• horse;
  • pressure algometry;
  • mechanical nociceptive threshold;
  • back pain;
  • exercise;
  • repeatability


Reasons for performing study: An objective measure of neck, back and croup pain is needed in horses with musculoskeletal injuries, vague upper limb lameness or poor performance.

Objectives: To establish mechanical nociceptive thresholds (MNTs) within the axial skeleton and evaluate the effects of subject status and ridden exercise.

Methods: Thirty-six mature horses (10 nonridden; 26 actively ridden) were used to assess MNTs evoked by a pressure algometer (PA) with a 1 cm2 rubber plunger tip at 62 midline and bilaterally symmetrical anatomical landmarks along the axial skeleton. Pressure was applied at a uniform rate of application until a local avoidance reaction was noted. The repeatability of 3 consecutive measurements was evaluated. Left-to-right comparisons and the effects of subject status and ridden exercise on MNTs were assessed.

Results: MNTs were repeatable and increased in a cranial-to-caudal gradient within the axial skeleton. Typically, there were no significant left-to-right differences. Within-horse variability was less than between-horse variability. Higher MNTs were measured in young, heavy, non-Thoroughbred, castrated males, and in horses that were ridden and actively exercised.

Conclusions and potential relevance: PA provides an objective, noninvasive, and repeatable tool to measure mechanical nociception in horses. MNTs vary in horses with differing subject status and ridden exercise level.