My heart goes out to all the horses and ponies that I constantly see on their own with no company at all. A friend of mine had her pony alone in a field once and I suggested she bring it over to be with my cob as her previous horse companion had been sold on by her owner. To my amazement my friend refused saying that it didn't get on with other horses and got picked on! I found out that it had been picked on once before as she had put it out with a herd of nine horses without even giving it a chance to make friends with one on it's own. All horses facing a herd and new yard must be given an adjustment period in an adjoining field and then with one other horse that it will bond with and only then into a herd situation with maybe a period with a smaller amount of horses and gradually into the bigger herd scene. The way she did it frightened the pony and made her too frightened to try it again thinking that her pony didn't get along with others of it's kind.
Every time I went by this pony in it's field it seemed lonely and when I rode my cob by the field it positively galloped across to say hello, afraid of it's own kind, nonsense!
I know some people don't want to put their horses in with a herd because they're afraid of getting their horses out to ride. This is our problem and should not influence our decision to do what's right for our equines. Get some help from an expert to get you over your fears but let your horse be a horse.
The main thing we should try not to forget are the basic needs of every horse, every day:
a) Freedom of movement in fields (large enough for natural movement).
b) Companions for herd life (one or more other equines to live and play with).
c) Free choice of grazing at ground level (the more wild plants the better).
d) Daily exposure to water for hooves (natural streams or even man made watering holes).
e) Barefoot, if possible (get those shoes off).
f) No clothing, as nature intended (let them feel the elements).
I know that sometimes stables are needed, rugs are necessary and barefoot can't always be done BUT doing things more naturally for the horse as much as we can will help keep them from illness, vices and unwanted behaviours.
Horses are herd animals....let them be horses ;)