Originally Posted by Miss L Toe
Why would a tie back make him choke?
A tie back is where the vocal chords are tied back out of the airway. Unfortunately this means taht they are also tied back out of the way of the oesophagus and the horse is more likely to breath in food and to regurgitate it back down its nose.
OP if your horse is an ex racer it's quite possible he has a tieback. You can't tell unless you scope them, the external scar is almost impossible to find on my horse.
Precautions are to always feed at ground level, damp (including the hay). Other than that there isn't much you can do except loosen or remove the band, but then your horse may not be able to breath, and some are very stressed by the laryngeal hemiplegia.