Original ResearchThermographic Eye Temperature as an Index to Body Temperature in Ponies
Introduction
Horse races, rodeos, shows, fairs, and other events, which result in the congregation of animals, are at high risk for the spread of disease among participating horses; this risk can be lowered through an effective biosecurity program [1]. An important part of a biosecurity program is to have a rapid method to obtain reliable body temperature measurements because changes in body temperature are often a vital indicator of infectious animal disease. Measuring body temperature in animals includes use of rectal thermometers, tympanic infrared thermometers, and thermal microchips [2], [3], [4], [5]. These methods of temperature measurement have different limitations such as intolerance to the procedure, time required to obtain the measurement, or the need to have a microchip implanted in each animal and a scanner that can read the microchip [2], [5].
A method for measuring temperature that does not have these limitations is infrared thermography (IRT) because it is passive, remote, rapid in the hands of trained personnel, and noninvasive. IRT uses a specialized camera that measures thermal radiation or surface temperature emitted from an object and displays the different temperatures detected as an image, with each color or shade in the image representing a different temperature. This camera is comparable in size with a camcorder (Fig. 1) and its use is similar to a digital camera, except that the thermographer needs to understand how emissivity, reflected temperature, focus, and other factors influence recording accuracy [6]. For IRT to measure body temperature, a surface location needs to correlate with the changes in body temperature; a possible location is the eye region. Ng and Kaw [7] identified that IRT of the eye region could be used to detect fevers in human beings. Dunbar et al. [8] found that thermographic eye temperature and core body temperature readings in mule deer were not significantly different. Schaefer et al. [9] identified that IRT of the orbital areas of cows had use as a predictor of bovine respiratory disease, which is often associated with a fever. Other IRT eye region applications have included detection of bovine viral diarrhea [10] and stress measurements [11], [12]. These latter studies did not specifically report on the relationship between eye temperature and body temperature.
Our objectives were to determine whether thermographic eye temperatures were associated with body temperatures and could be used to detect febrile ponies.
Section snippets
Study Population and Data Collection
Measurements were obtained from 24 male Welsh ponies aged 1 year undergoing a challenge study to determine the efficacy of an equine herpesvirus vaccine. The study was approved by the Animal Care and Use Committee of Colorado State University. The ponies were housed in outdoor pens with a three-sided shelter covering the northern end. Data collection occurred in the same barn where the animals were housed. Measurements were collected between 8:30 am and 11:30 am for 3 consecutive days in the
Results
The mean IRT temperature was 38.2°C (range: 34.7°C-41.4°C; 100.8°F, range: 94.5°F-106.5°F), the mean rectal temperature was 39.8°C (range: 37.4°C-41.4°C; 103.6°F, range: 99.3°F-106.5°F), and mean microchip temperature was 39.9°C (range: 36.6°C-42.1°C; 103.8°F, range: 97.8-107.8°F). These temperatures were collected under clear skies with a mean ambient temperature of 14.2°C (range: 7°C-22°C; 57.6°F, range: 44.6°F-71.6°F). The result from the bivariate linear regression analysis showed a
Discussion
To be a good replacement to other methods used to measure body temperature, IRT needs to be rapid, easily accepted by the animals, and strongly associated with body temperature, as determined by the current standard in veterinary practice, the rectal thermometer. The results of this study support the use of IRT as an additional method, but not as a sole method, for measuring body temperature.
For the first two qualities, IRT was rapid because multiple readings were recorded in the time taken by
Acknowledgments
The authors thank Matt Dubois for animal handling assistance, Mike Dunbar for use of the IRT camera, and Christine Ellis for proofreading the document.
References (13)
- et al.
The use of infrared thermography as an early indicator of bovine respiratory disease complex in calves
Res Vet Sci
(2007) - et al.
Non-invasive measurement of stress in dairy cows using infrared thermography
Physiol Behav
(2007) - et al.
Infection control strategies for horses in the new millennium
Proc Am Assoc Equine Pract
(2001) Comparison of body temperature of goats, horses, and sheep measure with a tympanic infrared thermometer, and implantable microchip transponder, and a rectal thermometer
Contemp Top Lab Anim Sci
(1998)- et al.
Comparison of rectal, microchip transponder and infrared thermometry techniques for obtaining body temperature in laboratory rabbit (Oryctolagus cuniculus)
J Am Assoc Lab Anim Sci
(2006) - et al.
Comparison of three methods of temperature measurement in hypothermic, euthermic, and hyperthermic dogs
J Am Vet Med Assoc
(2007)
Cited by (121)
Deep learning-based automatic dairy cow ocular surface temperature detection from thermal images
2022, Computers and Electronics in Agriculture