A few other horses at my stable who were not previously biters have also picked up the habit the past week or so. About 5 in total so far, which is 1/4 of the horses boarded there who were not previous biters. Somebody said they have seen a lady coming through and feeding treats but I have never seen this myself. It is also rumored that it's the BO's friend that sometimes stays with him but I have not seen him lately to confirm this.
So far we have all notified the barn owner that our horses are now biters. Cinny now has a BIG sign on his stall that says he bites and not to hand feed him in bright red letters and put up with zebra duck tape...you can't miss it as it stands out like a sore thumb.
Now the work begins, I get to try to break him of his habit. So far myself and my daughter have given him a good smack on the lower neck (above the shoulder) when he does it, and I have even tried my old trick of biting him back on his upper lip but it doesn't seem to phase him at all. What are some of your tried and true ways of breaking biting? I really don't like hitting on the head/face as I don't want to make him head shy.