What is the origin of the idiom "a horse of a different color" and when to use it?

The idiom "a horse of a different color" is thought to have originated in the 17th century. It is believed to have come from the horse trade, where horses were often sold with false pedigrees. If a horse turned out to be different from what the buyer had been led to believe, it might be said to be "a horse of a different color." This idiomatic expression is used to describe something that is different from what is expected or usual.