Pressure Algometry in Icelandic Horses: Interexaminer and Intraexaminer Reliability

•Interexaminer reliability of pressure algometry (PA) is good.•Intraexaminer reliability of PA in horses is moderate to good.•Pressure algometry is a feasible tool in determining mechanical nociceptive thresholds in horses.

Reliability of pressure algometry as an outcome measure in equine research and therapy needs to be studied. The aim of the present study was to establish interexaminer and intraexaminer reliability of pressure algometry in Icelandic horses and to determine reference mechanical nociceptive threshold (MNT) values for that particular breed. Another aim was to create cutoff values, for clinical monitoring of asymmetry in musculoskeletal sensitivity in the Icelandic horse. Nine clinically sound Icelandic horses were tested with a pressure algometer on 11 anatomic landmarks on the neck, back, and croup, each by two examiners. Three weeks later, the procedure was repeated. Interexaminer reliability was good (intraclass correlation [ICC] = 0.64; P < .001). Short-term intraexaminer reliability over three repeated measurements was comparable to other studies. Intraexaminer reliability over 3 weeks was moderate for examiner 1 (ICC = 0.46; P < .001) and good for examiner 2 (ICC = 0.78; P < .001). Measurements of examiner 1 differed significantly from those of examiner 2 (P < .001). For each anatomic landmark and examiner, mean MNT values (standard deviation) were calculated. Asymmetry values were calculated for bilateral anatomic landmarks. It was concluded that the reliability of pressure algometry in a population of sound Icelandic horses was moderate to good. Future research is needed to assess the interexaminer and intraexaminer reliability of pressure algometry in horses with musculoskeletal pain.