 °C and 0.3 °C, respectively) but not by eye side, age and height at withers. There were significant effects of month and farm (maximal differences; 2.4 and 2.3 °C, respectively), between outdoor and indoor measurements (0.8 °C) and also between operators (0.2 °C). There were no correlations between MaxET and RT. These results demonstrate that in horses observed at rest in their home environment, MaxET is affected by endogenous (sex and breed) and environmental factors (farm, location and month of the year) and shows no relationship to RT. We strongly suggest that IRT technology should be used with great caution in field studies and only under conditions where these factors can be accurately accounted for.
Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.
Publication Date: 2020-10-23 PubMed ID: 33131744DOI: 10.1016/j.physbeh.2020.113218Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research focuses on factors affecting the basal eye temperature of domestic horses when measured using Infrared Thermography (IRT) under normal field conditions. The study sheds light on the impact of different biological and environmental factors on the eye temperature readings and highlights the need for careful use of IRT in field studies.
Objective of the Study
- The study’s main objectives were to understand the individual variations of maximal eye temperature (MaxET) in field conditions due to factors such as the individual horse itself, breed, body size, eye side, sex, and age.
- The research aimed to determine the influence of environmental conditions and the operator alongside studying the correlation between MaxET and the horse’s rectal temperature (RT).
Data Collection
- The researchers collected data of MaxET measurements from 32 horses in Sweden for a year across varying conditions – different months of the year, different farms, and indoor and outdoor locations.
- A total of 791 MaxET measurements were collected and analyzed.
Findings from the Study
- The study found that individual variability in horses’ is strong enough to affect the MaxET measurements, with the temperature ranging from 29.4 °C to 37.6 °C.
- Breed and sex of the horse were significant contributors to eye temperature. The maximal difference because of these factors was found to be 1.1 °C and 0.3 °C, respectively.
- Factors like eye side, age, and height at withers, on the other hand, had no significant effect on the MaxET.
- Environmental factors such as the month of the year, the farm, location (indoor or outdoor), and even the operator played significant roles in varying MaxET measurements. The maximal differences due to the month and farm were 2.4 °C and 2.3 °C, respectively.
- Interestingly, the study found no notable correlation between MaxET and RT.
Conclusions from the Study
- With both biological and environmental factors affecting MaxET, the study concluded that great care should be exercised when using IRT technology in field studies.
- Studying horses at rest in their natural environment helped establish that MaxET is influenced by endogenous (sex and breed) and environmental factors (farm, location, and month of the year).
- The research also suggested that conditions should be accurately accounted for in such studies to eliminate misinterpretations.
Cite This Article
APA
Jansson A, Lindgren G, Velie BD, Solé M.
(2020).
An investigation into factors influencing basal eye temperature in the domestic horse (Equus caballus) when measured using infrared thermography in field conditions.
Physiol Behav, 228, 113218.
https://doi.org/10.1016/j.physbeh.2020.113218 Publication
Researcher Affiliations
- Swedish Department of Anatomy, Physiology and Biochemistry, Box 7011, SE-750 07 Uppsala, Sweden.
- Swedish University of Agricultural Sciences, Department of Animal Breeding and Genetics, Box 7023, SE-750 07 Uppsala, Sweden; KU Leuven, Faculty of Bioscience Engineering, Livestock Genetics group, Department of Biosystems, B-3001 Heverlee, Belgium.
- University of Sydney, School of Life & Environmental Sciences, NSW 2006 Sydney, Australia.
- Swedish University of Agricultural Sciences, Department of Animal Breeding and Genetics, Box 7023, SE-750 07 Uppsala, Sweden. Electronic address: marina.sole@slu.se.
MeSH Terms
- Animals
- Body Temperature
- Eye
- Horses
- Infrared Rays
- Sweden
- Temperature
- Thermography
Citations
This article has been cited 12 times.- Mota-Rojas D, Pereira AMF, Martínez-Burnes J, Domínguez-Oliva A, Mora-Medina P, Casas-Alvarado A, Rios-Sandoval J, de Mira Geraldo A, Wang D. Thermal Imaging to Assess the Health Status in Wildlife Animals under Human Care: Limitations and Perspectives. Animals (Basel) 2022 Dec 15;12(24).
- Travain T, Valsecchi P. Infrared Thermography in the Study of Animals' Emotional Responses: A Critical Review. Animals (Basel) 2021 Aug 26;11(9).
- Menchetti L, Dalla Costa E, Minero M, Padalino B. Development and Validation of a Test for the Classification of Horses as Broken or Unbroken. Animals (Basel) 2021 Aug 4;11(8).
- Mota-Rojas D, Pereira AMF, Wang D, Martínez-Burnes J, Ghezzi M, Hernández-Avalos I, Lendez P, Mora-Medina P, Casas A, Olmos-Hernández A, Domínguez A, Bertoni A, Geraldo AM. Clinical Applications and Factors Involved in Validating Thermal Windows Used in Infrared Thermography in Cattle and River Buffalo to Assess Health and Productivity. Animals (Basel) 2021 Jul 30;11(8).
- Gobbo E, Zupan Šemrov M. Neuroendocrine and Cardiovascular Activation During Aggressive Reactivity in Dogs. Front Vet Sci 2021;8:683858.
- Zhang Y, Han Y, Li X, Zeng X, Shakweer WME, Liu G, Wang J. High-Performance Automated Detection of Sheep Binocular Eye Temperatures and Their Correlation with Rectal Temperature. Animals (Basel) 2025 Aug 22;15(17).
- Kim S, Yamagishi N, Ishikawa S, Tsuchiaka S. AI-enhanced infrared thermography for reliable detection and spatial mapping of temperature patterns in calf eyes and muzzles. BMC Vet Res 2025 Jul 15;21(1):468.
- Kim S, Yamagishi N, Ishikawa S, Tsuchiaka S. Unique temperature change patterns in calves eyes and muzzles: a non-invasive approach using infrared thermography and object detection. Front Vet Sci 2025;12:1548906.
- Aragona F, Rizzo M, Arfuso F, Acri G, Fazio F, Piccione G, Giannetto C. Eye Temperature Measured with Infrared Thermography to Assess Stress Responses to Road Transport in Horses. Animals (Basel) 2024 Jun 26;14(13).
- Reza MN, Ali MR, Samsuzzaman, Kabir MSN, Karim MR, Ahmed S, Kyoung H, Kim G, Chung SO. Thermal imaging and computer vision technologies for the enhancement of pig husbandry: a review. J Anim Sci Technol 2024 Jan;66(1):31-56.
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