Rectal thermometers vs. thermal imaging cameras
Which works better for early disease detection in pigs?
By Samantha Nixon, Maite Dias and Matheus O. Costa
Elevated body temperature (fever) is one of the first signs that thebody is fighting infection. Identifying the onset of fever is crucial forthe detection of septicaemic diseases, early treatment intervention, and for preventing the spread of a pathogen within and between pigs.
With timely detection and treatment, the overall efficiency of labor in swine management is improved. Sick animals can be identified and treated more quickly, reducing the workload associated with managing widespread outbreaks and reducing the need for mass use of antibiotics. Avoiding unnecessary and indiscriminate use of antibiotics help mitigate antimicrobial resistance.
The use of rectal thermometers is a traditional method for measuring body temperature in pigs. However, it is invasive, labor intensive and time consuming.
Thermal imaging cameras measure the radiated temperature and offer a non-invasive and rapid alternative for monitoring body temperature in swine barns. Cameras can be set up for continuous monitoring, providing real-time data on body temperature variations for individual or groups of animals. This continuous surveillance enhances the chances of early detection of fever or abnormal temperature patterns, allowing for proactive intervention and treatment.
Research comparisonFive-week-old cross-bred pigs (n = 12) from a high health herd werehoused under controlled conditions. All animals were clinically monitored daily over 19 days. An electronic rectal thermometer and a professional handheld thermal imaging camera (SeekThermal, Shotpro, Wisconsin, USA) were used to measure body temperature once daily, in the morning. Rectal thermometer was only used for rectal temperature, whereas radiated temperature was assessed on the right ear, left ear and whole dorsal body. Data was analyzed using repeated measures ANOVA followed by Tukey’s post-hoc.
ResultsThe average rectal temperature across all animals during the entire study period was 39.25°C (± 0.15°C). The average right ear (38.30°C ± 1.3°C), left ear (37.34°C ± 1.0°C), and whole dorsal body (38.52°C (± 0.5°C) temperatures were lower than the average rectal temperature, and were statistically different among themselves (P < .001). Unsurprisingly, rectal temperatures also showed the lowest variation across all the explored methods. A summary of the data is presented in Figure 1.
DiscussionRectal temperature measurement provides a reliable and consistent method for core temperature assessment. Thermal imaging cameras are becoming increasingly popular as a diagnostic tool for evaluating the health of pigs. They provide the opportunity to reduce stress and curb the spread of disease by functioning as an automated surveillance system.1 Their quick assessment of skin temperatures allows for the estimation of body temperature without the need for restraint or direct contact.
Since fever is one of the first indicators of septicaemic disease, a non-contact method could improve time and labor efficiency in detecting and treating affected animals. However, our data showed that thermal imaging is more susceptible to variation and may artificially provideunderestimated data.
One of the limitations of thermal imaging is that it measures surface temperature rather than core temperature. While changes in surface temperature can indicate potential health issues, they may not reflect variations in core body temperature.
Since skin temperature is constantly influenced by its surroundings, there is a greater potential for variation compared to core temperatures.2 For instance, variations in barn temperature, drafts or direct exposure to sunlight may influence surface temperature and impact the readings obtained through thermal imaging cameras.
Future trials using animals with fever may shed a light on the usefulness of thermal imaging during disease outbreaks. These trials may help establish correlations between changes in surface temperature captured by thermal imaging and actual increases in core body temperature.Combining thermal imaging with other diagnostic tools, such as rectal thermometry or clinical assessments, may provide a more accurate and nuanced understanding of animal health, in lieu of increased labor.
References1. Marina Stukelj, Melita Hajdinjak, Igor Pusnik. Stress-free measure-ment of body temperature of pigs by using thermal imaging – Use-ful fact or wishful thinking. Computers and Electronics in Agriculture.February 2022. Accessed November 13, 2023.https://doi.org/10.1016/j. compag.2021.1066562. Simone M. Schmid, Wolfgang Buscher, Julia Steinhoff-Wagner. Suit-ability of Different Thermometers for Measuring Body Core and SkinTemperatures in Suckling Piglets. National Library of Medicine. April 2021. Accessed November 13, 2023. https://doi.org/10.3390%2Fani11041004
Nixon is a second-year veterinary student, Dias is an adjunct professor and Costa is an assistant professor in the Department of Large Animal Clinical Sciences, all with the University of Saskatchewan, Western College of Veterinary Medicine.
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