Board Thread:Suggestions forum/@comment-28813058-20160730193323/@comment-26236093-20160731095138

Zombielizard wrote: yea, horses honestly makes sense, they hated the rohirrim, not horses

Indeed, and there is certainly reference to Dunlending Horsemen in the Unfinished Tales. "In it's van were some Dunlending horseman and a great pack of Orcish wolfriders, feared by horses."

- The Battle of the Fords of Isen