White Mane (1953)
(available on Netflix streaming, or for purchase on Amazon.com)
At only 40 minutes, White Mane is a really sweet, lovely movie about a boy who befriends one of the wild horses of the Camargue in southern France. It is 95% without dialogue, and filmed in black and white in a more documentary style. In fact, the only sound at all is a light soundtrack and some sound effects that are more for imaginary effect than realism (a horse galloping through the water does not make the same noises as a person walking through a puddle, I'm just saying.)
It's very, very French, and filled with "don't try this at home, kids" moments - lots of scary, dangerous things done by everyone involved, from horses to kid to wranglers. It's somewhat nonsensical in its portrayal of the main character, the wild stallion White Mane, who is imbued with all the Black Stallion qualities you could hope for.
The ending is...ambiguous and somewhat difficult and somewhat sad. If it tells you anything, this film is by the same director as The Red Balloon. You can choose to elevate the entire story to a fairy tale, and believe the narrator about the fate of the boy and his horse; that's what I'd recommend. The whole movie builds toward a more fantastical interpretation of its own events rather than a realistic one, so it works.
Definitely recommended. In fact, if I'd discovered this as a kid it would've been a top 10 for sure.