My sister-in-law has a horse that she got back in April. The people that owned him had basically starved him. He has come a long way since April. The only problem is he puts his neck over the gait and pushes down gagging his self. He does this all during the day, not just after eating grain. He does it even after grazing. I have not heard him sucking wind. My sis in law is thinking of purchasing a cribbing collar for him. He is still not as fat as he needs to be, but is coming along. We wondered if this "gagging" if hindering his weight gain? The vet we talked to had not seen this behavior.