Can I Keep My Horse Alone?
Absolutely NOT! Horses are "herd" animals. Everything that is needed for them to experience a sense of well being is found within the herd's social structure. Isolate a horse and you'll literally drive him crazy with stress and anxiety causing him to lose all self confidence, making him insecure and causing him to nervous about everything.
Sounds pretty serious and it is! Keeping a horse to himself is one of the cruelest things you could do to them. Even bad company for a horse is better than no company but please understand I don't expect your horse to share a stall or even a paddock because there are risks involved with horses being together in smaller spaces but by all means have your horse somewhere where he can see, hear, smell and perhaps even touch another because without this he will go mad.
I suppose there's always some exception to this rule out there but in all the years I've been around horses I haven't found one. I've only seen a few poor creatures subjected to the depravity of being denied something that it's instincts have required since the beginning weaving and cribbing as a result of their attempts to pacify their need for company. It's so sad and guaranteed to break your heart.
Now that I've convinced you of the importance of a horse having a companion I must point out a few things that should be considered.
If your horse is stabled with only one friend then you must be careful taking them away from each other. Be prepared for your horse or the other to act up. Try pacifying the one left behind with a bit of hay or something to distract him so they don't incessantly call out to one another working themselves into a tether.
Make it a common practice to separate them for brief periods so they, like a little child will learn that the other will return. Build up their time apart gradually and never let them be apart long enough for one of them to stop drinking their water due to anxiousness. Unsoothed nerves in a horse can cause them to not only become dehydrated but colic leading to a costly Vet's visit or worse.
Of course having several horses together near enough that they can be social is ideal but being able to see another horse only from a far off pasture doesn't quite qualify. In some cases it only makes the horse that's left alone worse for he yearns desperately to have a companion. He can't help it. It's in his DNA!
Besides being with other horses some equines enjoy the interaction with other animals as well and can become attached to goats, a chicken or a dog but none of these are a replacement for him knowing he's not the only horse on the planet and the longer he's all alone the worse his neurosis gets leading him to lifelong stable vices that can never be fixed even when another horse does come into the picture.
So please I'm pleading with you, never under any circumstance plan to keep a horse all alone and to himself. It's just not kind nor fair nor right. Be aware of your horse's need and give to it what God had created him to have. A friend!