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A Protocol of Manual Tests to Measure Sensation and Pain in Humans
Published on: December 19, 2016
Repeatability and test-retest reliability of thermal and pressure pain threshold testing in healthy thoroughbred
J L Khatib1, C De Gennaro1, T M Masters1
1Department of Comparative, Diagnostic and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL, United States.
Introduction:
Quantitative sensory testing (QST) has been used in horses to assess nociceptive responsiveness but its broader clinical application is limited by variability across anatomical sites, environmental conditions, operator technique, and behavioral endpoints. This study aimed to evaluate the feasibility, within-session repeatability, and test-retest reliability of thermal threshold (TT) and pressure pain threshold (PPT) testing in healthy Thoroughbred horses.
Methods:
Eleven adult Thoroughbred horses (4 mares, 7 geldings; median [IQR] age 6 [5-6] years; body weight 558 ± 47 kg) underwent QST on two occasions 1 week apart. Thermal threshold testing was performed at the nostrils, withers, and coronary band using a handheld contact heat probe (0.6 °C/s ramp; 55 °C cut-off). Pressure pain threshold testing was assessed at the temporomandibular joint (TMJ), seventh rib, and dorsal metacarpophalangeal joint (D-MCP) using a blunt-tipped pressure algometer (2,500 g safety cut-off). Three repeated measurements were collected at each site per session. Within-session repeatability was assessed by coefficient of variation (CV) and test-retest reliability by intraclass correlation coefficient (ICC), calculated from the average of the two closest of three measurements per session.
Results:
TT showed moderate to high within-session repeatability (CV 8.9%-13.6%) but poor test-retest reliability at all sites. PPT within-session repeatability was low (CV 34%-57%), with test-retest reliability varying by site: the D-MCP showed moderate reliability, the TMJ fair, and the seventh rib poor.
Discussion:
Equine QST reliability is strongly influenced by site selection, environmental conditions, behavioral responsiveness, the biological homogeneity of the cohort, which restricted between-subject variance. These findings support QST as a feasible research tool in horses but highlight the need for repeated trials, strict temperature control, and consistent operator technique. Validation in larger, more diverse populations and in horses with naturally occurring pain conditions is warranted.
