Horses get lonely, just like the rest of us. Left isolated, they become withdrawn and take on bad habits called stable vices.
To combat this, horse owners pair them up with companion ponies, sidekicks that keep them social. But sometimes horses find their own friends. On a farm, for instance, a cat or dog or goat with the right disposition could fill the part.
Racehorses benefit tremendously from these relationships. A companion can make responding to the anxiety of situations like the frenzy of the track manageable. The famous racehorse Seabiscuit befriended an old horse named Pumpkin, a stray dog named Pocatell, and even a spider monkey named Jo-Jo.
The Dalmatian dog has an interesting link to this tradition, too. They were bred as far back as 400 B.C. to run alongside horses during hunting, and much later aristocrats sought them out as carriage companions. This is how Dalmatians eventually became so fused with the image of the firehouse—fire fighters worked from horse-drawn carriages and the Dalmatian was the breed of choice to accompany the crew.
Because of all this, some researches think horses could serve as a useful model for understanding our own depression. But no matter their pick, it seems horses need friends just like the rest of us.