No horses. Anywhere

I cannot reproduce. Are you sure you have searched everywhere?

I used a seed that previously had tons of horses in the plains biome. So far, even though I have encountered several plains biomes, I have found no horses yet. I've been searching in the direction that they were previously known to exist and beyond.
EDIT: Tons of sheep instead
EDIT2: I have finally found 3. (Went into creative mode and started flying everywhere.) 3 is a far cry from what this seed used to produce.

That is evidence of a horse spawning change. If they are spawning, it is very unlikely to be a bug.

Sorry, but am I to understand that horse spawning has been seriously reduced? 😞

Evidently. I didn't have any trouble in my world, try creating a new world. Remember, the seed is interpreted differently across versions so the fact that this seed produced horses in 1.6 means nothing regarding 1.7.

Cannot reproduce.