Horse

The Horse was the only known horse in the series. It pulled Cluny the Scourge's cart into Mossflower Woods. The horse crushed Skullface when Cluny ordered him to bite it to make it move faster. It later escaped in a cart crash; its fate is unknown.

Why is there only one horse?

This topic has come up time and time again. In Redwall.org's "Ask Brian Volume 4," Brian Jacques stated that as Redwall was his first novel, he didn't expect it to be published. As such, he included human-like elements that were later removed, e.g. the horse, dogs, pigs, etc.