Can horses have more than 15 hearts?

In Minecaft (vanilla), is it possible for horses to have more than 15 hearts? The Minecraft Wiki says that is the max, but everyone I have talked to (as well as a faint memory I have from a while back) says horses can have more than 15 hearts.

No, a horse's base health cannot exceed 15 hearts. Well, except for some special circumstances. For one, it's obviously rather easily modifiable through editing and modding.

But even in vanilla Minecraft, it's theoretically possible to raise a horse's health above the maximum: The Health Boost and Absorption Status Effects. Both of these grant extra hearts that will vanish once the effect expires or is countered. (The Health Boost effect is currently not accessible, however.)