Horse Socialization is an important part of owning a horse. If the horse exhibits a lack of socialization, its mental and possibly physical health will suffer.
Being naturally herding creatures, horses are social animals that enjoy companionship. If your horse is in a stable, make sure that this environment is not a jail. Pick a stable with open-feeling stalls with boards or bars instead of walls where they can interact with their friends.
If your horse is stabled by itself, consider getting it a friend. This does not necessarily have to be a horse. It could be a cat, goat, chicken, dog, lamb, or pig. Being alone does not suit most horses' natures.
Enroll in a Class
With more people focusing on their animals' mental health now than ever, there is a range of socialization classes available. Enrolling your horse in a socialization class would allow it to interact with other horses while teaching it good manners and how to be more responsive to you.
Bad Habits
Horses can acquire bad habits through lack of socialization. Following is a list of catalysts for bad behavior in horses.
Confinement goes against the natural order for horses, who uses to sweep across the plains in great herds. Unless the horse is kept from boredom and is given “jobs,” bad habits most likely will set in.
Along the same lines, lack of activity can be a large contributor to problems in your horse’s behavior. If pent-up energy is allowed to accumulate in the animal, it will become irascible and impossible to manage.
Lack of communication with other animals is a problem for most horses. Unless they have access to their pals, they will most likely become isolated or aggressive, which is a problem.
Horse Breeds 
Horse Behavior - Training 
