Is this horse bored? How old? Stalled alot? My sisters horse does alot of "gumming" of stuff/ I think this might have been since he was a show Morgan before we got him and he might have gotten bored in the stall. It also might just be his perosonality lol. :) Would he enjoy a toy of some sort? Something to push around? If he was nibbling at people, I would give him a smart "tap" under the chin when he does it...remember, three second rule though! Do it right away, just so he gets the message. Not enough to make him headshy or anything.
Shaneequah, 1998 gaited Bashkir CurlyxArab mare
Treyue, 1999 3-gaited Icelandic gelding
Loki, 2001-2015 Icelandic gelding