Investigating the effects of fly masks on equine (Equus caballus) affective states and social communication.

Introduction: Fly masks are a mesh screen for the equine face used for insect prevention to avoid distress. There is almost no peer-reviewed research systematically testing their efficacy in reducing discomfort or promoting welfare in equines (Machtinger, et al., 2012). Given the social organisation of equids the potential occlusion of socially-relevant communication signals by fly masks may have welfare implications (Wathan and McComb, 2014). With that in mind, the authors contend that it is important to understand if masks are associated with changes in communication and interactive behaviours. Materials and Methods: The impact of fly masks on equine behaviour was explored using observational methods to assess seven mature geldings. Using instantaneous sampling, individuals were observed in the stable via video recording to measure behaviours indicative of individual affective response to fly-masks throughout four conditions for a total of 20 minutes. To measure social behaviours, pairs were observed in the field by a single researcher throughout three conditions across 45 minutes. Observations were repeated for each individual horse, both with and without a fly mask. Raw data was transcribed into Microsoft Excel where descriptive analysis was conducted. Inferential analysis was conducted in SPSS to identify statistical significance. Results: Behaviours were compared in the presence and absence of a fly-mask. There were no statistically significant differences in individual affective behaviours in the presence or absence of a mask. However, social behaviours were found to be significantly impacted by the fly mask. Distance between horses increased (f = 8.027, p = 0.001) and frequency of affiliative (X2= 11.06, p = <0.001) and play (X2 = 4.42, p = 0.04) behaviours decreased when a single horse wore a fly mask. Discussion and Conclusions: These results are discussed with reference to the implications of fly masks for equine conspecific interaction and wellbeing, and applied equine welfare. Given that these findings highlight the potential for fly masks to influence equine social behaviour, owner awareness should be increased in order to ensure they are able to make informed choices surrounding the products or methods used for insect relief. The experimental nature of this study plays an important role in creating a foundation for future research in this area.