What is a horse with no wins called?

There's no specific term for a horse with no wins. You could simply describe it as a:

* "Winless horse"

* "Horse that has yet to win"

* "Horse without a win"

You could also use more informal terms, such as:

* "Maiden horse" (for a horse that hasn't won a race yet)

* "Unbeaten horse" (though technically, it means they've never lost, which is different from never winning)

Ultimately, the best way to describe a horse with no wins depends on the context and the level of formality you're aiming for.