Social Relationships in the Domestic Horse
Studies have shown that, in the wild, a horse will typically have one or two close friendships within a group, regardless of the size of the group (Feh, 1987). When we consider the many different domestic situations horses find themselves in today, however, many of them are not at liberty to live as nature intended, and many facilities are not equipped to cater for that scenario either.
The ideal situation is for a group of horses to be brought together by natural means rather than human selection, living in an environment sufficient to provide natural cover, and enough outside space to support the movement, activities, and nutritional requirements of the group. At present, unfortunately, this scenario is not viable in many situations.
Horses form a vital part of human life nevertheless and this cannot just be wiped out, but it leaves us with the dilemma over just what constitutes an adequate level of welfare and ethical management practices. What, then, can we do to ensure the horses in our care receive the best solutions we can offer? 
Natural Friendships
Within their daily routine, we can always find opportunities for horses to meet each other and start the beginnings of social interaction, whether they are in hand, being ridden, or in neighbouring stalls. Giving horses this vital interaction will result in them getting to know each other and the observant person will see who they move towards as friendships develop. This is valuable information for management strategies, welfare, and safety.
Keep Friends in Adjoining Stables
Once friendships start to be observed, we can stable those horses next to each other. Being separated and housed individually is not natural to the horse, but if he is near his friends it can help make the situation less stressful.
Turn out Friends Together
Where possible, horses that have developed friendships will benefit from being turned out together. Horses form strong friendships and their social environment and friendship is extremely important to the psychological welfare of the horse.
Keep Groups Stable
Horses form long-lasting friendships and changes to those in the group can have a considerable impact on the individual. Horses do not engage in relationships with passing acquaintances. Their social structure is complicated and friends are made as they get to know each other. Maintaining an establishment where there is minimal change to those horses living there helps to keep friendships and group structures stable and stress-free.
Raise Foals with Other Foals
It is well documented that foals isolated from their peers grow up with a lack of self-confidence and social skills. Foals need to play with others of a similar age for proper development (McDonnell & Poulin, 2002). If establishments and individuals can share information on pregnancies, perhaps plans can be put in place for mothers and foals to live together, providing a rich environment for the foals as they grow.
Group Dynamics
Understanding which horses will be the right fit for any group can assure the group's success. With so many horses being relied upon to perform a job to their best ability, establishments and owners should carefully choose which horses they take to ensure the highest welfare standards. A well thought-out solution to social structure and friendships results in a healthier horse in both mind and body, which in turn results in better performance, and increased safety.
Force-Free
People that keep horses have specific requirements of their animals that need to be met at specific times, but as anyone who keeps their horses on large areas of land knows, they do not always come when called. They may even avoid being caught if they are scared or do not like what they will be asked to do. The solution is to move to working force-free, where each horse is eager to interact with people and do his job, with interactions between horse and human based on mutual agreement. This scenario is a long way off for many horses, but by looking at how horses are managed now, we can put measures in place to reach that goal.
References
Feh, C. (1987). Etude du développement des relations sociales chez des étalons de race Camargue et de leur contribution à l’organisation sociale du groupe. University of Aix-Marseille, France: Thèse d’université
McDonnell, S.M., & Poulin, A. (2002, September). Equid play ethogram. Applied Animal Behaviour Science 78 2-4 263-290. Available at: https://www.sciencedirect.com/science/article/pii/S0168159102001120
Resources
Berger, J. (1977). Organizational systems and dominance in feral horses in the Grand Canyon. Behavioral Ecology and Sociobiology (2) 2 131-146. Available at: https://link.springer.com/article/10.1007/BF00361898
Linklater, W.L., Cameron, E.Z., Stafford, K.J., & Veltman, C.J. (2000). Social and spatial structure and range use by Kaimanawa wild horses (Equus caballus: Equidae). New Zealand Journal of Ecology 24 (2) 139-152. Available at: https://newzealandecology.org/system/files/articles/NZJEcol24_2_139.pdf
