At the barn I volunteer at, the pasture fences are made out of wood (old wood, not rotting but kind of weak). When I go to bring horses in, I notice that the fence has been chewed on before. At first I thought the horse that cribs in his stall must be doing it out there, too. However, the other day, I watched two horses literally bite little splintery pieces off the fence and eat them. If this gives any clue, I've only seen them do it when the fence is wet, but the fence is almost never dry because of rain.
Is this dangerous behavior, or is it normal and I've just never seen it before? Could it be caused by stress? Poor diet? I'm worried that they might ingest some splinters or something and hurt themselves, and all of the pastures with vinyl-type fences are flooded. I haven't asked anyone else about it and I won't be back until after the holidays. What should I do once I get back? Thanks!