CHAPTER III.
DISEASES OF THE ŒSOPHAGUS.
Fig. 64.—Schema illustrating anatomy of the œsophagus: a strong external layer of muscle, intermediate cellulo-elastic layer, inner layer of mucous membrane lying in folds and capable of great dilatation.
The œsophageal tube is of very simple anatomical construction, and performs an equally simple physiological function; nevertheless, in the ox it is liable to a large number of diseased conditions. These conditions may affect only a circumscribed area of the mucous membrane or the entire extent of the tube. Again, both the muscular and mucous tissues may be affected, as in inflammation of the œsophagus accompanied or followed by contraction, and in the formation of œsophageal abscesses and tumours; or the muscular tissue alone may be affected, as in cases of dilatation. Even where no lesion is apparent the normal rhythm of deglutition may be interfered with, either by the presence of a foreign body (obstruction) or by spasm of the muscular layers (œsophagismus) or by compression due to tissues surrounding the œsophagus (false contractions).
We shall successively study the different forms of œsophagitis, contraction, and dilatation, together with their complications; then obstructions, ruptures of the œsophagus, œsophagismus, and false contractions.
ŒSOPHAGITIS.
Inflammation of the œsophagus may be due to many different causes, and may occur in one of three different degrees of severity. It may be either superficial, i.e., limited to the epithelial layer of the mucous membrane; or deep, affecting the entire thickness of the mucous membrane (epithelium, corium, and œsophageal glands); or, finally, it may attack both the mucous and muscular layers. German authors recognise various divisions, such as erythematous, catarrhal, follicular, and phlegmonous œsophagitis. In reality these are not always different forms, but simply successive stages in the evolution of a single morbid condition. Here we shall only study the ordinary forms of œsophagitis, leaving on one side those which occur symptomatically during foot-and-mouth disease, cattle plague, gangrenous coryza, actinomycosis, etc.
Causation. The causes of œsophagitis may be divided into three groups of different character:—(a) Rough fodder (clover containing wrestharrow, thistles, thorns, furze, or splinters of wood, etc.) must be placed in the first rank, for its repeated action abrades and irritates the mucous membrane to such an extent as finally to produce inflammation. This inflammation usually remains superficial and of moderate intensity; its occurrence can be anticipated during years of scarcity, when the animals feed on rough and irritating material like fern, broom, heather, furze, etc.
(b) Hot drinks, whether in the nature of beverages or medicinal draughts, are a frequent cause of œsophagitis if administered by careless or inexperienced persons. The mucous membrane is scalded over a varying area and with different degrees of severity, or is destroyed by the chemical action of such drugs as ammonia, dilute acids, iodine solution, etc.
(c) Rough or clumsy manipulation in withdrawing or displacing foreign bodies, or merely passing the probang, produces that variety of œsophagitis termed traumatic. In clumsy hands œsophageal sounds or catheters may abrade or even tear the mucous membrane and subjacent tissues.