The relationship between EquiFACS and physiological measures during rest, grooming and tacking up

Abstract:
Measurements of animal welfare commonly include observed behaviours e.g. spontaneous blink rate, and physiological responses e.g. eye temperature, in the context of the external environment. More recently, measurements of affective state have been incorporated into animal welfare research. For example, eye core temperature (ECT) has been used to assess emotional state in dogs in terms of arousal, whilst spontaneous blink rate (SBR) has been used to measure stress responses. This study set out to investigate whether these physiological measures would correlate with behavioural units from the equine facial activity coding system (EquiFACS) to determine whether facial activity patterns could provide further insights into welfare and affective states. Fifteen horses (mixed age, breed, sex) were observed for five minutes in each of three conditions; control, manual grooming and being tacked up.
Video recording enabled retrospective collection of frequency data using continuous focal sampling for SBR (amount of blinks) and EquiFACS units (present/ absent). ECT was recorded at one-minute intervals. The observer had completed training to become a certified EquiFACS coder. Shapiro-Wilk test indicated that only ECT data was non-parametric. Paired sample t-tests and Wilcoxon Signed test were used to identify differences between different conditions. Mean SBR whilst tacking up (9.3 +4.17 blinks) was significantly higher (Pblink rate. However, facial activity did not significantly differ across the conditions. Results suggest that tacking up altered the physiological state of the horse compared to control and grooming conditions. Relationships were detected between measurements of arousal and some EquiFACS units, however these were not specific to different conditions. Equine facial activity maybe a useful indicator in day to day management of domestic horses but further research is necessary to determine how they are symptomatic of equine affective state.
Lay persons’ message:
This study investigated facial expressions seen in horses during everyday activities that are part of domestic horses’ routines. Frequency of horses’ facial expressions were found to correlate with physiological measurements however more research is required to understand how these might be indicative of equine emotion. Physiological changes indicative of arousal were recorded during tacking up compared to rest and grooming.