Wind Sucking becomes a drug addiction with horses. They are addicts. Each time they suck and gulp air they receive a hit of endorphins which is similar to a drug, hence it's addiction.
The habit is generally caused by boredom in the stables environment and/or copying other horses that do it. Such boredom can be increased by the lack of opportunity for the horse to graze, which they do for around 16 hours in their paddock environment. The feeding of lot's of hay keeps horses occupied whereas in the Racing Industry where small hard feeds are fed, the chances of boredom and eventual wind sucking is drastically increased and in real life this is where I meet most of them.
To carry out this nasty habit, they usually need to be able to grab on to a door, log, wooden rail or whatever else with their front teeth and then to gulp air down into their gut. Some do not however.
You should take a look at it's front teeth to see if they have any unusual wear from wind sucking. Their front teeth gradually get worn down on an angle because of the horse grabbing on to wooden rails, tree stumps, doors or whatever else they can find to achieve their addiction. I have even seen a horse wind suck on it's own front leg.
So you own one and what do you do to manage it? They rarely give it up. We have found that using electric fencing to the point where the horse cannot get hold of an object with it's teeth, does stop them in the stable environment. We paint any other target points with creosote and are ever vigilant. If we see a new location being invented by the horse, we will immediately paint that too.
It does not pay to allow a wind sucker to be in the company of your other good horses, unless it cannot do it. The Saddlery Shops sell a collar that is called either a 'wind sucking collar' or a 'Miracle Collar' as they are sometimes called. These have some success but not on all horses so do not just fit one and not observe your horse after. It works on the basis of stopping the esophagus from radically expanding so the horse cannot get the large volume of air down the throat at once.
One scientific investigation suggested that the horse does not take the air down into either it's lungs or the gut. It found that the air is merely taken into the mouth and throat area.