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. =Symptoms.= These vary to some extent, according to the intensity of the inflammatory phenomena. If the lesions are superficial and only implicate the epithelium, as in catarrhal œsophagitis, the symptoms often pass unnoticed, and only produce difficulty in swallowing. When inflammation has involved the entire thickness of the mucous membrane the immediate consequence is loss of appetite due to pain during swallowing. After the bolus of food has been masticated, and has passed into the pharynx, the animal stretches out its head and neck and seems to be making efforts to force it down the œsophageal canal. The progress of the bolus is slow and clearly difficult.