Effect of attentional focus levels on spontaneous eyeblink rate in horses.

OBJECTIVE: Spontaneous eyeblink rate (SEBR) is inversely proportional to the level of attentional focus in humans. The objective of this study was to evaluate the effects of attentional focus on SEBR in horses. PROCEDURES: Twenty client-owned horses (2.5-23 years of age, five mares, 15 geldings) were evaluated. A GoPro HERO5 Session™ video recorder was attached to the halter and directed toward the eyes. Horses were acclimated for two hours before study commencement. Horses were filmed in five scenarios requiring different levels of attention: alone in a stall ("stall"), stall with an observer ("person"), standing in an arena ("stand"), walking in an arena ("walk"), and trotting in arena ("trot"). Each of the five scenarios was filmed for ten minutes. Video recordings were reviewed, and SEBR (incomplete, complete, and total blinks) was measured for both eyes in each scenario. RESULTS: The median (25%,75%) total SEBRs (blinks/min) were as follows: STALL: OD-16.6 (12.4, 24.3), OS-18.8 (11.5, 26.9); PERSON: OD-17.7 (14.6, 24.2), OS-17.4 (13.9, 24.4); STAND: OD-18.7 (15.1, 24.4), OS-19.4 (16.2, 24.7); WALK: OD-40.1 (34.1, 44.8), OS-40.6 (33.8, 44.7); and TROT: OD-39.7 (30.3, 44.6), OS-39.4 (28.6, 45.0). The total SEBRs at walk and trot were significantly greater than SEBR in stationary scenarios. CONCLUSIONS: Despite requiring increased levels of attentional focus, activities involving motion caused increased SEBR in horses. We hypothesize the need for additional tear distribution due to tear evaporation (associated with air movement over the corneas) prevailed over the level of attentional focus to increase the SEBR.