Your horse needs a buddy - but what are your options when another horse is not available? There are other friends that may work just as well. Let's review the choices in companionship!
Donkeys can be a great choice for a companion. Their management and nutritional needs are the same as a horse, so they require no special treatment. They are hardy, healthy, low-maintenance animals with a very long lifespan. They also make great guard animals! Donkeys can be very loud however, so keep that in mind if you live in close proximity to neighbors.
Goats are another option for your horse's buddy. Many horses can enjoy the company of a goat, and they are easy to feed. Goats are browsers, and are great at clearing away weeds and brush that your horse won't eat. They typically do not require grain, and a few pounds of hay daily is enough to keep your goat happy. Goats are escape artists, so proper fencing is a must.
Llamas can pull double duty - they can be a companion and a guard animal. The llama's territorial nature means they will help guard your pasture from unwanted visitors. They do well even on low quality hay (ensure clean and mold-free). Llamas have a thick coat that can be both positive and negative. They require grooming and some require shearing, however you can use their coat to make fiber!
Alpacas have very similar needs to llamas, and can also be great companions. They are inexpensive to feed, however since they are considerably smaller than llamas, they cannot be used as guard animals. Alpacas make wonderful soft fleece that is great for fiber.
This one is a no-brainer. Other horses or ponies are the ideal companion. If you cannot afford two horses at your property, offering to board another person's horse is a great compromise. Your horse gets a friend, and the other person gets a place to keep their horse. Alternatively, boarding your horse gives him plenty of friends that are not on your bill!
This is a quick introduction to companion animals for your horse. I encourage you to do some additional research before bringing home a donkey, goat, llama, or alpaca. Best of luck finding your horse his new best friend!
The Info Pony