Evaluation of a telemetric gastrointestinal pill for continuous monitoring of gastrointestinal temperature in horses at rest and during exercise

Abstract

OBJECTIVE To evaluate use of a telemetric gastrointestinal (GI) pill to continuously monitor GI temperature in horses at rest and during exercise and to compare time profiles of GI temperature and rectal temperature. ANIMALS 8 Standardbred horses. PROCEDURES Accuracy and precision of the GI pill and a rectal probe were determined in vitro by comparing temperature measurements with values obtained by a certified resistance temperature detector (RTD) in water baths at various temperatures (37°, 39°, and 41°C). Subsequently, both GI and rectal temperature were recorded in vivo in 8 horses over 3 consecutive days. The GI temperature was recorded continuously, and rectal temperature was recorded for 3.5 hours daily. Comparisons were made between GI temperature and rectal temperature for horses at rest, during exercise, and after exercise. RESULTS Water bath evaluation revealed good agreement between the rectal probe and RTD. However, the GI pill systematically underestimated temperature by 0.14°C. In vivo, GI temperature data were captured with minimal difficulties. Most data loss occurred during the first 16 hours, after which the mean ± SD data loss was 8.6 ± 3.7%. The GI temperature was consistently and significantly higher than rectal temperature with an overall mean temperature difference across time of 0.27°C (range, 0.22° to 0.32°C). Mean measurement cessation point for the GI pill was 5.1 ± 1.0 days after administration. CONCLUSIONS AND CLINICAL RELEVANCE This study revealed that the telemetric GI pill was a reliable and practical method for real-time monitoring of GI temperature in horses.

Continuous Monitoring of the Thermoregulatory Response in Endurance Horses and Trotter Horses During Field Exercise: Baselining for Future Hot Weather Studies

“…The GI pill proved to be a more accurate and precise tool to monitor thermal response than serial T re measurements. Importantly, the GI temperature (T c ) was consistently and significantly higher than the T re (mean difference 0.3°C, with a range of 0.2–0.3°C) and T c increased earlier than T re on all occasions ( Verdegaal et al, 2017 ).…”

“…However, this approach is generally not feasible and too invasive under field conditions; only one study reported similar invasive methods in three horses during free field exercise using thermistors to measure blood and brain temperature ( Mitchell et al, 2006 ). A few studies are available that focus on continuous monitoring of equine thermoregulation during exercise and recovery in the field ( Smith et al, 2006 ; Verdegaal et al, 2017 ). Smith et al (2006) used intra-uterine temperature loggers as a non-surgical, minimally invasive method to measure evolvement of intra-uterine temperature during field exercise.…”

“…In contrast, our telemetric recording method is able to provide real-time results and does not require subsequent time-critical analysis. This could be undertaken at any time after completion of the exercise period ( Verdegaal et al, 2017 ).…”

“…It is important to note that most existing field studies compare rectal temperature (T re ) before and after exercise ( Kohn and Hinchcliff, 1995 ; Kohn et al, 1995 ; Hargreaves et al, 1999 ; Jeffcott et al, 2009 ; Wallsten et al, 2012 ). However, T re is reported to significantly lag behind the core body temperature both during and after exercise ( Hodgson et al, 1993 ; Geor et al, 1995 ; Verdegaal et al, 2017 ). This means that the heating of the core of the body is always reflected in the T re at a much later stage and at a lower temperature.…”

“…This means that the heating of the core of the body is always reflected in the T re at a much later stage and at a lower temperature. Recently, we reported and validated a novel real-time temperature monitoring method namely a gastrointestinal (GI) pill that allows for accurate continuous recording of the GI temperature in exercising horses in the field ( Verdegaal et al, 2017 ). The GI pill proved to be a more accurate and precise tool to monitor thermal response than serial T re measurements.…”