What should you be concerned about if you see a horse that is distressed, drooling, and has feed running out of his nose?
Choke (esophageal obstruction) is most common in older horses with poor dentition (worn down/missing teeth), because they cannot chew their feed properly, and often swallow large boluses of food. Other causes of choke can include swallowing large chunks of treats (apples/carrots) without chewing, eating too quickly(usually when a horse is given grain), or having an esophageal stricture(narrow portion of the esophagus).
Choke should always be treated as an emergency. Do not let the horse eat anything (including shavings/grass), and try to keep him/her calm (for example, if you bring the horse into a stall make sure there is a buddy nearby). Call your vet ASAP, because the longer the choke goes on the more difficult it is to resolve. Luckily, many chokes will resolve on their own if the horse allows the esophagus to relax, but sometimes the horse is so distressed that sedation is needed. If the food bolus is firm or very large, it can sometimes be felt on the left side of the neck. However, many chokes occur in the distal part of the esophagus beyond the neck, so not being able to feel an obstruction does not rule it out.
In most cases the choke can be resolved by lavaging copious amounts of warm water through a nasogastric tube to moisten and break up the food bolus until it is small enough to enter the stomach. Sometimes an endoscopic instrument is needed to pick apart the food bolus if lavage is not sufficient.
Some of the complications after a choke is resolved include aspiration pneumonia and esophageal stricture (due to chronic dilation of the esophagus leading to inflammation/necrosis in that region), so it is crucial to give your horse the prescribed antibiotics and monitor him/her for any breathing abnormalities/exercise intolerance/nasal discharge/coughing for at least a week after the choke has resolved. Prevention includes splitting up food into small meals, using a hay net or other slow-feeder device, putting rocks into the horse's feed tub to slow down eating, feeding soaked pellets/cubes instead of hay to geriatric horses with poor dentition, and having your veterinarian perform regular oral exams and floating the teeth as needed every 6-12 months.