Obstruction is termed “total” or “partial,” according as the obstructing body fills the entire calibre of the œsophagus at the point of obstruction, or only occupies a part of the space. Partial obstructions produced by beet and turnip tops, etc., are usually but momentary; liquids and saliva are still able to pass between the obstruction and the walls of the tube, and as soon as the arrested food becomes a little softened it is displaced and the œsophagus again becomes patent. =Causation.= The circumstances under which this accident occurs are extremely easy to understand. Obstructions are produced by apples, potatoes, turnips, carrots, cabbage-stalks, beetroots, etc., which, whether sliced or not, are swallowed gluttonously. Not having been sufficiently comminuted, and being of larger size than the œsophagus can readily accommodate, they become arrested at some point between the commencement of the œsophagus or a few inches behind the pharynx, or just in front of the point of entry of the gullet into the stomach. The latter is the commonest position, though not infrequently the obstruction occurs in the intra-thoracic portion. It may occur in the stable, but is commoner in animals which, having broken loose, have entered orchards, gardens or potato or turnip fields and attempted to swallow apples, cabbages, potatoes, etc., found there. In sheep, obstruction of the œsophagus is due to similar causes, but in their case the above-mentioned objects are replaced by small wild apples, turnip shells, Jerusalem artichokes, horse-chestnuts, carrots, etc. The symptoms may be divided into general and local. =General symptoms.= As soon as the foreign body becomes fixed in position, the animal begins to make exceptional efforts to swallow. The head is extended on the neck, and the œsophagus and the muscles surrounding the trachea are violently contracted. These efforts proving fruitless, feeding is necessarily stopped, and the animal at once appears slightly anxious. Very soon afterwards salivation sets in, saliva being continuously secreted. If the obstruction is total, the saliva cannot be swallowed, and is either returned in quantities by antiperistaltic movements or escapes in frothy filaments from the mouth. Tympanites is not long in appearing. It is progressive, and results both from arrest of eructation and from continued fermentation in the rumen. It may eventually come to a standstill, or may continue and threaten to produce asphyxia. =Local symptoms.= The local symptoms are difficult to appreciate, except in cases of cervical obstruction. Sometimes the foreign body produces a local swelling, which changes the outline of the jugular furrow, most frequently on the left side. In many cases it can only be detected by manipulating the parts between the trachea and the lower surface of the cervical vertebræ. When the obstruction is within the thorax, the probang alone can detect its position.