I think anyone could make it cruel. But if we were to really analyze it, any of it could be considered cruel - the prison-like box they're kept in, the metal in their mouth, the tight thing wrapping around their stomach, the nails being driven through their hooves...
But, realistically, I'd like to think that a well treated horse will eventually enjoy it's life.
Tumai - (Sorry to throw it off topic, I had to ask) - Do you get to keep her?