Thermal-sensing microchips show potential for monitoring horses after exercise

Thermal-sensing microchips may help to detect the early stages of exertional heat illness in horses.
Thermal-sensing microchips may help to detect the early stages of exertional heat illness in horses. (File image)

Thermal-sensing microchips inserted through the skin of horses show potential as an option to continuously monitor their body temperature after exercise, researchers in Australia report.

The frequent monitoring of a horse’s body temperature after strenuous exercise is critical to prevent or alleviate exertional heat illness, Hyungsuk Kang and his fellow researchers wrote in the journal Animals.

Identifying the accuracy and usefulness of microchips as a way to monitor the body temperature of horses after hard exercise may help to detect the early stages of the condition and determine if aggressive intervention is required.

Their study confirmed the potential of the chips as a tool to do so. However, the accuracy of the temperature readings obtained, and their relationship to core body temperature, was found to be dependent on where they are implanted.

Four Standardbred geldings and one Thoroughbred gelding were used in the study. Each was implanted with four thermal-sensing microchips, placed in the nuchal ligament of the neck, the right splenius muscle, the right gluteal muscle, and the right pectoral muscle.

Temperatures at the sites, collected through two microchip scanners, were monitored during treadmill exercise, and following the application of three different cool-down methods – no water application, water application only, and water application following scraping.

The central venous temperature and rectal temperature of each horse were also monitored.

The microchip technology provided a practical, safe, and quick means of measuring body temperature in horses, the University of Queensland researchers reported.

The three muscle readings showed strong relationships with the central venous temperature after treadmill exercise without water application, while the nuchal ligament temperature showed a poor relationship with the core temperature. The relationships between the central venous temperature and the microchip temperatures became weaker with water application.

Overall, the pectoral muscle temperature measured by microchip had the most constant relationships with the central venous temperature and showed the greatest potential, they said.

The researchers, discussing their findings, noted that while rectal temperature via a digital thermometer is the most commonly used procedure to monitor the body temperature of horses across a range of equestrian disciplines, there are occasions where it may not be safe to obtain rectal temperature post-exercise.

The study team found that the rectal temperature during and immediately after treadmill exercise did not accurately represent the core body temperature of the horses. Using the rectal temperature may therefore not be the most accurate approach to monitor a horse’s body temperature after exercise, they said.

Previous studies have reported a lower rectal temperature compared to the central venous temperature after exercise and a lag on the increase of rectal temperature compared to the central venous temperature after exercise, they noted.

The current study also showed similar results, they said. However, the differences between the two in this study were a bit larger than in previous studies at the maximum speed during treadmill exercise.

“The continuous monitoring of body temperature immediately post-exercise is crucial in determining whether a more aggressive intervention to cool horses is required,” they said. “However, as rectal temperature did not show a good relationship to core body temperature post-exercise, the way in which a horse’s body temperature is monitored should be further considered.”

The authors said that even though the statistical analysis showed no significant differences between the cool-down methods on central venous temperature during the first 10 minutes after exercise, the application of cold water (6 degrees Celsius) with one-minute intervals between reapplication resulted in a faster cooling effect during the first two minutes, than just walking without the application of cold water.

Furthermore, although statistically not different, the cold-water application itself exhibited a slightly further cooling effect on the central venous temperature than scraping the cold water from the body.

“This has also been documented in a similar previous study, suggesting that constant water application is more effective in cooling horses than the use of scraping.

“Additional investigations using the same technique in horses exercising under hot and humid conditions is necessary to adapt this technology broadly to screen the body temperature of exercised horses at racetracks and other equestrian disciplines.”

The study team comprised Kang, Rebeka Zsoldos, Jazmine Skinner, John Gaughan, Vincent Mellor and Albert Sole-Guitart, all with the University of Queensland.

Kang, H.; Zsoldos, R.R.; Skinner, J.E.; Gaughan, J.B.; Mellor, V.A.; Sole-Guitart, A. The Use of Percutaneous Thermal Sensing Microchips to Measure Body Temperature in Horses during and after Exercise Using Three Different Cool-Down Methods. Animals 2022, 12, 1267.

The study, published under a Creative Commons License, can be read here.

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