THORACIC CHOKE. 
287 
tween the two layers of the posterior mediastinum, through 
the diaphragm at the opening in its right pillar to the smaller 
curvature of the stomach. It is an easy dilatable tube, com¬ 
posed of mucous and muscular coats, the former adhering 
but slightly to the latter, over which it glides. The muscular 
coat becomes thicker and thicker as it nears the stomach, so 
much so, that at and near its connection with that organ it 
becomes so thick and rigid that it forms a tube so narrow as 
to be almost if not entirely filled with folds of the mucous 
layer. This anatomical conformation, coupled with the man¬ 
ner in which many horses gulp their feed, I think the principal 
cause of low choke ; again, horses with sharp-edged molars will 
gulp feed, when they would not if these teeth had proper at¬ 
tention, this manner of swallowing without sufficient chewing 
causing choking from lack of saliva to lubricate the passage 
of the feed down. More than ninety per cent, of all cases of 
choking coming under our observation have been due to 
feeding dry oats to old horses and to well known greedy 
feeders. 
The feed often grabbed and gulped without a single effort 
at chewing, forms a bolus which passes down the more dilat¬ 
able and less muscular part of the oesophagus, but is too large 
to pass through what we will call the constricted part, or if 
not at first too large, is too dry and stops from lack of gliding 
material, (the saliva) soon becoming enlarged by further ad¬ 
ditions of food. It now requires but a short time for an ac¬ 
cumulation of moisture to start this food to swell, and also 
this food acting as a foreign body causes irritation and we 
have an enlargment of that part of the oesophagus, with a 
constriction above and below, resembling to some extent a 
bag tied at both ends. Many cases of supposed choking we 
have found due to a piece of stick, but oftener a cob lodged 
crosswise of the mouth between the last molars of upper jaw, 
and sometimes wedged so tightly as to require considerable 
strength to dislodge it. 
The general symptoms of choking are given as flow of 
saliva, coughing, retching, throwing up the head with a 
peculiar squeal, partial sweats, etc., and these are given by 
