Evaluation of contact heat thermal threshold testing for standardized assessment of cutaneous nociception in horses - comparison of different locations and environmental conditions.
Authors: Poller Christin, Hopster Klaus, Rohn Karl, Kästner Sabine Br
Journal: BMC veterinary research
Summary
# Editorial Summary Researchers assessed the reliability of contact heat thermal threshold testing as a standardised method for measuring pain sensitivity in horses, examining whether location on the body and environmental factors affected results. Five warmblood horses underwent thermal stimulation at three sites—nostril, withers, and coronary band—across varying conditions including different housing environments (box stall versus stocks), time of day, and ambient temperatures, with skin temperature, thermal threshold, and percent thermal excursion calculated for each measurement. Thermal thresholds varied significantly between anatomical locations and environmental conditions, with the percentage thermal excursion metric showing greater consistency across variables than absolute threshold temperatures alone, indicating that environmental factors do influence raw thermal measurements. Reaction types and behavioural responses were documented, and no adverse skin lesions occurred at any stimulation site. For equine professionals using or considering thermal nociception testing—whether for lameness investigation, chronic pain assessment, or medication efficacy trials—these findings suggest that standardising measurement location and documenting environmental conditions is essential for valid comparison between tests, and that percent thermal excursion may be a more reliable metric than absolute temperature when comparing assessments conducted under different circumstances.
Read the full abstract on PubMed
Practical Takeaways
- •If using thermal threshold testing for clinical or research purposes, standardize location (nostril, withers, or coronary band), ambient temperature, and time of day to enable meaningful comparison between horses or repeat measurements
- •Be aware that coronary band testing may yield different values than withers or nostril testing due to anatomical differences in skin properties and temperature regulation
- •This method appears safe for repeated use without causing skin damage, making it suitable for longitudinal pain assessment studies
Key Findings
- •Contact heat thermal threshold testing can be standardized across different body locations (nostril, withers, coronary band) in horses with reliable measurement of percent thermal excursion
- •Thermal thresholds and skin temperature vary significantly between testing locations and environmental conditions (ambient temperature, time of day, housing environment)
- •Environmental factors including ambient temperature and time of day influence thermal nociceptive thresholds, requiring standardization for consistent assessment
- •No skin lesions occurred at any stimulation site, indicating the method is safe for repeated cutaneous testing in horses