The social dimension of equine welfare: social contact positively affects the emotional state of stalled horses

Abstract

The housing conditions of domestic animals influence their welfare; their emotional state can be negatively affected if their needs are not met. This can lead to behavioural changes or disorders that can damage the animal–human relationship. In social species such as horses, Equus caballus, social contact is a fundamental need that is severely restricted by individual housing. Thus, this study aimed to evaluate the impact of socialization on the emotional state of horses in different contexts. We studied 20 adult horses housed in individual stalls. The horses were divided equally into two experimental conditions: horses without social interaction (isolated condition) and horses with the opportunity to interact temporarily with a conspecific (social condition). For 4 months, the horses under the social condition interacted in pairs for 1 h daily in a meeting box. Throughout this period, the behaviour of the entire sample of horses in individual stalls and during grooming sessions with humans was recorded. In addition, a judgement bias test was conducted at the end of the study period. In the individual stall, we collected indicators of poor welfare such as hypervigilance, apathy, aggressiveness towards humans and stereotypies. During grooming, we observed negative and positive behaviours, alertness levels and general attitude. Horses in the social condition exhibited fewer stereotyped behaviours in the individual stall than the isolated ones. During grooming, they expressed fewer negative behaviours, spent less time in a vigilant state and showed a less tense attitude. In the judgement bias test, horses in the social condition showed an optimistic bias compared with the isolated horses. These findings indicate that horses that are allowed to interact socially perceive their environment more positively than their isolated counterparts. Temporary but regular social contacts positively affect the emotional state of horses in various contexts, indicating an overall improved welfare.