It's a known fact some actors hate working with animals. In the main because the animals often upstage the actors and people remember the animal's antics and some times cannot even recall the actor's name. The artist Norman Thelwell encapsulates every little girl's dream of owning their very own pony. Of course in drawings he emphasises all the pitfalls alongside amusing and heartfelt moments of owning said pony. The pony he features most tend to be Shetland's, which are often the first pony a child is gifted. They're tough little critters, cute, individualistic, and basically barrels on legs. Some need a good kick-start, others only have to see a whip in their peripheral vision and they drop into second gear as fast as a sports saloon. Whatever their character they're pure fun!
Probably the most famous horse in literature was/is Black Beauty!
The novel itself was written from the viewpoint of equines = a master stroke of genius. Beautiful and good-natured Black Beauty had it all but fate had cruel tricks in store.
Or perhaps you recall Black Bess: Dick Turpin's famous mare.
It's true to say her great feat from London to York was nowhere near as fast as claimed, but hell, she was a real horse: she was Black Bess.
Then of course there were those bred for war.
Whatever horse one chooses to star alongside characters in a book, they can become vital to a reader, who wishes to know their name and their colour just as they want to know the same of the hero and heroine, and believe it, a horse lover will closely follow what happens to horses throughout a book. They are characters too, and don't ever forget their presence can take the lead in many scenes: sometimes happy occasions, sometimes sad affairs especially if disaster strikes. And, often as not equines can drive a plot forward.
Love 'em or hate 'em horses were part and parcel of life before the car!