Table 1. Facial expressions during the interventions as defined by the HFI method.
| Eye white increase (AD1) | Nostril dilator (AD38) | Inner brow raiser (AU101) | Blink (AU145) | Half blink (AU47) | Upper lid raiser (AU5) | “Ear flicker” | Ear rotator (EAD104) | |
|---|---|---|---|---|---|---|---|---|
| Transportation | ||||||||
| Percentage of AUs during intervention / control | 8.2% / 4.8% | 13.1% / 8.4% | 5.3% / 8.1% | 12.7% / 19.6% | 7.7% / 11.2% | 8.0% / 5.7% | 18.9 / 17.7% | Not selected |
| Difference in frequency | 113.7% | 106.2% | 31.4% | 30.1% | 35.8% | 98.6% | 76.2% | Not selected |
| Social isolation | ||||||||
| Percentage of AUs during intervention / control | 7.8% / 3.9% | 15.0% / 7.0% | 15.0% / 12.1% | 18.1% / 19.8% | Not selected | Not selected | 16.6% / 20.2% | 5.3% / 6.2% |
| Difference in frequency | 85.7% | 90.9% | 43.0% | 12.8% | Not selected | Not selected | 1.9% | 6.1% |
| Combined | ||||||||
| Percentage of AUs during intervention / control | 8.2% / 4.8% | 13.4% / 8.4% | 7.2% / 8.1% | 13.8% / 19.6% | 8.0% / 11.2% | 7.0% / 5.7% | 18.4% /17.7% | Not selected |
| Difference in frequency | 106.8% | 101.8% | 52.1% | 29.3% | 30.5% | 80.7% | 66.4% | Not selected |
Action units (AUs) and action descriptors (ADs) selected using the Human FACS Investigation (HFI) method to represent stressful interventions in horses in the transportation and social isolation groups and together as a combined group.