Torcivia, C., McDonnell, S. 2020. In-person caretaker visits disrupt ongoing discomfort behavior in hospitalized equine orthopedic surgical patients. Animals 10(2), 210.

Horses have evolved to show little indication of discomfort or disability when in the presence of potential predators, including humans. This natural characteristic complicates the recognition of pain in equine patients. It has been our clinical impression that, whenever a person is present, horses tend to “perk up” and ongoing discomfort behavior (DB) more or less ceases. The objective of this study was to quantitatively evaluate and describe this effect. For each of 20 orthopedic surgical patients, continuous 24-h video was reviewed to record all occurrences of DB during a caretaker visit (3.23 to 7.75 min), for comparison to the hour preceding as well as the hour following when undisturbed. The mean ± S.E. DB observed per minute during the preceding and following hours, respectively, were 1.65 ± 0.17 and 1.49 ± 0.22. The difference was not significant (p > 0.05). In contrast, mean DB per minute during the visit was 0.40 ± 0.11. This was significantly lower than during both the preceding and following hours (p < 0.0001). All 20 patients expressed fewer observable DB per minute during the visit, with a mean reduction of 77.4% ± 0.17%. For 30% of these patients, ongoing DB ceased altogether during the visit. These findings confirm our clinical impression that caretaker visits interrupt DB, resulting in under-appreciation of discomfort.