I can only keep one horse, how can I keep him happy

Horses are social animals and prefer to live in a herd. Being prey animals living in a herd keeps them safe from predators and allows them to display their natural behaviours. It isnt ideal to keep a horse on their own but sometimes the decision may have to be made due to restrictions on time space or money.
How can you tell if a horse is lonely?
When a horse feels lonely or misses having other horses around they may try whinnying for other horses pace along the edge of a field or constantly look for other horses. Sometimes horses can develop unwanted behaviours such as windsucking or cribbiting if they feel lonely or stressed. And some can even seem withdrawn lose their appetite or look stressed or agitated.

What can I do to help my horse?
1 Trying to find a companion for your horse is the best thing that you can do
Try to find an older retired horse or pony first of all. If this isnt possible you could consider a farm animal such as a sheep or a goat. However farm animals can have different feed and management requirements to horses so make sure you research carefully before getting one. A donkey is another alternative as they are similar to horses. And therefore can mimic the relationship that a horse may have with another horse. 
2 Try to keep your horse busy by giving them things to do
Horses are curious animals so will explore and play if given the chance. You can therefore use puzzle feeders or treat balls to keep them entertained.
3 Horses are grazers and need to have access to food for the majority of the day
This keeps their digestive system working effectively ensuring that there is enough grass for them to eat is very important. If there isnt enough grass in the horses field then make sure you have provided enough hay for them either by placing piles of hay around the field or by using small holed haynets or slow feeder haynets. This will help to prevent them from eating all of the hay at once.
4 One of the activities that horses do with each other is grooming
Not only is this good for removing dirt or parasites but they seem to create a bond with other horses when they are grooming each other. If your horse lives alone make sure you groom them regularly not only to